11 results about "Electrocaloric effect" patented technology

A method for improving the electrocaloric effect of ferroelectric perovskite material, by weighing Ba source, Sr source, Ca source, Hf source, Sn source, Zr source, Ti source and mixing uniformly according to stoichiometric ratio, pre-sintering to obtain (Ba x Sr y Ca z A 1‑x‑y‑z )(Hf a Sn b Zr c Ti d B 1‑a‑b‑c‑d )O3 powder; after fine grinding and mixing with binder, granulation, shaping, aging, plastic removal treatment to obtain ceramic green body; finally, through sintering, high electrocaloric performance barium titanate-based ferroelectric perovskite electrocaloric material is obtained, the application takes barium titanate ceramic as matrix, introduces zirconium, hafnium, tin, strontium, calcium and other element precursors during synthesis by solid phase method, simultaneously substitutes BaTiO3 material at A and B positions with multi-element doping, after blending, high temperature sintering to obtain finished product. The method has simple preparation condition, mature process, low cost and high reliability. Under the induction of electric field, great entropy change and electrocaloric effect are generated.

The invention provides a solid electric heating material as well as a preparation method and application thereof. The chemical formula of the solid electric heating material is [(CH3) 3NCH2Cl] CdCl3. The material is a typical first-level phase change material, phase change causes huge phase change latent heat and entropy change, and the entropy change in the phase change process can reach 50 J kg <-1 > K <-1 >. Meanwhile, the hysteresis of the material is small, the minimum thermal hysteresis can be as low as 3.2 K, the phase change of the material is sensitive to an electric field, and the isothermal entropy change under the small electric field of 7.3 MV m <-1 > exceeds 30 J Kg <-1 > K <-1 > and is far higher than that of an existing material. The [(CH3) 3NCH2Cl] CdCl3 material provided by the invention can realize a large electrothermal effect under a small electric field, so that the [(CH3) 3NCH2Cl] CdCl3 material has a huge potential application value in an electrothermal refrigeration technology.

The invention relates to the technical field of dielectric refrigeration device materials, in particular to bismuth ferrite-based lead-free ferroelectric ceramic with a negative electrocaloric effect as well as a preparation method and application of the bismuth ferrite-based lead-free ferroelectric ceramic, the chemical composition of the bismuth ferrite-based lead-free ferroelectric ceramic is 0.7 BiFe < 0.999 > Mn < 0.001 > O < 3-0.3 > BaTi < 1-x > Sn < x > O < 3 >, and x is greater than or equal to 0 and less than or equal to 0.1. The bismuth-ferrite-based lead-free ferroelectric ceramic has a wide working temperature area, a working temperature range close to room temperature and a relatively large negative electrocaloric effect, does not cause harm to the ecological environment and human health in the preparation, use and waste processes, and is suitable for development of miniature refrigerators in the future.

The invention discloses a high-sensitivity electrocaloric effect measuring device and measuring method, and relates to the technical field of electrocaloric effect measurement. The device comprises a constant-temperature cavity, a heat preservation cavity, a front signal amplifier, an oscilloscope, a heat dissipation substrate, a heat flow sensor, a gold electrode, a to-be-tested ceramic chip, a signal generator and a high-voltage amplifier. According to the measurement method, based on the signal response characteristics of the heat flow sensor, accurate measurement of the electrocaloric effect is achieved through reference calibration and integral calculation. The method solves the problems that in the prior art, the measurement period is long, the heat loss influence is large, and the intrinsic electrocaloric effect is underestimated, has the advantages of being high in measurement speed, high in sensitivity and high in accuracy, and can efficiently provide data support for high electrocaloric material design.

The invention belongs to the technical field of electronic functional materials and devices, and particularly relates to a PZT-based composite film with a wide-temperature-range negative electrocaloric effect, the PZT-based composite film with the wide-temperature-range negative electrocaloric effect is obtained by alternately overlapping a TiO2 component layer, an Hf0. 5Zr0. 5O2 component layer, a PbO component layer and a PbZrxTi1-xO3 component layer in sequence, x represents a mole fraction and is larger than or equal to 0.20 and smaller than or equal to 0.60, and each component layer is a single-layer sheet or is formed by overlapping multiple layers of sheets. The invention also provides a preparation method of the PZT-based composite film. According to the method disclosed by the invention, the large electrocaloric effect is effectively excited by regulating and controlling the defect dipole, so that the PZT-based composite film has the effect of the negative electrocaloric effect in a wide temperature range.

The application relates to an auxiliary loading device for observing an electroplastic effect in situ, comprising an in-situ electric pulse loading platform, a wire, a pulse power supply, a Hall current sensor, a data acquisition card, a computer, a probe and a scanning electron microscope; the probe is correspondingly arranged on one side of the in-situ electric pulse loading platform; the in-situ electric pulse loading platform is arranged on a sample stage of the scanning electron microscope; the in-situ electric pulse loading platform is connected to positive and negative poles of the pulse power supply through wires respectively, and the wire connected to the positive pole of the pulse power supply is connected to the data acquisition card through the Hall current sensor; the data acquisition card and the probe are both connected to the computer. The application can finely load a sample, observe the change of a structure by using a scanning electron microscope and an EBSD in-situ characterization, synchronously observe the influence law of the electroplastic effect of a pulse current on stress, strain, temperature and a structure of a material in situ, facilitate comparison of the structure performance change of different current densities and traditional isothermal heating with the same parameters, and help quantitatively distinguish a pure electric effect and an electric heating effect.

The application belongs to the technical field of middle infrared thermal emission control, and more particularly relates to a method and device for electrically driving narrow-band middle infrared thermal emission controlled by a polar substrate. The method provided by the application completely abandons the dependence on the design and processing of complex micro-nano structures, and only uses the intrinsic phonon properties of the polar crystal substrate and the electro-thermal effect of the low-dimensional material to achieve narrow-band and polarized emission, thereby greatly simplifying the implementation path, reducing the process cost and being conducive to large-scale preparation. In addition, the method creatively applies an electric signal as a core driving step, instead of traditional overall thermal heating, so that the intensity of thermal emission can be modulated in real time, quickly and programmably. While obtaining structural simplicity, the method first gives high-speed dynamic electric control capability to the thermal emission source without micro-nano structures, and solves the long-standing technical contradiction.

The application relates to the technical field of electronic functional materials and devices, and relates to a sodium bismuth titanate-based relaxor ferroelectric ceramic material with a composition gradient structure and a preparation method. 0.47 Na 0.47 Ba 0.06 Ti 1‑x (Li 1 / 4 Nb 3 / 4 ) x O3, and the preparation method comprises the following steps: according to the chemical formula, mixing raw materials, and sequentially performing a first ball milling, discharging, drying, pre-sintering, a second ball milling, discharging, drying, roller milling, flow casting, laminating and pressing, degassing and sintering processes to obtain the ceramic material. Compared with the prior art, the material provided by the application is a multilayer composite lead-free material, the ceramic has a novel design structure, the high electrocaloric effect in a wide temperature range is excellent, has great application prospects in the field of novel solid-state refrigeration technology, is not easy to pollute and damage the environment, has low preparation cost, good stability and the like.

A method for improving the electrocaloric effect of a ferroelectric perovskite material, comprising: weighing Ba, Sr, Ca, Hf, Sn, Zr, and Ti sources and mixing same uniformly according to a stoichiometric ratio; performing pre-sintering to obtain (BaxSryCazA1-x-y-z)(Hf aSn bZrcTidB1-a-b-c-d)O3 powder; after fine grinding and mixing with a binder, granulating the mixture, followed by forming, aging, and de-plasticizing to obtain a ceramic green body; and finally performing sintering to obtain a barium titanate-based ferroelectric perovskite electrocaloric material having high electrocaloric performance. In the present invention, barium titanate ceramic is used as a matrix, and elemental precursors such as zirconium, hafnium, tin, strontium, and calcium are introduced during solid-phase synthesis, and multi-element doping is performed at both the A-site and B-site to substitute into the BaTiO3 material. After blending and high-temperature sintering, the finished product is obtained. The method features simple preparation conditions, mature processes, low costs, and high reliability. Under the induction of an electrical field, a large entropy change and strong electrocaloric effect are generated.

The invention discloses a double-layer polymer film manufacturing method based on an electrocaloric effect, which comprises the following steps: blending a terpolymer P (VDF-TRFE-CFE) and BSZMT nano powder, adding an N, N-dimethylformamide solvent, and stirring until the mixture is clarified to prepare a nano composite solution; spraying the nano composite solution on the surface of a glass slide under pressure to form a first layer of wet film; drying the glass slide on which the first layer of wet film is formed at a first temperature, and annealing the dried glass slide at a second temperature to form a first layer of polymer film; printing carbon paste on the surface of the first layer of polymer film to form an intermediate layer electrode; spraying the nano composite solution on the surface of the first layer of polymer film under pressure to form a second layer of wet film; drying the glass slide on which the second layer of wet film is formed at a third temperature, and annealing at a fourth temperature to form a second layer of polymer film; and a polymerization structure formed by clamping the middle layer electrode between the first layer polymerization film and the second layer polymerization film is stripped from the surface of the glass slide, so that the double-layer polymerization film with high heat dissipation efficiency can be obtained.

The invention provides a thermal field adjusting device, a single crystal furnace and a thermal field adjusting method.The thermal field adjusting device is applied to the single crystal furnace, the single crystal furnace comprises a furnace body, a guide cylinder is arranged in the furnace body, the center of the guide cylinder is arranged to be a crystal bar lifting area, and the thermal field adjusting device is arranged between the inner side wall of the guide cylinder and the crystal bar lifting area; the thermal field adjusting device comprises an electric heating film and an electrode layer which are stacked in the radial direction of the guide cylinder, and a control unit arranged outside the furnace body; the control unit is configured to adjust the intensity of an electric field applied to the electric heating film by controlling the power-on state of the electrode layer, so that the electric heating film is switched between a heat absorption state and a heat release state. Based on the electrothermal effect principle, the control unit controls the electrode layer to be powered on and powered off so that the electrothermal film can be switched between the heat absorption state and the heat release state, the response speed of a thermal field can be remarkably increased, and instantaneous temperature fluctuation can be effectively restrained.