The electromechanical behavior of europium doped BaTiO3

The electromechanical response of BaTiO3 doped with 2% of Eu2O3 is studied in the vicinity of the tetragonal to cubic phase transition, as a function of temperature and applied electric field. The electromechanical experiments have been carried out from room temperature through the Curie region and in the paraelectric phase using two methods: dynamic and quasistatic. The contributions of piezoelectric effect, electrostriction and domain switching to the strain produced during the application of an alternating electric field are discussed by describing the strain-electric field (S-E) loops. The coefficients s11, k31, d31 and d33 have been calculated. The electrostrictive coefficient M11 was derived from S(E) dependences in the paraelectric phase. The observed anomalies in the temperature dependence of piezoelectric coefficients within the temperature range from room temperature to TC have been found to be most probably due to Eu doping. It was found that addition of Eu ions leads to formation of a new intermediate phase. The performed XPS measurements revealed that Eu ions may have 2 + and 3 + oxidation state and the same occupy both A and/or B position in the perovskite lattice. All these results are finally analyzed in terms of charge compensation phenomena.