Structure And Formation Mechanisms Of (K0.46na0.46la0.08)(Nb0.94sb0.06)O-3 Particles Under Hydrothermal Conditions

(K0.46Na0.46La0.08)(Nb0.94Sb0.06)O-3 powders were synthesized via hydrothermal method. The effects of different reaction conditions on crystal structure, micro-morphology and phase formation were analysed by XRD and SEM in detail. The results reveal that (K0.46Na0.46La0.08)(Nb0.94Sb0.06)O-3 powders with orthorhombic lattice structure are synthesized at 200 degrees C for 18 h with the total initial alkali concentration of 8 mol/l. The average particle size of synthesized powders is about 500-700 nm, which has regular cubic morphology with uniform distribution. Moreover, doping with La3+ and Sb5+ inhibits the crystal growth. The phase evolution of the powders revealed that the hydrothermal synthesis of (K0.46Na0.46La0.08)(Nb0.94Sb0.06)O-3 underwent two steps, where an intermediate product of K4Na4Nb6O19 center dot 9 H2O was found in the early stage at 140 degrees C. Based on the results, the formation mechanism of (K0.46Na0.46La0.08)(Nb0.94Sb0.06)O-3 powders was proposed. It can be inferred that the crystal growth model of (K0.46Na0.46La0.08)(Nb0.94Sb0.06)O-3 is dissolution-crystal growth-recrystallization with the characteristics of layered growth.