Hydrothermal Synthesis and Characterization of K _x Na _{(1− x )} NbO ₃ Powders

NaNbO ₃ , KNbO ₃ , and K _x Na _{(1− x )} NbO ₃ powders were successfully prepared by the hydrothermal method. The phase of the products was identified to be orthorhombic structure by X‐ray diffraction (XRD) technique, and the XRD results revealed that the x value of the K _x Na _{(1− x )} NbO ₃ gradually increased with the increase in the ratio of K ⁺ to Na ⁺ in alkaline solution. The morphology and the microstructure were investigated by scanning electron microscopy, energy‐dispersive spectroscopy, and transmission electron microscopy, and the results indicated that the ratio of K ⁺ to Na ⁺ in the solution had a great effect on the morphology and the size of products. Na _0.5 K _0.5 NbO ₃ with morphotropic phase boundary composition could be synthesized when the molar ratio of K ⁺ to Na ⁺ was between 4:1 and 6:1 in the solution. A possible formation mechanism of the K _x Na _{(1− x )} NbO ₃ crystal was also proposed based on the experimental results.