Polaron transport studies in La_2O-V_2O_5-P_2O_5 glasses

摘要

The glass transition temperature and electrical conductivity in the temperature range 325 K to 525 K have been investigated in a set of La_2O doped vanado-phosphate glasses. The measured variation of density and glass transition temperature with La_2O content revealed that glass network becomes continuously loose packed with increasing La_2O content. Conductivity variation with La_2O revealed the contribution of lanthanum ions to the total conductivity. Temperature behavior of conductivity has been explained using Mott's small polaron and variable range hopping models. Various physical and polaron hopping parameters such as, activation energy, polaron hopping energy, polaron radius, effective dielectric constant, polaron bandwidth, electron-phonon coupling constant, hopping site energy and variable range hopping distance have been determined.