Temperature Dependence Of Piezoelectric Coefficients Research Articles

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.

Phase transitions in Pb[(Ni1/3Sb2/3)xTiyZrz]O3 solid solution ceramics studied by piezoelectric measurements

The piezoelectric properties of Pb[(Ni1/3Sb2/3)xTiyZrz]O3 solid solution, where x+y+z = 1, x = 0.08 and y = 0.44–0.49 have been investigated in a wide temperature region using a resonance technique. The physical properties of PZT near the morphotropic phase boundary modified with the relaxor Pb(Ni1/3Sb2/3)O3 have been studied. The coefficients s11, k31 and d31 have been calculated basing on the damped harmonic oscillator model of piezoelectricly vibrating sample. Several anomalies in the temperature dependence of piezoelectric coefficients within the temperature range from 300 to 600 K have been found. For y > 0.46 the coexistence of rhombohedral and tetragonal phases occurs. The observed low piezoelectric activity confirms the existence of polar regions above Tm in Pb[(Ni1/3Sb2/3)xTiyZrz]O3.

Numerical characterization of functionally graded active materials under electricaland thermal fields

This paper deals with a class of functionally graded materials (FGMs) calledactive FGM that has electro-thermo-elastically graded material phases. The focusis on the characterization of active FGM under electrical and thermal fields.The structure comprises a substrate, an electro-thermo-elastically gradedlayer and an active layer. Using augmented piezoelectric constitutive law,the effect of temperature on the piezoelectric properties is incorporatedin the model. A formulation for exact solutions of the system based onEuler–Bernoulli theory is presented. Polynomial compositional variations of theconstituent phases in the graded layer are considered and their performancefor a range of stiffness and electrical property ratios of the active andsubstrate materials is studied under electrical and thermal fields. Theeffect of temperature dependence of piezoelectric coefficients on the stressdistribution in the active FGM is discussed. It is also observed that thecompositional variation significantly influences the actuation authority of gradedmaterials depending on the modular ratio of the constituent materials.