Electrostrictive coefficients of pb(Mg_1/3Nb_2/3)O₃ ceramics

The electrostrictive coefficients Q₃₃ and Q₁₃ of Pb(Mg_1/3Nb_2/3)O₃ ceramics have been precisely determined over a wide temperature range from −110°C to 100°C, using three different methods: strain gauge, piezoelectric resonance and interferometric techniques. A quadratic relation between induced strain and electric polarization holds even in the ferroelectric phase, as well as in the paraelectric phase. The electrostrictive coefficients are nearly temperature-independent with values of Q₃₃= 2.3(±0.2)×10⁻² m⁴C⁻² and Q₁₃= −0.64(±0.05)×10⁻² m⁴C⁻². The field-induced piezoelectric coefficients d₃₃ and d₃₁ were also measured at room temperature as a function of dc bias field. The values of d₃₃/ε₃ and d₃₁/ε₃ are proportional to the induced electric polarization. The electrostrictive coefficients calculated from the slopes are in good agreement with those obtained by the strain-gauge method.