TITLE:
The Thermal Stability of (CaTiO3)1-x (Cr3/4Fe5/4O3)x Ceramic Composites in the Microwave Region
AUTHORS:
Francisco Nivaldo Aguiar Freire, Manoel Roberval Pimentel Santos, Hélio Henrique Barbosa Rocha, Ana Fabiola Leite Almeida, Selma Elaine Mazzetto, Antonio Jefferson Mangueira Sales, Antonio Sergio Bezerra Sombra
KEYWORDS:
Ceramics, Composites, Dielectric Properties
JOURNAL NAME:
Materials Sciences and Applications,
Vol.7 No.4,
April
27,
2016
ABSTRACT: The
thermal stability, structural and dielectric properties of the (CaTiO3)1-x(Cr3/4Fe5/4O3)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
CaTiO3 and trigonal structural phase of Cr3/4Fe5/4O3 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 CaTiO3 was +921 ppm·℃-1 and for the matrix Cr3/4Fe5/4O3 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.