Dielectric investigation of the composites based on thiourea

The composites of thiourea and lithium niobate as well as lead titanate and barium titanate (thiourea fraction was 0.90 for all cases) have been studied by dielectric spectroscopy close to structural phase transitions in thiourea. It was found that the hysteresis increased and the temperature of ferroelectric phase transition from phase I to phase II decreased for all compositions investigated in comparison with the same properties of polycrystalline thiourea. The largest lowering of the phase transition temperature was observed for the thiourea and barium titanate composite. The results are analyzed within the framework of Landau–Ginzburg theory.