鐠鈣錳氧化物的介電性質

Abstract

The synthesis, characterization and dielectric properties of Praseodymium substituted calcium manganese oxides [PrxCa2-xMnO4] compounds were investigated. The dielectric properties of these compounds were studied in the frequency range from 20 Hz to 1 MHz between 10 K and 300 K. The low temperature dielectric properties were studied for the x = 0 ~ 0.5 compounds. Dielectric permittivity, dissipation factor, activation energy with thermally activated process, modulus spectra, and Cole-Cole plot have been investigated. The ε'(T) curves of samples show that the value of real dielectric permittivity has apparent high value (ε' ~ 104) near 270 K for x = 0.2, 0.3, 0.4, 0.5. The tanδ(T) curves of these compounds exhibit dielectric relaxation at low temperature. The highest values in M”-T relation are found to increase with increasing with increasing x for the PrxCa2-xMnO4 system. The peak temperatures of tanδ shift from low to high temperatures as the test frequency  increases in all samples. In these samples we also observed Jonscher power law behavior.