32 results about "Ceramic chemistry" patented technology

The invention discloses a microwave dielectric ceramic and a preparation method thereof. The microwave dielectric ceramic is mainly composed of ZrO2, TiO2 and Nb2O5; the microwave dielectric property of the microwave dielectric ceramic can be improved by selectively adding MgO, CoO, ZnO, NiO and MnO2; the chemical constitution formula of the ceramic is xZrO3-YTiO2-zA(1+W)/3Nb(2-w)/2O3; in formula (I), A is one or more elements of Mg, Co, Zn, Ni and Mn; x, y and z are molar ratios, wherein x is between 0.2 and 0.7, y is between 0.2 and 0.6,, z is between 0.1 and 0.2, and, x plus y plus z is equal to 1; numerical range of w is l between 0 and 0.5. According to the microwave dielectric ceramic and the preparation method thereof, the ceramic has the characteristics that the dielectric constant is high, the loss is low, and the temperature coefficient is close to zero, and is liable to sinter; the preparation method has the characteristics that the price of raw materials is low, and a technology during production is simple.

The present invention relates to a high pressure-resistant energy-storing medium ceramic and its preparation method. The chemical composition of said ceramic is Sr(Ti0.95 Zr0.05) O3+Xmol% CaTiSiO5, in which X is greater than O and less than or equal to 20. Its preparation method includes the following steps: adopting solid-phase method, using SrCO3 and TiO2 to synthesize SrTiO3; using SrCO3 and ZrO2 to synthesize SrZrO3; using CaCO3 SiO2 and TiO2 to synthesize CaTiSiO5 powder body; mixing materials according to the above-mentioned chemical composition formula; ball-grinding according to the ratio of material; ball: water=1:1:1-1.2, drying; adding polyvinyl alcohol solution as binding agent, granulating, sieving with 40 meshes, press-forming, slowly heating to 600-650deg.C to remove binding agent, sintering at 1260-1420deg.C, heat-insulating for 2-6hr, so as to obtain the invented product.

The invention discloses high-energy-storage silver niobate-based lead-free antiferroelectric ceramic and a preparation method thereof.The chemical formula of the high-energy-storage silver niobate-based lead-free antiferroelectric ceramicis Ag<1-3x>La<x>Nb<0.9>Ta<0.1>O<3>, wherein x is the molar percentage, and the value of x can meets the electric neutrality requirement. The preparation method ofthe high-energy-storage silver niobate-based lead-free antiferroelectric ceramic comprises the following steps: (1) weighing raw materials according to a stoichiometric ratio in thechemical formula Ag<1-3x>La<x>Nb<0.9>Ta<0.1>O<3>, carrying out ball-milling mixing, drying, sieving and tabletting on the raw materials, and presintering the raw materials for 4-6 hours to obtain a rough blank; (2) grinding the rough blank, carrying out secondary ball milling, drying, sieving, granulating, and uniaxial compression molding, and carrying out isostatic cool compression molding to obtain a biscuit; (3)discharging glue from the biscuit, and sintering to obtain a ceramic chip; and (4) grinding and polishing the ceramic chipinto a ceramic sheet, brushing the ceramic sheet with a silver electrode, calcining, and cooling. The energy storage ceramic with high energy storage density and high energy storage efficiency can be obtained by doping a trace amount of La < 3 + > at ceramicA site, the energystorage density is up to 4.6 J/cm < 3 >, and the energy storage efficiency is up to 59%.

The invention relates to high-entropy ceramic with high hardness and high conductivity as well as a preparation method and application of the high-entropy ceramic. The chemical formula of the high-entropy ceramic is (AaBbCcDdEe)B12. The dodecaboride high-entropy ceramic provided by the invention has high hardness and high conductivity, enriches a boride high-entropy ceramic material system, has the advantages of low cost, simplicity, feasibility, wide application range and the like, and has great application potential in the field of electrical equipment bearing high stress and high conductivity.

The invention discloses a method for preparing low-loss wolframite-structure microwave dielectric ceramic by means of a reaction sintering technology.The chemical composition expression of the ceramic is AZrNb2O8, wherein A represents Mg, Co, Ni and Mn.When the ceramic is prepared, the raw materials such as ZrO2, MgO, CoO, NiO, MnO and Nb2O5 are blended according to the chemical formula, the technologies of material mixing, drying, sieving, granulating, compression molding and the like are conducted, sintering is conducted at 1,250 DEG C-1,300 DEG C by means of the reaction sintering technology, and the AZrNb2O8 ceramic is obtained.According to the method for preparing the low-loss wolframite-structure microwave dielectric ceramic by means of the reaction sintering technology, the technological processes of presintering and secondary material mixing are omitted, the preparation time is greatly reduced, the preparation cost is reduced, the reaction sintering process technology is simple, the obtained ceramic is excellent in microwave dielectric property, the process is environmentally friendly, and the ceramic has a great application value in industry.

Disclosed is a microwave dielectric ceramic with near-zero frequency temperature coefficient and preparation method, wherein the ceramic has the chemical formula of Ca1-xZnxLa4Ti5O17, wherein x=0.005-0.4, the ceramic is prepared from BaCO3, ZnO, La2O3, TiO2 as raw material through wet grinding and mixing, drying into powder, calcining at 1100-1200 deg. C, wet grinding again, drying and charging polyvinyl alcohol (PVA), press forming, calcining 2-4 hours in high temperature furnace, the prepared microwave dielectric ceramics can be widely applied to the manufacture of various dielectric resonators, electric wave filters and other microwave devices.

The invention belongs to the technical field of ceramic materials, and discloses a lithium-magnesium-niobium-aluminum-tungsten microwave dielectric ceramic and a preparation method thereof. The chemical expression of the ceramic is Li3Mg2Nb1-x(Al1/3W2/3)xO6, and x is larger than or equal to 0.02 and smaller than or equal to 0.08. The preparation method comprises the following steps: by adopting asolid-phase synthesis method, mixing Li2CO3, MgO, Nb2O5, Al2O3 and WO3 according to a stoichiometric ratio, carrying out ball milling, drying and sieving, presintering at 925-1000 DEG C to obtain presintered powder, performing ball milling again, drying, sieving and granulating, pressing into a green body, sintering the green body at 1075-1175 DEG C, keeping the temperature, and cooling to room temperature to obtain the required microwave dielectric ceramic. The microwave dielectric ceramic has the advantages of excellent microwave dielectric properties, low cost, simple preparation technique,no toxicity or pollution, and wide application prospects.

The invention provides lanthanum aluminate green ceramic as well as a preparation method and application thereof, and relates to the technical field of ceramic. The chemical component of the lanthanum aluminate green ceramic provided by the invention is LaAl < 11-2X-YNi < X > Cr < Y > Ti < X > O < 18 >, X is equal to 1.5-5.0, and Y is equal to 0.0-2.0. The lanthanum aluminate ceramic provided by the invention is green and bright in color, and has relatively high hardness, toughness and color saturation.

The invention discloses magnesium-zircon-germanium-niobium microwave dielectric ceramic with a low dielectric constant and an ultra-low dielectric loss and a preparation method and an application. A chemical expression of the microwave dielectric ceramic is Mg(Zr1-xGex)Nb2O8, wherein x is greater than 0 and less than or equal to 0.4. The preparation method comprises the following steps of: (1) preparing raw materials according to the chemical formula Mg(Zr1-xGex)Nb2O8 (x greater than 0 and less than or equal to 0.4), adding a certain proportion of deionized water and zirconia grinding media for ball milling on a ball mill, (2) drying the raw materials ball-milled in step (1), screening the raw materials with a 40-mesh sieve to form even grained powder, (3) calcining the powder in step (2),(4) performing secondary ball milling, drying and pelletizing on the ceramic powder prefired in step (3), screening the ceramic powder with a 60-mesh sieve, pressing the powder into a green body through a powder compressing machine, and (5) sintering the green body in step (4) at 1260-1320 DEG C for 3-6h to form the magnesium-zircon-germanium-niobium microwave dielectric ceramic. The microwave dielectric ceramic is applied in the field of communication. According to the microwave dielectric ceramic, the very excellent microwave dielectric property can be obtained only by partially replacing zircon ions with micro germanium ions.

The invention relates to the technical field of ceramic materials, in particular to reversible photochromic transparent ceramic as well as a preparation method and application thereof. The chemical composition of the reversible photochromic transparent ceramic is Ba (AxMgyBz) O3, wherein A is selected from at least one of Zr, Sn, Ti and Hf; b is selected from at least one of Ta and Nb; 4x + 2y + 5z = 4, x is greater than 0 and less than 1, y is greater than 0 and less than 1, and z is greater than 0 and less than 1. The reversible photochromic transparent ceramic disclosed by the invention has the characteristic of reversible conversion from grey white to brown. The Ba (AxMgyBz) O3 photochromic ceramic changes color under the condition of irradiation of about 365 nm and can restore to the original shape under the condition of irradiation of about 450 nm or heating, and the reversible photochromic transparent ceramic is high in color change contrast.

The invention, on one aspect, provides an organic dye-infrared up-conversion luminescent transparent ceramic composite material, which is composed of an organic dye and an infrared up-conversion luminescent transparent ceramic. The composite material is an organic matter with a strong absorption effect on near-infrared light with a wavelength of 780nm-1100nm. The chemical formula of the infrared up-conversion luminescent transparent ceramic is (HoxYbyY1-x-yZr0.03)2O3, wherein x is greater than or equal to 0.0005 and less than or equal to 0.02, and y is greater than or equal to 0.005 and less than or equal to 0.2. And the composite material is uniformly coated on a surface of the infrared up-conversion luminescent transparent ceramic. According to the material, organic dye molecules with strong absorption and long excited state service life in an infrared region are used as a sensitizing layer to absorb infrared light firstly, and then excited state electrons are transferred to a <2>F5/2 excited state energy level of Yb<3+> ions through resonance energy transfer, so that infrared up-conversion luminescence enhancement is realized. The up-conversion luminescent transparent ceramic Ho<3+>/Yb<3+>:Y2O3 and the preparation method thereof have important application in biomedicine and infrared sensing.

The present invention relates to low temperature sintered microwave dielectric ceramic and its preparation process, and belongs to the field of microwave dielectric ceramic technology. The material has the composition of Li2+xNb3xTi1-4xO3+yB2O3, where 0 C04B 35/462 C04B 35/622 H01B 3/12 1 8 2 2006/3/9 1821171 2006/8/23 100378031 2008/4/2 2008/4/2 2008/4/2 Shanghai Inst. of Ceramic Chemistry and Technology, CAS Shanghai 200050 Li Wei Zeng Qun Shi Jianlin Wu Wenjun Guo Jingkun

The invention relates to a high-dielectric low-loss doped barium calcium titanate ceramic and a preparation method thereof, and belongs to the technical field of inorganic non-metallic materials. The lead-free, non-volatile and toxic element-free doped barium calcium titanate ceramic is prepared by adopting a traditional solid-phase reaction method, the chemical formula is Ba0. 70Ca0. 30Ti1-x (Nb0. 5Fe0. 5) xO3, x is the mole number of (Nb0. 5Fe0. 5) 4 < + > and is larger than or equal to 0.04 and smaller than or equal to 0.06, and the material is simple in preparation process, low in cost, low in sintering temperature (1230-1300 DEG C), larger than 4100 in room temperature relative dielectric constant and low in dielectric loss (tan delta lt below 1kHz); 0.037), the dielectric temperature stability is good (the change rate 1t of the relative dielectric constant along with the temperature in the range of room temperature to 200 DEG C; the preparation method is suitable for preparing a high-energy density memory and a high-capacity capacitor, and has a relatively high industrial application value.

The invention discloses a high-dielectric microwave dielectric ceramic and a preparation method thereof, the chemical composition expression of the ceramic is aLi2O.bCoO.cLn2O3.dNb2O5.eCeO2 (I), and Ln is equal to Y, La or Sm. The microwave dielectric ceramic contains oxides of rare earth elements Y, La or Sm and has good microwave dielectric properties, and the microwave dielectric ceramic obtained by sintering the two oxides of the rare earth elements, Nb2O5 and CeO2 together has good microwave dielectric properties.

The invention discloses a method for promoting cold sintering of potassium-sodium niobate-based leadless piezoelectric ceramics through heat treatment of powder in a reducing atmosphere. The method comprises the following steps: firstly preparing potassium-sodium niobate powder, then carrying out heat treatment in a reducing atmosphere to improve the wettability of the powder and promote cold sintering, then adding deionized water into the potassium-sodium niobate powder, performing grinding, carrying out molding at a set temperature and uniaxial pressure, and then carrying out drying and sintering to obtain the KNN ceramic with excellent performance. The method is simple in process step and easy to operate, the wettability of the powder surface is improved, the problem that a liquid phase is not uniformly distributed on the surfaces of KNN particles in a conventional cold sintering process is solved, the surfaces of the KNN particles are wrapped with a potassium-rich phase more completely, volatilization of K and Na elements is effectively inhibited, deviation of a stoichiometric ratio of the KNN ceramic is reduced, and the performance of the potassium-sodium niobate-based ceramics is improved.

The invention discloses a polycrystalline YAG (yttrium aluminum garnet) ceramic chemical mechanical polishing solution, and belongs to the technical field of precision/ultra-precision machining. The pH value of the polycrystalline YAG ceramic chemical mechanical polishing solution is 7, and the polycrystalline YAG ceramic chemical mechanical polishing solution comprises a solute and a solvent, wherein the solvent is deionized water. The polishing solution comprises the following components in percentage by mass: 10-30wt% of silica sol, 1-5wt% of aluminum oxide abrasive particles, 0.1-0.5 wt% of an abrasive particle dispersing agent and a proper amount of a pH (Potential of Hydrogen) regulator according to the total mass fraction of 100%, and all the substances are uniformly mixed in deionized water through ultrasonic waves. By adopting the polishing solution, the ultra-smooth polishing of the polycrystalline YAG ceramic can be realized, the grain boundary height difference of the polished polycrystalline YAG crystal surface is obviously reduced, and the ultra-smooth and damage-free polycrystalline YAG crystal surface can be obtained; the grain boundary height difference can be effectively inhibited, and the purpose of super-smooth surface is achieved; and in addition, by adopting the polishing solution provided by the invention, the material removal efficiency is high, and compared with a polishing solution only containing silica sol or aluminum oxide, the removal efficiency is obviously improved.