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Y2GeO5 (yttrium germanium pentaoxide) was synthesized by solid-state reaction at 1443 K. The arrangement, which has monoclinic symmetry, is isostructural with Dy2GeO5 and presents two independent sites for the Y atoms. Around these atoms there are distorted six-coordinated YO6 octahedra and seven-coordinated YO7 pentagonal bipyramids. The YO7 polyhedra are linked together, sharing their edges along a surface parallel to ab, forming a sheet. Each of these parallel sheets is interconnected by means of GeO4 tetrahedra, sharing an edge (or vertex) on one side and a vertex (or edge) on the other adjacent side. Parallel sheets of YO7 polyhedra are also interconnected by undulating chains of YO6 octahedra along the c axis. These octahedra are joined together, sharing a common edge, to form the chain and share edges with the YO7 polyhedra of the sheets.
For the isotypic structure of Dy2GeO5, see: Brixner et al. (1985 ). Different synthesis methods have been reported for this compound, including preparation by conventional r.f. magnetron sputtering (Minami et al., 2003 ), solid-state reactions at high temperatures (Zhao et al., 2003 ), MOCVD and LSMCD (Natori et al., 2004 ). For bond-valence parameters, see: Brese & O’Keeffe (1991 ), and for the bond-valence model, see: Brown (1981 , 1992 ). For oxide phosphors, see: Minami et al. (2001 , 2002 , 2004 ). Data used to model the second phase present in the reaction product, Y2Ge2O7, were taken from Redhammer et al. (2007 ). For related literature on technological applications, see: Fei et al. (2003 ).
Data collection: DIFFRAC/AT (Siemens, 1993 ); cell refinement: DICVOL91 (Boultif & Louëer 1991 ); data reduction: FULLPROF (Rodríguez-Carvajal, 2006 ); method used to solve structure: coordinates taken from an isotypic compound (Brixner et al., 1985 ); program(s) used to refine structure: FULLPROF; molecular graphics: ATOMS (Dowty, 2000 ); software used to prepare material for publication: FULLPROF.
Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536809026579/br2110sup1.cif
Rietveld powder data: contains datablocks I. DOI: 10.1107/S1600536809026579/br2110Isup2.rtv
The authors acknowledge the collaboration of Manuel Aguilar Franco for performing the conventional X-ray diffraction measurements, and projects CONACyT SEP-2007–81700.
The reactive mixture was prepared from Y2O3 (Aldrich.99.99%) and GeO2 (CERAC 99.999%) according to the stoichiometric proportions desired. The mixture was first powdered using an agate mortar; and then was heated in air in a tube furnace at 1373 K for 5 days with intermediate regrindings. A second thermal treatment at 1443 K for two days was applied. The characterization of the bulk material by conventional X-ray powder diffraction data indicated the presence of a well crystallized phase showing reflections that match with the isostructural phase DyGeO5 (PDF 01–078–0478). Very small amount of a secondary phase Y2Ge2O7 (PDF 38–288) was identified.
The starting structural parameters for perform a Rietveld refinement of the Y2GeO5 phase were taken from the isostructural data reported for Dy2GeO5 (ICSD 61373) by Brixner et al. (1985). For modeling the second phase Y2Ge2O7 (ICSD 240989), the data were those reported by Redhammer et al. (2007). The following parameters were refined: zero point and scale factors, cell parameters, half-width profile parameters, overall temperature factors, atomic coordinates, and asymmetries. For the Y2Ge2O7 phase the atomic coordinates were fixed to their starting values. The final Rietveld refinement of conventional diffraction pattern is shown in Fig. 2.
|Y2GeO5||Z = 8|
|Mr = 330.43||F(000) = 1200|
|Monoclinic, I2/a||Dx = 4.868 Mg m−3|
|Hall symbol: -I 2ya||Cu Kα radiation, λ = 1.540560 Å|
|a = 10.4706 (2) Å||T = 300 K|
|b = 6.8292 (1) Å||Particle morphology: spherical|
|c = 12.8795 (2) Å||white|
|β = 101.750 (3)°||flat sheet, 20 × 20 mm|
|V = 901.66 (3) Å3||Specimen preparation: Prepared at 1443 K|
|Bruker Advance D8 diffractometer||Data collection mode: reflection|
|Radiation source: sealed X-ray tube, Cu Kα||Scan method: step|
|graphite||2θmin = 7.98°, 2θmax = 80.00°, 2θstep = 0.02°|
|Specimen mounting: packed powder sample container|
|Least-squares matrix: full with fixed elements per cycle||Profile function: pseudo-Voigt modified by Thompson et al. (1987)|
|Rp = 0.053||105 parameters|
|Rwp = 0.069||Weighting scheme based on measured s.u.'s|
|Rexp = 0.024||(Δ/σ)max = 0.02|
|χ2 = 8.410||Background function: The background was refined first by mean of a linear interpolation between 55 background points with adjustable heights. At the end of the refinement, the values for all of these heights of the background were fixed.|
|3704 data points|
|Y1||0.3011 (2)||0.6277 (2)||0.6380 (1)||0.0096 (7)|
|Y2||0.0708 (2)||0.2567 (3)||0.5355 (1)||0.0090 (7)|
|Ge1||0.6236 (2)||0.5933 (3)||0.8155 (2)||0.0121 (9)|
|O1||0.1210 (9)||0.604 (1)||0.5178 (8)||0.009 (2)|
|O2||0.2950 (9)||0.298 (1)||0.6172 (7)||0.009 (2)|
|O3||0.5212 (9)||0.654 (1)||0.6971 (8)||0.009 (2)|
|O4||0.551 (1)||−0.006 (1)||0.4155 (8)||0.009 (2)|
|O5||0.2412 (8)||0.572 (1)||0.7926 (8)||0.009 (2)|
|Y1—O1||2.189 (8)||Y2—O2i||2.655 (10)|
|Y1—O1i||2.321 (10)||Y2—O3iv||2.327 (10)|
|Y1—O2||2.270 (8)||Y2—O4i||2.358 (9)|
|Y1—O3||2.283 (8)||Y2—O4v||2.287 (9)|
|Y1—O5||2.238 (10)||Ge1—O2vi||1.767 (8)|
|Y1—O5ii||2.316 (8)||Ge1—O3||1.727 (8)|
|Y2—O1||2.447 (8)||Ge1—O4vii||1.732 (10)|
|Y2—O1iii||2.203 (8)||Ge1—O5viii||1.739 (9)|
|Y1—O1—Y1ix||53.6 (2)||Y1—O2—Y2xiii||118.8 (3)|
|Y1—O1—Y2x||128.7 (3)||Y2xii—O2—Y2xiii||61.19 (6)|
|Y1ix—O1—Y2x||78.64 (6)||Y1—O3—Y2xiv||110.7 (3)|
|Y1ix—O1—Y2xi||90.44 (7)||Y2xv—O4—Y2xvi||124.20 (7)|
|Y2x—O1—Y2xi||157.05 (6)||Y1—O5—Y1xvii||89.8 (2)|
Symmetry codes: (i) −x+1/2, y, −z+1; (ii) −x+1/2, −y+3/2, −z+3/2; (iii) −x, −y+1, −z+1; (iv) x−1/2, −y+1, z; (v) x−1/2, −y, z; (vi) −x+1, y+1/2, −z+3/2; (vii) x, −y+1/2, z+1/2; (viii) x+1/2, −y+1, z; (ix) −x+3/2, y, −z+1; (x) −x, −y, −z; (xi) x+1/2, −y+1, z+1; (xii) −x+1/2, y, −z; (xiii) −x+1, −y, −z+1; (xiv) −x+3/2, y+1, −z; (xv) x+1, y, z+1; (xvi) −x+3/2, y, −z; (xvii) −x+3/2, y+2, −z+2.
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: BR2110).