FAR INFRARED SPECTROSCOPY AND ORIGIN OF MICROWAVE LOSSES IN LOW-LOSS CERAMICS

The theory of intrinsic and extrinsic microwave and far-infrared losses is briefly reviewed and compared with experimental results obtained on low-loss ceramic materials using infrared reflectivity, submillimetre and near-millimetre transmission technique. The problem of extrapolation of the losses from polar mode range down to the microwave region is discussed. The influence of the basic ionic parameters on the intrinsic microwave losses and permittivity is discussed for the cubic complex perovskite Ba(B'B-1/2"(1/2))O-3 system. Possibilities for further research are suggested.