Effects of CuO Sintering Aids on Microstructure and Electric Properties for (Na0.48K0.473Li0.04Sr0.007) (Nb0.883Ta0.05Sb0.06Ti0.007)O3 Ceramics

In this paper, the effects of CuO sintering aids on microstructure and electric properties are investigated for the non-stoichiometric (Na0.48K0.473Li0.04Sr0.007)(Nb0.883Ta0.05Sb0.06Ti0.007)O3+x mol% CuO lead free ceramics. As the amounts of CuO equal 1 mol%, the sintering temperature is 975 °C and the piezoelectric parameters are d33 = 200 pC/N, g33 = 38 (10−3 Vm/N), d33 × g33 = 7600 (10−15 m2/N), kp = 0.38, Qm = 240, Pr = 18.93 μC/cm2 and EC = 8.75 kV/cm. The piezoelectric properties are changed to hard type and suitable for energy harvester with multilayer technology. The physical response mechanisms are suggested that the diffused phase transitions are enhanced, the Cu2+ ions substitute for the B-site ions with forming the Oxygen vacancies and the domain walls are pinning.

Crystal Structure and Electrical Characteristics of (0.965)(Li0.03(Na0.5K0.5)0.97)(Nb1−xSbx)O3−0.035(Bi0.5Na0.5)0.9(Sr)0.1ZrO3 Ceramics Doped with CuO, B2O3, and ZnO

Recently, the need has arisen to enhance the piezoelectric properties and temperature stability of (Na,K)NbO3 system ceramics. The (0.965)(Li0.03(Na0.5K0.5)0.97)(Nb1−xSbx)O3−0.035 (Bi0.5Na0.5)0.9(Sr)0.1ZrO3 ceramics were newly manufactured using the sintering aids of CuO, B2O3, and ZnO as a function of antimony substitution, and the their crystal structure and electrical characteristics were analyzed. The grain size was apparently refined as the amount of antimony increased. The dielectric constant was enhanced and Curie temperature was decreased due to the content of the antimony substitution. The x = 0.07 sample sintered at 1060 °C presented the best electrical characteristics, which were bulk density = 4.488 g/cm3, piezoelectric constant d33 = 330 pC/N, electromechanical coupling factor kp = 0.427, mechanical coupling factor Qm = 61, and dielectric constant εr = 2521. We believe that the x = 0.07 sample is the best material for piezoelectric speakers.