Rare earth hafnate high-entropy ceramic powder through low-temperature synthesis and preparation method

Abstract

The invention relates to rare earth hafnate high-entropy ceramic powder through low-temperature synthesis and a preparation method, wherein the chemical formula of the rare earth hafnate high-entropyceramic powder is (5RE0.2)2Hf2O7, and rare earth elements RE are La, Ce, Nd, Pr, Sm and Eu. The preparation method specifically comprises the following steps: by taking hafnium tetrachloride (HfCl4) and hydrated rare earth nitrate (RE(NO3)3.xH2O) as raw materials and selecting urea as a combustion agent, mixing the components in a solution, combusting in an air atmosphere at a low temperature to generate fluffy powder, and carrying out high-temperature carbon removal treatment to obtain high-purity (5RE0.2)2Hf2O7 powder. Compared with high-energy ball milling, spray pyrolysis, coprecipitationand other oxide high-entropy ceramic synthesis methods, the method has the advantages of low synthesis temperature, simple operation, high preparation speed and the like.

Description

technical field [0001] The invention belongs to the field of powder synthesis, and relates to a low-temperature synthesis of rare earth hafnate high-entropy ceramic powder and a preparation method. Background technique [0002] High-entropy ceramics (HECs), sometimes called high-entropy compounds, are single-phase ceramics containing no fewer than four cations and anions. The concept of high-entropy ceramics comes from high-entropy alloys. High-entropy alloys exhibit excellent properties such as high strength and high hardness, making high-entropy ceramics a hot research topic in recent years. High-entropy ceramics have high hardness, low thermal and electrical conductivity, excellent dielectric properties, and excellent lithium-ion cycle stability, making them widely used as wear-resistant materials, thermal protection materials, dielectric materials, and lithium battery anode materials Applications. At the same time, the RE of the pyrochlore structure 2 f 2 o 7 , unde...

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Problems solved by technology

[0003] At present, there are few studies on oxide high-entropy ceramics, and their preparation processes mainly include: high-energy ball milling, spray pyrolysis, and co-precipitation, etc. These preparation methods have disadvantages such as high energy consumption, long production cycle, high equipment requirements, and complicated processes. , so the combustion method, as a low-temperature synthetic ceramic technology with simple process and short preparation cycle, has very broad development prospects.

[0004] Literature 1 "Z. Zhao, H. Xiang, F. Dai, et al., (La 0.2 Ce 0.2 Nd 0.2 SM 0.2 Eu 0.2 ) 2 Zr 2 o 7 : A novel high-entropy ceramic with low thermal conductivity and sluggish grain growth[J]. Journal of Materials Science&Technology, 2019.35(11): 2647-2651."Preparation of high-entropy ceramics by co-precipitation method (La 0.2 Ce 0.2 Nd 0.2 SM 0.2 Eu 0.2 ) 2 Zr 2 o 7 , the calcination and sintering temperatures in the preparation process are 1300°C and 1500°C respectively. The preparation temperature of this method is relatively high. In addition, the addition of precipitant may make the local concentration too high, resulting in agglomeration or uneven composition

[0005] Literature 2 "K.Chen, X.Pei, L.Tang, et al., A five-component entropy-stabilized fluorite oxide[J].Journal of the European Ceramic Society, 2018.38(11):4161-4164." via High Energy Five kinds of high-entropy ceramics with fluorite structure were prepared by ball milling-sintering-high energy ball milling-sintering method. This process has high calcination and sintering temperature, long holding time, and long time ball milling when mixing samples, which is time-consuming and energy-consuming.

[0006] Document 3 "Chellali, M.R., et al., On the homogeneity of high entropy oxides: An investigation at the atomic scale [J]. Scripta Materialia, 2019.166:58-63." Using spray pyrolysis to prepare a variety of calcium Single-phase oxide high-entropy ceramics with titanium ore structure. This process is carried out at a temperature of 1150°C to 1250°C and a pressure of 900mbar. Therefore, this process has high requirements for equipment and increases production costs.

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