engleski

Influence of GeO2 on lithium ion transport in lithium borophosphate glasses

The frequency and temperature dependences of the electrical conductivity and dielectric permittivity of the Li2O-B2O3-P2O5-GeO2 glasses have been investigated in the 0.01 Hz to 1 MHz frequency range and over the temperature range from 183 to 523 K. The observed increase in dc conductivity with addition of GeO2 is a result of the depolymerisation of phosphate chains and incorporation of Ge atoms into network which enables formation of the continuous channels for an easier migration of lithium ions. The frequency dependent ac conductivity was described using Jonscher's power law. The temperature dependent behaviour of the frequency exponent (s) suggested that the correlated barrier hopping model was the most appropriate to explain the electrical transport in studied glasses. The dielectric properties have been analyzed in the framework of complex dielectric permittivity and complex electrical modulus formalisms. The evolution of the complex permittivity as a function of frequency and temperature has been investigated. The thermal activated relaxation mechanism dominated the observed relaxation behaviour. The activation energy associated with dielectric relaxation was almost identical to that of dc conductivity suggesting that the similar energy barriers are involved in both processes.

Lithium borophosphate glasses; impedance spectroscopy

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