Preparation method of binary gradiently doped barium strontium titanate (BST) film

A gradient doping and binary doping technology, which is applied in the field of functional materials, can solve the problem that the comprehensive dielectric properties of BST films are difficult to improve, and achieve the effects of meeting the needs of microwave applications, small dielectric loss, and widening the Curie temperature range

Inactive Publication Date: 2011-09-07
UNIV OF ELECTRONICS SCI & TECH OF CHINA
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0004] Aiming at the limitation that the conventional BST film has a single ferroelectric phase or paraelectric phase and the technical problem that it is difficult to improve the comprehensive dielectric properties of the BST film, the present invention provides a method for preparing a binary gradient doped BST film

Method used

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  • Preparation method of binary gradiently doped barium strontium titanate (BST) film
  • Preparation method of binary gradiently doped barium strontium titanate (BST) film
  • Preparation method of binary gradiently doped barium strontium titanate (BST) film

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Embodiment 1

[0048] Embodiment 1: Gradient doping on yttrium and manganese (Ba 0.6 Sr 0.4 ) 0.8 TiO 3 Film preparation. Conditions: 6 layers, (Ba+Sr) / Ti=0.8, the doping concentration of the first film yttrium and manganese is 0.5% molar ratio, the doping concentration gradient is 0.1% molar ratio, the sixth layer film yttrium and manganese The doping concentration is 1% molar ratio. Its structural diagram is as figure 2 (a) shown.

[0049] Its preparation steps are as follows:

[0050] (1) Press (Ba 0.6 Sr 0.4 ) 0.8 TiO 3 The molar ratio of Ba, Sr, and Ti is 0.48:0.32:1 to prepare barium acetate, strontium acetate, and butyl titanate. Dissolve barium acetate and strontium acetate in hot glacial acetic acid to form a barium strontium precursor solution, and dissolve butyl titanate in Acetylacetone forms a titanium precursor solution; mix the two precursor solutions with 0.75% molar ratio of PVP to prepare a strontium barium titanate precursor solution, adjust the pH value to 3-4...

Embodiment 2

[0056] Embodiment 2: Gradient doping under yttrium and manganese (Ba 0.6 Sr 0.4 ) 0.8 TiO 3Film preparation. Conditions: 6 layers, (Ba+Sr) / Ti=0.8, the doping concentration of the first film yttrium and manganese is 1% molar ratio, the doping gradient is 0.1% molar ratio, the doping concentration of the sixth film yttrium and manganese The impurity concentration is 0.5% molar ratio. Its structural diagram is as image 3 (a) shown.

[0057] The preparation steps are as follows:

[0058] Steps (1)~(3) are identical with embodiment 1, just:

[0059] (4) Evenly drip BST sol with Mn and Y doping concentration of 1% molar ratio on the substrate, use CKF-411 type purification glue applicator to uniform glue at 3000~3500 rpm for 5~8 seconds, and then use Apply glue at 4500-5000 rpm for 25-30 seconds to form the first layer of wet film. The wet film is dried at 100-120°C for 5-10 minutes, pyrolyzed at 250-350°C for 10-15 minutes, preheated at 500-600°C for 10-15 minutes, and na...

Embodiment 3

[0062] Embodiment 3: Gradient doping on yttrium and manganese (Ba 0.6 Sr 0.4 ) 0.8 TiO 3 Film preparation. Conditions: 12 layers, (Ba+Sr) / Ti=0.8, the doping concentrations of Y and Mn in the first and second layers are both 0.5% molar ratio, and the doping concentrations in the third and fourth layers are both 0.6% Molar ratio, and so on, the doping gradient of two adjacent odd-numbered layers or even-numbered layers is 0.1% molar ratio, and the doping concentration of the eleventh and twelfth film is 1% molar ratio. Its structural diagram is as Figure 4 (a) shown.

[0063] The preparation steps are as follows:

[0064] Steps (1)~(3) are identical with embodiment 1, just:

[0065] (4) Evenly drip BST sol with Mn and Y doping concentration of 0.5% molar ratio on the substrate, use CKF-411 type purification glue applicator to uniform glue at 3000~3500 rpm for 5~8 seconds, and then use Apply glue at 4500-5000 rpm for 25-30 seconds to form the first layer of wet film. Th...

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Abstract

The invention provides a preparation method of a binary gradiently doped barium strontium titanate (BST) film, aiming at the technical problem that the comprehensive dielectric property of the BST film is difficult to increase owning to the ferroelectric phase or paraelectric phase single-phase structure caused by the narrow Curie temperature (Tc) range of the conventional BST film, and belonging to the technical field of functional materials. By controlling the molar ratio of Ba and Sr to Ti, the doping element, the concentration, the gradient, the direction and the film design and the preheating treatment and the film thickness (or layer number), the binary gradiently doped BST film with a wider Tc range, a ferroelectric phase and paraelectric phase composite structure and excellent comprehensive performance can be prepared, wherein the dielectric constant is less than 240, the tuning rate is more than 25%, the dielectric loss is less than 0.63% and the permittivity-temperature coefficient is less than 0.0024/K. The method is convenient, fast, cheap and efficient; and the prepared binary gradiently doped BST film can be used in microwave tuning elements.

Description

technical field [0001] The invention belongs to the technical field of functional materials, and relates to a preparation method of a binary gradient doped BST thin film, which broadens the range of the Curie temperature and greatly improves the comprehensive dielectric properties of the BST thin film. Background technique [0002] The non-linear variation of dielectric constant of BST film with external electric field has broad application prospects in the microwave field, and it has become the preferred material to replace ferrite and semiconductor. In order to realize the application of BST film in the microwave field, it is required that the film has excellent comprehensive dielectric tuning performance, that is, it has a dielectric tuning rate of more than 20%, a dielectric loss of less than 1%, a dielectric constant of less than 300 and a dielectric constant of less than 0.005 / K dielectric temperature coefficient. However, the curie temperature range of conventional B...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C04B35/468C04B35/624
Inventor 廖家轩尉旭波徐自强汪澎魏雄邦
Owner UNIV OF ELECTRONICS SCI & TECH OF CHINA
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