Piezoelectric and ferroelectric properties of Na0.5Bi4.5Ti4O15–BaTiO3 composite ceramics with Mg doping

Abstract

As one of the representatives of lead-free NBT ceramics, Na[Formula: see text]Bi[Formula: see text]Ti4O[Formula: see text] has still attracted much attention due to its excellent dielectric properties and has become the focus of research. However, its piezoelectric properties are far from satisfactory. In order to improve the piezoelectric properties of Na[Formula: see text]Bi[Formula: see text]Ti4O[Formula: see text], Na[Formula: see text]Bi[Formula: see text]Ti[Formula: see text]MgxOy–BaTiO3 (NBTM–BT) composite ceramics were synthesized by a conventional mixed oxide route and sintered at 1040∘C through two-step method. We optimized the electrical properties of NBTM–BT by changing the stoichiometric ratio of Mg content and studied its microscopic mechanism. The piezoelectric coefficient ([Formula: see text]) is stable at about 20 pC/N. Moreover, the maximum remanent polarization (2[Formula: see text]) of the ceramic is 3.08[Formula: see text][Formula: see text]C/cm2 with the coercive field of 18.01[Formula: see text]kV/cm. The dielectric constant and dielectric loss for Na[Formula: see text]Bi[Formula: see text]Ti[Formula: see text]Mg[Formula: see text]–BT composite ceramic were found to be 486 and 0.17 at 10[Formula: see text]kHz, respectively. The characteristic peaks of BT and Na[Formula: see text]Bi[Formula: see text]Ti4O[Formula: see text] can be observed clearly from the X-ray diffraction analysis. SEM analysis showed that all samples were well crystallized. Consequently, the piezoelectric and ferroelectric properties of Na[Formula: see text]Bi[Formula: see text]Ti4O[Formula: see text]–BT composite ceramic will be enhanced much by Mg doping, which means it has a wider range of applications in electronic devices such as piezoelectric devices.