Dielectric properties of new oxide phases Ln(0.65)Sr(1.35)Co(0.5)Ti(0.5)O(4) (Ln = La, Nd, Pr) with the K2NiF4 - type structure

摘要

New complex oxides of the composition Ln(0.65)Sr(1.35)Co(0.5)Ti(0.5)O(4) (Ln = La, Nd, Pr) with the K2NiF4 - type structure were synthesized using the citrate-nitrate method. Their crystal chemical characteristics and dielectric properties are researched. Different values of frequency-independent dielectric constants are observed in a wide frequency range of 10(3)-10(7) Hz in ceramics prepared at a temperature of 1300 degrees C. The highest permittivity epsilon is about 10(2)(at ambient temperature) in the frequency range from 1 kHz to 1 MHz for La0.65Sr1.35Co0.5Ti0.5O4 and Pr0.65Sr1.35Co0.5Ti0.5O4 samples. Co3+ and rare earth elements (La, Nd, Pr) co-doping Sr2TiO4 solid solution distorts the coordination polyhedra (Co,Ti)O-6 and SrO9, which leads to an Re epsilon increase by several times. The surface microstructure of ceramics was investigated. The samples relative density correlates with the dielectric constant value. A sample of the Nd0.65Sr1.35Co0.5Ti0.5O4 composition has a lower relative density and, accordingly, a lower Re epsilon value. The results of dielectric properties researches show that the structure anisotropy and the samples morphology have a significant effect on the value of the dielectric constant.