32results about How to "Wide absorption bandwidth" patented technology

Disclosed are an electromagnetic wave absorber using a dielectric loss sheet, a method for fabricating the same, and a wind turbine blade having an electromagnetic wave function. The electromagnetic wave absorber comprises: a support layer for providing a resonant space of electromagnetic waves; a highly conductive backing layer assigned to a back surface of the dielectric support layer; and a dielectric lossy composite sheet layer formed on a front surface of the dielectric support layer, said dielectric lossy composite sheet layer having such a dielectric permittivity so as to generate a resonant peak with the electromagnetic waves reflected from the highly conductive backing layer.

The invention discloses a chrome iron ion double-doped complex selenium zinc sulfide laser material and a preparation method thereof. The molecular formula of the chrome iron ion double-doped complex selenium zinc sulfide laser material is Cr, Fe:ZnSxSe1-x, wherein x is not less than 0 and not more than 1. For the Cr and Fe transition metal ion energy band, the bandwidth is in a middle infrared wavelength range, the absorption and emission bandwidths are wide, the absorption and emission section areas are large, and ultrashort and ultrafast laser output with high peak power can be obtained. The Cr, Fe: ZnSSe laser material with excellent laser optical property can be subjected to LD (Laser Diode) direct pumping to manufacture an ultrafast laser device with low threshold, thus, the laser device is promoted to be more succinct and more miniature.

The invention discloses a BiFeO3/RGO composite wave-absorbing material and a preparation method thereof. The preparation method comprises the following steps: adding bismuth ferrite powder and hexadecyl trimethyl ammonium bromide into a graphene oxide aqueous solution together, stirring and ultrasonically dispersing uniformly, carrying out hydrothermal reaction on an obtained suspension, cooling to room temperature, washing and drying to obtain the reduced graphene oxide loaded bismuth ferrite particle composite material. The reduced graphene oxide loaded bismuth ferrite particle composite material has impedance matching and electromagnetic wave attenuation characteristics, is a good dielectric loss type stealth wave-absorbing material and has a good application prospect in the field of wave absorption.

A homogeneous core-shell composite material PPy @ PANI and a preparation method thereof. The invention relates to a core-shell composite material and a preparation method thereof and solves the problems that when a wave-absorbing material is prepared from polyaniline, a large quantity of auto-polymerization exists due to increase of the use amount of the polyaniline, thereby causing low use amount of the polyaniline, less coating quantity and non-uniformity of particles. In the homogeneous core-shell composite material PPy @ PANI, polypyrrole is employed as a core material and polyaniline is employed as a wall material. The preparation method includes following steps: (1) preparing PPy micro-spheres; and (2) dispersing the PPy micro-spheres into an acid solution, stirring the dispersion in ice-water bath, adding an aniline monomer and ammonium persulfate, performing a reaction in the ice-water bath, and cleaning and drying a reaction product to obtain the homogeneous core-shell composite material PPy @ PANI. A wave-absorption material prepared from the homogeneous core-shell composite material PPy @ PANI is thin in wave-absorption layer, is light in weight, is wide in absorption band and is strong in adsorption capability. The material can be used in the field of stealth technology and electromagnetic wave shielding.

The invention discloses a terahertz switch and a control method based on a periodic graphene structure absorption characteristic. According to the invention, a multilayer graphene array is adopted, and the multilayer graphene array is provided with different resonance absorption peaks, so that wider absorption bandwidth is obtained; the resonance absorption frequency of the graphene array is adjusted by changing a bias voltage, thereby controlling the on-off of the corresponding frequency of the output wave and realizing the switching function; due to the high electron mobility characteristicof the graphene, the switch has a faster switching speed; the ON/OFF state of the switch is switched by adopting an electric tuning mode, and the switch is simple in operation and low in energy consumption; the switch works in the terahertz frequency band, the application range of the terahertz device is widened; By changing the effective length of the graphene unit of the graphene array, the terahertz switch is suitable for the input wave and the output wave which are terahertz wave, microwave, infrared or visible light.

The invention discloses an organic/perovskite bulk heterojunction nanowire photodetector, which comprises three parts, namely a substrate, a perovskite/2,7-dioctyl[1] benzothieno[3,2-b] benzothiophenebulk heterojunction nanowire light absorption layer and an electrode. A preparation method comprises the following steps of preparing the substrate, and cleaning and processing the substrate; preparing a perovskite material solution; preparing perovskite/2,7-dioctyl[1] benzothieno[3,2-b] benzothiophene mixed material precursor solution; preparing a perovskite/2,7-dioctyl[1] benzothieno[3,2-b] benzothiophene bulk heterojunction nanowire by using spin-coating, blade-coating and printing methods to obtain a high-quality light absorption layer; and preparing an electrode by adopting an evaporation or printing method. The product disclosed by the invention has the advantages of being short in response time, high in photoresponsivity and stable in air, and has an important application prospect.

The invention discloses a lightweight composite wave-absorbing material and a preparation method thereof. The lightweight composite wave-absorbing material comprises magnetic powder and a lightweightmatrix, the lightweight matrix is formed by compounding microspheres with a hollow structure and a binder, and the magnetic powder is dispersed among the microspheres. The preparation method comprisesthe following steps: (1) preparing a lightweight matrix solution, namely uniformly mixing and stirring a solvent and a binder until the solvent and the binder are completely dispersed, and then adding microspheres; uniformly stirring and dispersing the binder and the microspheres in a solvent to form a light matrix solution; and (2) preparing the light composite wave-absorbing material: adding magnetic powder into the lightweight matrix solution obtained in the step (1), stirring to uniformly disperse the magnetic powder, and curing to remove the solvent to obtain the lightweight composite wave-absorbing material.

The invention discloses an oriented honeycomb wave-absorbing material and a preparation method thereof, and belongs to the technical field of electromagnetic wave functional materials. The preparation method comprises the following steps: (1) dipping treatment of a honeycomb base material: dipping the honeycomb base material in magnetic absorbent slurry to obtain a honeycomb material coated with a magnetic wave-absorbing coating; and (2) orientation and molding of the honeycomb material: rotating the honeycomb material coated with the magnetic wave-absorbing coating in a magnetic field for 6-12 hours, and then heating and curing to obtain the oriented honeycomb wave-absorbing material. An impregnation method and a magnetic field induction method are combined, on the basis of an existing honeycomb structure wave-absorbing material, the spatial arrangement of the absorbent on the honeycomb wall is changed by applying a magnetic field, the orientation degree of the absorbent is improved, the obtained honeycomb material has remarkably improved magnetic loss, and especially in a P frequency band, and the low-frequency absorption performance of the wave-absorbing material is effectively improved.

The invention provides a low-frequency broadband composite micro-perforated plate sound absorption structure which comprises a perforated plate, a sound absorption back cavity with an opening in the upper end and a plurality of inclined back plates, submillimeter holes are formed in the perforated plate, the perforated plate covers the opening in the upper end of the sound absorption back cavity, and the inclined back plates are arranged in the sound absorption back cavity. All the inclined back plates are sequentially and fixedly connected end to end from top to bottom to form a snakelike fold line structure, the included angles between all the inclined back plates and the horizontal plane are the same, one ends of the inclined back plates are alternately fixed to the front frame plate and the rear frame plate, and slits are formed between the other ends of the inclined back plates and the left frame plate and the right frame plate. And all the inclined back plates divide the sound absorption back cavity into bent channels. The inclined back plate structure is added in the micro-perforated plate sound absorber, so that the frequency of the sound absorption peak of the micro-perforated plate sound absorber is reduced, and the sound absorption coefficient at the peak frequency is improved; an additional absorption peak is introduced on an original sound absorption curve; and after the porous material is added into the structure, the sound absorption frequency band of the perforated plate is effectively widened.

Disclosed is a neodymium-doped lanthanum strontium aluminate tantalate laser crystal and process for preparation, wherein the crystal has a structural formula of (NdxLa(0.3-x)Sr0.7)(Al0.65Ta0.35)O3, wherein the value range of x is between 0.1-10 at%, the preparation method of the crystal comprises the following steps: (1) weighing raw materials of La2O3, SrCO3, Al2O3, Ta205 and Nd203 according to the molecular formula and chemical measurement, (2) mixing the raw material homogeneously, tabletting and placing aluminium oxide crucible into a Muffle furnace, sintering more than ten hours at 1200 deg C, (3) loading the sintered Nd:(La,Sr)(Al,Ta)O3 into a iraurite crucible, using (La,Sr)(Al,Ta)O3 single crystal as seed crystal, growing with intermediate frequency induction Czochralski method in inert gas atmosphere.

The invention discloses a metal-carbon composite particle and a preparation method and application thereof. The preparation method of the metal-carbon composite particles comprises the following steps: 1) dispersing cobalt salt or/and nickel salt and trimesic acid in a solvent, and reacting to obtain cobalt or/and nickel-based MOF (Metal Organic Framework); and 2) calcining the cobalt or/and nickel-based MOF in a protective atmosphere to obtain the metal-carbon composite particles. The metal-carbon composite particle has the advantages of excellent microwave absorption performance, wide absorption bandwidth, good impedance matching performance, light weight and simple preparation method, can be used in electromagnetic wave absorption materials, and has a very wide application prospect.