Preparation method of CaCu3Ti4O12 ceramic

A technology of ceramics and cuo, applied in the field of preparation of CaCu3Ti4O12 ceramics, can solve the problems of secondary growth of crystal grains, ceramic properties, influence of ceramic structure, densification, deterioration, etc., to reduce high temperature and low frequency dissipation, uniform particle size, structure dense effect

Inactive Publication Date: 2011-09-07
NORTHWESTERN POLYTECHNICAL UNIV
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AI-Extracted Technical Summary

Problems solved by technology

The selection of sintering temperature, holding time and heating rate all directly affect the structure and densification of ceramics, espec...
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Abstract

The invention discloses a preparation method of CaCu3Ti4O12 (CCTO) ceramic, and the method can be used for solving the technical problem of high dielectric loss caused by the existing preparation method of the CaCu3Ti4O12 ceramic. The technical scheme of the invention is as follows: a casting technology is adopted to prepare a CCTO ceramic wafer, then a two-step sintering technology is adopted to obtain a ceramic material with dense structure and uniform particle size; and according to the changes of the dielectric constant epsilon r and dielectric loss tan delta of the CCTO ceramic along with the testing frequency and the temperature, CCTO crystalline integrity, grain boundary, defect and other aspects can directly influence the high dielectric constant. In addition, at the room temperature and 1KHz, when the sintering temperature is 1025-1100 DEG C and heat preservation is performed for 10 hours, the epsilon r of the CCTO ceramic prepared through two-step sintering is 104, which is more or less the same with the value reported in literatures; and the dielectric loss is reduced from 0.3-0.6 reported in the background art to 0.03, which shows that the concentration of oxygen vacancies can be reduced by adopting the two-step sintering method. Therefore, the high-temperature low-frequency dissipation of the ceramic can be significantly reduced; and the lattice distortions can be reduced along with the increase of the heat preservation time.

Technology Topic

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  • Preparation method of CaCu3Ti4O12 ceramic
  • Preparation method of CaCu3Ti4O12 ceramic
  • Preparation method of CaCu3Ti4O12 ceramic

Examples

  • Experimental program(4)

Example Embodiment

[0019] Embodiment 1: with high-purity 3.0414g CaCO 3 (>99%), 7.2514g CuO (>99%), 9.7074gTiO 2 (>99%) powder as the raw material, according to the CCTO stoichiometric ratio, mix 20g of material, ball mill in distilled water medium for 12h; dry and sieve the powder and pre-calcine at 960°C for 2h. Add 15.4ml ethanol, 0.25ml n-butanol and 0.36ml trioleic acid glyceride to the powder after pre-burning, then put into the nylon ball mill jar, and use ZrO 2 The ball is used as the grinding medium, and it is put into a planetary ball mill with a speed of 400rad/min for wet grinding for 23 hours; 0.9592g of polyethylene glycol, 1.0ml of dioctyl phthalate, and 1.3174g of polyethylene are added to the wet material that has been ground for 23 hours. Alcohol butyral and 0.24ml cyclohexane, and then ball milled for 20h at a speed of 350rad/min; pour the slurry into a small beaker and take out all the ZrO 2 Then pour the slurry into a casting machine with a clean and smooth glass plate, so that it moves at a constant speed on the glass ribbon to form a thin casting belt. The thickness of the cast is controlled by the cast blade, and the speed of movement also has a direct impact on the thickness of the thin strip; open the blowing equipment to dry for 12 hours, and then remove the film to obtain the cast green body, and the formed green The billet is cut into rectangular slices; then degumming is performed, and the degumming heating rate is controlled as follows: from room temperature to 100°C, 2°C/min, at 100°C for 1 hour; from 100°C to 550°C, 1°C/min, at 550°C Keep it warm for 2 hours to ensure that the organic matter can be completely removed, create conditions for firing and make the green body obtain a certain mechanical strength; sinter the green body after debinding treatment at 1025°C, and control the sintering heating rate: from room temperature to the required sintering Temperature 1050°C, 3°C/min; 1025°C to 960°C, 4°C/min, then cool with the furnace.

Example Embodiment

[0020] Embodiment 2: with high-purity 3.344g CaCO 3 (>99%), 7.9765g CuO (>99%), 10.6788gTiO 2 (>99%) powder as the raw material, according to the CCTO stoichiometric ratio of 22g material, ball milled in distilled water medium for 12h; the dried and sieved powder was pre-fired at 960°C for 2h. Add 15.48ml ethanol, 0.3ml n-butanol and 0.4ml triolein to the powder after pre-burning, then put it into a nylon ball mill jar, and use ZrO 2 The ball is used as the grinding medium, and it is put into a planetary ball mill with a speed of 400rad/min for wet grinding for 20 hours; 0.960g of polyethylene glycol, 0.997ml of dioctyl phthalate, and 1.321g of polyethylene are added to the wet material that has been ground for 20 hours. Alcohol butyral and 0.28ml cyclohexane, and then ball milled for 20h at a speed of 400rad/min; pour the slurry into a small beaker and take out all the ZrO 2Then pour the slurry into a casting machine with a clean and smooth glass plate, so that it moves at a constant speed on the glass ribbon to form a thin casting belt. The thickness of the cast is controlled by the cast blade, and the speed of movement also has a direct impact on the thickness of the thin strip; open the blowing equipment to dry for 12 hours, and then remove the film to obtain the cast green body, and the formed green The billet is cut into rectangular slices; then degumming is performed, and the degumming heating rate is controlled as follows: from room temperature to 100°C, 2°C/min, at 100°C for 1 hour; from 100°C to 550°C, 1°C/min, at 550°C Keep it warm for 2 hours to ensure that the organic matter can be completely removed, create conditions for firing and make the green body obtain a certain mechanical strength; the green body after debinding treatment is sintered at 1050°C, and the sintering temperature rise rate is controlled: from room temperature to the required sintering Temperature 1050°C, 3°C/min; 1050°C to 960°C, 4°C/min, then cool with the furnace. from figure 1 It can be seen from the figure that it is relatively dense, the particles are evenly arranged and have clear prismatic boundaries, forming better polygonal particles, and the crystal shape is better, but the crystal grains are relatively small and there are small grain inclusions.

Example Embodiment

[0021] Embodiment 3: with high-purity 3.7561g CaCO 3 (>99%), 8.9555g CuO (>99%), 11.9886gTiO 2 (>99%) powder as the raw material, according to the CCTO stoichiometric ratio of 24.7g material, ball milled in distilled water medium for 10h; the dried and sieved powder was pre-fired at 960°C for 2h. ; Add 15.5ml ethanol, 0.4ml n-butanol and 0.4ml trioleic acid glyceride to the powder after pre-burning, then put into the nylon ball mill jar, and use ZrO 2 The ball is used as the grinding medium, put it into a planetary ball mill with a rotation speed of 400rad/min for 24 hours; add 0.9663g of polyethylene glycol, 0.99ml of dioctyl phthalate, and 1.34g of polyethylene to the wet material that has been ground for 24 hours Alcohol butyral and 0.3ml cyclohexane, and then ball milled for 20h at a speed of 400rad/min; pour the slurry into a small beaker and take out all the ZrO 2 Then pour the slurry into a casting machine with a clean and smooth glass plate, so that it moves at a constant speed on the glass ribbon to form a thin casting belt. The thickness of the cast is controlled by the cast blade, and the speed of movement also has a direct impact on the thickness of the thin strip; open the blowing equipment to dry for 12 hours, and then remove the film to obtain the cast green body, and the formed green The billet is cut into rectangular slices; then degumming is performed, and the degumming heating rate is controlled as follows: from room temperature to 100°C, 2°C/min, at 100°C for 1 hour; from 100°C to 550°C, 1°C/min, at 550°C Keep warm for 2 hours to ensure that the organic matter can be completely removed, create conditions for firing and make the green body obtain a certain mechanical strength; the green body after debinding treatment is sintered at 1075°C, and the sintering temperature rise rate is controlled: from room temperature to the required sintering Temperature 1750°C, 3°C/min; 1750°C to 960°C, 4°C/min, then cool with the furnace. from figure 2 It can be seen that the particles are obviously enlarged and the contact between particles is close.
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