INFRARED DIELECTRIC RESPONSE IN BATAO2N

The frequency dependence of the dielectric response deduced from the a nalysis of infrared reflection spectra of the BaTaO2N perovskite is re ported. The results are compared with those of barium titanate and dis cussed. It is concluded that the substitution of one nitrogen for oxyg en - together with replacement of Ti-+IV by Ta-+V to ensure the proper charge balance - appears to cancel the possibility offered by some ox idic perovskites to observe very high dielectric constants since here no soft mode behaviour is found.