阅读说明：本技术 一种离子补偿混合物共沉淀制备钙钛矿型复合氧化物高熵陶瓷粉的方法 (Method for preparing perovskite type composite oxide high-entropy ceramic powder by coprecipitation of ion compensation mixture ) 是由 仲晓羽 陈智慧 邱建华 任玉荣 朱媛媛 于 2019-11-06 设计创作，主要内容包括：本发明公开了一种离子补偿混合物共沉淀法制备钙钛矿型复合氧化物高熵陶瓷粉的方法,属于无铅介质陶瓷材料领域。该方法包括以下步骤：将Ba、Sr的氯化物或二者的混合物,以及Zr、Sn、Ti、Nb(Hf)、Y或Ce、Er(Mn)的氯化物及草酸盐溶解、混合配置成混合盐溶液,其中,对易流失组分Ba、Sn、Ti和Hf进行浓度补偿；以氨水水溶液为沉淀剂或以碳酸钠和氨水混合水溶液作为沉淀剂；混合盐溶液与沉淀剂溶液在剧烈搅拌下发生反应形成沉淀物；采用碳酸氢氨溶液作为缓冲溶液,对沉淀物进行反复清洗、过滤；经减压共沸蒸馏和焙烧后得到高熵陶瓷粉体。(The invention discloses a method for preparing perovskite type composite oxide high-entropy ceramic powder by an ion compensation mixture coprecipitation method, and belongs to the field of lead-free dielectric ceramic materials. The method comprises the following steps: dissolving and mixing chlorides of Ba and Sr or a mixture of the chlorides of Ba and Sr, chlorides of Zr, Sn, Ti, Nb (Hf), Y or Ce and Er (Mn) and oxalate to prepare a mixed salt solution, wherein the concentration of easily-lost components of Ba, Sn, Ti and Hf is compensated; taking an aqueous solution of ammonia water as a precipitator or taking a mixed aqueous solution of sodium carbonate and ammonia water as the precipitator; reacting the mixed salt solution with a precipitator solution under vigorous stirring to form a precipitate; adopting ammonium bicarbonate solution as buffer solution, and repeatedly cleaning and filtering the precipitate; and obtaining the high-entropy ceramic powder after reduced pressure azeotropic distillation and roasting.)

1. The perovskite type composite oxide high-entropy ceramic powder is characterized in that the high-entropy ceramic powder is ABO ₃Perovskite structure having Ba, Sr or Ba as the atom occupying the A position _0.5Sr _0.5(ii) a When A is Ba, the five metal atoms occupying the B position are Zr, Sn, Ti, Nb and a rare earth atom M respectively, wherein M is Y, Ce or Er; when A is Sr, the five metal atoms occupying the B position are Zr, Sn, Ti, Hf and a rare earth atom M respectively, wherein M is Mn or Y; when A is Ba _0.5Sr _0.5When the metal atoms occupy the B position, the five metal atoms are respectively Zr, Sn, Ti, Nb and Y; after five metal ions occupy the B site of the perovskite structure, the tolerance factor is between 0.95 and 1.05; the percentage expression of B-site atoms is Zr _x1Sn _x2Ti _x3Nb(Hf) _x4M _x5Wherein x1, x2, x3, x4, x5 are numbers between 0.15 and 0.25, and x1+ x2+ x3+ x4+ x5 is 1; A. the molar ratio of the B-site atoms is (1.02-1.06): 1.

2. The method for preparing the perovskite type composite oxide high-entropy ceramic powder as claimed in claim 1, wherein the composite oxide high-entropy ceramic powder is prepared by an ion compensated mixture coprecipitation method, and the method comprises the following steps:

(1) dissolving analytically pure concentrated hydrochloric acid in deionized water to prepare 0.1mol/L hydrochloric acid solution; mixing TiCl ₄、SnCl ₂(HfCl ₄) Respectively adding into hydrochloric acid solution to prepare TiCl ₄、SnCl ₂(HfCl ₄) Hydrochloric acid solution, dripping hydrochloric acid into the solution, and adjusting the pH value; dissolving the rest metal chlorides in turnDissolving in deionized water, mixing and stirring for 60 min, and slowly adding TiCl ₄、SnCl ₂(HfCl ₄) Continuously stirring the hydrochloric acid solution for 30 minutes to obtain a mixed salt solution, dropwise adding hydrochloric acid into the mixed salt solution, and adjusting the pH value; wherein, in order to compensate for the decomposition loss of Sn-containing precipitate and Ti in the reaction process under alkaline condition ⁴⁺、Hf ⁴⁺The hydrolysis loss of ions is controlled to be 1 (1.05-1.15) to 1 (1.00-1.05) to 1: 1; the molar ratio of Zr, Sn, Ti, Hf and M is controlled to be 1 (1.05-1.15): 1.00-1.05): 1.05-1.15): 1;

(2) taking an aqueous solution of ammonia water as a precipitator, or respectively preparing a sodium carbonate solution and an aqueous solution of ammonia water and mixing to obtain a precipitator solution; continuously injecting the mixed salt solution and the precipitant solution into a reactor, and reacting under vigorous stirring to form precipitate;

(3) quickly diluting the formed precipitate with a large amount of deionized water, centrifugally filtering the precipitate slurry, repeatedly cleaning the obtained filter cake by using absolute ethyl alcohol as a washing liquid, and removing a large amount of deionized water in the filter cake; adding ammonium bicarbonate-ammonia water solution into the washing solution as a buffer solution, wherein the molar ratio of the ammonium bicarbonate to the ammonia water is 1:100, and regulating and controlling the pH value of the washing solution to be 7.5-8.5 to prevent the precipitate from dissolving; obtaining solid precipitate after pumping;

(4) mixing the solid precipitate with n-butanol, performing reduced pressure azeotropic distillation, gradually heating the water bath temperature from room temperature to 100 ℃, and preserving the temperature for 3 hours to obtain precursor powder;

(5) and roasting the precursor powder in a muffle furnace at 1100 ℃ for 2 hours to obtain the perovskite type composite oxide high-entropy ceramic powder.

3. The method for preparing a perovskite-type composite oxide high-entropy ceramic powder according to claim 2, wherein the concentration of the mixed salt solution in the step (1) is 0.6 to 1.0mol/L, and the pH value is 2 to 4.

4. The method for producing a perovskite-type composite oxide high-entropy ceramic powder according to claim 2, wherein the precipitation in the step (2)When the A site is Ba, the used precipitator is aqueous ammonia solution, and the molar ratio of the mixed salt solution to the aqueous ammonia solution is 1: 6; when the A site is Sr, the used precipitator is a mixed solution of a sodium carbonate solution and an aqueous solution of ammonia water, and the molar ratio of the mixed salt solution to the precipitator solution is 1: 5; when the A site is Ba _0.5Sr _0.5In the process, the used precipitator is a mixed solution of a sodium carbonate solution and an aqueous solution of ammonia water, and the molar ratio of the mixed salt solution to the precipitator solution is 1: 5.5.

5. The method for preparing a perovskite type composite oxide high-entropy ceramic powder according to claim 4, characterized in that when the A site is Sr, the precipitant is a mixed solution of a sodium carbonate solution and an aqueous solution of ammonia water, and the molar ratio of the two is 1: 4; when the A site is Ba _0.5Sr _0.5In the case of the method, the used precipitator is a mixed solution of a sodium carbonate solution and an aqueous ammonia solution, and the dosage ratio of the sodium carbonate solution to the aqueous ammonia solution is 1: 10.

6. The method for preparing a perovskite-type composite oxide high-entropy ceramic powder according to claim 2, wherein the speed of injecting the mixed salt solution and the precipitant solution of step (2) into the reactor is 20L/h to 100L/h; the stirring speed is 800rpm-4000 rpm.

Technical Field

The invention belongs to the field of lead-free dielectric ceramic materials, and particularly relates to a method for preparing perovskite type composite oxide high-entropy ceramic powder by coprecipitation of an ion compensation mixture.

Background

Lead perovskite type dielectric ceramic material is important in electronic devices and communicationThe basic material is needed, but with the increasing awareness of environmental protection, the lead-containing ceramic material is replaced by the lead-free ceramic. At present, however, simple perovskite-type ceramic materials, such as BaTiO ₃、CaTiO ₃、SrTiO ₃And SrZrO ₃And the like cannot meet the application requirements. The formation of composite perovskite type compounds in a solid solution or doping manner, the change of the element combination at A, B in the perovskite structure and the improvement of the ceramic preparation method are important means for improving the dielectric characteristics of lead-free perovskite type ceramics. The B-site complex perovskite structure may be represented as A (B B') O ₃In the B-lattice composite perovskite compound, A (B) ³⁺ _1/2B ⁵⁺ _1/2)O ₃(B ³⁺＝La,Nd,Sm,Yb；B ⁵⁺Nb, Ta) ceramics have microwave dielectric characteristics.

Luo et al in 2018 propose that five metal ions can jointly occupy ABO according to the same molar ratio ₃B site of perovskite structure. There are a number of possibilities for the arrangement of atoms of different sizes, thus eliminating any possibility of forming a regular crystal structure, thereby creating a multi-host material with more uniform physical properties (Sicong Jiang, Tao Hu, Jian Luo, et al. A new class of high-entry Perovskite oxides, script Material 142(2018) 116-120). At present, only a few documents report such multi-principal element materials, most of which focus on alloy materials and non-oxide ceramic materials, and related powder preparation methods mainly relate to a solid phase method and a spray pyrolysis method. The powder prepared by the solid phase method has large granularity, poor dispersibility and higher roasting temperature; the spray pyrolysis method has complex equipment and preparation flow, high reaction temperature and high pressure.

The coprecipitation method is a method in which a precipitant is added to a mixed solution of metal salts to precipitate two or more cations contained in the solution at the same time, and is an important method for preparing a composite oxide powder. The coprecipitation method has the characteristics of simple preparation process, low cost, easy control of preparation conditions, short synthesis period and the like, and the prepared powder has good dispersibility and uniformity.

However, the concentration, rate and pH range of each cation in the multi-principal oxide are different, and the change of the precipitant varies with the pH, causing component segregation and deviation of the final product from the stoichiometric ratio. How to simultaneously precipitate all the cationic components and keep the stoichiometric ratio of the product is the technical bottleneck of preparing the composite multi-principal-element perovskite structure ceramic powder by a coprecipitation method. The breakthrough of the technology has important significance for developing multi-principal element materials and exploring new functions of the materials.

Disclosure of Invention

In order to overcome the technical defects in the prior art, the invention aims to provide a preparation method of perovskite type composite oxide high-entropy ceramic powder, which is simple in process and low in cost. The method comprises the following specific steps:

(1) dissolving analytically pure concentrated hydrochloric acid in deionized water to prepare 0.1mol/L hydrochloric acid solution; mixing TiCl ₄、SnCl ₂(HfCl ₄) Respectively adding into hydrochloric acid solution to prepare TiCl ₄、SnCl ₂(HfCl ₄) Hydrochloric acid solution, hydrochloric acid is dripped into the hydrochloric acid solution, and the pH value is adjusted; dissolving the rest metal chloride and niobium oxalate in deionized water in sequence, mixing and stirring for 60 minutes, and then slowly adding TiCl into the mixture ₄、SnCl ₂(HfCl ₄) And (3) continuously stirring the hydrochloric acid solution for 30 minutes to obtain a mixed salt solution, dropwise adding hydrochloric acid into the mixed salt solution, and adjusting the pH value. Wherein, in order to compensate for the decomposition loss of Sn-containing precipitate and Ti in the reaction process under alkaline condition ⁴⁺、Hf ⁴⁺The hydrolysis loss of ions is controlled to be 1 (1.05-1.15) to 1 (1.00-1.05) to 1: 1; the molar ratio of Zr, Sn, Ti, Hf and M is controlled to 1 (1.05-1.15): 1.00-1.05): 1.05-1.15): 1.

(2) Taking an aqueous solution of ammonia water as a precipitator, or respectively preparing a sodium carbonate solution and an aqueous solution of ammonia water and mixing to obtain a precipitator solution; continuously injecting the mixed salt solution and the precipitant solution into a reactor, and reacting under vigorous stirring to form precipitate;

(3) quickly diluting the formed precipitate with a large amount of deionized water, centrifugally filtering the precipitate slurry, repeatedly cleaning the obtained filter cake by using absolute ethyl alcohol as a washing liquid, and removing a large amount of deionized water in the filter cake; adding ammonium bicarbonate-ammonia water solution into the washing solution as a buffer solution, wherein the molar ratio of the ammonium bicarbonate to the ammonia water is 1:100, and regulating and controlling the pH value of the washing solution to be 7.5-8.5 to prevent the precipitate from dissolving; obtaining solid precipitate after pumping;

(4) mixing the solid precipitate with n-butanol, performing reduced pressure azeotropic distillation, gradually heating the water bath temperature from room temperature to 100 ℃, and preserving the temperature for 3 hours to obtain precursor powder;

(5) and roasting the precursor powder in a muffle furnace at 1100 ℃ for 2 hours to obtain the perovskite type composite oxide high-entropy ceramic powder.

The concentration of the mixed salt solution is 0.6-1.0mol/L, hydrochloric acid is dripped into the mixed salt solution, and the pH value is adjusted to 2-4. When the A site is Ba, the used precipitator is an aqueous ammonia solution, and the molar ratio of the mixed salt solution to the aqueous ammonia solution is 1: 6; when the A site is Sr, the used precipitator is a mixed solution of a sodium carbonate solution and an aqueous solution of ammonia water, the molar ratio of the sodium carbonate solution to the aqueous solution of ammonia water is 1:4, and the molar ratio of the mixed salt solution to the precipitator solution is 1: 5; when the A site is Ba _0.5Sr _0.5In the process, the used precipitating agent is a sodium carbonate solution and an aqueous solution of ammonia water, and the dosage ratio of the sodium carbonate solution to the aqueous solution of ammonia water is 1: 10; the molar ratio of the mixed salt solution to the precipitant solution is 1: 5.5.

The speed of injecting the mixed salt solution and the precipitant solution into the reactor is 20L/h-100L/h; the stirring speed is 800rpm-4000 rpm; the pH value of the precipitation reaction is between 7.8 and 8.5.

In the washing process (the preparation is that the obtained filter cake is repeatedly washed), absolute ethyl alcohol is used as washing liquid, ammonium bicarbonate solution is used as buffer solution, and ammonia water is used for adjusting the pH value of the buffer solution to 7.5-8.5.

The perovskite type composite oxide high-entropy ceramic powder prepared by the method is ABO ₃The tolerance factor of the perovskite structure is between 0.95 and 1.05 after five metal ions occupy the B site of the perovskite structure. When a is Ba, the five metal atoms occupying the B position are Zr, Sn, Ti, Nb, and a rare earth atom M (M ═ Y, Ce, Er), respectively; when A is Sr, the five metal atoms occupying the B site are Zr and Sn respectivelyTi, Hf and rare earth atoms M (M ═ Mn, Y); when A is Ba _0.5Sr _0.5When the metal atoms occupy the B position, the five metal atoms are respectively Zr, Sn, Ti, Nb and Y. The percentage expression of B-site atoms is Zr _x1Sn _x2Ti _x3Nb _x4M _x5Wherein x1, x2, x3, x4, x5 are numbers between 0.15 and 0.25, and x1+ x2+ x3+ x4+ x5 is 1; A. the molar ratio of the B-site atoms is (1.02-1.06): 1. In order to compensate for the micro decomposition of Ba precipitate in the filtering process after the coprecipitation of Ba and Ti, the raw material Ba ions are excessive by 2-6%.

The elements involved in the invention are complex, such as: ba ²⁺Filtering under alkalescent condition after precipitate formation to avoid precipitate decomposition, and performing Ba precipitation in precursor solution preparation process ²⁺Compensating the concentration, and preparing a weak alkaline buffer solution in the filtering process; acid addition to inhibit Ti ⁴⁺、H _f ⁴⁺The problem of hydrolysis of (a); sn (tin) ⁴⁺The pH range of the generated precipitate is from weak acidity to neutrality; and the mutual solubility problem of the mixing of all the cations. The invention adopts the modes of ion compensation, respective preparation, one-by-one mixing, pH value control and the like to realize the stoichiometric ratio of the final product. And the tolerance factor of five metal ions at the B site is between 0.95 and 1.02 by reasonably matching A, B site elements, so that a pure-phase perovskite high-entropy structure can be obtained.

Compared with the prior art, the invention has the following technical effects:

the invention utilizes an ion compensation mixture coprecipitation method to prepare A, B lattice composite multi-principal-element perovskite structure dielectric ceramic powder, and the method accurately regulates and controls the stoichiometric ratio of each cation by a method of ion concentration compensation and buffer solution preparation to prevent ion loss, so as to prepare the multi-principal-element perovskite structure ceramic oxide powder.

Drawings

FIG. 1 shows Sr (Zr) obtained in example 1 _0.2Sn _0.2Ti _0.2Hf _0.2Mn _0.2)O ₃TEM image of high entropy ceramic powder;

FIG. 2 is an XRD pattern of a sample prepared in example 1;

fig. 3 is an XRD spectrum of the sample prepared in comparative example 2.

Detailed Description

The present invention will be described in detail with reference to specific examples.