Crystal structures of lazulite-type oxidephosphates Ti{sup III}Ti{sup IV}{sub 3}O{sub 3}(PO{sub 4}){sub 3} and M{sup III}{sub 4}Ti{sup IV}{sub 27}O{sub 24}(PO{sub 4}){sub 24} (M{sup III}=Ti, Cr, Fe)

Journal Article · Sun Jun 15 04:00:00 EDT 2008 · Journal of Solid State Chemistry

DOI:https://doi.org/10.1016/j.jssc.2008.02.039· OSTI ID:21128321

Schoeneborn, M ^[1]; Reinauer, F ^[1]

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1. Institut fuer Anorganische Chemie, Universitaet Bonn, Gerhard-Domagk-Strasse 1, D-53121 Bonn (Germany)

Single crystals of the oxidephosphates Ti{sup III}Ti{sup IV}{sub 3}O{sub 3}(PO{sub 4}){sub 3} (black), Cr{sup III}{sub 4}Ti{sup IV}{sub 27}O{sub 24}(PO{sub 4}){sub 24} (red-brown, transparent), and Fe{sup III}{sub 4}Ti{sup IV}{sub 27}O{sub 24}(PO{sub 4}){sub 24} (brown) with edge-lengths up to 0.3 mm were grown by chemical vapour transport. The crystal structures of these orthorhombic members (space group F2dd ) of the lazulite/lipscombite structure family were refined from single-crystal data [Ti{sup III}Ti{sup IV}{sub 3}O{sub 3}(PO{sub 4}){sub 3}: Z=24, a=7.3261(9) A, b=22.166(5) A, c=39.239(8) A, R{sub 1}=0.029, wR{sub 2}=0.084, 6055 independent reflections, 301 variables; Cr{sup III}{sub 4}Ti{sup IV}{sub 27}O{sub 24}(PO{sub 4}){sub 24}: Z=1, a=7.419(3) A, b=21.640(5) A, c=13.057(4) A, R{sub 1}=0.037, wR{sub 2}=0.097, 1524 independent reflections, 111 variables; Fe{sup III}{sub 4}Ti{sup IV}{sub 27}O{sub 24}(PO{sub 4}){sub 24}: Z=1, a=7.4001(9) A, b=21.7503(2) A, c=12.775(3) A, R{sub 1}=0.049, wR{sub 2}=0.140, 1240 independent reflections, 112 variables). For Ti{sup III}Ti{sup IV}O{sub 3}(PO{sub 4}){sub 3} a well-ordered structure built from dimers [Ti{sup III,IV}{sub 2}O{sub 9}] and [Ti{sup IV,IV}{sub 2}O{sub 9}] and phosphate tetrahedra is found. The metal sites in the crystal structures of Cr{sub 4}Ti{sub 27}O{sub 24}(PO{sub 4}){sub 24} and Fe{sub 4}Ti{sub 27}O{sub 24}(PO{sub 4}){sub 24}, consisting of dimers [M{sup III}Ti{sup IV}O{sub 9}] and [Ti{sup IV,IV}{sub 2}O{sub 9}], monomeric [Ti{sup IV}O{sub 6}] octahedra, and phosphate tetrahedra, are heavily disordered. Site disorder, leading to partial occupancy of all octahedral voids of the parent lipscombite/lazulite structure, as well as splitting of the metal positions is observed. According to Guinier photographs Ti{sup III}{sub 4}Ti{sup IV}{sub 27}O{sub 24}(PO{sub 4}){sub 24} (a=7.418(2) A, b=21.933(6) A, c=12.948(7) A) is isotypic to the oxidephosphates M{sup III}{sub 4}Ti{sup IV}{sub 27}O{sub 24}(PO{sub 4}){sub 24} (M{sup III}: Cr, Fe). The UV/vis spectrum of Cr{sub 4}Ti{sub 27}O{sub 24}(PO{sub 4}){sub 24} reveals a rather small ligand-field splitting {delta}{sub o}=14,370 cm{sup -1} and a very low nephelauxetic ratio {beta}=0.72 for the chromophores [Cr{sup III}O{sub 6}] within the dimers [Cr{sup III}Ti{sup IV}O{sub 9}]. - Graphical abstract: Single crystals of the oxidephosphates Ti{sup III}Ti{sup IV}{sub 3}O{sub 3}(PO{sub 4}){sub 3} (black), Cr{sup III}{sub 4}Ti{sup IV}{sub 27}O{sub 24}(PO{sub 4}){sub 24} (red-brown, transparent), and Fe{sup III}{sub 4}Ti{sup IV}{sub 27}O{sub 24}(PO{sub 4}){sub 24} (brown) with edge-lengths up to 0.3 mm were grown by chemical vapour transport. The crystal structures of these orthorhombic members of the lazulite/lipscombite structure family were refined from single-crystal data.

• OSTI ID: 21128321
• Journal Information: Journal of Solid State Chemistry, Journal Name: Journal of Solid State Chemistry Journal Issue: 6 Vol. 181; ISSN 0022-4596; ISSN JSSCBI
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
CHROMIUM COMPOUNDS
CRYSTAL GROWTH
DIMERS
IRON COMPOUNDS
LIGANDS
MONOCRYSTALS
ORTHORHOMBIC LATTICES
PHOSPHATES
SPACE GROUPS
TITANIUM COMPOUNDS
ULTRAVIOLET SPECTRA
VISIBLE SPECTRA
VOIDS