Dielectric Dispersion at Microwave Frequencies of Some Low Loss Mixed Oxide Perovskites

Abstract

This paper reports the dielectric permittivities of several low loss ceramics of A(B11/2B21/2)O3 mixed oxide perovskites, Ba(Mg1/3Ta2/3)O3 (BMT), Sr(Al1/2Nb1/2)O3 (SAN), Sr(Al1/2Ta1/2)O3 (SAT), Sr(Ga1/2Ta1/2)O3 (SGT), and their modified compositions 0.7Sr(Al1/2Nb1/2)O3-0.3NdGaO3 (SAN-NG) and 0.7Sr(Al1/2Ta1/2)O3-0.3NdGaO3 (SAT-NG), measured at microwave frequencies. Measurements of the frequency-dependent dielectric constant and loss tangent are reported. Their loss tangent values are on the order of 10− 4 to 10− 5, which can not be evaluated by the traditional reflection/transmission spectra or impedance measurement techniques. A parallel-plate dielectric resonance method was adopted for dielectric measurements for such low loss materials. The frequency spectra of dielectric constants and loss tangents of were investigated by the well known classical oscillator model.