Investigando a Estabilidade Térmica dos Compósitos da Matriz Ba2CoNbO6 (BCNO)1-X – CaTiO3(CTO)X] Operando Em Altas Frequências (Banda C)

Abstract

In this work, composites based on the ceramic matrix Ba2CoNbO6 (BCNO) 1-X- CaTiO3 (CTO) X were manufactured using the solid state reaction method. Cylindrical resonators were manufactured from a mixture of Ba2CoNbO6 and CTO using 0, 5, 12, 20 and 37% by weight of CTO. X-ray diffraction and scanning electron microscopy were used for structural and morphological characterization of the material. Rietveld's refinement was good, showing a single phase. Complex impedance spectroscopy showed high values for real impedance at low frequency, indicating polarization effects, as well as the imaginary impedance portrayed shifts in the peak frequency, showing that the conduction process is term activated, obeying Arrhenius law and the BCNO's calculated binding energy was 0.34 eV and 0.38 eV, showing that the conduction processes are the same. The complex impedance diagrams showed the contribution of the grain and the grain boundary to the conduction processes, being non-Debye processes. The temperature variation as a function of frequency was analyzed by the Silva-Fernandes-Sombra (SFS) technique to analyze the thermal stability of the material, in the microwave range, and for the concentration of 37%, it found a value of 0.98 ppm/ºC Hakki-Coleman, indicating that the insertion of the CTO improved the thermal stability of the material. The Hakki-Coleman technique showed values for permittivity ranging from 15.73 to 18.74. The cylindrical resonators were tested as antennas and distant field parameters such as bandwidth, directivity, gain, loss of return were analyzed, presenting values that enable the composite to work as a dielectric resonator antenna (DRA), operating in the range of 3 GHz to 5 GHz .