Study On Potassium Sodium Niobate Based Piezoelectric Ceramics Preparation And Properties

Potassium sodium niobate-based piezoelectric ceramic powders were prepared by KOH, NaOH, Nb₂O₅, Sb₂O₃, Ta2O₅, ZnO, MgO through hydrothermal route. The influence of raw materials on A bit different K/Na ratio and the effect of sintering aid?Zn O and MgO? on the structure and properties of potassium sodium niobate-based piezoelectric ceramics were investigated. Use XRD, SEM to characterize the composition and microstructure of the products. To optimized the preparation conditions by testing and analysis of piezoelectric constant, relative dielectric constant and dielectric loss.Sb-doping of potassium sodium niobate-based ceramic powders were prepared by hydrothermal method at 200 °C for 24 h, and the ceramics were obtained after granulation, tabletting, and sintering. When the substitution amount of Sb was 0.05, the ceramics had a single perovskite structure, and good grain morphology. The particles were blocks, and the grain size was between 3-4 ?m. The piezoelectric constant increased at first and then decrease with the increasing concentration of K. When K/Na ratio is 0.46/0.54, the product(K_0.46Na_0.54Nb_0.95Sb_0.05O₃) obtained the high piezoelectric constant. The optimized hydrothermal method conditions and sintering system progress were discussed under K/Na ratio is 0.46/0.54. When the hydrothermal reaction temperature was 200 °C for 24 h and the sintering temperature was 1060 °C for 2 h, ceramics got the best performance, the piezoelectric constants d33=73 pC/N, density ?=4.55 g/cm3 and linear shrinkage D%=0.48.As for K_0.46Na_0.54Nb_0.95Sb_0.05O₃ ceramics, this paper researched the influence of sintering aids ZnO and MgO by orthogonal test and analysis. When the amount of ZnO, MgO achieved 10 mol%, 5 mol% respectively, and the sintering temperature of 1000 °C for 2h, the performance of ceramics reached the maximum, d33=93 pC/N, ?r=354.02, tan?=0.016, ?=4.12 g/cm3, D%=2.60. The crystal phase remained single perovskite structure, and grain size was between 2-3?m.For the same method, Ta element doped potassium sodium niobate-based ceramics were prepared. The ceramic powders were prepared by hydrothermal method at 200 °C for 24 h, and the ceramics were obtained after granulation, tabletting, and sintering at 1040°C for 2 h. As increase of Ta content, the XRD showed a transformation phase structure from orthorhombic phase to tetragonal phase, and the ceramics had a single perovskite structure. When K/Na ratio is 0.54/0.46, the product K_0.54Na_0.46Nb_0.8Ta_0.2O₃ obtained the high piezoelectric constant. When the hydrothermal reaction temperature was 200 °C for 24 h and the sintering temperature was 1060 °C for 1 h, ceramics got the better performance.As for K_0.54Na_0.46Nb_0.8Ta_0.2O₃ ceramics, this paper researched the influence of sintering aids ZnO and MgO by orthogonal test and analysis. When the amount of ZnO, MgO achieved 6 mol%, 5 mol% respectively, and the sintering temperature of 1060 °C for 1 h, the performance of ceramics reached the maximum, d33=55 pC/N, ?r=336.54, tan?=0.0148, ?=4.66 g/cm3, D%=1.29. The crystal phase remained single perovskite structure with the coexistence of orthorhombic phase and tetragonal phase, and the hollow in crystals was smaller.