HONG Lu, LI Yueming, SHEN Zongyang, WANG Zhumei, HONG Yan HONG Qian
(School of Materials Science and Engineering, Jingdezhen Ceramic Institute; Key Laboratory of Functional Ceramic Materials of
China Light Industry; Jingdezhen 333403, Jiangxi, China)
Abstract: 0.96 (KxNa1-xNbO3)-0.04Bi0.5Na0.5ZrO3(0.96KxN1-xN-0.04BNZ, x =0.48, 0.49, 0.50, 0.51, 0.52) ceramics were prepared by conventional solid state reaction method. The crystal structure, micromorphology and electrical properties of 0.96KxN1-xN-0.04BNZ piezoceramics were systemically investigated. The results indicated that all the samples have a pure perovskite structure, and a morphortropic phase boundary (MPB) region with the coexistence of orthorhombic and tetragonal phases can be found in the composition x range of 0.5-0.51. The bulk density of the sample first increases and then decreases with the firing temperature increasing. The highest density was achieved at 1120℃ for 3 h, the bulk density of the sample first increases and then decreases with the content of K increasing, the bulk density reaches the maximum (ρ=4.56 g/cm3) at x = 0.5. The piezoelectric constant d33, electromechanical coupling factor kp and the dielectric constant εr of the samples first increases and then decreases with the increasing of x content, while the mechanical quality factor Qm and dielectric loss tanδof the ceramics show opposite trend. The optimized piezoelectric properties can be obtained for the ceramics with x = 0.50 composition as follows: d33=305 pC/N, kp=36.8%, Qm = 49, εr = 1390, tanδ = 3.2% and Curie temperature TC = 320 ℃.
Key words: Potassium sodium niobate; Lead-free piezoelectric ceramics; Bismuth sodium zirconate; piezoelectric properties;