KNbO3 Powders Research Articles

Preparation Of Single-Phase Knbo3, Using Bimetallc Alkoxides

ABSTRACTSingle-phase KNbO3 was prepared using bimetallic alkoxides. Potassium-niobium ethoxide, KNb(OC2H5)6, and potassium-niobium propoxide, KNb(OC3H7)6, were synthesized and subsequently hydrolyzed using several water concentrations. Potassium-deficient particles were rapidly precipitated when higher water concentrations were used and this resulted in the formation of a multiphase material after calcination. In contrast, single-phase KNbO3 powders could be prepared by two methods: (1) hydrolysis of KNb(OC3H7)6/propanol solutions using 1 mole water (per mole of propoxide) added as a water/propanol solution and (2) hydrolysis of KNb(OC2H5)6,/ethanol solutions using 1 mole of water (per mole of ethoxide) added as a water/methanol solution. The latter method was also used to form thin films of KNbO3.

Characterization of KNbO3 Thin Films Deposited by Ion Beam Sputtering using a Computer-Controlled Rotating Target Holder

ABSTRACTKNbO3 is a strong candidate as a material for use as channel waveguides due to a high electrooptic figure of merit. High quality single crystals are difficult to obtain due to incongruent melting of the compound. Control of cation concentration and oxygen incorporation are problems encountered in current thin film processing routes.In order to overcome the problems discussed above, an ion beam deposition system featuring a computer-controlled rotatable target holder and quartz crystal resonator (QCR) feedback loop has been developed. Multicomponent films are produced via sputtering from elemental or compound targets sequentially exposed to an ion beam. Initial results are presented on the use of this new technique for the deposition of KNbO3. Pressed KNbO3, Nb2O5, and KO2 powders were used as sputtering targets. By varying the programmed thickness of deposited film from each target being sputtered, the ratio of K:Nb could be reproducibly controlled. The variation in sticking coefficients due to substrate temperature was also compensated for in this manner.Thin films were analyzed by X-ray diffraction and TEM to determine phases present and film microstructure. Film morphology and composition has been studied as a function of substrate temperature, layer thickness, and ion beam process parameters. The relation between deposition parameters and film characteristics are discussed.