Investigation of phosphate glasses with the general formula A(x)B(y)P(3)O(12) where A=Li, Na or K and B=Fe, Ga, Ti, Ge, V or Nb

Physical and thermal properties, crystallization behaviour and de conductivity of glasses with the general formula A(x)B(y)P(3)O(12) where A is an alkali ion and B = Fe, Ga, Ti, Ge, V or Nb have been investigated. Glasses of compositions A(3)B(2)P(3)O(12), A(5)BP(3)O(12) and A(4)BP(3)O(12) have been prepared by quenching the melts. Molar volumes of these glasses change considerably on inter alkali substitution (by 30-40% on going from Li to K). The glass transition temperatures are within the small range of 30 K for the Li, Na and K members, except in the vanadium containing glasses. The glasses with B = Fe, Ti or Ge are found to crystallize immediately above the glass transition temperature. Iso-compositional crystallization was observed in Na3Fe2P3O12. The DSC crystallization exotherms are often not simple, indicating stages of crystallization. Crystallization kinetics of the Na3Fe2P3O12 glass reveal a lower activation energy for isothermal crystallization than for the non-isothermal crystallization. The de conductivities estimated from impedance plots are in the range of 10(-9) Omega(-1) cm(-1) to 10(-7) Omega(-1) cm(-1) at 298 K and the conductivity activation energies are in the range 0.5-0.8 eV, with no variation between Li+ and K+ containing glasses, greater than errors of measurement.