Effect of A-site modification on structural and microwave dielectric properties of calcium titanate

Abstract

This article presents studies on characteristics properties of CaTiO3, Ca0.8Sr0.2TiO3, and Ca0.6La0.8/3TiO3 ceramics. These ceramics were synthesized using the solid-state reaction process. Structural examination revealed that the grown ceramics have an orthorhombic structure with the Pbnm space group. The random distribution of particle size was shown through morphological investigation. Apparent density of developed ceramics was determined using the Archimedes technique and found to be ˂ 90%. The microwave dielectric properties of grown ceramics are compared on the basis of ionic polarizability. It is observed that partial replacement of Ca-ions by Sr-ions provides a high permittivity value (er = 168.93), higher quality factor Q × f = 9,330 GHz), and enhanced positive temperature coefficient of resonant frequency (tf  =  908.17). However, the substitution of Ca-ions by La-ions offers a low permittivity value (113.35), higher quality factor (16,730 GHz), and decreased temperature coefficient of resonant frequency (229.49 ppm/°C). These materials can be used with the ceramics possessing a negative temperature coefficient of resonant frequency to balance its tf- value nearly to zero.