Relaxor ferroelectric ceramic with high electrocaloric effect at room temperature, and preparation method and applications thereof

A technology of electric card effect and ferroelectric ceramics, which is applied in the field of ferroelectric relaxation materials, can solve the problems of limited applied electric field strength, hindering the application of refrigerators, and low cooling degree, so as to improve mechanical properties and improve dielectric properties. properties, ferroelectricity, and the effect of improving density

Active Publication Date: 2019-11-26
SUZHOU UNIV OF SCI & TECH
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0004] The invention provides a relaxor ferroelectric ceramic with a high electric card effect at room temperature and a preparation method thereof, which are used to solve the problems of limited applied electric field strength, working temperature region much higher than room temperature or electric card problems in existing ferroelectric relaxor materials. Many problems such as the cooling degree not higher than 1.1K near room temperature and the low efficiency |ΔT / ΔE| of the electric card hinder the application of this ideal room temperature solid-state refrigerator

Method used

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  • Relaxor ferroelectric ceramic with high electrocaloric effect at room temperature, and preparation method and applications thereof
  • Relaxor ferroelectric ceramic with high electrocaloric effect at room temperature, and preparation method and applications thereof
  • Relaxor ferroelectric ceramic with high electrocaloric effect at room temperature, and preparation method and applications thereof

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Experimental program
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Effect test

Embodiment 1

[0041] The relaxor ferroelectric ceramic with high electric card effect at room temperature has a chemical composition of: 0.9KNbO 3 -0.1BaTiO 3 (KN / BT(9 / 1)), the specific preparation process is as follows:

[0042] 1) Take Nb 2 o 5 、K 2 CO 3 As raw material, according to the chemical formula: KNbO 3 For batching, use absolute ethanol as the medium to wet grind for 2 hours, dry and press into large pieces Φ15*15mm 2 , placed in a muffle furnace and kept at 640°C for 2 hours for calcination; the calcined block was crushed through a 40-mesh sieve and then ball-milled for 24 hours, dried and passed through a 200-mesh sieve for use; the prepared KNbO 3 Powder and Nano BaTiO 3 By 0.9KNbO 3 -0.1BaTiO for preparation, mixed by ball milling and drying, after drying, pressed into large pieces Φ15*15mm 2 , put it into a muffle furnace for calcination at 900°C for 2 hours, smash the block material in a mortar, pass through a 40-mesh sieve, wet-grind with absolute ethanol as a me...

Embodiment 2

[0047] The relaxor ferroelectric ceramic with high electric card effect at room temperature has a chemical composition of: 0.85KNbO 3 -0.15BaTiO 3 (KN / BT=8.5 / 1.5), the specific preparation process is as follows:

[0048] 1) Take Nb 2 o 5 、K 2 CO 3 As raw material, according to the chemical formula: KNbO 3 For batching, wet grinding with absolute ethanol as the medium for 2.5 hours, after drying, press into large pieces Φ15*15mm 2 , placed in a muffle furnace and kept at 640°C for 1.5 hours for calcination; the calcined block was crushed through a 40-mesh sieve and then ball-milled for 24 hours, dried and passed through a 200-mesh sieve for use; the prepared KNbO 3 Powder and Nano BaTiO 3 According to 0.85KNbO 3 -0.15BaTiO for preparation, mixed by ball milling and drying, after drying, pressed into large pieces Φ15*15mm 2 , put it into a muffle furnace for calcination at 900°C for 5 hours, smash the block material in a mortar, pass through a 200-mesh sieve, use absolu...

Embodiment 3

[0052] Embodiment 3 test experiment

[0053] The relaxor ferroelectric ceramics of high electric card effect under the room temperature that adopts embodiment 1 preparation carries out following test as test sample:

[0054] 1) Carry out XRD test at 1050°C, the XRD pattern is as follows figure 1 As shown, it can be found that the sample presents a pure KN-BT (9 / 1) perovskite structure at 1050 ° C;

[0055] 2) SEM was carried out on the natural surface and section of the sample, and the test results were as follows: figure 2 As shown, the natural surface is obviously composed of uniformly distributed fine grains and coarse grains, wherein the fine grains have a particle size of 0.2-0.5 μm, and the coarse grains have a particle size of 10-50 μm.

[0056] 3) EDS test and analysis of fine and coarse crystals in the sample, such as image 3 As shown, the molar ratios K:Nb and Ba:Ti are close to the stoichiometric ratio of 1:1, respectively, and the components do not segregate; ...

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Abstract

The invention belongs to the technical field of ferroelectric relaxor material, and more specifically relates to a relaxor ferroelectric ceramic with high electrocaloric effect at room temperature, and a preparation method and applications thereof. The chemical formula is (1-x)KNbO<3-x>BaTiO<3>. The relaxor ferroelectric ceramic comprises fine crystals and crude crystals based on crystal particlesize distribution. The preparation method comprises following steps: solid phase synthesis is adopted to prepare a first KN-BT powder; sol-gel method is adopted to prepare a second KN-BT powder and KN-BT ceramic blocks. The technology is capable of realizing synthesis of the high-density impure-phase-free stoichiometric-ratio-segregation-free KN-BT ceramic blocks, at room temperature (RT) conditions, great electrocaloric effect is achieved, the preparation method is simple and convenient, cost is controllable, and the application prospect and market value in the field of solid state refrigerators are promising and high.

Description

technical field [0001] The invention belongs to the technical field of ferroelectric relaxation materials, and in particular relates to a relaxation ferroelectric ceramic with high electric card effect at room temperature, a preparation method and application thereof. Background technique [0002] In recent years, the sustainable development of human society has put forward higher requirements for traditional vapor-compression refrigeration technology in terms of environmental protection and energy efficiency. The development of environmentally friendly, energy-saving and high-efficiency new refrigeration technology that truly achieves zero carbon emissions has become the current focus of the refrigeration industry. Urgent request. The principle of ferroelectric refrigeration (Electrocaloric Effect, ECE) is that applying or removing an electric field to a ferroelectric under adiabatic conditions will cause the temperature of the ferroelectric to change. [0003] That is, ap...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C04B35/495C04B35/622
CPCC04B35/495C04B35/622C04B2235/3201C04B2235/3215C04B2235/3232C04B2235/602C04B2235/656C04B2235/6567
Inventor 张红芳高炬
Owner SUZHOU UNIV OF SCI & TECH
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