Effects Of Doping On The Properties Of Sodium Niobate Based Lead-free Piezoceramic Ceramics And Stack

In this paper, we study on Li/Ta/Sb co-doped lead-free (K, Na)NbO3ceramics synthesized usingthe conventional solid-state reaction method. And studying SrTiO3and CuO doped(K0.4425Na0.52Li0.0375)(Nb0.8825Sb0.07Ta0.0475)O3(KNLNST0.0475) ceramics. Searching the mostappropriate composition and using this composition to prepare multilayer actuator by tape-casting.At first, Li/Ta/Sb co-doped lead-free (K0.4425Na0.52Li0.0375)(Nb0.93-xTaxSb0.07)O3(abbreviatedKNLNSTx) piezoelectric ceramics were synthesized using the conventional solid-state reactionmethod and studied the influence of Ta content and the sintering temperature on the dielectricproperties, phase transition and microstructure of KNLNSTxceramics. The results showed that thevaration of Ta content not only induced phase transition behavior and change of microstructure, butalso lead to a great change of the electric properties. The densities of the ceramics first increased andthen decreased as the sintering temperature. When x=0.0475, sintering temperature is at1130C andpoling temperature is at70C, the excellent dielectric properties of samples can be obtained.Secondly, in order to improve the temperature stability of KNLNSTx, SrTiO3dopedKNLNST0.0475has been studied. The results indicated that the piezoelectric property decreased asSrTiO3content increased and SrTiO3doped induce largely decreased of phase transition temperatureTO-Twhich could improve the temperature stability of ceramics. When molar content of SrTiO3is0.5%, the ceramics showed the excellent piezoelectric properties of d33=300pC/N and TO-T=26C.For the sake of studying the low temperature sintering of KNLNSTxceramics, the ceramics of(K0.4425Na0.52Li0.0375)(Nb0.8825Sb0.07Ta0.0475)O3+0.005SrTiO3+zCuO has been studied. It has been foundthat CuO could reduce sintering temperature and improve Qmof ceramics largely. But the addition ofCuO also decrease d33and eliminated the influence of SrTiO3on the ceramic phase transitontemperature TO-T.Finally, combined with the electric properties and sintering character of ceramics, thecomposition of (K0.4425Na0.52Li0.0375)(Nb0.8825Sb0.07Ta0.0475)O3has been used to prepare for laminationby tape-casting. The ceramics composed by lamination has been measured and the results show thatthe electrical performance of multilayer ceramics is lower than common ceramics, and theperformance of multilayer ceramics laminated by100m lamination is more excellent than the onelaminated by300m. Due to high sintering temperature of samples, Platinum has been used asinternal electrode and multilayer actuator prepared by co-fired。When the voltage is100V andfrequency is5Hz,10Hz,20Hz respectively, the displacement of multilayer actuator with three layers is91nm,93nm,106nm. For five layers multilayer actuator, the displacement is131nm,139nm,146nm, respectively.