Improved upconversion photoluminescence properties of 0.965K0.4Na0.58Li0.02Nb0.96Sb0.04O3-0.035Bi0.5K0.5ZrO3:0.25%Er/xIn lead-free piezoelectric ceramics with balanced piezoelectric coefficient and Curie temperature

A series of erbium- and indium-doped 0.965K(0.40)Na(0.58)Li(0.02)Nb(0.96)Sb(0.04)O(3)-0.035Bi(0.5)K(0.5)ZrO(3):0.25%Er/xIn lead-free piezoelectric ceramics with upconversion photoluminescence (UCPL) properties were prepared by the conventional solid state reaction. A systematical investigation into the effects of In3+ doping on the structural, dielectric, ferroelectric, piezoelectric, and UCPL properties of the ceramics was carried out. The distribution of Er3+-sites could be modified by In3+ doping according to the analysis of UV-Vis-NIR absorption cross-section, resulting in improved piezoelectric and photoluminescence properties of the ceramics. The optimized comprehensive properties are performed by the x=0.25% samples of which the piezoelectric coefficient d(33)similar to 257 pC/N, Curie temperature T-C similar to 273 degrees C, remanent polarization P-r similar to 12.5 mu C/cm(2), dielectric constant epsilon(r)similar to 1551, and d(33)similar to 257 pC/N which is the supreme piezoelectric coefficient achieved in KNN-based UCPL ceramics as of now. The results demonstrate that erbium and indium co-doped KNN-based ceramics may have potential applications in electro-optical devices.