Search

CN-121974681-A - Semiconductor ceramic material composition and preparation method thereof

CN121974681ACN 121974681 ACN121974681 ACN 121974681ACN-121974681-A

Abstract

The invention relates to the technical field of functional ceramic materials and preparation thereof, and discloses a semiconductor ceramic material composition and a preparation method thereof, wherein the composition comprises, by weight, 90-99.5 parts of a main component, wherein the main component is formed by compounding SrTiO 3 and BaTiO 3 , the molar ratio of SrTiO 3 to BaTiO 3 is 0.3-0.8:0.2-0.7, 0.2-1.0 part of a grain dopant, the grain dopant is at least one of rare earth element oxide or Nb 2 O 5 , and 0.3-1.5 parts of a grain boundary modifier. According to the invention, through a specific molar ratio composite main component system of SrTiO 3 and BaTiO 3 , the dielectric response temperature region of the material is widened from the source, the optimal matching of the phase structure and the lattice constant is realized, and the foundation of excellent temperature stability is laid.

Inventors

  • XIONG ZHIHONG
  • ZHU FENG
  • ZHENG SIWEN

Assignees

  • 广州仕上科技有限公司

Dates

Publication Date
20260505
Application Date
20260206

Claims (10)

  1. 1. A semiconductor ceramic material composition characterized by comprising, in parts by weight: 90-99.5 parts of main component, wherein the main component is formed by compounding SrTiO 3 and BaTiO 3 , and the mol ratio of SrTiO 3 to BaTiO 3 is 0.3-0.8:0.2-0.7; 0.2-1.0 part of grain dopant, wherein the grain dopant is at least one of rare earth element oxide or Nb 2 O 5 ; 0.3-1.5 parts of grain boundary modifier, wherein the grain boundary modifier comprises MnO 2 and SiO 2 , and the weight ratio of MnO 2 to SiO 2 is 0.5-2:1; And 0.5-5.0 parts of a sintering aid, wherein the sintering aid comprises CaCO 3 or SrCO 3 or a mixture of the two.
  2. 2. A semiconductive ceramic material composition according to claim 1, wherein the method of preparation of the main component comprises: Respectively adopting a solid phase method to synthesize high-purity SrTiO 3 and BaTiO 3 powder, and then mechanically mixing according to the molar ratio to obtain uniform composite powder; Preparing a mixed metal ion solution by taking strontium nitrate, barium nitrate and tetrabutyl titanate as precursors according to the molar ratio of SrTiO 3 to BaTiO 3 , and dripping a precipitant into the mixed metal ion solution by adopting a chemical coprecipitation method under stirring to enable Sr 2+ 、Ba 2+ 、Ti 4 + ions to realize molecular-level mixing to form precipitation; filtering to obtain bottom sediment, and calcining to obtain (Sr, ba) TiO 3 composite powder with uniform components.
  3. 3. The semiconductor ceramic material composition of claim 2, wherein the rare earth element oxide is one or more of Y 2 O 3 、Er 2 O 3 or La 2 O 3 , and the dopant is introduced by the following method: in the primary ball milling mixing stage of the main component powder, the main component powder is directly added in the form of nano Y 2 O 3 、Er 2 O 3 or La 2 O 3 powder; or soaking in soluble nitrate or acetate solution to obtain powder, and drying and thermal decomposing to obtain the final product.
  4. 4. A semiconductive ceramic material composition according to claim 3, wherein the grain boundary modifier further comprises Al 2 O 3 in an amount of 0.5-5% by weight of the total weight of the grain boundary modifier, which is prepared by: Mixing tetraethoxysilane with absolute ethyl alcohol, deionized water and a catalyst, hydrolyzing at 60-80 ℃ to form silica sol, and sequentially and slowly adding a manganese nitrate aqueous solution and an aluminum isopropoxide alcoholic solution with specified stoichiometric ratio into the silica sol under continuous stirring to obtain a uniform and transparent Mn-Si-Al ternary composite precursor solution; Regulating the pH value and the temperature of the precursor solution, performing polycondensation reaction at 40-60 ℃ to gradually form wet gel, standing and ageing the wet gel in a closed environment for 12-48 hours to strengthen the network structure of the wet gel, and then performing repeated exchange washing on the gel by using ethanol to remove residual moisture, nitrate ions and other byproducts in the system; And (3) performing supercritical drying on the washed gel to obtain xerogel with low density and high porosity, calcining the xerogel in air at 500-700 ℃ for 2-4 hours to thoroughly remove organic matters and stabilize inorganic oxide phases, obtaining superfine MnO 2 -SiO 2 -Al 2 O 3 composite oxide powder, and performing light grinding on the calcined powder to obtain a modifier precursor with uniform molecular-level mixture and nano-level particle size.
  5. 5. A semiconductive ceramic material composition according to claim 4, wherein the weight ratio of CaCO 3 to SrCO 3 in the sintering aid is 0.8-1.2:1; the preparation method comprises weighing analytically pure CaCO 3 and SrCO 3 powder in proportion, ball-milling and mixing in ethanol medium for 4-8h, drying, and sieving to obtain mixed auxiliary agent powder with uniform activity.
  6. 6. The semiconducting ceramic material composition of claim 5, wherein the composition feedstock has a powder specific surface area of 4.0-8.0 m2/g and a cumulative particle size distribution d90≤1.2 μm.
  7. 7. A method for preparing a semiconductive ceramic material composition according to any one of claims 1-6, comprising in particular the steps of: S11, weighing the raw materials of each component according to the weight portion, placing the raw materials in a ball milling tank, and performing wet ball milling and mixing by taking deionized water and zirconia balls as media to obtain uniform slurry; S12, drying the slurry, and calcining the solid precipitate obtained after the drying is completed at 1100-1250 ℃ for 2-4 hours to obtain presintered powder; S13, performing secondary ball milling on the presintered powder until the specific surface area is 5.0-7.5 m < 2 >/g, and then adding a binder for granulating to obtain powder for molding; S14, pressing the molding powder to form a blank, and then performing glue discharging treatment for 0.5-2h at 800-1000 ℃ in air; and S15, sintering the gel-discharged green body for 1-3 hours at 1300-1400 ℃ in a reducing atmosphere, and then performing heat treatment for 1-4 hours at 900-1100 ℃ in an oxidizing atmosphere to obtain the semiconductor ceramic material.
  8. 8. The method for preparing a semiconductor ceramic material composition according to claim 7, wherein in S11, specific process parameters of the wet ball milling mixing are: The ball-material ratio is controlled at 5-10:1, the rotating speed of the ball mill is 200-400r/min, and the mixing time is 6-24h, so as to ensure that the components reach the uniform mixing of molecular level; In S12, the drying treatment adopts a spray drying method, the inlet temperature is controlled to be 180-220 ℃ and the outlet temperature is controlled to be 80-100 ℃ so as to obtain spherical particles with good fluidity, and then the dried particles are placed in an alumina crucible and are heated to the calcination temperature at a heating rate of 2-5 ℃ per minute under an air atmosphere.
  9. 9. The method for producing a semiconductive ceramic material composition according to claim 7, wherein in S13, the secondary ball milling is performed by using a planetary ball mill using zirconia balls having a diameter of 0.5 to 2mm as a milling medium, and the powder is ball milled to have an accumulated particle size distribution D50 of 0.4 to 0.8 μm and d90≤1.5 μm; the added binder is polyvinyl alcohol aqueous solution with the concentration of 5-8wt%, and the addition amount is 3-6% of the total weight of the presintered powder; In S14, the pressing forming adopts an isostatic pressing process, the pressure is 100-200MPa, the dwell time is 30-90S, and the glue discharging treatment is carried out at the temperature rising rate of 0.5-2 ℃ per minute from room temperature to the glue discharging temperature.
  10. 10. The method for producing a semiconductor ceramic material composition according to claim 9, wherein in S15, the reducing atmosphere is a mixed gas having a volume fraction of 2 to 5%H 2 and the balance of N 2 , and the gas flow rate is maintained at a slight positive pressure in the furnace; The temperature raising program of the sintering process in the reducing atmosphere is that the temperature is raised from room temperature to 1000 ℃ at 3-5 ℃ per minute, and then raised to the highest sintering temperature at 1-2 ℃ per minute, and the blank body after the glue discharging treatment needs to be subjected to surface cleaning and accurate weighing before entering S15, so that the blank body is determined to reach 50-60% of theoretical density.

Description

Semiconductor ceramic material composition and preparation method thereof Technical Field The invention relates to the technical field of functional ceramic materials and preparation thereof, in particular to a semiconductor ceramic material composition and a preparation method thereof. Background The semiconductor ceramic is a functional material with unique electrical properties, and is characterized in that conductive crystal grains and insulating crystal boundaries exist in the ceramic body at the same time, so that physical properties such as high nonlinear volt-ampere characteristics, high dielectric constants and the like are shown, a main technical system in the field is mainly developed around two main types of materials, namely, ferroelectric material-based semiconductor ceramic represented by barium titanate (BaTiO 3), the semi-conductivity of the crystal grains is realized through donor doping (such as rare earth elements, nb and the like), and an insulating layer is formed by utilizing acceptor impurities (such as Mn, cu and the like) or additives (such as SiO 2、Al2O3 and the like) segregated at the crystal boundaries, and the material is widely applied to PTC thermistors and boundary layer capacitors, the performance of the material is highly dependent on phase changes near the Curie temperature, the resistance mutation characteristics are obvious, but the performance stability of the material in a high-temperature region above the Curie point faces challenges. The other is a non-ferroelectric or paraelectric material-based semiconductor ceramic represented by strontium titanate (SrTiO 3), which is of interest because of its more stable dielectric properties over a wide temperature range, and has potential in particular in high voltage varistors and energy absorbing elements. The traditional preparation process adopts a solid phase reaction method, namely, mixing, ball milling and calcining oxide or carbonate raw materials, forming and finally sintering in a specific atmosphere. Despite the significant progress made in the prior art, several technical problems to be solved are still exposed in the need of pursuing higher performance, better stability and more complex application scenarios: In the material system level, single BaTiO 3 -based or SrTiO 3 -based materials are difficult to combine high nonlinearity and wide temperature range stability, the performance of the BaTiO 3 -based materials is sensitive to temperature, while the SrTiO 3 -based materials are sometimes inferior to the former in obtaining high nonlinearity coefficients, simple physical mixing or attempting to form solid solutions, if deep understanding and accurate control on component proportions are lacking, unstable material phase structures and unsatisfactory dielectric properties are easily caused, or the action mechanism of doping elements is complicated, and independent and accurate regulation and control of grain conductivity and grain boundary insulativity are difficult to realize; although the reduction-reoxidation process is effective in the preparation process, the parameters are wide, the fine control on the key stage of cooling after sintering is lacking, and the rapid cooling can lead to concentration of grain boundary stress and uneven glass phase distribution, so that the height of a grain boundary barrier is discrete, and the uniformity of breakdown voltage of a product is poor and leakage current is large. Based on the above, a novel semiconductor ceramic material with scientific component design, accurate process control and high synergy of all links and a preparation method thereof are developed, and the method has important significance for promoting technical progress of industry. Disclosure of Invention The invention aims to provide a semiconductor ceramic material composition and a preparation method thereof, which widen the dielectric response temperature region of the material from the source through a specific molar ratio composite main component system of SrTiO 3 and BaTiO 3, realize the optimized matching of a phase structure and a lattice constant, lay the foundation of excellent temperature stability and aim at solving the problems in the prior art. The invention is realized in that a semiconductor ceramic material composition comprises the following components in parts by weight: 90-99.5 parts of main component, wherein the main component is formed by compounding SrTiO 3 and BaTiO 3, and the mol ratio of SrTiO 3 to BaTiO 3 is 0.3-0.8:0.2-0.7; 0.2-1.0 part of grain dopant, wherein the grain dopant is at least one of rare earth element oxide or Nb 2O5; 0.3-1.5 parts of grain boundary modifier, wherein the grain boundary modifier comprises MnO 2 and SiO 2, and the weight ratio of MnO 2 to SiO 2 is 0.5-2:1; And 0.5-5.0 parts of a sintering aid, wherein the sintering aid comprises CaCO 3 or SrCO 3 or a mixture of the two. Further, the preparation method of the main component comprises the following