ThuliumV1, Pmc, Corpus, bibRecord, 000342

Thortveitite-type Tm2Si2O7

Identifieur interne : 000342 ( Pmc/Corpus ); précédent : 000341; suivant : 000343

Thortveitite-type Tm2Si2O7

Auteurs : Volker Kahlenberg ; Paul Aichholzer

Source :

Acta Crystallographica Section E: Structure Reports Online [ 1600-5368 ] ; 2014.

RBID : PMC:4120532

Abstract

Single crystals of dithulium disilicate, Tm₂Si₂O₇, were obtained in flux synthesis experiments in the system SiO₂–Tm₂O₃–LiF at ambient pressure. The compound belongs to the group of sorosilicates, i.e. it is based on [Si₂O₇]-units and crystallizes in the thortveitite (Sc₂Si₂O₇) structure type. The Tm³⁺ cation (site symmetry .2.) occupies a distorted octahedral site, with Tm—O bond lengths in the range 2.217 (4)–2.289 (4) Å. Each of the octahedra shares three of its edges with adjacent [TmO₆] groups, resulting in the formation of layers parallel to (001). The individual [SiO₄] tetrahedra are more regular, i.e. the differences between the bond lengths between Si and the bridging and non-bridging O atoms are not very pronounced. The layers containing the octahedra and the sheets containing the [Si₂O₇] groups (point group symmetry 2/m) form an alternating sequence. Linkage is provided by sharing common oxygen vertices.

Url:

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4120532

DOI: 10.1107/S1600536814013142
PubMed: 25161507
PubMed Central: 4120532

Links to Exploration step

PMC:4120532

Le document en format XML

<record><TEI><teiHeader><fileDesc><titleStmt><title xml:lang="en">Thortveitite-type Tm<sub>2</sub>
Si<sub>2</sub>
O<sub>7</sub>
</title>
<author><name sortKey="Kahlenberg, Volker" sort="Kahlenberg, Volker" uniqKey="Kahlenberg V" first="Volker" last="Kahlenberg">Volker Kahlenberg</name>
<affiliation><nlm:aff id="a">University of Innsbruck, Institute of Mineralogy & Petrography, Innrain 52, A-6020 Innsbruck,<country>Austria</country>
</nlm:aff>
</affiliation>
</author>
<author><name sortKey="Aichholzer, Paul" sort="Aichholzer, Paul" uniqKey="Aichholzer P" first="Paul" last="Aichholzer">Paul Aichholzer</name>
<affiliation><nlm:aff id="a">University of Innsbruck, Institute of Mineralogy & Petrography, Innrain 52, A-6020 Innsbruck,<country>Austria</country>
</nlm:aff>
</affiliation>
</author>
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<sourceDesc><biblStruct><analytic><title xml:lang="en" level="a" type="main">Thortveitite-type Tm<sub>2</sub>
Si<sub>2</sub>
O<sub>7</sub>
</title>
<author><name sortKey="Kahlenberg, Volker" sort="Kahlenberg, Volker" uniqKey="Kahlenberg V" first="Volker" last="Kahlenberg">Volker Kahlenberg</name>
<affiliation><nlm:aff id="a">University of Innsbruck, Institute of Mineralogy & Petrography, Innrain 52, A-6020 Innsbruck,<country>Austria</country>
</nlm:aff>
</affiliation>
</author>
<author><name sortKey="Aichholzer, Paul" sort="Aichholzer, Paul" uniqKey="Aichholzer P" first="Paul" last="Aichholzer">Paul Aichholzer</name>
<affiliation><nlm:aff id="a">University of Innsbruck, Institute of Mineralogy & Petrography, Innrain 52, A-6020 Innsbruck,<country>Austria</country>
</nlm:aff>
</affiliation>
</author>
</analytic>
<series><title level="j">Acta Crystallographica Section E: Structure Reports Online</title>
<idno type="eISSN">1600-5368</idno>
<imprint><date when="2014">2014</date>
</imprint>
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<front><div type="abstract" xml:lang="en"><p>Single crystals of dithulium disilicate, Tm<sub>2</sub>
Si<sub>2</sub>
O<sub>7</sub>
, were obtained in flux synthesis experiments in the system SiO<sub>2</sub>
–Tm<sub>2</sub>
O<sub>3</sub>
–LiF at ambient pressure. The compound belongs to the group of sorosilicates, <italic>i.e.</italic>
 it is based on [Si<sub>2</sub>
O<sub>7</sub>
]-units and crystallizes in the thortveitite (Sc<sub>2</sub>
Si<sub>2</sub>
O<sub>7</sub>
) structure type. The Tm<sup>3+</sup>
 cation (site symmetry .2.) occupies a distorted octahedral site, with Tm—O bond lengths in the range 2.217 (4)–2.289 (4) Å. Each of the octahedra shares three of its edges with adjacent [TmO<sub>6</sub>
] groups, resulting in the formation of layers parallel to (001). The individual [SiO<sub>4</sub>
] tetrahedra are more regular, <italic>i.e.</italic>
 the differences between the bond lengths between Si and the bridging and non-bridging O atoms are not very pronounced. The layers containing the octahedra and the sheets containing the [Si<sub>2</sub>
O<sub>7</sub>
] groups (point group symmetry 2/<italic>m</italic>
) form an alternating sequence. Linkage is provided by sharing common oxygen vertices.</p>
</div>
</front>
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<pmc article-type="research-article"><pmc-dir>properties open_access</pmc-dir>
  <front><journal-meta><journal-id journal-id-type="nlm-ta">Acta Crystallogr Sect E Struct Rep Online</journal-id>
<journal-id journal-id-type="iso-abbrev">Acta Crystallogr Sect E Struct Rep Online</journal-id>
<journal-id journal-id-type="publisher-id">Acta Cryst. E</journal-id>
<journal-title-group><journal-title>Acta Crystallographica Section E: Structure Reports Online</journal-title>
</journal-title-group>
<issn pub-type="epub">1600-5368</issn>
<publisher><publisher-name>International Union of Crystallography</publisher-name>
</publisher>
</journal-meta>
<article-meta><article-id pub-id-type="pmid">25161507</article-id>
<article-id pub-id-type="pmc">4120532</article-id>
<article-id pub-id-type="publisher-id">wm5029</article-id>
<article-id pub-id-type="doi">10.1107/S1600536814013142</article-id>
<article-id pub-id-type="coden">ACSEBH</article-id>
<article-id pub-id-type="pii">S1600536814013142</article-id>
<article-categories><subj-group subj-group-type="heading"><subject>Inorganic Papers</subject>
</subj-group>
</article-categories>
<title-group><article-title>Thortveitite-type Tm<sub>2</sub>
Si<sub>2</sub>
O<sub>7</sub>
</article-title>
<alt-title><italic>Tm<sub>2</sub>
Si<sub>2</sub>
O<sub>7</sub>
</italic>
</alt-title>
</title-group>
<contrib-group><contrib contrib-type="author"><name><surname>Kahlenberg</surname>
<given-names>Volker</given-names>
</name>
<xref ref-type="aff" rid="a">a</xref>
<xref ref-type="corresp" rid="cor">*</xref>
</contrib>
<contrib contrib-type="author"><name><surname>Aichholzer</surname>
<given-names>Paul</given-names>
</name>
<xref ref-type="aff" rid="a">a</xref>
</contrib>
<aff id="a"><label>a</label>
University of Innsbruck, Institute of Mineralogy & Petrography, Innrain 52, A-6020 Innsbruck,<country>Austria</country>
</aff>
</contrib-group>
<author-notes><corresp id="cor">Correspondence e-mail: <email>volker.kahlenberg@uibk.ac.at</email>
</corresp>
</author-notes>
<pub-date pub-type="collection"><day>01</day>
<month>7</month>
<year>2014</year>
</pub-date>
<pub-date pub-type="epub"><day>11</day>
<month>6</month>
<year>2014</year>
</pub-date>
<pub-date pub-type="pmc-release"><day>11</day>
<month>6</month>
<year>2014</year>
</pub-date>
<pmc-comment> PMC Release delay is 0 months and 0 days and was based on the 
 							. </pmc-comment>
      <volume>70</volume>
<issue>Pt 7</issue>
<issue-id pub-id-type="publisher-id">e140700</issue-id>
<fpage>i34</fpage>
<lpage>i35</lpage>
<history><date date-type="received"><day>24</day>
<month>5</month>
<year>2014</year>
</date>
<date date-type="accepted"><day>05</day>
<month>6</month>
<year>2014</year>
</date>
</history>
<permissions><copyright-statement>© Kahlenberg and Aichholzer 2014</copyright-statement>
<copyright-year>2014</copyright-year>
<license license-type="open-access" xlink:href="http://creativecommons.org/licenses/by/2.0/uk/"><license-p>This is an open-access article distributed under the terms of the Creative Commons Attribution Licence, which permits
unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are cited.</license-p>
</license>
</permissions>
<self-uri xlink:type="simple" xlink:href="http://dx.doi.org/10.1107/S1600536814013142">A full version of this article is available from Crystallography Journals Online.</self-uri>
<abstract><p>Single crystals of dithulium disilicate, Tm<sub>2</sub>
Si<sub>2</sub>
O<sub>7</sub>
, were obtained in flux synthesis experiments in the system SiO<sub>2</sub>
–Tm<sub>2</sub>
O<sub>3</sub>
–LiF at ambient pressure. The compound belongs to the group of sorosilicates, <italic>i.e.</italic>
 it is based on [Si<sub>2</sub>
O<sub>7</sub>
]-units and crystallizes in the thortveitite (Sc<sub>2</sub>
Si<sub>2</sub>
O<sub>7</sub>
) structure type. The Tm<sup>3+</sup>
 cation (site symmetry .2.) occupies a distorted octahedral site, with Tm—O bond lengths in the range 2.217 (4)–2.289 (4) Å. Each of the octahedra shares three of its edges with adjacent [TmO<sub>6</sub>
] groups, resulting in the formation of layers parallel to (001). The individual [SiO<sub>4</sub>
] tetrahedra are more regular, <italic>i.e.</italic>
 the differences between the bond lengths between Si and the bridging and non-bridging O atoms are not very pronounced. The layers containing the octahedra and the sheets containing the [Si<sub>2</sub>
O<sub>7</sub>
] groups (point group symmetry 2/<italic>m</italic>
) form an alternating sequence. Linkage is provided by sharing common oxygen vertices.</p>
</abstract>
</article-meta>
</front>
<body><sec id="sec1"><title>Related literature   </title>
<p>For applications of oxosilicates containing trivalent rare earth elements (<italic>REE</italic>
), see: Kitai (2008<xref ref-type="bibr" rid="bb18"> ▶</xref>
); Piccinelli <italic>et al.</italic>
 (2009<xref ref-type="bibr" rid="bb22"> ▶</xref>
); Qiao <italic>et al.</italic>
 (2014<xref ref-type="bibr" rid="bb23"> ▶</xref>
); Luo <italic>et al.</italic>
 (2012<xref ref-type="bibr" rid="bb21"> ▶</xref>
); Streit <italic>et al.</italic>
 (2013<xref ref-type="bibr" rid="bb30"> ▶</xref>
); Han <italic>et al.</italic>
 (2006<xref ref-type="bibr" rid="bb14"> ▶</xref>
); Sun <italic>et al.</italic>
 (2012<xref ref-type="bibr" rid="bb31"> ▶</xref>
). For structures isotypic with that of the title compound, see: Zachariasen (1930<xref ref-type="bibr" rid="bb34"> ▶</xref>
); Smolin <italic>et al.</italic>
 (1973<xref ref-type="bibr" rid="bb29"> ▶</xref>
); Christensen (1994<xref ref-type="bibr" rid="bb8"> ▶</xref>
); Redhammer & Roth (2003<xref ref-type="bibr" rid="bb24"> ▶</xref>
). For polymorphic forms of Tm<sub>2</sub>
Si<sub>2</sub>
O<sub>7</sub>
 and other structure types adopted by (<italic>REE</italic>
)<sub>2</sub>
Si<sub>2</sub>
O<sub>7</sub>
 compounds, see: Bocquillon <italic>et al.</italic>
 (1977<xref ref-type="bibr" rid="bb5"> ▶</xref>
); Hartenbach <italic>et al.</italic>
 (2003<xref ref-type="bibr" rid="bb15"> ▶</xref>
); Felsche (1973<xref ref-type="bibr" rid="bb12"> ▶</xref>
); Fleet & Liu (2005<xref ref-type="bibr" rid="bb13"> ▶</xref>
); Shannon & Prewitt (1970<xref ref-type="bibr" rid="bb27"> ▶</xref>
). For discussions of the [Si<sub>2</sub>
O<sub>7</sub>
]-unit with a linear bridging angle, see: Baur (1980<xref ref-type="bibr" rid="bb2"> ▶</xref>
); Bianchi <italic>et al.</italic>
 (1988<xref ref-type="bibr" rid="bb4"> ▶</xref>
); Cruickshank <italic>et al.</italic>
 (1962<xref ref-type="bibr" rid="bb9"> ▶</xref>
); Kimata <italic>et al.</italic>
 (1998<xref ref-type="bibr" rid="bb17"> ▶</xref>
); Liebau (1961<xref ref-type="bibr" rid="bb19"> ▶</xref>
). For general aspects on the crystal chemistry of silicates, see: Liebau (1985<xref ref-type="bibr" rid="bb20"> ▶</xref>
). For definition of distortion parameters, see: Robinson <italic>et al.</italic>
 (1971<xref ref-type="bibr" rid="bb25"> ▶</xref>
). For bond-valence analysis, see: Brown (2002<xref ref-type="bibr" rid="bb6"> ▶</xref>
). For definition and calculation of similarity descriptors, see: Tasci <italic>et al.</italic>
 (2012<xref ref-type="bibr" rid="bb32"> ▶</xref>
); Bergerhoff <italic>et al.</italic>
 (1999<xref ref-type="bibr" rid="bb3"> ▶</xref>
). For ionic radii, see: Shannon (1976<xref ref-type="bibr" rid="bb26"> ▶</xref>
). For the Inorganic Crystal Structure Database, see: ICSD (2014<xref ref-type="bibr" rid="bb16"> ▶</xref>
).</p>
</sec>
<sec id="sec2"><title>Experimental   </title>
<sec id="sec2.1"><title></title>
<sec id="sec2.1.1"><title>Crystal data   </title>
<p><list list-type="simple" id="l1"><list-item><p>Tm<sub>2</sub>
Si<sub>2</sub>
O<sub>7</sub>
</p>
</list-item>
<list-item><p><italic>M</italic>
<italic><sub>r</sub>
</italic>
 = 506.04</p>
</list-item>
<list-item><p>Monoclinic, <inline-formula><inline-graphic xlink:href="e-70-00i34-efi5.jpg" mimetype="image" mime-subtype="gif"></inline-graphic>
</inline-formula>
</p>
</list-item>
<list-item><p><italic>a</italic>
 = 6.8205 (14) Å</p>
</list-item>
<list-item><p><italic>b</italic>
 = 8.9062 (18) Å</p>
</list-item>
<list-item><p><italic>c</italic>
 = 4.6937 (11) Å</p>
</list-item>
<list-item><p>β = 101.78 (2)°</p>
</list-item>
<list-item><p><italic>V</italic>
 = 279.11 (10) Å<sup>3</sup>
</p>
</list-item>
<list-item><p><italic>Z</italic>
 = 2</p>
</list-item>
<list-item><p>Mo <italic>K</italic>
α radiation</p>
</list-item>
<list-item><p>μ = 31.99 mm<sup>−1</sup>
</p>
</list-item>
<list-item><p><italic>T</italic>
 = 293 K</p>
</list-item>
<list-item><p>0.05 × 0.03 × 0.01 mm</p>
</list-item>
</list>
</p>
</sec>
<sec id="sec2.1.2"><title>Data collection   </title>
<p><list list-type="simple" id="l2"><list-item><p>Agilent Xcalibur (Ruby, Gemini ultra) diffractometer</p>
</list-item>
<list-item><p>Absorption correction: multi-scan (<italic>CrysAlis PRO</italic>
; Agilent, 2014<xref ref-type="bibr" rid="bb1"> ▶</xref>
) <italic>T</italic>
<sub>min</sub>
 = 0.231, <italic>T</italic>
<sub>max</sub>
 = 1</p>
</list-item>
<list-item><p>894 measured reflections</p>
</list-item>
<list-item><p>340 independent reflections</p>
</list-item>
<list-item><p>330 reflections with <italic>I</italic>
 > 2σ(<italic>I</italic>
)</p>
</list-item>
<list-item><p><italic>R</italic>
<sub>int</sub>
 = 0.020</p>
</list-item>
</list>
</p>
</sec>
<sec id="sec2.1.3"><title>Refinement   </title>
<p><list list-type="simple" id="l3"><list-item><p><italic>R</italic>
[<italic>F</italic>
<sup>2</sup>
 > 2σ(<italic>F</italic>
<sup>2</sup>
)] = 0.018</p>
</list-item>
<list-item><p><italic>wR</italic>
(<italic>F</italic>
<sup>2</sup>
) = 0.045</p>
</list-item>
<list-item><p><italic>S</italic>
 = 1.15</p>
</list-item>
<list-item><p>340 reflections</p>
</list-item>
<list-item><p>32 parameters</p>
</list-item>
<list-item><p>Δρ<sub>max</sub>
 = 1.62 e Å<sup>−3</sup>
</p>
</list-item>
<list-item><p>Δρ<sub>min</sub>
 = −1.42 e Å<sup>−3</sup>
</p>
</list-item>
</list>
</p>
</sec>
</sec>
<sec id="d5e588"><title></title>
<p>Data collection: <italic>CrysAlis PRO</italic>
 (Agilent, 2014<xref ref-type="bibr" rid="bb1"> ▶</xref>
); cell refinement: <italic>CrysAlis PRO</italic>
; data reduction: <italic>CrysAlis PRO</italic>
; program(s) used to solve structure: <italic>SIR2002</italic>
 (Burla <italic>et al.</italic>
, 2003<xref ref-type="bibr" rid="bb7"> ▶</xref>
); program(s) used to refine structure: <italic>SHELXL97</italic>
 (Sheldrick, 2008<xref ref-type="bibr" rid="bb28"> ▶</xref>
); molecular graphics: <italic>ATOMS for Windows</italic>
 (Dowty, 2011<xref ref-type="bibr" rid="bb10"> ▶</xref>
); software used to prepare material for publication: <italic>publCIF</italic>
 (Westrip, 2010<xref ref-type="bibr" rid="bb33"> ▶</xref>
) and <italic>WinGX</italic>
 (Farrugia, 2012<xref ref-type="bibr" rid="bb11"> ▶</xref>
).</p>
</sec>
</sec>
<sec sec-type="supplementary-material"><title>Supplementary Material</title>
<supplementary-material content-type="local-data"><p>Crystal structure: contains datablock(s) global, I, New_Global_Publ_Block. DOI: <ext-link ext-link-type="uri" xlink:href="http://dx.doi.org/10.1107/S1600536814013142/wm5029sup1.cif">10.1107/S1600536814013142/wm5029sup1.cif</ext-link>
</p>
<media mimetype="chemical" mime-subtype="x-cif" xlink:href="e-70-00i34-sup1.cif" xlink:type="simple" id="d35e116" position="anchor"></media>
</supplementary-material>
<supplementary-material content-type="local-data"><p>Structure factors: contains datablock(s) I. DOI: <ext-link ext-link-type="uri" xlink:href="http://dx.doi.org/10.1107/S1600536814013142/wm5029Isup2.hkl">10.1107/S1600536814013142/wm5029Isup2.hkl</ext-link>
</p>
<media mimetype="text" mime-subtype="plain" xlink:href="e-70-00i34-Isup2.hkl" xlink:type="simple" id="d35e123" position="anchor"></media>
</supplementary-material>
<supplementary-material content-type="local-data"><p>CCDC reference: <ext-link ext-link-type="uri" xlink:href="http://scripts.iucr.org/cgi-bin/cr.cgi?rm=csd&csdid=1006971">1006971</ext-link>
</p>
</supplementary-material>
<supplementary-material content-type="local-data"><p>Additional supporting information: <ext-link ext-link-type="uri" xlink:href="http://scripts.iucr.org/cgi-bin/sendsupfiles?wm5029&file=wm5029sup0.html&mime=text/html"> crystallographic information</ext-link>
; <ext-link ext-link-type="uri" xlink:href="http://scripts.iucr.org/cgi-bin/sendcif?wm5029sup1&Qmime=cif">3D view</ext-link>
; <ext-link ext-link-type="uri" xlink:href="http://scripts.iucr.org/cgi-bin/paper?wm5029&checkcif=yes">checkCIF report</ext-link>
</p>
</supplementary-material>
</sec>
</body>
<back><fn-group><fn id="fnu1"><p>Supporting information for this paper is available from the IUCr electronic archives (Reference: <ext-link ext-link-type="uri" xlink:href="http://scripts.iucr.org/cgi-bin/sendsup?wm5029">WM5029</ext-link>
).</p>
</fn>
</fn-group>
<app-group><app><title>supplementary crystallographic 
information</title>
<sec id="comment"><title>S1. Comment </title>
<p>Oxosilicates that contain trivalent rare earth elements have been studied
frequently because of their potential usage in the field of luminescense
including applications in devices and circuits for electronic, optoelectronic
as well as communication industries (Kitai, 2008; Piccinelli <italic>et
al.</italic>,
2009; Qiao <italic>et al.</italic>
, 2014; Luo <italic>et al.</italic>,
2012; Streit <italic>et al.</italic>,
2013; Han <italic>et al.</italic>
, 2006; Sun <italic>et al.</italic>,
2012).</p>
<p>In the course of an ongoing project on the synthesis of
alkali-<italic>REE</italic>
-silicates (<italic>REE</italic> is a rare earth element),
single-crystals of Tm<sub>2</sub>
Si<sub>2</sub>
O<sub>7</sub> have been obtained and structurally
characterized. Synthetic Tm<sub>2</sub>
Si<sub>2</sub>
O<sub>7</sub> is isotypic with thortveitite
(Sc<sub>2</sub>
Si<sub>2</sub>
O<sub>7</sub>), a rare scandium silicate mineral (Zachariasen, 1930;
Smolin
<italic>et al.</italic>, 1973). The compound is a sorosilicate and contains
isolated
[Si<sub>2</sub>
O<sub>7</sub>]-groups. The bridging oxygen atom of the dimer resides on a centre
of symmetry, resulting in a linear Si—O—Si angle. The conformation of the
group is staggered with a dihedral angle (or azimuth) of 60° (Fig. 1). In the
past, the question whether or not Si—O—Si angles can exhibit a value of
180° has been discussed controversially and, actually, the thortveitite
structure-type played an important role in this debate (Liebau, 1961;
Cruickshank, <italic>et al.</italic>, 1962). However, a critical analysis of
published
data performed by Baur (1980) revealed that linear Si—O—Si bridging
angles
do exist and cannot be attributed to incorrect space group assignments. To
date, it is generally accepted that a description of the thortveitite
structure-type in the centrosymmetric space group <italic>C</italic>
2/<italic>m</italic> (implying
a linear Si—O—Si angle) is correct (Bianchi <italic>et al.</italic>, 1988;
Kimata
<italic>et al.</italic>, 1998). The present structure determination of
Tm<sub>2</sub>
Si<sub>2</sub>
O<sub>7</sub>also confirms this model. The spread in the Si—O and O—Si—O angles is
not very pronounced and the values are in the expected limits for silicates
(Liebau, 1985). Numerically, the degree of distortion can be expressed
by the
quadratic elongation QE and the angle variance AV (Robinson <italic>et al.</italic>,
1971). The values of these distortion parameters for a single
[SiO<sub>4</sub>]-tetrahedron are very small: 1.001 (for QE) and 4.95 (for AV),
respectively. The Tm<sup>3+</sup> cations are octahedrally coordinated by O atoms (Fig.
2), with Tm—O bond lengths in the range 2.217 (4) – 2.289 (4) Å and an
average of 2.247 Å. The mean value compares well with those observed for the
thortveitite representatives of the directly neighbouring <italic>REE</italic> Yb
(=2.240 Å) and Er (=2.253 Å) (Christensen, 1994).
The
differences can be attributed to the increasing ionic radii of the trivalent
cations in the series Yb<sup>3+</sup>
 - Tm<sup>3+</sup>
 - Er<sup>3+</sup> (Shannon, 1976). The
octahedra
show a distortion with moderate QE-values (1.061) and very high values for the
angle variance. The high AV value of 219.7 seems to be a characteristic
feature of the thortveitite structure-type and has been also observed for
other members of this family (Redhammer & Roth, 2003). Each of the
octahedra
shares three of its edges with adjacent [TmO<sub>6</sub>]-groups resulting in the
formation of layers parallel to (001). These pseudo-hexagonal sheets (Fig. 3)
are similar to the layers in dioctahedral micas. The above-mentioned
pronounced angular distortions can be rationalized by a combination of (i) a
shortening of the common edges of adjacent octahedra (in order to reduce the
repulsive interactions between adjoining Tm<sup>3+</sup> cations) and (ii) a widening
of the corresponding opposite unshared O—O edges. Successive layers
containing octahedra are linked by the [Si<sub>2</sub>
O<sub>7</sub>]-groups in such a way that
each of both tetrahedra shares two of its corners with two different octahedra
from the same and one corner with an octahedron from the other surrounding
layer.</p>
<p>Bond valence sum calculations using the parameter sets for the Tm—O and
Si—O bonds given by Brown (2002) resulted in the following values (in
v.u.)
for the cation-anion interactions up to 3.4 Å: Tm: 3.09, Si: 4.01, O1: 2.12,
O2: 1.99 and O3: 1.99.</p>
<p>As mentioned above, the present structure is isotypic with that of
thortveitite. For the calculation of several quantitative descriptors for the
characterization of the degree of similarity between the crystal structures of
Tm<sub>2</sub>
Si<sub>2</sub>
O<sub>7</sub>
 and Sc<sub>2</sub>
Si<sub>2</sub>
O<sub>7</sub>
, the program <italic>COMPSTRU</italic>
 (Tasci <italic>et
al.</italic>, 2012) was employed. For the given two structures, the degree
of
lattice distortion (S), <italic>i.e.</italic> the spontaneous strain obtained from the
eigenvalues of the finite Lagrangian strain tensor calculated in a Cartesian
reference system, has a value of (S) = 0.0222. After application of an origin
shift of p = (0, 0, 1/2) the structure of Tm<sub>2</sub>
Si<sub>2</sub>
O<sub>7</sub> was
transformed to the most similar configuration of Sc<sub>2</sub>
Si<sub>2</sub>
O<sub>7.</sub> The
calculations revealed the following atomic displacements (in Å) between the
corresponding atoms in Sc<sub>2</sub>
Si<sub>2</sub>
O<sub>7</sub>
 (first entry) and Tm<sub>2</sub>
Si<sub>2</sub>
O<sub>7</sub> (second
entry): Sc—Tm: 0.025; Si—Si: 0.043; O1—O2: 0.000; O2—O1: 0.083;
O3—O3: 0.070 <italic>i.e.</italic> the maximum displacement is lower than 0.10 Å.
The measure of similarity (Δ) as defined by Bergerhoff <italic>et al.</italic>(1999)
has a value of 0.059.</p>
<p>Since the beginning of the 1970ies a large number of different
structure types
have been described for rare earth element silicates with composition
(<italic>REE</italic>
)<sub>2</sub>
Si<sub>2</sub>
O<sub>7</sub> (Felsche, 1973). To date, at least twelve
different
forms (<italic>A—I</italic>
, <italic>K</italic>
, <italic>L</italic>
 and <italic>X</italic>) have to be distinguished
(Fleet & Liu, 2005). Tm<sub>2</sub>
Si<sub>2</sub>
O<sub>7</sub>, for example, exhibits a high
degree of
polymorphism where five different modifications can be realised. The synthesis
of polycrystalline Tm<sub>2</sub>
Si<sub>2</sub>
O<sub>7</sub>
 adopting the thortveitite- or <italic>C</italic>-type
has been described by Bocquillon <italic>et al.</italic> (1977) in the
temperature range
between 1473 and 1673 K. However, the stability field of <italic>C</italic>-type
Tm<sub>2</sub>
Si<sub>2</sub>
O<sub>7</sub> extends to higher pressures as well: synthesis runs performed
at 65 kbar/1773 K (Shannon & Prewitt, 1970) as well as 10 kbar/973 K
and 18 kbar/973 K (Bocquillon <italic>et al.</italic>, 1977) also resulted in the
formation of
the <italic>C</italic>
-phase. Other high-pressure modifications of Tm<sub>2</sub>
Si<sub>2</sub>
O<sub>7</sub>
crystallize in the <italic>B</italic>
–, <italic>D</italic>
–, <italic>X</italic>
– and <italic>L</italic>-types
(Fleet & Liu, 2005; Shannon & Prewitt, 1970). The
<italic>B</italic>-type, however, has
been also prepared at ambient pressure and 1173 K (Hartenbach <italic>et al.</italic>,
2003). In summary, one can say that more than forty years after the
first
systematic investigations to chart the <italic>p</italic>
,<italic>T</italic>-behaviour of
Tm<sub>2</sub>
Si<sub>2</sub>
O<sub>7</sub>, there are still open questions. The new flux synthesis route
using lithium fluoride as a mineralizer offers the possibility to grow large
single-crystals suited for <italic>in situ</italic> X-ray diffraction or Raman
spectroscopic high-pressure studies in diamond anvil cells.</p>
</sec>
<sec id="experimental"><title>S2. Experimental </title>
<p>Starting materials for the flux growth experiments were dried reagent grade
Tm<sub>2</sub>
O<sub>3</sub>
, SiO<sub>2</sub> and LiF. Due to the pronounced hygroscopicity of the alkali
fluoride, sample preparation was performed in a glove bag under nitrogen
atmosphere. 0.1 g of the nutrient consisting of a mixture of Tm<sub>2</sub>
O<sub>3</sub>
:SiO<sub>2</sub>in the molar ratio 1:4 was homogenized in an agate mortar with 0.1 g LiF.
Subsequently, the educts were loaded into a platinum tube with an outer
diameter of 3 mm and with 20 mm length. After sealing, the tube and its
content were heated in a resistance furnace from 373 K to 1373 K with a rate
of 50 K/h and isothermed for 2 h at the target temperature. The sample was
cooled down to 1073 K with a rate of 5 K/h and, finally, the temperature was
reduced to 373 K with a rate of 100 K/h. Removal of the flux with water left a
residue of transparent, colorless, optically biaxial and highly birefringent
crystals up to 500 µm in size. One of the optically biaxial crystals showing
sharp extinction when observed between crossed polarizers was selected for
further structural studies and mounted on the tip of a glass fiber using
finger nail hardener as glue.</p>
</sec>
<sec id="refinement"><title>S3. Refinement </title>
<p>Similar sets of lattice parameters could be found in the recent WEB-based
version of the Inorganic Crystal Structure Database (ICSD, 2014) for
the
chemically closely related thortveitite-type materials with composition
(<italic>REE</italic>
)<sub>2</sub>
Si<sub>2</sub>
O<sub>7</sub> pointing to an isostructural relationship, which was
confirmed by the subsequent structure analysis by direct methods. For
structure determination a data set corresponding to a hemisphere of reciprocal
space was collected.</p>
</sec>
<sec id="figures"><title>Figures</title>
<fig id="Fap1"><label>Fig. 1.</label>
<caption><p>Representation of a single [Si2O7]-unit. Ellipsoids are drawn at the 60% probability level. [Symmetry codes: (i) x, y, -1 + z (ii) -x, y, -z (iii) -x, y, 1 - z (iv) x, -y, -1 + z].</p>
</caption>
<graphic xlink:href="e-70-00i34-fig1"></graphic>
</fig>
<fig id="Fap2"><label>Fig. 2.</label>
<caption><p>Representation of the coordination around the trivalent Tm ion. Ellipsoids are drawn at the 60% probability level. [Symmetry codes: (i) 1 - x, y, 1 - z (ii) 1/2 + x, 1/2 - y, z (iii) 1/2 - x, 1/2 - y, 1 - z].</p>
</caption>
<graphic xlink:href="e-70-00i34-fig2"></graphic>
</fig>
<fig id="Fap3"><label>Fig. 3.</label>
<caption><p>Single layer of edge-sharing octahedra and one of the two adjacent sheets containing [Si2O7]-units in a projection parallel to [001]. Red, grey and blue spheres represent oxygen, silicon and thulium ions.</p>
</caption>
<graphic xlink:href="e-70-00i34-fig3"></graphic>
</fig>
</sec>
<sec id="tablewrapcrystaldatalong"><title>Crystal data</title>
<table-wrap position="anchor" id="d1e547"><table rules="all" frame="box" style="table-layout:fixed" summary=""><colgroup span="2"><col span="1"></col>
<col span="1"></col>
</colgroup>
<tr><td rowspan="1" colspan="1">Tm<sub>2</sub>
Si<sub>2</sub>
O<sub>7</sub>
</td>
<td rowspan="1" colspan="1"><italic>F</italic>
(000) = 444</td>
</tr>
<tr><td rowspan="1" colspan="1"><italic>M</italic>
<italic><sub>r</sub>
</italic>
 = 506.04</td>
<td rowspan="1" colspan="1"><italic>D</italic>
<sub>x</sub>
 = 6.021 Mg m<sup>−</sup>
<sup>3</sup>
</td>
</tr>
<tr><td rowspan="1" colspan="1">Monoclinic, <italic>C</italic>
2/<italic>m</italic>
</td>
<td rowspan="1" colspan="1">Mo <italic>K</italic>
α radiation, λ = 0.71073 Å</td>
</tr>
<tr><td rowspan="1" colspan="1">Hall symbol: -C 2y</td>
<td rowspan="1" colspan="1">Cell parameters from 762 reflections</td>
</tr>
<tr><td rowspan="1" colspan="1"><italic>a</italic>
 = 6.8205 (14) Å</td>
<td rowspan="1" colspan="1">θ = 3.8–29.3°</td>
</tr>
<tr><td rowspan="1" colspan="1"><italic>b</italic>
 = 8.9062 (18) Å</td>
<td rowspan="1" colspan="1">µ = 31.99 mm<sup>−</sup>
<sup>1</sup>
</td>
</tr>
<tr><td rowspan="1" colspan="1"><italic>c</italic>
 = 4.6937 (11) Å</td>
<td rowspan="1" colspan="1"><italic>T</italic>
 = 293 K</td>
</tr>
<tr><td rowspan="1" colspan="1">β = 101.78 (2)°</td>
<td rowspan="1" colspan="1">Platy fragment, colourless</td>
</tr>
<tr><td rowspan="1" colspan="1"><italic>V</italic>
 = 279.11 (10) Å<sup>3</sup>
</td>
<td rowspan="1" colspan="1">0.05 × 0.03 × 0.01 mm</td>
</tr>
<tr><td rowspan="1" colspan="1"><italic>Z</italic>
 = 2</td>
<td rowspan="1" colspan="1"></td>
</tr>
</table>
</table-wrap>
</sec>
<sec id="tablewrapdatacollectionlong"><title>Data collection</title>
<table-wrap position="anchor" id="d1e671"><table rules="all" frame="box" style="table-layout:fixed" summary=""><colgroup span="2"><col span="1"></col>
<col span="1"></col>
</colgroup>
<tr><td rowspan="1" colspan="1">Agilent Xcalibur (Ruby, Gemini ultra) diffractometer</td>
<td rowspan="1" colspan="1">340 independent reflections</td>
</tr>
<tr><td rowspan="1" colspan="1">Radiation source: Enhance (Mo) X-ray Source</td>
<td rowspan="1" colspan="1">330 reflections with <italic>I</italic>
 > 2σ(<italic>I</italic>
)</td>
</tr>
<tr><td rowspan="1" colspan="1">Graphite monochromator</td>
<td rowspan="1" colspan="1"><italic>R</italic>
<sub>int</sub>
 = 0.020</td>
</tr>
<tr><td rowspan="1" colspan="1">Detector resolution: 10.3575 pixels mm<sup>-1</sup>
</td>
<td rowspan="1" colspan="1">θ<sub>max</sub>
 = 27.6°, θ<sub>min</sub>
 = 3.8°</td>
</tr>
<tr><td rowspan="1" colspan="1">ω scans</td>
<td rowspan="1" colspan="1"><italic>h</italic>
 = −8→8</td>
</tr>
<tr><td rowspan="1" colspan="1">Absorption correction: multi-scan (<italic>CrysAlis PRO</italic>
; Agilent, 2014)</td>
<td rowspan="1" colspan="1"><italic>k</italic>
 = −11→11</td>
</tr>
<tr><td rowspan="1" colspan="1"><italic>T</italic>
<sub>min</sub>
 = 0.231, <italic>T</italic>
<sub>max</sub>
 = 1</td>
<td rowspan="1" colspan="1"><italic>l</italic>
 = −4→6</td>
</tr>
<tr><td rowspan="1" colspan="1">894 measured reflections</td>
<td rowspan="1" colspan="1"></td>
</tr>
</table>
</table-wrap>
</sec>
<sec id="tablewraprefinementdatalong"><title>Refinement</title>
<table-wrap position="anchor" id="d1e791"><table rules="all" frame="box" style="table-layout:fixed" summary=""><colgroup span="2"><col span="1"></col>
<col span="1"></col>
</colgroup>
<tr><td rowspan="1" colspan="1">Refinement on <italic>F</italic>
<sup>2</sup>
</td>
<td rowspan="1" colspan="1">Primary atom site location: structure-invariant direct methods</td>
</tr>
<tr><td rowspan="1" colspan="1">Least-squares matrix: full</td>
<td rowspan="1" colspan="1">Secondary atom site location: difference Fourier map</td>
</tr>
<tr><td rowspan="1" colspan="1"><italic>R</italic>
[<italic>F</italic>
<sup>2</sup>
 > 2σ(<italic>F</italic>
<sup>2</sup>
)] = 0.018</td>
<td rowspan="1" colspan="1"><italic>w</italic>
 = 1/[σ<sup>2</sup>
(<italic>F</italic>
<sub>o</sub>
<sup>2</sup>
) + (0.0265<italic>P</italic>
)<sup>2</sup>
] where <italic>P</italic>
 = (<italic>F</italic>
<sub>o</sub>
<sup>2</sup>
 + 2<italic>F</italic>
<sub>c</sub>
<sup>2</sup>
)/3</td>
</tr>
<tr><td rowspan="1" colspan="1"><italic>wR</italic>
(<italic>F</italic>
<sup>2</sup>
) = 0.045</td>
<td rowspan="1" colspan="1">(Δ/σ)<sub>max</sub>
 < 0.001</td>
</tr>
<tr><td rowspan="1" colspan="1"><italic>S</italic>
 = 1.15</td>
<td rowspan="1" colspan="1">Δρ<sub>max</sub>
 = 1.62 e Å<sup>−</sup>
<sup>3</sup>
</td>
</tr>
<tr><td rowspan="1" colspan="1">340 reflections</td>
<td rowspan="1" colspan="1">Δρ<sub>min</sub>
 = −1.42 e Å<sup>−</sup>
<sup>3</sup>
</td>
</tr>
<tr><td rowspan="1" colspan="1">32 parameters</td>
<td rowspan="1" colspan="1">Extinction correction: <italic>SHELXL97</italic>
 (Sheldrick, 2008), Fc<sup>*</sup>
=kFc[1+0.001xFc<sup>2</sup>
λ<sup>3</sup>
/sin(2θ)]<sup>-1/4</sup>
</td>
</tr>
<tr><td rowspan="1" colspan="1">0 restraints</td>
<td rowspan="1" colspan="1">Extinction coefficient: 0.0072 (6)</td>
</tr>
</table>
</table-wrap>
</sec>
<sec id="specialdetails"><title>Special details</title>
<table-wrap position="anchor" id="d1e965"><table rules="all" frame="box" style="table-layout:fixed"><tr><td rowspan="1" colspan="1">Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes)
are estimated using the full covariance matrix. The cell e.s.d.'s are taken
into account individually in the estimation of e.s.d.'s in lengths, angles and
torsion angles; correlations between e.s.d.'s in cell parameters are only used
when they are defined by crystal symmetry. An approximate (isotropic)
treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s.
planes.</td>
</tr>
<tr><td rowspan="1" colspan="1">Refinement. Refinement of <italic>F</italic>
<sup>2</sup>
 against ALL reflections. The weighted <italic>R</italic>-factor
<italic>wR</italic>
 and goodness of fit <italic>S</italic>
 are based on <italic>F</italic>
<sup>2</sup>, conventional
<italic>R</italic>
-factors <italic>R</italic>
 are based on <italic>F</italic>
, with <italic>F</italic> set to zero for
negative <italic>F</italic>
<sup>2</sup>
. The threshold expression of <italic>F</italic>
<sup>2</sup> >
σ(<italic>F</italic>
<sup>2</sup>
) is used only for calculating <italic>R</italic>
-factors(gt) <italic>etc</italic>.
and is not relevant to the choice of reflections for refinement.
<italic>R</italic>
-factors based on <italic>F</italic>
<sup>2</sup> are statistically about twice as large
as those based on <italic>F</italic>
, and <italic>R</italic>-factors based on ALL data will be
even larger.</td>
</tr>
</table>
</table-wrap>
</sec>
<sec id="tablewrapcoords"><title>Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å<sup>2</sup>
)</title>
<table-wrap position="anchor" id="d1e1065"><table rules="all" frame="box" style="table-layout:fixed" summary=""><tr><td rowspan="1" colspan="1"></td>
<td rowspan="1" colspan="1"><italic>x</italic>
</td>
<td rowspan="1" colspan="1"><italic>y</italic>
</td>
<td rowspan="1" colspan="1"><italic>z</italic>
</td>
<td rowspan="1" colspan="1"><italic>U</italic>
<sub>iso</sub>
*/<italic>U</italic>
<sub>eq</sub>
</td>
<td rowspan="1" colspan="1"></td>
</tr>
<tr><td rowspan="1" colspan="1">Tm</td>
<td rowspan="1" colspan="1">0.5</td>
<td rowspan="1" colspan="1">0.19345 (4)</td>
<td rowspan="1" colspan="1">0.5</td>
<td rowspan="1" colspan="1">0.0045 (2)</td>
<td rowspan="1" colspan="1"></td>
</tr>
<tr><td rowspan="1" colspan="1">Si</td>
<td rowspan="1" colspan="1">0.2186 (3)</td>
<td rowspan="1" colspan="1">0</td>
<td rowspan="1" colspan="1">0.9130 (5)</td>
<td rowspan="1" colspan="1">0.0044 (5)</td>
<td rowspan="1" colspan="1"></td>
</tr>
<tr><td rowspan="1" colspan="1">O1</td>
<td rowspan="1" colspan="1">0.3804 (9)</td>
<td rowspan="1" colspan="1">0</td>
<td rowspan="1" colspan="1">0.2130 (12)</td>
<td rowspan="1" colspan="1">0.0069 (12)</td>
<td rowspan="1" colspan="1"></td>
</tr>
<tr><td rowspan="1" colspan="1">O2</td>
<td rowspan="1" colspan="1">0</td>
<td rowspan="1" colspan="1">0</td>
<td rowspan="1" colspan="1">0</td>
<td rowspan="1" colspan="1">0.0129 (19)</td>
<td rowspan="1" colspan="1"></td>
</tr>
<tr><td rowspan="1" colspan="1">O3</td>
<td rowspan="1" colspan="1">0.2357 (6)</td>
<td rowspan="1" colspan="1">0.1505 (5)</td>
<td rowspan="1" colspan="1">0.7213 (9)</td>
<td rowspan="1" colspan="1">0.0073 (8)</td>
<td rowspan="1" colspan="1"></td>
</tr>
</table>
</table-wrap>
</sec>
<sec id="tablewrapadps"><title>Atomic displacement parameters (Å<sup>2</sup>
)</title>
<table-wrap position="anchor" id="d1e1161"><table rules="all" frame="box" style="table-layout:fixed" summary=""><tr><td rowspan="1" colspan="1"></td>
<td rowspan="1" colspan="1"><italic>U</italic>
<sup>11</sup>
</td>
<td rowspan="1" colspan="1"><italic>U</italic>
<sup>22</sup>
</td>
<td rowspan="1" colspan="1"><italic>U</italic>
<sup>33</sup>
</td>
<td rowspan="1" colspan="1"><italic>U</italic>
<sup>12</sup>
</td>
<td rowspan="1" colspan="1"><italic>U</italic>
<sup>13</sup>
</td>
<td rowspan="1" colspan="1"><italic>U</italic>
<sup>23</sup>
</td>
</tr>
<tr><td rowspan="1" colspan="1">Tm</td>
<td rowspan="1" colspan="1">0.0032 (3)</td>
<td rowspan="1" colspan="1">0.0043 (3)</td>
<td rowspan="1" colspan="1">0.0058 (3)</td>
<td rowspan="1" colspan="1">0</td>
<td rowspan="1" colspan="1">0.00056 (15)</td>
<td rowspan="1" colspan="1">0</td>
</tr>
<tr><td rowspan="1" colspan="1">Si</td>
<td rowspan="1" colspan="1">0.0049 (11)</td>
<td rowspan="1" colspan="1">0.0043 (11)</td>
<td rowspan="1" colspan="1">0.0042 (11)</td>
<td rowspan="1" colspan="1">0</td>
<td rowspan="1" colspan="1">0.0013 (9)</td>
<td rowspan="1" colspan="1">0</td>
</tr>
<tr><td rowspan="1" colspan="1">O1</td>
<td rowspan="1" colspan="1">0.006 (3)</td>
<td rowspan="1" colspan="1">0.007 (3)</td>
<td rowspan="1" colspan="1">0.005 (3)</td>
<td rowspan="1" colspan="1">0</td>
<td rowspan="1" colspan="1">−0.004 (2)</td>
<td rowspan="1" colspan="1">0</td>
</tr>
<tr><td rowspan="1" colspan="1">O2</td>
<td rowspan="1" colspan="1">0.008 (4)</td>
<td rowspan="1" colspan="1">0.019 (5)</td>
<td rowspan="1" colspan="1">0.011 (5)</td>
<td rowspan="1" colspan="1">0</td>
<td rowspan="1" colspan="1">0.001 (4)</td>
<td rowspan="1" colspan="1">0</td>
</tr>
<tr><td rowspan="1" colspan="1">O3</td>
<td rowspan="1" colspan="1">0.006 (2)</td>
<td rowspan="1" colspan="1">0.007 (2)</td>
<td rowspan="1" colspan="1">0.009 (2)</td>
<td rowspan="1" colspan="1">0.0042 (17)</td>
<td rowspan="1" colspan="1">0.0026 (17)</td>
<td rowspan="1" colspan="1">0.0045 (17)</td>
</tr>
</table>
</table-wrap>
</sec>
<sec id="tablewrapgeomlong"><title>Geometric parameters (Å, º)</title>
<table-wrap position="anchor" id="d1e1282"><table rules="all" frame="box" style="table-layout:fixed" summary=""><colgroup span="4"><col span="1"></col>
<col span="1"></col>
<col span="1"></col>
<col span="1"></col>
</colgroup>
<tr><td rowspan="1" colspan="1">Tm—O3<sup>i</sup>
</td>
<td rowspan="1" colspan="1">2.217 (4)</td>
<td rowspan="1" colspan="1">Si—O3<sup>vi</sup>
</td>
<td rowspan="1" colspan="1">1.632 (4)</td>
</tr>
<tr><td rowspan="1" colspan="1">Tm—O3<sup>ii</sup>
</td>
<td rowspan="1" colspan="1">2.217 (4)</td>
<td rowspan="1" colspan="1">Si—O3</td>
<td rowspan="1" colspan="1">1.632 (4)</td>
</tr>
<tr><td rowspan="1" colspan="1">Tm—O1</td>
<td rowspan="1" colspan="1">2.236 (4)</td>
<td rowspan="1" colspan="1">O1—Si<sup>vii</sup>
</td>
<td rowspan="1" colspan="1">1.602 (6)</td>
</tr>
<tr><td rowspan="1" colspan="1">Tm—O1<sup>iii</sup>
</td>
<td rowspan="1" colspan="1">2.236 (4)</td>
<td rowspan="1" colspan="1">O1—Tm<sup>iii</sup>
</td>
<td rowspan="1" colspan="1">2.236 (4)</td>
</tr>
<tr><td rowspan="1" colspan="1">Tm—O3</td>
<td rowspan="1" colspan="1">2.289 (4)</td>
<td rowspan="1" colspan="1">O2—Si<sup>viii</sup>
</td>
<td rowspan="1" colspan="1">1.624 (2)</td>
</tr>
<tr><td rowspan="1" colspan="1">Tm—O3<sup>iv</sup>
</td>
<td rowspan="1" colspan="1">2.289 (4)</td>
<td rowspan="1" colspan="1">O2—Si<sup>vii</sup>
</td>
<td rowspan="1" colspan="1">1.624 (2)</td>
</tr>
<tr><td rowspan="1" colspan="1">Si—O1<sup>v</sup>
</td>
<td rowspan="1" colspan="1">1.602 (6)</td>
<td rowspan="1" colspan="1">O3—Tm<sup>ii</sup>
</td>
<td rowspan="1" colspan="1">2.217 (4)</td>
</tr>
<tr><td rowspan="1" colspan="1">Si—O2<sup>v</sup>
</td>
<td rowspan="1" colspan="1">1.624 (2)</td>
<td rowspan="1" colspan="1"></td>
<td rowspan="1" colspan="1"></td>
</tr>
<tr><td rowspan="1" colspan="1"></td>
<td rowspan="1" colspan="1"></td>
<td rowspan="1" colspan="1"></td>
<td rowspan="1" colspan="1"></td>
</tr>
<tr><td rowspan="1" colspan="1">O3<sup>i</sup>
—Tm—O3<sup>ii</sup>
</td>
<td rowspan="1" colspan="1">102.3 (2)</td>
<td rowspan="1" colspan="1">O3—Tm—O3<sup>iv</sup>
</td>
<td rowspan="1" colspan="1">160.7 (2)</td>
</tr>
<tr><td rowspan="1" colspan="1">O3<sup>i</sup>
—Tm—O1</td>
<td rowspan="1" colspan="1">154.9 (2)</td>
<td rowspan="1" colspan="1">O1<sup>v</sup>
—Si—O2<sup>v</sup>
</td>
<td rowspan="1" colspan="1">106.4 (2)</td>
</tr>
<tr><td rowspan="1" colspan="1">O3<sup>ii</sup>
—Tm—O1</td>
<td rowspan="1" colspan="1">93.47 (17)</td>
<td rowspan="1" colspan="1">O1<sup>v</sup>
—Si—O3<sup>vi</sup>
</td>
<td rowspan="1" colspan="1">111.8 (2)</td>
</tr>
<tr><td rowspan="1" colspan="1">O3<sup>i</sup>
—Tm—O1<sup>iii</sup>
</td>
<td rowspan="1" colspan="1">93.47 (17)</td>
<td rowspan="1" colspan="1">O2<sup>v</sup>
—Si—O3<sup>vi</sup>
</td>
<td rowspan="1" colspan="1">108.14 (18)</td>
</tr>
<tr><td rowspan="1" colspan="1">O3<sup>ii</sup>
—Tm—O1<sup>iii</sup>
</td>
<td rowspan="1" colspan="1">154.9 (2)</td>
<td rowspan="1" colspan="1">O1<sup>v</sup>
—Si—O3</td>
<td rowspan="1" colspan="1">111.8 (2)</td>
</tr>
<tr><td rowspan="1" colspan="1">O1—Tm—O1<sup>iii</sup>
</td>
<td rowspan="1" colspan="1">79.2 (2)</td>
<td rowspan="1" colspan="1">O2<sup>v</sup>
—Si—O3</td>
<td rowspan="1" colspan="1">108.14 (18)</td>
</tr>
<tr><td rowspan="1" colspan="1">O3<sup>i</sup>
—Tm—O3</td>
<td rowspan="1" colspan="1">117.09 (17)</td>
<td rowspan="1" colspan="1">O3<sup>vi</sup>
—Si—O3</td>
<td rowspan="1" colspan="1">110.4 (3)</td>
</tr>
<tr><td rowspan="1" colspan="1">O3<sup>ii</sup>
—Tm—O3</td>
<td rowspan="1" colspan="1">75.78 (17)</td>
<td rowspan="1" colspan="1">Si<sup>vii</sup>
—O1—Tm</td>
<td rowspan="1" colspan="1">129.10 (12)</td>
</tr>
<tr><td rowspan="1" colspan="1">O1—Tm—O3</td>
<td rowspan="1" colspan="1">85.4 (2)</td>
<td rowspan="1" colspan="1">Si<sup>vii</sup>
—O1—Tm<sup>iii</sup>
</td>
<td rowspan="1" colspan="1">129.10 (12)</td>
</tr>
<tr><td rowspan="1" colspan="1">O1<sup>iii</sup>
—Tm—O3</td>
<td rowspan="1" colspan="1">79.74 (18)</td>
<td rowspan="1" colspan="1">Tm—O1—Tm<sup>iii</sup>
</td>
<td rowspan="1" colspan="1">100.8 (2)</td>
</tr>
<tr><td rowspan="1" colspan="1">O3<sup>i</sup>
—Tm—O3<sup>iv</sup>
</td>
<td rowspan="1" colspan="1">75.78 (17)</td>
<td rowspan="1" colspan="1">Si<sup>viii</sup>
—O2—Si<sup>vii</sup>
</td>
<td rowspan="1" colspan="1">180.00 (14)</td>
</tr>
<tr><td rowspan="1" colspan="1">O3<sup>ii</sup>
—Tm—O3<sup>iv</sup>
</td>
<td rowspan="1" colspan="1">117.09 (17)</td>
<td rowspan="1" colspan="1">Si—O3—Tm<sup>ii</sup>
</td>
<td rowspan="1" colspan="1">130.3 (3)</td>
</tr>
<tr><td rowspan="1" colspan="1">O1—Tm—O3<sup>iv</sup>
</td>
<td rowspan="1" colspan="1">79.74 (18)</td>
<td rowspan="1" colspan="1">Si—O3—Tm</td>
<td rowspan="1" colspan="1">122.6 (2)</td>
</tr>
<tr><td rowspan="1" colspan="1">O1<sup>iii</sup>
—Tm—O3<sup>iv</sup>
</td>
<td rowspan="1" colspan="1">85.43 (19)</td>
<td rowspan="1" colspan="1">Tm<sup>ii</sup>
—O3—Tm</td>
<td rowspan="1" colspan="1">104.22 (17)</td>
</tr>
</table>
</table-wrap>
<p>Symmetry codes: (i) <italic>x</italic>
+1/2, −<italic>y</italic>
+1/2, <italic>z</italic>
; (ii) −<italic>x</italic>
+1/2, −<italic>y</italic>
+1/2, −<italic>z</italic>
+1; (iii) −<italic>x</italic>
+1, −<italic>y</italic>
, −<italic>z</italic>
+1; (iv) −<italic>x</italic>
+1, <italic>y</italic>
, −<italic>z</italic>
+1; (v) <italic>x</italic>
, <italic>y</italic>
, <italic>z</italic>
+1; (vi) <italic>x</italic>
, −<italic>y</italic>
, <italic>z</italic>
; (vii) <italic>x</italic>
, <italic>y</italic>
, <italic>z</italic>
−1; (viii) −<italic>x</italic>
, −<italic>y</italic>
, −<italic>z</italic>
+1.</p>
</sec>
</app>
</app-group>
<ref-list><title>References</title>
<ref id="bb1"><mixed-citation publication-type="other">Agilent (2014). <italic>CrysAlis PRO</italic>
 Agilent Technologies, Yarnton, England.</mixed-citation>
</ref>
<ref id="bb2"><mixed-citation publication-type="other">Baur, W. H. (1980). <italic>Acta Cryst.</italic>
 B<bold>36</bold>
, 2198–2202.</mixed-citation>
</ref>
<ref id="bb3"><mixed-citation publication-type="other">Bergerhoff, G., Berndt, M., Brandenburg, K. & Degen, T. (1999). <italic>Acta Cryst.</italic>
 B<bold>55</bold>
, 147–156.</mixed-citation>
</ref>
<ref id="bb4"><mixed-citation publication-type="other">Bianchi, R., Pilati, T., Diella, V., Gramaccioli, C. M. & Mannucci, G. (1988). <italic>Am. Mineral.</italic>
<bold>73</bold>
, 601–607.</mixed-citation>
</ref>
<ref id="bb5"><mixed-citation publication-type="other">Bocquillon, C., Chateau, C., Loriers, C. & Loriers, L. (1977). <italic>J. Solid State Chem.</italic>
<bold>20</bold>
, 135–141.</mixed-citation>
</ref>
<ref id="bb6"><mixed-citation publication-type="other">Brown, I. D. (2002). <italic>The Chemical Bond in Inorganic Chemistry: The Bond Valence Model</italic>
, p. 292. Oxford University Press.</mixed-citation>
</ref>
<ref id="bb7"><mixed-citation publication-type="other">Burla, M. C., Camalli, M., Carrozzini, B., Cascarano, G. L., Giacovazzo, C., Polidori, G. & Spagna, R. (2003). <italic>J. Appl. Cryst.</italic>
<bold>36</bold>
, 1103.</mixed-citation>
</ref>
<ref id="bb8"><mixed-citation publication-type="other">Christensen, A. N. (1994). <italic>Z. Kristallogr.</italic>
<bold>209</bold>
, 7–13.</mixed-citation>
</ref>
<ref id="bb9"><mixed-citation publication-type="other">Cruickshank, D. W. J., Lynton, H. & Barclay, G. A. (1962). <italic>Acta Cryst.</italic>
<bold>15</bold>
, 491–498.</mixed-citation>
</ref>
<ref id="bb10"><mixed-citation publication-type="other">Dowty, E. (2011). <italic>ATOMS for Windows</italic>
 Shape Software, Kingsport, USA.</mixed-citation>
</ref>
<ref id="bb11"><mixed-citation publication-type="other">Farrugia, L. J. (2012). <italic>J. Appl. Cryst.</italic>
<bold>45</bold>
, 849–854.</mixed-citation>
</ref>
<ref id="bb12"><mixed-citation publication-type="other">Felsche, J. (1973). <italic>Struct. Bond.</italic>
<bold>13</bold>
, 99–197.</mixed-citation>
</ref>
<ref id="bb13"><mixed-citation publication-type="other">Fleet, M. E. & Liu, X. (2005). <italic>J. Solid State Chem.</italic>
<bold>178</bold>
, 3275–3283.</mixed-citation>
</ref>
<ref id="bb14"><mixed-citation publication-type="other">Han, X., Lin, J., Li, Z., Qi, X., Li, M. & Wang, X. (2006). <italic>J. Rare Earth</italic>
, <bold>24</bold>
, 108–110.</mixed-citation>
</ref>
<ref id="bb15"><mixed-citation publication-type="other">Hartenbach, I., Lissner, F. & Schleid, T. (2003). <italic>Z. Naturforsch. Teil B</italic>
, <bold>58</bold>
, 925–927.</mixed-citation>
</ref>
<ref id="bb16"><mixed-citation publication-type="other">ICSD (2014). Inorganic Crystal Structure Database. FIZ-Karlsruhe, Germany, and the National Institute of Standards and Technology (<italic>NIST</italic>
), USA. http://www.fiz-karlsruhe.de/icsd_home.html</mixed-citation>
</ref>
<ref id="bb17"><mixed-citation publication-type="other">Kimata, M., Saito, S., Matsui, T., Shimizu, M. & Nishida, N. (1998). <italic>Neues Jarhb. Mineral. Monatsh.</italic>
<bold>1998</bold>
, 361–372.</mixed-citation>
</ref>
<ref id="bb18"><mixed-citation publication-type="other">Kitai, A. (2008). <italic>Luminescent Materials and Applications</italic>
, p. 298. London: John Wiley & Sons.</mixed-citation>
</ref>
<ref id="bb19"><mixed-citation publication-type="other">Liebau, F. (1961). <italic>Acta Cryst.</italic>
<bold>14</bold>
, 1103–1109.</mixed-citation>
</ref>
<ref id="bb20"><mixed-citation publication-type="other">Liebau, F. (1985). <italic>Structural Chemistry of Silicates</italic>
, p. 347. Berlin, Heidelberg, New York, Tokyo: Springer.</mixed-citation>
</ref>
<ref id="bb21"><mixed-citation publication-type="other">Luo, Y. Y., Jo, D. S., Senthil, L., Tezuka, S., Kakihana, M., Toda, K., Masaki, T. & Yoon, D. H. (2012). <italic>J. Solid State Chem.</italic>
<bold>189</bold>
, 68–74.</mixed-citation>
</ref>
<ref id="bb22"><mixed-citation publication-type="other">Piccinelli, F., Speghini, A., Mariotto, G., Bovo, L. & Bettinelli, M. (2009). <italic>J. Rare Earth</italic>
, <bold>27</bold>
, 555–559.</mixed-citation>
</ref>
<ref id="bb23"><mixed-citation publication-type="other">Qiao, J., Zhang, J., Zhang, X., Hao, Z., Liu, Y. & Luo, Y. (2014). <italic>Dalton Trans.</italic>
<bold>43</bold>
, 4146–4150.</mixed-citation>
</ref>
<ref id="bb24"><mixed-citation publication-type="other">Redhammer, G. J. & Roth, G. (2003). <italic>Acta Cryst.</italic>
 C<bold>59</bold>
, i103–i106.</mixed-citation>
</ref>
<ref id="bb25"><mixed-citation publication-type="other">Robinson, K., Gibbs, G. V. & Ribbe, P. H. (1971). <italic>Science</italic>
, <bold>172</bold>
, 567–570.</mixed-citation>
</ref>
<ref id="bb26"><mixed-citation publication-type="other">Shannon, R. D. (1976). <italic>Acta Cryst.</italic>
 A<bold>32</bold>
, 751–767.</mixed-citation>
</ref>
<ref id="bb27"><mixed-citation publication-type="other">Shannon, R. D. & Prewitt, C. T. (1970). <italic>J. Solid State Chem.</italic>
<bold>2</bold>
, 199–202.</mixed-citation>
</ref>
<ref id="bb28"><mixed-citation publication-type="other">Sheldrick, G. M. (2008). <italic>Acta Cryst.</italic>
 A<bold>64</bold>
, 112–122.</mixed-citation>
</ref>
<ref id="bb29"><mixed-citation publication-type="other">Smolin, Yu. I., Shepelev, Yu. F. & Titov, A. P. (1973). <italic>Sov. Phys. Crystallogr.</italic>
<bold>17</bold>
, 749–750.</mixed-citation>
</ref>
<ref id="bb30"><mixed-citation publication-type="other">Streit, H. C., Kramer, J., Suta, M. & Wickleder, C. (2013). <italic>Materials</italic>
, <bold>6</bold>
, 3079-3093.</mixed-citation>
</ref>
<ref id="bb31"><mixed-citation publication-type="other">Sun, Z., Wang, M., Song, X. & Jiang, Z. (2012). <italic>J. Rare Earth</italic>
, <bold>31</bold>
, 957–961.</mixed-citation>
</ref>
<ref id="bb32"><mixed-citation publication-type="other">Tasci, E. S., de la Flor, G., Orobengoa, D., Capillas, C., Perez-Mato, J. M. & Aroyo, M. I. (2012). <italic>EPJ Web of Conferences</italic>
, <bold>22</bold>
, 00009.</mixed-citation>
</ref>
<ref id="bb33"><mixed-citation publication-type="other">Westrip, S. P. (2010). <italic>J. Appl. Cryst.</italic>
<bold>43</bold>
, 920–925.</mixed-citation>
</ref>
<ref id="bb34"><mixed-citation publication-type="other">Zachariasen, W. H. (1930). <italic>Z. Kristallogr.</italic>
<bold>73</bold>
, 1–6.</mixed-citation>
</ref>
</ref-list>
</back>
</pmc>
</record>

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