The Thermal Stability of (CaTiO₃)1-x (Cr_3/4Fe_5/4O₃)_x Ceramic Composites in the Microwave Region

Abstract

The thermal stability, structural and dielectric properties of the (CaTiO 3 ) 1-x (Cr 3/4 Fe 5/4 O 3 ) x ceramic composites with x = 0, 0.1, 0.5, 0.9 and 1 have been examined in microwave region. The samples were produced via the solid-state reaction. The orthorhombic structural phase of CaTiO 3 and trigonal structural phase of Cr 3/4 Fe 5/4 O 3 were confirmed by the X-Ray Powder Diffraction (XRPD). The XRPD patterns for composites reveal the quantities of each original phase present. The infrared spectra of the samples reinforce this structural verification indicating no or minimal occurrence of unwanted reactions. The first sample ( x = 0) and last sample ( x = 1) in this series exhibit the maximum and the minimum of the relative dielectric permittivity and values range from 140.1 to 8.3 respectively. The measured temperature coefficient of the matrix CaTiO 3 was +921 ppm · ℃ -1 and for the matrix Cr 3/4 Fe 5/4 O 3 was -56 ppm· ℃ - 1 . With the study of series of composites, it was possible to make a mathematical prediction for a composition reach the temperature coefficient near zero. The proposed ceramic has potential use as thermostable material in the microwave region and can be applied to resonators, low-noise amplifiers, filters, and so on.