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A trace of Zn doped 0.997K0.37Na0.63NbO3-0.003BaBiO3 based lead-free piezoelectric single crystals were prepared by a seed-free, solid-state method. The effects of Zn doping on the growth, microstructure and electrical properties of the single crystals were systematically studied. The results show that the Zn doping does not change the perovskite crystalline structure of the crystals. Compared with many other dopants, Zn doping can effectively reduce or even avoid crystal cracking, and bending/warping deformation during the growth process. With the increase of Zn content, the volume of the grown crystal first increases and then decreases, while the roughness of the crystal exposed surface first decreases and then increases. When the Zn-doping content is 0.8at.%, the size of the crystal reaches the maximum value of 12 × 10 × 2 mm3. The influence of Zn-doping content on the main electrical properties of the crystals also shows a similar changing relationship. For the crystal doped with 0.8at.% Zn, excellent electrical properties can be obtained as below: d33 = 354 pC/N, Pr = 47.2 µC/cm2, Tanδ = 0.6%, kt = 0.68, εr = 515, Tc = 402 °C. The results imply that the crystal has promising development and application prospects. [ABSTRACT FROM AUTHOR]

K0.5Na0.5NbO3(KNN)-based piezoelectric single crystals have relatively high Curie temperature and piezoelectric properties. Seed-free solid state crystal growth (SFSSCG) method has many advantages, such as simple process, low cost, easy composition control and no seed crystal required, etc. In this work, (1 − x)[0.997(0.996K0.5Na0.5NbO3–0.004MnBiO3)–0.003B2O3]–xLi2CO3 (x = 0, 0.001, 0.003, 0.005, 0.007) single crystals were prepared by the SFSSCG method with B2O3 used as a sintering aid. And the effects of Li doping on the growth, morphology, structure and electrical properties of the crystals were investigated. The investigation results indicate that Li-doping is beneficial to the growth of the crystal. The formation of tetragonal phase, a secondary phase, is promoted by the addition of appropriate amount of Li, especially at 0.3at.%. The electrical properties of the crystals are enhanced obviously after Li-doped. When doped with 0.3at.% Li, the crystal has excellent piezoelectric properties as follows: d33 = 422 pC/N, tanδ = 0.034, TC = 429°C, and Qm=166, etc. These results suggest that the obtained crystals have potential and promising application prospects in the field of environmental-friendly piezoelectric devices. [ABSTRACT FROM AUTHOR]