Tin germanate glasses

Abstract Glasses of composition xSnO(1−x)GeO2 have been prepared with 0.3⩽x⩽0.6. Crystallisation occurred for x⩾0.7. Mossbauer and NMR spectra indicate that the Sn(II) environment is at least as asymmetric as that found in crystalline SnO and stannosilicate glasses. Mossbauer isomer shifts are larger and quadrupolar splittings smaller than for the corresponding silicates, reflecting increased s-electron density at the nucleus with the lower covalency in the Sn–O–Ge link. Neutron diffraction data show a peak at ∼2.12 A, assigned to 3-coordinated Sn(II) and a second peak at ∼2.35 A, assigned to 6-coordinated Sn(II).