FAR-INFRARED REFLECTIVITY STUDY OF BA(MG1 3TA2/3)O-3-LA(MG2/3TA1/3)O-3 COMPLEX PEROVSKITE CERAMICS/

In order to study the lattice vibrations of the Ba(Mg1/3Ta2/3)O-3-La(M g2/3Ta1/3)O-3 (BMT-LMT) solid solution system, far-infrared reflection spectra of (BMT)(1-x)(LMT)(x) (0 less than or equal to x less than or equal to 1) are measured at room temperature in the frequency region 50-4000 cm(-1) by Fourier transform infrared spectroscopy These spectr a are analyzed based on the classical dispersion theory together with a Kramers-Kronig analysis. The dispersion parameters such as mode freq uency, damping factor, and oscillator strength obtained from the analy sis are reported. We find appreciable changes in the reflectance spect ra of (BMT)(1-x)(LMT)(x) around x = 0.2 and x = 0.7, which are discuss ed in relation to the variations of the crystal structure and ordering type with IF. The microwave dielectric properties are also estimated from the obtained dispersion parameters and the results are compared w ith the measured values.