The crystal structure of InYGe2O7 germanate
Por:
Juárez-Arellano E.A., Bucio L., Ruvalcaba J.L., Moreno-Tovar R., García-Robledo J.F., Orozco E.
Publicada:
1 ene 2002
Resumen:
A new indium yttrium germanate presenting the thortveitite structure with symmetry described by the space group C2/m (No. 12) has been prepared by high temperature solid state reaction as polycrystalline powder material. This crystallizes in the monoclinic system, with cell parameters a = 6.8286(1) Å, b = 8.8836(2) Å, c = 4.9045(1) Å, ? = 101.8340(7)°, V= 291.195(9) Å3 and Z = 2. The structure was characterized by X-ray powder diffraction and Rietveld refinement of the diffraction pattern. The In3+ and y3+ cations occupy the same octahedral site forming a hexagonal arrangement on the ab planes. In their turn, the hexagonal arrangements of InO6/YO6 octahedral layers are held together by sheets of isolated diorthogroups constituted by a double tetrahedra sharing a common vertex. In this compound, the Ge2O7 diorthogroup shows the C2h symmetry implying a Ge-O-Ge angle of 180°, being an important feature of the thortveitite structure, which has been controversial in some reported papers. A remarkable photo-luminescence effect (in comparison with glass) was observed when the sample was irradiated with ?-particles beam during the RBS experiments employed to analyze the chemical stoichiometry.
Filiaciones:
Instituto de Física, UNAM, Apartado Postal 20-364, 01000 México D.F., Mexico
|