Method for synthetizing leadless piezoelectric ceramic K0.65Na0.35NbO3 powder adopting two-step hydrothermal method

Abstract

The invention provides a method for synthetizing leadless piezoelectric ceramic K0.65Na0.35NbO3 powder adopting a two-step hydrothermal method. Excess potassium hydroxide and excess sodium hydroxide are taken as a potassium source and a sodium source respectively and dissolved in deionized water; then niobium pentoxide is added into the solution respectively, and precursor solutions of KNbO3 and NaNbO3 can be synthesized respectively after even stirring; the precursor solutions are sealed in a hydrothermal kettle respectively, the hydrothermal kettle is placed in a thermostat for hydrothermal synthesis at a certain temperature, cooling to the room temperature is performed after the reaction, and powder obtained through the reaction is washed with deionized water for several times and dried finally. After a grinding process, KNbO3 powder and NaNbO3 powder are accurately weighed and mixed in the deionized water; microwave oscillation is performed after stirring; the mixture is poured into a hydrothermal reaction kettle and sealed for hydrothermal synthesis, cooling to the room temperature is performed after the reaction, and a mixed liquid obtained through the reaction is fully dried to obtain the powder. According to the method, the two-step hydrothermal method is adopted to synthetize the K0.65Na0.35NbO3 powder, the preparation technology is good in repeatability, the material component proportion is accurate, the powder is good in uniformity and high in purity, and crystal grains are complete in development and even in distribution.

Description

technical field [0001] The invention relates to the field of piezoelectric ceramic powder preparation, in particular to a two-step hydrothermal synthesis of lead-free piezoelectric ceramic K 0.65 Na 0.35 NbO 3 powder method. Background technique [0002] The currently used piezoelectric ceramic material is lead zirconate titanate, wherein lead oxide in the lead-based piezoelectric ceramic accounts for about 70% of the total weight of the raw material. Since lead oxide is a volatile toxic substance, it will cause serious harm to humans and the ecological environment during use and disposal; at the same time, it needs to be sealed and sintered during the preparation process, which not only increases the cost of the product, but also causes damage to the product. performance consistency is poor. With the implementation of the social sustainable development strategy and the enhancement of people's awareness of environmental protection, the research and application of lead-fr...

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Problems solved by technology

For this purpose, chemical precipitation method and sol-gel method have been adopted successively. The above methods are either complicated in operation, or complex in process, long in cycle and poor in repeatability.

In contrast, the hydrothermal method has certain advantages in the synthesis of potassium sodium niobate, so it is the method adopted by most researchers, but the traditional hydrothermal method cannot avoid problems: because the binding abilities of K and Na ions to Nb are too different Large, if synthesized by the traditional one-step hydrothermal method, often (K, Na)NbO 3 The existence of K cannot be reflected in the powder at all; but the use of NaNbO 3 , KNbO 3 Separate synthesis and then mix, if mixed during washing, (K,Na)NbO 3 The ratio of potassium to sodium cannot be accurately controlled at all; if the prepared NaNbO 3 , KNbO 3 Powder weighing and mixing, although accurate potassium and sodium ratios can be guaranteed, but the uniformity after mixing will not be guaranteed

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