MCuSi4O10 (M= Ba, Ca e Sr) para aplicação em dispositivos de microondas e rádio frequência

Abstract

A series of MCuSi4O10 (M = Ca2+, Sr2+ and Ba2+) electroceramics have been prepared by solid-state reaction and sintered at 1150 (CaCuSi4O10, CCSO), 1100 (SrCuSi4O10, SCSO) and 1150 °C (BaCuSi4O10, BCSO). The structure and dielectric properties of the samples were studied by powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), impedance spectroscopy (IS) at radiofrequency (RF) and dielectric resonator antenna (DRA) at microwaves. The electroceramics presented thermo-activated processes with activation energies (Ea) ranging from 0.65 to 1.66 eV. In addition, fitting plots showed the equivalent circuit consisting of two parallel (R/CPE) connected in series, which is associated with the grain and grain boundary electrical contributions. The dielectric properties in microwaves showed values of electrical permissives (εr) of 3.47, 5.04 and 5.40 and quality factor (Q x f) 11350.00, 11438.60 and 28983.00 GHz for CCSO, SCSO and BCSO, respectively. All the samples have a great potential for microwave applications, especially the CCSO and BCSO based-DRA, due to the near-zero temperature coefficient of resonant frequency (τf) values (-2.24 and -7.41 ppm.°C-1, respectively). The preliminary results indicate that MCuSi4O10 electroceramics are satisfactory for use as a commercial antenna for C-and X-band applications.