Synthesis and crystal structures of CaY2Ge3O 10 and CaY2Ge4O12

Hisanori Yamane, Ryouji Tanimura, Takahiro Yamada, Junichi Takahashi, Takashi Kajiwara, Masahiko Shimada

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23 Citations (Scopus)

Abstract

New compounds CaY2Ge3O10 and CaY 2Ge4O12 were prepared by heating mixtures of CaCO3, Y2O3 and GeO2 at 1200 °C. CaY2Ge3O10 is stable at 1300 °C, while CaY2Ge4O12 decomposes into a melt and CaY 2Ge3O10 at approximately 1250 °C. We obtained single crystals of CaY2Ge3O10 by cooling a sample with an initial composition of Ca:Y:Ge=1:2:8 from 1300 °C with a rate of -6 °C/h. The crystal structure of CaY2Ge 3O10 was determined by single crystal X-ray diffraction. CaY2Ge3O10 crystallizes in the monoclinic space group P21/c with a=6.0906(8), b=6.8329(8), c=18.752(2)Å and β=109.140(3)°, Z=4, and R1=0.029 for I>2σ(I). In the structure of CaY2Ge3O10, Ca and Y atoms are situated disorderly in three 7-fold coordination sites between isolated germanate groups of triple GeO4 tetrahedra, Ge3O10. The structural formula of CaY2Ge3O10 is expressed as (Ca0.45Y0.55)(Ca0.46Y0.54) (Ca0.09Y0.91)Ge3O10. The crystal structure of CaY2Ge4O12 was analyzed by the Rietveld method for the X-ray powder diffraction pattern. CaY2Ge 4O12 is isotypic with SrNa2P4O 12, crystallizing in the orthorhombic space group P4/nbm, a=9.99282(6), c=5.06701(4)Å, Z=2, Rwp=0.092, Rp=0.067. CaY 2Ge4O12 contains four-membered GeO 4-tetrahedra rings, Ge4O12. Eight-fold coordinated square-anitiprism sites and 6-fold octahedral sites between the layers of the Ge4O12 rings are occupied by Y atom and Ca/Y atoms, respectively The structural formula is Y(Ca0.5Y 0.5)2Ge4O12.

Original languageEnglish
Pages (from-to)289-295
Number of pages7
JournalJournal of Solid State Chemistry
Volume179
Issue number1
DOIs
Publication statusPublished - 2006 Jan

Keywords

  • Calcium yttrium germanates
  • Crystal structure
  • Germanate group
  • X-ray diffraction

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Ceramics and Composites
  • Condensed Matter Physics
  • Physical and Theoretical Chemistry
  • Inorganic Chemistry
  • Materials Chemistry

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