Phase structure and electrical properties of lead-free (1 − x)(Bi 0.5Na 0.5) 0.88Ba 0.12TiO 3– xAg 0.9Li 0.1NbO 3 piezoelectric ceramics

Abstract

Lead-free (1 − x)(Bi 0.5Na 0.5) 0.88Ba 0.12TiO 3– xAg 0.9Li 0.1NbO 3 [(1 − x)BNBT12– xALN10, x = 0–0.06] piezoelectric ceramics were synthesized by conventional oxide-mixed method. The phase structure, ferroelectric, piezoelectric, and dielectric properties of the ceramics were examined. The X-ray diffraction analysis shows that Ag +, Li +, and Nb 5+ ions have diffused into the BNBT12 lattice forming a solid solution with a pure perovskite structure. The morphotropic phase boundary (MPB) between tetragonal and pseudocubic phases is formed at x = 0.01–0.02. The addition of ALN10 can improve the electrical properties of BNBT12 ceramics. The ceramics with x = 0.025 exhibit the optimum electrical properties: d 33 = 155 pC/N, k p = 14.8%, k t = 40.2%, P r = 21.9 μC/cm 2, and E c = 2.30 kV/mm. The temperature dependence of dielectric and piezoelectric properties shows that the depolarization temperature ( T d) is shifted towards lower temperatures with increasing x. For the ceramics with x ≥ 0.03, ferroelectric and nonpolar phases may coexist at room temperature, resulting in a sharp decline in the ferroelectricity and piezoelectricity.