Ionic conductivity and crystal structure of fired crystalline zirconium phosphate completely and half exchanged with some monovalent cations

For LiLi-form, the decomposition of dilithium zirconium phosphate with a layered structure and formation of lithium dizirconium triphosphate and zirconium pyrophosphate was achieved by firing at 600°C or above. For NaNa- and KK-forms, any distinct variations of the external apperance were not confirmed by heat-treatments, while the crystal growth was detected for RbRb- and CsCs-forms fired at 900°C. For half ion-exchanged forms, monovalent cation dizirconium triphosphate was mainly formed on heating up to 600°C or above. The activation energy in ionic conduction decreases with increasing monovalent cation radius. This dependency can be realized by Anderson and Stuart's model based on the classical ideas of ionic crystal theory and elasticity theory. The activation energy for the fully exchanged form is slightly higher than that for the half-exchanged form and the pre-exponential factor in σT=σ₀ exp (-E/kT) for the former is less than that for the latter.