Investigation of dielectric, ferroelectric and piezoelectric properties of Sm & Eu doped Pb(Mg_1/3Nb_2/3)_0.71Ti_0.29O₃ ceramics

Recently rare earth doping has attracted widespread attention as an optimized method to enhance the electromechanical properties of Pb-based piezo ceramics. In this study Sm and Eu doped PMN-PT ceramics were prepared via a conventional two-step solid-state reaction method. The results showed that the Sm and Eu were introduced into the lattice of PMN-PT ceramics, all samples had a pure perovskite structure with a little amount of pyrochlore phase. The addition of Sm and Eu significantly increased the dielectric constant and reduced the phase transition temperature. As the frequency increased from 1 kHz to 1 MHz, the dielectric constant peak value of all ceramics was decreased and T<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</inf> shifted towards higher temperature, which is the characteristic of the relaxor behavior. Compared to pure ceramic, the value of diffusiveness constant (γ) decreased from 1.95 to 1.83 and 1.85 for Sm and Eu doped PMN-PT ceramics respectively. Ferroelectric studies shows the well saturated loops for all the ceramics, whereas the value of remanent polarization (P<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">r</inf>) and saturation polarization (P<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">s</inf>) decreases due to doping, The slight decrease in P<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">r</inf> suggests that Sm and Eu-doping has a minor disruptive impact on the ferroelectric order of the PMN-PT ceramics. Notably, for Sm and Eu doped samples, a significant increase in piezoelectric coefficient (d<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">33</inf>) of 585 and 575 pC/N respectively were observed in comparison to 320 pC/N for undoped ceramic.