Synthesis of KNbO3 Ceramics from Powder Fabricated by Sol-gel Process

Lead-free KNbO₃ ceramics were synthesized from alkoxy-derived powders fabricated by sol-gel process. The powders size-controlled from about 200 to 400 nm by different solvents and calcination temperatures were formed to ceramic discs by an ordinary ceramics processing, then sintered at 1020degC in K₂O-rich atmosphere. Single phase KNbO₃ ceramics were obtained by using a precursor solution refluxed at 120degC, however, their porosity showed about 31.5%, and constituted of fine pore with 20-320 nm in size. The Curie temperature (T_c) showed at 382degC, and was about 50degC lower than dense KNbO₃ ceramics.