(K0.5Na0.5)(Nb1-xTax)O3lead-free piezoelectric ceramics have been prepared by an ordinary sintering technique. The results of X-ray diffraction reveal that Ta5+diffuses into the K0.5Na0.5NbO3lattices to form a solid solution with an orthorhombic perovskite structure. Because of the high melting temperature of KTaO3, the (K0.5Na0.5)(Nb1-xTax)O3ceramics can be sintered at higher temperatures. The partial substitution of Ta5+for the B-site ion Nb5+decreases both paraelectric/cubic-ferroelectric/tetragonal and ferroelectric/tetragonal- ferroelectric/orthorhombic phase transition temperatures, TCand TO-T. It also induces a relaxor phase transition and weakens the ferroelectricity of the ceramics. The ceramics become 'softened', leading to improvements in d33, kp, ktand εrand a decease in Ec, Qmand Np. The ceramics with x=0.075-0.15 become optimum, having d33=127-151 pC/N, kp=0.43-0.44, kt=0.43-0.44, εr=541-712, tanδ=1.75-2.48% and TC=378-329 °C.
|Number of pages||5|
|Journal||Applied Physics A: Materials Science and Processing|
|Publication status||Published - 1 Apr 2008|
ASJC Scopus subject areas
- Materials Science(all)