Preparation method of strontium titanate spherical nanocrystals

Abstract

The invention discloses a method for preparing strontium titanate spherical nanocrystals, which mainly solves the problems that the traditional strontium titanate preparation method is complicated, impurities are easily produced, and the purity and particle size of the strontium titanate powder are difficult to meet the requirements. Its realization scheme is: add amphoteric surfactant lauryl dimethyl betaine aqueous solution or cocamidopropyl betaine aqueous solution to the prepared strontium titanium mixed solution to obtain amphoteric surfactant modified strontium Titanium mixed solution; then add the prepared sodium hydroxide solution to it to obtain strontium titanium nano-precipitate modified by amphoteric surfactant; then filter, wash, dry, grind, dry and sinter the nano-precipitate in sequence , to obtain strontium titanate spherical nanocrystals. The invention has simple preparation operation requirements, short preparation period, is suitable for industrial production, has good sample dispersion and no agglomeration, has the characteristics required for the preparation of grain boundary layer capacitors, and can be widely used in radios, televisions, and computer circuits.

Description

technical field [0001] The invention belongs to the technical field of chemical materials, and in particular relates to a method for preparing strontium titanate spherical nanocrystals, which can be used for photocatalysis, medium and high voltage large-capacity ceramic capacitors, grain boundary layer capacitors, piezoresistors, PTC thermistors, multiple Functional sensors, these electronic functional ceramic materials and devices, can also be used in the frontier development and research of micro-nano devices such as various microelectronic heterostructures, micro-sensors, solar cells, multilayer ceramic capacitors and micro-thermoelectric devices. Background technique [0002] Strontium titanate is a typical perovskite-type electronic material with unique chemical and physical properties, namely photocatalysis and piezoelectricity, ferroelectricity and high dielectric constant. Due to its excellent physical and chemical properties, Coupled with its excellent photocorrosio...

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Problems solved by technology

But at the same time, nano-strontium titanate also exhibits high surface energy, which is particularly prone to "agglomeration", which hinders its development and application.

For example: the high-temperature solid-phase preparation process requires very high energy, the reaction must be carried out at high temperature, the reaction particle size is large, the particle size distribution is wide, the solid mixing is difficult, the raw materials cannot be completely reacted, and the quality of the obtained powder is poor. The impurity content is high, and the chemical composition is not single; at the same time, because the particles are easy to agglomerate with the primary particles in the micron size range with a wide size distribution, it is difficult to meet the needs of some advanced electronic functional ceramic devices

Another example is the microwave synthesis method, whose reaction temperature is high, which tends to cause the grain size to be too large, which is easy to mix, and the powder with high purity cannot be obtained. The surface activity is poor, and it is easy to form agglomerates, and the reaction is not complete.

[0007] 2. The preparation process is complicated, the process is dangerous, and it is harmful to the environment. The results of the prepared samples need to be improved, and the preparation process cycle is too long.

The weak point of this method is: (1) the use of hydrothermal reaction kettle increases the danger and the complexity of preparation technology; , this washing waste liquid containing ethanol is harmful to the environment

The disadvantages of this method are: (1) the use of nitric acid and ammonia increases the danger and complexity of the preparation process; (2) the preparation process cycle is too long; (3) requires that a transparent gel must be prepared, and Vacuum drying is required, which increases the complexity of the preparation process

The disadvantages of this method are: (1) the strontium salt solution is added dropwise in the fatty alcohol solution of titanate / titanium alkoxide, which is unfavorable for industrialized large-scale production; (2) the gel must be Each of the four temperature ranges of 200-250°C, 300-450°C, 550-650°C, and 800-900°C must be sintered for 1-2 hours, and the gel must be aged until fat is precipitated on the surface. The preparation process requirements of alcohol solvent and water, so the preparation cycle time is too long, and the complexity of the preparation process is increased

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