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A polycrystalline sample of Ba[Ti.sub.0.85]([[Fe.sub.1/2][Nb.sub.1/2]].sub.0.15])[O.sub.3] is synthesized by high temperature solid state reaction technique. The x-ray diffraction of the sample at room temperature shows a cubic phase and a high value of dielectric permittivity in a wide temperature interval approximately (200-450K) is obtained in Ba[Ti.sub.0.85]([[Fe.sub.1/2][Nb.sub.1/2]].sub.0.15])[O.sub.3] ceramic.

A study was conducted on the influence of lead vacancies on the R-nFe transition in a Pb(B'1/3B'2/3)O3 compound. The results indicate that both the relaxor behavior and the phase transition are strongly dependent on the lead vacancies content. Moreover, a change in the polar clusters size resulting from lead vacancies formation weakens the dipolar interactions and inhibits the spontaneous relaxor to ferroelectric phase transition.

Unpoled and efficient nonlinear optical (NLO) poled sodium niobium borophosphate glasses are studied with the use of dielectric spectroscopy. The results have suggested that the ion transport is due to hopping mechanism implying at least [Na.sup.+] and this is an example of poled glasses where an efficient NLO response is directly correlated to the conductivity of the material enhanced by a high alkali loading.

The influence of chemical ordering on PSN ceramic properties is studied by means of electrical measurements. The dielectric response of PSN is strongly dependent on the chemical ordering which may favor a relaxor behavior.