76results about How to "Moderate dielectric constant" patented technology

The invention provides a microwave dielectric ceramic material and a preparation method thereof, belonging to the technical field of electronic materials. The microwave dielectric ceramic material comprises the following components in percentage by mass: 25-35% of MgO, 60-68% of TiO2, 1-10% of CaO, 0-2% of SiO2, 0-2% of MnO2, 0-2% of Nb2O5 and 0-2% of CeO2; the microwave dielectric ceramic material is prepared by proportioning the MgO, TiO2, CaO, SiO2, MnO2, Nb2O5 and CeO2 according to the mass percentage of each component; performing ball milling and mixing; pre-calcining a mixture at a temperature in a range of 1050-1200 DEG C and sintering the mixture at the temperature in a range of 1250-1360 DEG C. In the invention, the microwave dielectric ceramic material is prepared by utilizing atraditional solid-phase sintering method, the process is simple and the cost is low; according to the prepared microwave dielectric ceramic material, the Q*f value is in a range of 63,000-83,000 GHz,the relative dielectric constant epsilon r is in a range of 20-22, and the temperature coefficient of resonance frequency is within +/-10 ppm/DEG C, so that the preparation requirements of a high-performance microwave device can be met.

The composite microwave tuning strontium barium titanate ceramics consists of strontium barium titanate and low dielectric loss material. The low dielectric loss material is preferably one with perovskite structure, such as LaAlO3, NdGaO3, La(Mg1/2Ti1/2)O3, La(Zn1/2Ti1/2)O3, etc. The said perovskite structure material and the strontium barium titanate have similar lattice constant and thus are easy to form solid solution, and have no harmful second phase created, no degradation in microwave dielectric loss and high tuning rate of strontium barium titanate. The material of the present invention may be used in phase shifter, adjustable filter, delay line, vibrator, resonator, phase-controlled array antenna and other microwave devices.

The invention discloses a method for preparing a porous barium strontium titanate field pyroelectric ceramic, comprising the following steps: firstly, mixing raw materials according to a stoichiometric ratio of respective chemical formula; pre-sintering the mixture at 800-1200 DEG C for 1-6 hours to obtain pre-sintered ceramic powder; then adding an organic substance pore-forming agent, mixing uniformly, tabletting and forming; heating again to remove organic substances; sintering, grinding, cleaning, adding an electrode and sintering the electrode. The porous BST field pyroelectric ceramic of the invention has the advantages of high pyroelectric coefficient, low dielectric loss, proper dielectric constant and excellent comprehensive pyroelectric property, and meets the requirements for manufacturing pyroelectric infrared detectors.

The invention discloses a multielement composite pyroelectric ceramic material and a preparation method thereof. The chemical general formula of the material is xPb(Me1/3Nb2/3)O3-yPb(Fe1/2Nb1/2)O3-zPb(Zr0.9Ti0.1)O3-mMe', wherein Me is one of Mn or Zn; x, y and z are respectively a mole coefficient, x is greater than or equal to 0.01 and less than or equal to 0.07, y is greater than or equal to 0.01 and less than or equal to 0.07, z is greater than or equal to 0.9 and less than or equal to 0.92, and x + y + z = 1; and Me' is a modifying metal element, m is a mole coefficient, and m is greater than or equal to 0 mol % and less than or equal to 5 mol %. The multielement composite pyroelectric ceramic material provided by the invention has a high pyroelectric coefficient, proper dielectric properties and a low dielectric loss, and the electrical properties can be adjusted, therefore, the multielement composite pyroelectric ceramic material has a good prospect in devices such as pyroelectric detectors and the like.

The invention discloses a low-temperature sintered microwave ceramic material and a preparation method thereof, and belongs to the technical field of materials. The low-temperature sintered microwave ceramic material comprises a main material-BaO-ZnO-TiO2, a first additive-BaCu(B2O5), a second additive-composite oxide and a third additive-MnO2. The preparation method comprises the following steps: taking BaCO3, ZnO and TiO2 as raw materials for synthesizing the main material-BaO-ZnO-TiO2, taking BaCO3, CuO and B2O3 as raw materials for synthesizing the first additive, taking BaCO3, ZnO, TiO2, SiO2 and B2O3 as raw materials for synthesizing the second additive, adding the first to third additives into the main material, performing ball-milling, drying, sieving, pelletizing, forming and rubber removing, and sintering in air at the temperature of 850-940 DEG C. The low-temperature sintered microwave ceramic material has the characteristics of high Q value, near-zero and serialized frequency temperature coefficient, moderate dielectric constant and good process stability through detection.

The invention discloses a microwave-tuned composite ceramic material and a preparation method thereof. The composite ceramic material consists of BaZrxTi1-xO3 and a mixture, wherein the BaZrxTi1-xO3 is 30 to 95 weight percent, and x is equal to 0.1 to 0.50; and the mixture consists of Mg2SiO4 and MgO, wherein the Mg2SiO4 in the mixture is 1 to 99 weight percent. The preparation method for the microwave-tuned composite ceramic material comprises the following steps: based on the stoichiometric proportion, preparing the BaZrxTi1-xO3 and the Mg2SiO4 respectively; obtaining the powder of the BaZrxTi1-xO3 and the powder of the Mg2SiO4 respectively by ball-milling, discharging, drying and presintering; doping the Mg2SiO4 and the MgO into the BZT powder according to the component design; and performing ball-milling, drying, pelleting, molding, batching out, then sintering at the furnace temperature if between 1,200 and 1,400 DEG C for 2 to 4 hours, and obtaining the needed material. The microwave-tuned composite ceramic material has the characteristics of proper dielectric constant, low dielectric loss, high tuning rate, and high performance and low sintering temperature. The microwave-tuned composite ceramic material can be applied to a phase shifter, an adjustable filter, a delay line, an oscillator, a resonator, a phased-array antenna, and other microwave devices.

The invention relates to a novel CaTiO3-based linear energy-storage-medium ceramic material and a preparation method thereof. The novel CaTiO3-based linear energy-storage-medium ceramic material is characterized in that the expression is ZnxCa(0.97-x)La0.03Ti0.97Al0.03O3, and x ranges from 0.01 to 0.2. The preparation method comprises steps as follows: CaCo3, TiO2, La2O3, Al2O3 and ZnO are taken as raw materials, weighed in the stoichiometric ratio according to the chemical formula ZnxCa0(0.97-x)La0.03Ti0.97Al0.03O3 with x ranging from 0.01 to 0.2, mixed, subjected to ball milling, dried, pre-sintered at the temperature of 1,000-1,150 DEG C and subjected to secondary ball milling, pre-sintered powder is obtained, the pre-sintered powder is sieved, mixed with an adhesive, granulated and formed, a ceramic body is obtained after dumping and sintered in air at the temperature of 1,200-1,300 DEG C, and the novel CaTiO3-based linear energy-storage-medium ceramic material is obtained. CaTiO3 ceramic is co-doped with Zn<2+> and La<3+>/Al<3+>, and the ZnxCa(0.97-x)La0.03Ti0.97Al0.03O3 linear energy-storage-medium ceramic material is obtained. The material has the characteristics of low dielectric loss, good frequency stability, moderate dielectric constant and relatively high breakdown strength.

The invention relates to a Co-modified metal organic framework-derived ZrO2/C electromagnetic wave absorbing material, and a preparation method and an application thereof. The electromagnetic wave absorbing material is of a three-dimensional network structure formed by interweaving one-dimensional fibers. The fiber is composed of a carbonaceous matrix, ZrO2 and Co nanoparticles. The Co nanoparticles are embedded in the surface of the carbonaceous matrix uniformly distributed by ZrO2. The method comprises the steps that 1, a cobalt source, a zirconium source, an anhydrous acetic acid organic ligand and DMF are processed into a solvothermal solution, the organic ligand containing a carbon source, an MOF precursor is obtained after solvothermal reaction, the MOF precursor is washed and dried,then the MOF precursor is treated with the cobalt source, and cobalt source composite MOF is obtained; and (2) the compounded MOF precursor is placed in a protective atmosphere to convert cobalt ionsin a cobalt source into elemental cobalt, a zirconium source into ZrO2 and an organic ligand into a carbon matrix, thereby obtaining the catalyst. According to the preparation method disclosed by theinvention, ZrO2, Co and C are effectively subjected to nanoscale compounding, so that the prepared material has excellent performance.

The invention relates to a low-temperature-sintered temperature-stable composite microwave dielectric ceramic and a preparation method thereof. The composite microwave dielectric ceramic comprises the following components: a low-temperature-sintered microwave dielectric ceramic material with a negative resonant frequency temperature coefficient and a low-temperature-sintered microwave dielectric ceramic material with a positive resonant frequency temperature coefficient. According to the invention, the low-temperature-sintered microwave dielectric ceramic material with a negative resonant frequency temperature coefficient or the low-temperature-sintered microwave dielectric ceramic material with the positive resonant frequency temperature coefficient is used as a main material, a low-temperature-sintered microwave dielectric ceramic material with the same structure and an opposite resonant frequency temperature coefficient is added as an adjusting material through a two-phase compounding method, and compounding is conducted to form a multiphase ceramic material or a solid solution so as to obtain a low-temperature-sintered microwave dielectric ceramic material having a nearly-zero resonance frequency temperature coefficient. The problems that existing microwave dielectric ceramic is high in sintering temperature, and the temperature coefficient of resonance frequency changes greatly along with temperature are solved. The microwave dielectric ceramic material has a wide application scope in the LTCC low-temperature-sintered microwave dielectric ceramic materials.

The invention relates to a high-Curie-temperature strontium-barium niobate pyroelectric ceramic material and a preparation method thereof. The material has the composition general formula of SrxBa1-xNb2O6, wherein x is larger than or equal to 0.25 and smaller than or equal to 0.35. The SBN ceramic material high in density and pyroelectric performance is obtained by preparing power through a solid phase method, preparing an SBN blank through cold isostatic pressing forming and other processes, putting the SBN blank in a mold, filling and covering the SBN blank with ZrO2 powder, raising the temperature to 1100-1150 DEG C, linearly and evenly pressurizing to 100-200 MPa with the axis of the mold as the hot-press axis, raising the temperature to 1200-1300 DEG C, keeping the temperature and the pressure for 2-4 h in the air atmosphere, and linearly depressurizing and cooling inside a furnace to the room temperature. The problem that high-Curie-temperature SBN components are poor in pyroelectric performance is solved.

The invention discloses a bismuth silicate powder preparation method using stoichiometric ratio raw materials and a sol-gel method. The preparation method comprises the following steps of S1, adding citric acid into mixed liquor of ethyl alcohol and water, then adding a proper amount of ethyl orthosilicate into the solution, and stirring until the solution is not layered, so that liquid A is prepared; S2, dissolving bismuth silicate into a proper amount of glycol, so that liquid B is prepared. According to the preparation method, the used raw materials are soluble bismuth salt and tetraethoxysilane liquid with stoichiometric ratio, purity levels are analyzed, purification can be performed by recrystallization, distillation and other methods, mass production is facilitated, single-phase powder is easy to obtain, and the cost is greatly lower than that of a traditional solid phase method; the composite powder can be used for crystal growth so that the quality of grown crystals is greatly superior to that of grown crystals prepared by the solid phase method; the composite powder can also be used for preparing microwave dielectric ceramic so that the prepared ceramic has the characteristics of moderate dielectric constant, low dielectric loss, low ceramic sintering temperature and the like.

The invention discloses intermediate temperature stable microwave dielectric ceramics. The intermediate temperature stable microwave dielectric ceramics is formed by sintering a main material and auxiliary materials. The composition expression of the main material is aMgTil+xO3-bCaTiO3, wherein x is less than or equal to 0.05 and greater than or equal to 0; and a and b respectively represent molarratio, a is less than or equal to 0.95 and greater than or equal to 0.90, b is less than or equal to 0.1 and greater than or equal to 0.05, and a+b equals to 1. The auxiliary materials are La2O3 andZnO, wherein La2O3 accounts for 0-1 wt% of mass of the main material and ZnO accounts for 0-0.1 wt% of mass of the main material. The invention also discloses a preparation method of the intermediatetemperature stable microwave dielectric ceramics. The intermediate temperature stable microwave dielectric ceramics has excellent microwave dielectric properties, has good temperature stability at both high temperature and low temperature, and has a wide application prospect. In addition, raw materials for the preparation are nontoxic, the cost is low, and the preparation process is simple.

The invention belongs to the field of pyroelectric ceramics, and specifically relates to a preparation method of la ead scandium tantalate pyroelectric ceramics. The method comprises the following steps: first, weighing a PbO powder and a ScTaO4 powder according to stoichiometric ratio, adding an excess 2.5-7.5wt% PbO powder, and mixing by a wet ball milling method to obtain a Pb (Sc0.5Ta0.5)O3 powder; Then carrying out an insulation synthesis on the Pb (Sc0.5Ta0.5)O3 powder to obtain a Pb (Sc0.5Ta0.5) O3 solid solution powder; mixing the Pb (Sc0.5Ta0.5) O3 solid solution powder by ball milling, drying, adding a binder, and carrying out steps of aging, sieving and moulding, etc. to prepare a Pb (Sc0.5Ta0.5) O3 base substrate; at last, carrying out hot pressing sintering on the Pb (Sc0.5Ta0.5) O3 base substrate in an oxygen atmosphere to obtain the lead scandium tantalate pyroelectric ceramics. The preparation method provided by the invention enables a sintering temperature of the leadscandium tantalate to lower to 1290-1320 DEG C, and the lead scandium tantalate pyroelectric ceramics prepared through the method have high pyroelectric performance and can be applied to an uncooled infrared detector.

The invention belongs to the field of electromagnetic wave absorbing materials, and particularly relates to a TiO2/Co-supported carbonaceous fiber electromagnetic wave absorbing material and a preparation method and application thereof. The electromagnetic wave absorbing material is of a three-dimensional network structure formed by interweaving one-dimensional fibers, the fibers are composed of acarbonaceous substrate and TiO2 and Co nanoparticles, wherein the TiO2 and Co nanoparticles are distributed in the carbonaceous substrate and the surface of the carbonaceous substrate. The method comprises the steps that (1) a cobalt source, an oxygen-containing organic titanium source and anhydrous acetic acid are prepared into an electrospinning viscous solution, wherein the electrospinning viscous solution comprises a carbon source, then spinning is performed on the viscous solution by adopting a high-pressure electrostatic spinning method to obtain nanofibers, and then the nanofibers aredried and pre-oxidized; (2) the pre-oxidized calcined nanofibers are placed in a protective atmosphere to convert cobalt ions in the cobalt source into elemental cobalt and convert the oxygen-containing organic titanium source into TiO2, and the TiO2/Co-supported carbonaceous fiber electromagnetic wave absorbing material is obtained. The TiO2/Co-supported carbonaceous fiber electromagnetic wave absorbing material and the preparation method and application thereof have the advantages that nanoscale composition is effectively performed on the TiO2, Co and carbon fibers, and the prepared materialhas excellent properties.

The invention discloses a leadless pyroelectric ceramic material and a preparation method thereof. The leadless pyroelectric ceramic material has the following general formula: Cax(Sr0.5Ba0.5)1-xNb2O6, wherein x is equal to 0-0.20. The provided leadless pyroelectric ceramic material can be prepared by employing a conventional solid-phase powder preparation method and an air sintering technology. The prepared leadless pyroelectric ceramic material has the advantages of small crystal grain size, moderate dielectric constant and typical ferroelectric phase at room temperature, also has excellent intrinsic pyroelectric performance, and the pyroelectric coefficient of the leadless pyroelectric ceramic material at room temperature is capable of rivaling that of PZT serial lead-containing pyroelectric ceramic. Additionally, the preparation method has the advantages of simple technology, no special equipment, low cost and the like, is suitable for large-scale production and accords with industrialized production requirements.

The invention discloses a composite pyroelectric ceramic material and a preparation method thereof. The chemical general formula of the material is Pb {[(Me1/3Nb2/3)x(W1/3Fe2/3)1-x]y(Zr0.9Ti0.1) (1-y) }O3-nMe', wherein Me is Mg or Zn; x and y represent a mole fraction respectively, x is larger than or equal to 0.125 and smaller than or equal to 0.875, and y is larger than or equal to 0.08 and smaller than or equal to 0.11; Me' is a modified element and is one or more of Li, La and Sb, and the molar ratio range n is larger than or equal to 0 mol% and smaller than or equal to 5 mol%. The composite pyroelectric ceramic material has a higher pyroelectric coefficient and adjustable dielectric property, thereby having a better application prospect in various pyroelectric detectors.

The invention discloses a terahertz waveband medium material, a preparation method and a method of preparing a dielectric medium therefrom. The chemical formula of the medium material is [(Mg<1 x>Al<2/3x>)<1/3>Nb<2/3>]O<2> + y wt% ABSMV, 0<=x<=0.3, and y=1 or 2. The medium material has the advantages of low sintering temperature, low dielectric loss, and moderate dielectric constant.

The invention relates to a high-performance ceramic dielectric material and a preparation method thereof, the high-performance ceramic dielectric material is composed of a main component and a modified doping agent, and the main component is BaTiO3; the modified doping agent comprises BaxSr1-x (ZrySn1-y) O3, x is equal to 0.2 to 0.9, y is equal to 0.1 to 0.8, and Bi2Zr2O7, and further comprises three or more of the following components: ZnO, Al2O3, WO3, Nb2O5, ZrO2, Li2CO3, Nd2O3, Sm2O3 or MnCO3. The sintering temperature of the high-performance ceramic dielectric material is 1250-1320 DEG C,the dielectric constant is adjustable within 15000-21000, the dielectric loss is less than or equal to 0.75%, the dielectric strength is greater than or equal to 5KVAc/mm, the temperature characteristic change rate is less than + 20-80% (-25-85 DEG C), and the material is suitable for manufacturing Y5V characteristic ceramic dielectric capacitors.

The invention discloses a microwave dielectric ceramic and a preparation method thereof. The microwave dielectric ceramic is RO doped magnesium-calcium-titanium system ceramic, and the chemical composition expression of the microwave dielectric ceramic is aMgTiO3-bCaTiO3-RO. The magnesium-calcium-titanium system ceramic is a main material, the chemical expression of the magnesium-calcium-titanium system ceramic is aMgTiO3-bCaTiO3, a and b respectively represent molar ratios, a is more than or equal to 0.90 and less than or equal to 0.99, b is more than or equal to 0.01 and less than or equal to 0.1, and a + b is equal to 1; the RO is a sintering aid, and comprises at least one of MnO2, Fe2O3, ZnO, SiO2, Nb2O5, Cr2O3, La2O3, NiO, ZrO2 and Nd2O3. According to the microwave dielectric ceramic, the RO doped magnesium-calcium-titanium system ceramic serving as the sintering aid is used for forming the microwave dielectric ceramic, and the microwave dielectric ceramic has the advantages of excellent microwave dielectric property, high quality factor, moderate dielectric constant, better temperature stability, excellent mechanical property, wide application prospect, simple preparation process, convenience in operation and good repeatability.