Preparation method for cerium-doped barium strontium titanate (BST) thin film

Abstract

The invention relates to a preparation method for a cerium-doped barium strontium titanate (BST) thin film, belonging to the technical field of a functional material. The preparation method comprises the following steps: by taking barium salt, strontium salt, cerate and tetrabutyl titanate, not stronger than acetic acid, as raw materials, firstly preparing a barium-strontium precursor liquid, then adding cerate to form a barium strontium titanate precursor liquid, then adding PVP (Polyvinyl Pyrrolidone) to form a PVP barium strontium titanate precursor liquid, then adding ethylene glycol monomethyl ether and tetrabutyl titanate to form a cerium-doped BST precursor liquid, and then adding acetylacetone and metering the volume with glacial acetic acid to form BST sol; and then repeatedly leveling, drying, pyrolyzing, pre-crystallizing and cooling by adopting the BST sol to form a multilayered amorphous BST thin film, and finally crystallizing to obtain the cerium-doped BST thin film. According to the preparation method, the hydrolysis problem existing when the BST thin film is prepared by doping of high-concentration cerium (the cerium doping concentration is not lower than 5% of the concentration of titanium ions) can be solved, the prepared cerium-doped BST thin film has lower leakage current density and dielectric loss, thus meeting the microwave application of the cerium-doped BST thin film.

Description

technical field [0001] The invention belongs to the technical field of functional materials, and relates to a preparation method of barium strontium titanate (BST) thin film, especially a preparation method of cerium-doped BST thin film. Background technique [0002] Because of its unique dielectric properties, BST has broad application prospects in the fields of ferroelectric memory, pyroelectric detectors, and microwave tuning devices such as phase shifters. The relationship shows high tuning performance and becomes an important candidate material for microwave tuning devices. [0003] Cole et al clearly pointed out in Document 1 (Journal of applied physics, 2001, 89, 6336-6340) that in order to realize the microwave application of BST films, BST films must have low dielectric loss, high tuning rate, moderately small Dielectric constant, low leakage current density, dense ABO 3 Excellent comprehensive dielectric properties and structural characteristics such as perovskit...

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Problems solved by technology

Strong acid cerium salt is insoluble in acetic acid but easily soluble in water. In the preparation process of cerium-doped BST sol, deionized water needs to be added to the acetic acid solvent as a co-solvent to be widely used. However, the cerium salt and butyl titanate Hydrolysis necessarily precipitates the sol containing hydroxides of cerium and titanium

Although a sol can be obtained when doped at a low concentration, it is only because a small amount of deionized water corresponds to a relatively small amount of precipitation, which is almost slightly soluble in acetic acid and is not easy to detect. crystallization due to the reduction of , so that the gel contains precipitates, which seriously deteriorates the structure and dielectric properties of the BST film

When high-concentration cerium is doped, a large amount of deionized water needs to be added as a co-solvent, and a large amount of precipitation occurs due to strong hydrolysis, resulting in a suspension and no sol.

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