The Effect of Dopants on Sintering and Microstructure of Lead-free KNN Ceramics

Abstract

<p>Lead-free potassium sodium niobate (K_0.5Na_0.5)NbO₃ (KNN) has been prepared via conventional ceramic processing method. The influence of 0.5 wt% - 1.5 wt% MnO₂ and WO₃ addition on the sintering, crystallographic structure, microstructure and dielectric properties of KNN has been investigated. Optimal sintering temperatures of KNN ceramics were observed to be in the narrow interval: 1090 °C - 1110 °C for MnO₂ doped KNN; 1150 °C - 1170 °C for pure KNN and doped with WO₃. XRD patterns showed that all the samples have single perovskite structure with monoclinic structure. Microstructure of ceramics was changed greatly by using dopants.</p><p><a href="http://dx.doi.org/10.5755/j01.ms.17.1.251">http://dx.doi.org/10.5755/j01.ms.17.1.251</a></p

Structural refinement and optical band gap studies of manganese-doped modified sodium potassium lithium niobate lead — piezoelectric ceramics

“…MnO 2 doping in (Na 0.5 K 0.5 )NbO 3 (NKN) has led to enhanced piezoelectric and electromechanical properties. These results are appreciable and comparable to the PZT ceramics [4][5][6][7].…”

Stress Dynamics During O-T Phase Transitions in Lead-Free KNN-Based Piezoelectric Ceramics

“…Both the microstructure and grain distribution are affected by the incorporation of different Co-dopant amounts. Previous publications have also reported this fact, using different metal oxides as dopants [28][29][30]. Both samples have a plateshaped grain morphology with large grains surrounded by much smaller grains.…”

Effect of Different Compaction Pressure and Different Sintering Route on K0.5NA0.5NBO₃ Physical and Dielectric Properties

“…Many studies have been carried out in order to improve the piezoelectric properties of KNN-based ceramics. These include chemical modification to prepare compositions close to an MPB or the shift of the orthorhombic to tetragonal phase transition (T O-T ) to near or below room temperature, such as KNN-(Li, K, Ag) [16], KNN-Ag(Nb, Sb, Ta)O 3 [17], KNN-(Bi 0.5 Na 0.5 ) TiO 3 [18] and also adding sintering aids like MnO 2 and WO 3 [19] to achieve higher density of the final product.…”