Rare earth polishing powder and preparation method therefor, and polishing slurry

Abstract

A rare earth polishing powder and a preparation method therefor, and a polishing slurry. The chemical formula of the rare earth polishing powder is Ce1-xMxOyDz, wherein 0≤x≤0.6, 1.2≤y≤2.0, and 0≤z≤0.9; the mass percentage content of trivalent cerium in the rare earth polishing powder as a proportion of total cerium is less than or equal to 10%, and the mass percentage content of trivalent cerium in the surface layer area of rare earth polishing powder particles as a proportion of total cerium in the surface layer area of rare earth polishing powder particles is greater than or equal to 20%, wherein the surface layer area is an area that is 1-5 nm from the surface layer of the rare earth polishing powder particles; M is selected from any one or more of a transition metal element, an alkaline earth metal element, an aluminum element, a silicon element, an alkaline metal element, and a rare earth element other than cerium, and D is selected from any one or more of fluorine, chlorine, phosphorus, and sulfur. The described rare earth polishing powder has high structural stability, an excellent polishing rate and long service life, and can be processed to obtain a surface having extremely low roughness.

Description

Rare earth polishing powder and preparation method thereof, polishing slurry

[0001] This application is based on the Chinese application with CN application number 202310705329.7 and application date June 14, 2023, and claims its priority. The disclosed content of the CN application is again introduced as a whole into this application. Technical Field

[0002] The present invention relates to the technical field of rare earth polishing materials, in particular to rare earth polishing powder and a preparation method thereof, and polishing slurry. Background Art

[0003] Rare earth polishing powder is a polishing material with excellent performance. It has the advantages of moderate hardness, fast polishing rate, high polishing efficiency and clean operating environment. It is widely used in polishing silicon-containing materials such as flat glass, mobile phone cover glass, optical glass, liquid crystal display glass substrate and integrated circuit STI layer.

[0004] The polishing mechanism of rare earth polishing powders is chemical mechanical polishing. The mechanical action is influenced by factors such as powder particle size, uniformity, morphology, and hardness; the chemical action, in contrast, is related to the powder's composition, surface valence state, and structure, with the surface valence state having a significant influence on the chemical action. In rare earth polishing powders, trivalent cerium can form Ce-O-Si bonds with the surface being machined, enhancing the interaction between the polishing powder particles and the surface and weakening Si-O-Si bonds, thereby improving the removal ability of the rare earth polishing powder. Therefore, trivalent cerium is the fundamental cause of the chemical polishing activity of rare earth polishing powders, and increasing the trivalent cerium content is crucial for the preparation of high-performance rare earth polishing powders. Cerium oxide typically exists in a cubic fluorite phase in polishing powders. However, when trivalent cerium is present in the bulk phase of polishing powder particles, it forms oxygen vacancies, causing crystal defects and leading to crystal deformation. In particular, when a large amount of trivalent cerium is present in the bulk phase, cerium oxide forms a hexagonal phase, which in turn destabilizes the structural stability of the polishing powder. This results in easy breakage of the polishing powder particles during use, reduced polishing rate, and poor polishing stability.

[0005] Summary of the Invention

[0006] The main purpose of the present invention is to provide a rare earth polishing powder and a preparation method thereof, and a polishing slurry, so as to solve the problem of poor polishing activity and polishing stability of rare earth polishing powder in the prior art.

[0007] In order to achieve the above object, according to one aspect of the present invention, a rare earth polishing powder is provided. The chemical formula of the rare earth polishing powder is Ce 1-x M x O y D z, wherein, 0≤x≤0.6, 1.2≤y≤2.0, 0≤z≤0.9; the mass percentage of trivalent cerium in the total cerium in the rare earth polishing powder is ≤10%, and the mass percentage of trivalent cerium in the surface area of ​​the rare earth polishing powder particles in the total cerium in the surface area of ​​the rare earth polishing powder particles is ≥20%, wherein the surface area refers to the area 1 to 5 nm close to the surface of the rare earth polishing powder particles; M is selected from any one or more of transition metal elements, alkaline earth metal elements, aluminum element, silicon element, alkali metal elements and rare earth elements other than cerium, and D is selected from any one or more of fluorine, chlorine, phosphorus and sulfur.

[0008] Furthermore, the cerium oxide phase contained in the rare earth polishing powder is a cubic fluorite phase.

[0009] Furthermore, the mass percentage of the trivalent cerium in the surface region of the rare earth polishing powder particles in the total cerium in the surface region of the rare earth polishing powder particles is ≥25%.

[0010] Furthermore, 0≤x≤0.4, preferably 1.5≤y≤2, preferably 0≤z≤0.6; preferably M is selected from any one or more of lanthanum, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, thulium, ytterbium, yttrium, zirconium, iron, magnesium, sodium, calcium, and silicon, and preferably D is fluorine and / or phosphorus.

[0011] Furthermore, the median particle size D of the rare earth polishing powder is 50 It is 0.01 to 5 μm, preferably 0.01 to 2 μm.

[0012] According to another aspect of the present invention, a method for preparing the aforementioned rare earth polishing powder is provided, the preparation method comprising: step S1, calcining a raw material including a cerium compound in an oxidizing atmosphere to obtain a calcined product; step S2, hydrothermally treating the calcined product in a solution to obtain rare earth polishing powder.

[0013] Furthermore, in the above step S1, the cerium-containing compound is selected from any one or more of cerium-containing carbonates, fluorocarbonates, oxalates, and hydroxides; the cerium-containing compound is preferably synthesized by any one or more of a coprecipitation method, a sol-gel method, a microemulsion method, a combustion method, and a solid-phase method; the oxidizing atmosphere in step S1 is preferably oxygen or air; the calcination temperature in step S2 is preferably 300 to 1000°C, preferably 500 to 900°C; the calcination time is preferably 1 to 48 hours, preferably 1 to 24 hours.

[0014] Furthermore, in the above step S2, the temperature of the hydrothermal treatment is 100 to 250° C., preferably 120 to 200° C.; and the time of the hydrothermal treatment is preferably 1 to 48 hours, preferably 3 to 24 hours.

[0015] Furthermore, in the above step S2, the solution is an aqueous solution with a pH value of 4 to 12, preferably an aqueous solution with a pH value of 5 to 10, and the pH value of the solution is preferably adjusted to be within the above range using sodium hydroxide and / or potassium hydroxide.

[0016] Furthermore, in the above step S2, the solution includes a reducing substance, and the reducing substance is selected from any one or more of ammonia water, hydrogen peroxide, potassium sulfite, potassium bisulfite, and potassium metabisulfite. Preferably, the amount of the reducing substance is ≤ 30 wt% of the mass of the calcined product.

[0017] According to another aspect of the present invention, a polishing slurry is provided, comprising rare earth polishing powder, a surfactant, a pH regulator and water, wherein the rare earth polishing powder is the rare earth polishing powder mentioned above.

[0018] Furthermore, in terms of mass percentage, the content of rare earth polishing powder in the above-mentioned polishing slurry is ≤20%, preferably ≤10%; the content of surfactant in the polishing slurry is preferably ≤5%, preferably ≤1%, and the surfactant is preferably selected from any one or more of sodium hexametaphosphate, sodium polyacrylate, sodium salt of maleic acid-acrylic acid copolymer, and sodium pyrophosphate; the pH value of the polishing slurry is preferably 4 to 10.

[0019] By applying the technical solution of the present invention, the bulk phase of the rare earth polishing powder described above is primarily tetravalent cerium, with trivalent cerium concentrated on the surface of the rare earth polishing powder particles. This surface enrichment of trivalent cerium facilitates the formation of Ce-O-Si bonds, thereby increasing the polishing rate of the rare earth polishing powder. Furthermore, the bulk phase is primarily tetravalent cerium, preventing the presence of trivalent cerium in the bulk phase from disrupting the face-centered cubic structure of cerium oxide. This results in a high structural stability of the rare earth polishing powder, resulting in excellent polishing rates and service life, and the ability to produce extremely low-roughness surfaces. DETAILED DESCRIPTION

[0020] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present invention will be described in detail below with reference to the embodiments.

[0021] As analyzed in the background technology, the prior art has the problem that rare earth polishing powder has poor polishing activity and polishing stability. In order to solve this problem, the present application provides a rare earth polishing powder and a preparation method thereof, and a polishing slurry.

[0022] In a typical embodiment of the present application, a rare earth polishing powder is provided, the chemical formula of the rare earth polishing powder is Ce 1-x M x O y D z, wherein, 0≤x≤0.6, 1.2≤y≤2.0, 0≤z≤0.9; the mass percentage of trivalent cerium in the total cerium in the rare earth polishing powder is ≤10%, and the mass percentage of trivalent cerium in the surface area of ​​the rare earth polishing powder particles in the total cerium in the surface area of ​​the rare earth polishing powder particles is ≥20%, wherein the surface area refers to the area 1 to 5 nm close to the surface of the rare earth polishing powder particles; M is selected from any one or more of transition metal elements, alkaline earth metal elements, aluminum element, silicon element, alkali metal elements and rare earth elements other than cerium, and D is selected from any one or more of fluorine, chlorine, phosphorus and sulfur.

[0023] The bulk phase of the rare earth polishing powder described herein is primarily tetravalent cerium, with trivalent cerium concentrated on the surface of the rare earth polishing powder particles. This surface enrichment of trivalent cerium facilitates the formation of Ce-O-Si bonds, thereby increasing the polishing rate of the rare earth polishing powder. Furthermore, it helps prevent the presence of trivalent cerium in the bulk phase from disrupting the face-centered cubic structure of cerium oxide, resulting in a highly stable structure. This results in excellent polishing rates and service life, and allows for the production of extremely low-roughness surfaces.

[0024] The mass percentage of trivalent cerium in the rare earth polishing powder to the total cerium can be measured by the following method:

[0025] S1: The rare earth polishing powder was digested with concentrated phosphoric acid, and the cerium content was measured by titration with ammonium ferrous sulfate as a;

[0026] S2: The rare earth polishing powder is digested with a mixture of concentrated phosphoric acid and perchloric acid. The cerium content is measured by ammonium ferrous sulfate titration, ICP, etc., and the mass percentage of trivalent cerium in the total cerium is (b a ) / b×100%.

[0027] The mass percentage of the surface trivalent cerium content in the rare earth polishing powder to the total surface cerium can be tested by methods such as X-ray photoelectron spectroscopy (XPS), electron paramagnetic resonance (EPR), electron energy loss spectroscopy (EELS), and Raman.

[0028] Taking X-ray photoelectron spectroscopy (XPS) as an example, the test spectrum of rare earth polishing powder has peaks near 880.7eV, 882.8eV, 885.7eV, 885.9eV, 898.1eV, 899.4eV, 901.2eV, 904.8eV, 908.1eV, and 916.9eV, and the mass percentage of surface trivalent cerium content to total surface cerium content = (A 880.7 +A 885.7 +A 899.4 +A 899.4 ) / (A 882.8 +A 889.5 +A 898.1 +A901.2 +A 908.1 +A 916.9 )×100%, where A is the integrated area of ​​the peak.

[0029] Trivalent cerium is the fundamental reason for the chemical polishing activity of rare earth polishing powder. In some embodiments of the present application, the cerium oxide phase contained in the rare earth polishing powder is preferably a cubic fluorite phase, which can effectively avoid crystal defects (such as hexagonal phase) and crystal deformation caused by oxygen vacancies; thereby helping to improve the structural stability of the polishing powder, and further improve the polishing rate and polishing stability.

[0030] In order to further improve the polishing rate and service life of the rare earth polishing powder, it is preferred that the mass percentage of trivalent cerium in the surface region of the rare earth polishing powder particles is ≥25% of the total cerium in the surface region of the rare earth polishing powder particles.

[0031] In one embodiment of the present application, preferably 0≤x≤0.4, preferably 1.5≤y≤2, preferably 0≤z≤0.6; preferably M is selected from any one or more of lanthanum, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, thulium, ytterbium, yttrium, zirconium, iron, magnesium, sodium, calcium, and silicon, and preferably D is fluorine and / or phosphorus.

[0032] The preferred values ​​of x, y, and z above help to improve the synergistic effect between the elements in the rare earth polishing powder. The preferred M helps to improve Ce to a certain extent. 3+ The content makes the rare earth polishing powder have polishing activity, polishing stability and a long service life.

[0033] In one embodiment of the present application, the median particle size D of the rare earth polishing powder is 50 It is 0.01 to 5 μm, preferably 0.01 to 2 μm.

[0034] The rare earth polishing powder with the above-mentioned particle size can be used for polishing a variety of products on the market. In particular, the preferred small-particle rare earth polishing powder is more suitable for polishing precision products, and the surface roughness of the processed products is lower.

[0035] In another typical embodiment of the present application, a method for preparing the aforementioned rare earth polishing powder is provided, the preparation method comprising: step S1, calcining a raw material including a cerium compound in an oxidizing atmosphere to obtain a calcined product; step S2, hydrothermally treating the calcined product in a solution to obtain rare earth polishing powder.

[0036] Step S1 reduces the total trivalent cerium content of cerium oxide in the rare earth polishing powder, particularly the trivalent cerium content in the bulk phase, by calcining the cerium-containing compound in an oxidizing atmosphere. Step S2 increases the trivalent cerium content in the surface layer through hydrothermal treatment, resulting in the accumulation of trivalent cerium primarily in the surface layer of the rare earth polishing powder particles. The hydrothermal treatment also improves the system's dispersibility, reduction rate, and reduction effect, resulting in more uniform rare earth polishing powder particles.

[0037] In one embodiment of the present application, in the above-mentioned step S1, the cerium-containing compound is selected from any one or more of cerium-containing carbonates, fluorocarbonates, hydroxides, and fluoride oxides; the cerium-containing compound is preferably synthesized by any one or more of a co-precipitation method, a sol-gel method, a microemulsion method, a combustion method, and a solid-phase method; the oxidizing atmosphere in step S1 is preferably oxygen or air; the calcination temperature in step S2 is preferably 300-1000°C, preferably 500-900°C; the calcination time is preferably 1-48h, preferably 1-24h.

[0038] The higher the oxygen concentration in the oxidizing atmosphere, the more helpful it is to improve the efficiency and effect of roasting. It is preferred to carry out the above roasting in oxygen for the best effect. It is preferred to carry out the above roasting in air to help reduce costs. The preferred roasting temperature and time are conducive to improving the efficiency and effect of roasting, thereby reducing the trivalent cerium content in the rare earth polishing powder phase as much as possible.

[0039] In some embodiments of the present application, in the above-mentioned step S2, the temperature of the hydrothermal treatment is preferably 100-250°C, preferably 120-200°C; the time of the hydrothermal treatment is preferably 1-48 hours, preferably 3-24 hours, so as to help more trivalent cerium to be enriched in the surface layer of the rare earth polishing powder particles.

[0040] In some embodiments of the present application, in the above step S2, the solution is an aqueous solution with a pH value of 4 to 12, preferably an aqueous solution with a pH value of 5 to 10, and the pH value of the above solution is preferably adjusted to be within the above range using sodium hydroxide and / or potassium hydroxide.

[0041] The calcined product is subjected to hydrothermal treatment in an aqueous solution with the above pH value, which helps to modify the rare earth polishing powder through the interaction between hydroxide ions and the surface layer of the rare earth polishing powder, thereby increasing the surface trivalent cerium content.

[0042] In other embodiments of the present application, the above-mentioned step S2 includes a reducing substance, and the reducing substance is selected from any one or more of ammonia water, hydrogen peroxide, potassium sulfite, potassium bisulfite, and potassium metabisulfite. Preferably, the amount of the reducing substance is ≤ 30 wt% of the mass of the calcined product.

[0043] Hydrothermal treatment in an aqueous solution with a reducing substance added thereto is helpful in reducing tetravalent cerium to trivalent cerium, thereby increasing the trivalent cerium content in the surface layer of the rare earth polishing powder.

[0044] In another typical embodiment of the present application, a polishing slurry is provided, comprising rare earth polishing powder, a surfactant, a pH regulator and water, wherein the rare earth polishing powder is the aforementioned rare earth polishing powder.

[0045] The polishing slurry provided by the present invention has the advantages of the above-mentioned polishing powder and also has the characteristics of good suspension stability and excellent dispersion performance, which prevents the polishing rate and polishing accuracy from being reduced due to problems such as polishing powder sedimentation, agglomeration, and agglomeration during the polishing process.

[0046] In order to further improve the synergistic effect between the components of the rare earth polishing slurry, thereby improving the polishing activity and stability of the polishing slurry as much as possible, the content of rare earth polishing powder in the above-mentioned polishing slurry is preferably ≤20%, preferably ≤10%, in terms of mass percentage; the content of surfactant in the polishing slurry is preferably ≤5%, preferably ≤1%, and the surfactant is preferably selected from any one or more of sodium hexametaphosphate, sodium polyacrylate, sodium salt of maleic acid-acrylic acid copolymer, and sodium pyrophosphate; the pH value of the polishing slurry is preferably 4 to 10.

[0047] The polishing slurry provided by the present invention is suitable for flat glass, mobile phone cover glass, optical glass, liquid crystal display glass, glass substrate, and integrated circuit fields.

[0048] The present application is further described in detail below with reference to specific embodiments. These embodiments should not be construed as limiting the scope of protection claimed in this application.

[0049] Example 1

[0050] The cerium carbonate solid was calcined at 400°C in an oxygen atmosphere for 4 hours, and then crushed and classified to obtain a calcined product, which was dispersed in deionized water, and the pH value was adjusted to 4 with ammonia water. The product was hydrothermally heated at 100°C for 48 hours, and then the hydrothermal product was filtered, washed, and dried to obtain a rare earth polishing powder with the chemical formula CeO2.

[0051] Example 2

[0052] Cerium nitrate solution, lanthanum nitrate solution and ammonium bicarbonate solution were mixed in a stoichiometric ratio, and the precipitate was filtered, washed and dried to obtain a cerium-containing compound. After calcining it at 900°C in an oxygen atmosphere for 48 hours, the calcined product was crushed and classified to obtain a calcined product, which was dispersed in deionized water, adjusted to pH 7 using a sodium hydroxide / ammonia solution, and hydrothermally heated at 120°C for 24 hours. The hydrothermal product was then filtered, washed and dried to obtain a cerium-containing compound having the chemical formula Ce. 0.8 La 0.2 O1.9 Rare earth polishing powder.

[0053] Example 3

[0054] Cerium nitrate, praseodymium nitrate, lanthanum nitrate solution and ammonium bicarbonate solution were mixed in a stoichiometric ratio, and the precipitate was filtered, washed and dried to obtain a cerium-containing compound. The precipitate was calcined at 300°C in an oxygen atmosphere for 1 hour, crushed and classified to obtain a calcined product, which was dispersed in deionized water, adjusted to pH 5 using a potassium hydroxide / ammonia solution, and hydroheated at 150°C for 12 hours. The hydrothermal product was then filtered, washed and dried to obtain a cerium-containing compound having the chemical formula Ce. 0.6 Pr 0.2 La 0.2 O 1.8 Rare earth polishing powder.

[0055] Example 4

[0056] Cerium nitrate solution and ammonium bicarbonate solution are mixed in a stoichiometric ratio to obtain a precursor slurry, which is then wet-fluorinated with hydrofluoric acid. The fluorinated product is filtered, washed, and dried to obtain a cerium-containing compound. It is calcined at 1000°C in an oxygen atmosphere for 24 hours, crushed and classified to obtain a calcined product, which is dispersed in deionized water, adjusted to pH 6 with ammonia water, and hydrothermally heated at 180°C for 1 hour. The hydrothermal product is then filtered, washed, and dried to obtain a product with the chemical formula CeO 1.7 F 0.6 Rare earth polishing powder.

[0057] Example 5

[0058] Cerium chloride, lanthanum chloride, neodymium chloride solution and ammonium bicarbonate solution were mixed in a stoichiometric ratio, and the precipitate was filtered, washed and dried to obtain a cerium-containing compound. After calcining it at 700°C in an air atmosphere for 12 hours, the calcined product was crushed and classified to obtain a calcined product, which was dispersed in deionized water, adjusted to pH 8 with sodium hydroxide, and hydrothermally heated at 200°C for 3 hours. The hydrothermal product was then filtered, washed and dried to obtain a cerium-containing compound having the chemical formula Ce. 0.9 La 0.05 Nd 0.05 O 1.95 Rare earth polishing powder.

[0059] Example 6

[0060] Cerium oxalate, lanthanum oxalate and ammonium bicarbonate solution are mixed in a stoichiometric ratio to obtain a precursor slurry, which is then wet-fluorinated with hydrofluoric acid. The fluorinated product is filtered, washed and dried to obtain a cerium-containing compound. The product is calcined at 500°C in an air atmosphere for 6 hours, crushed and classified to obtain a calcined product, which is dispersed in deionized water, adjusted to a pH of 10 with potassium hydroxide, and hydrothermally heated at 220°C for 8 hours. The hydrothermal product is then filtered, washed and dried to obtain a product with the chemical formula Ce. 0.4 La 0.6 O 1.25 F 0.9 Rare earth polishing powder.

[0061] Example 7

[0062] A cerium nitrate solution and ammonia water are mixed in a stoichiometric ratio, and the precipitate is filtered, washed, and dried to obtain a cerium-containing compound. This precipitate is then calcined at 600°C in an oxygen atmosphere for 8 hours, crushed and classified to obtain a calcined product, which is then dispersed in deionized water, adjusted to a pH of 12 using an ammonia / sodium hydroxide mixture, and hydrothermally heated at 250°C for 15 hours. The hydrothermal product is then filtered, washed, and dried to obtain a rare earth polishing powder with the chemical formula CeO2.

[0063] Example 8

[0064] Cerium nitrate solution, ammonia water, and sodium hexametaphosphate were mixed in a stoichiometric ratio, and the precipitate was filtered, washed, and dried to obtain a cerium-containing compound. After calcining it at 600°C in an oxygen atmosphere for 8 hours, the calcined product was crushed and classified to obtain a calcined product, which was dispersed in deionized water, adjusted to a pH of 12 using an ammonia water / sodium hydroxide mixed solution, and hydrothermally heated at 250°C for 15 hours. The hydrothermal product was then filtered, washed, and dried to obtain a cerium-containing compound having the chemical formula Ce. 0.9 P 0.1 O2 rare earth polishing powder.

[0065] Example 9

[0066] The difference from Example 7 is that ammonia water is used to adjust the pH value to 4, and finally CeO2 rare earth polishing powder is obtained.

[0067] Example 10

[0068] The difference from Example 7 is that ammonia water is used to adjust the pH value to 5, and finally CeO2 rare earth polishing powder is obtained.

[0069] Example 11

[0070] The difference from Example 7 is that ammonia water is used to adjust the pH value to 6, and finally CeO2 rare earth polishing powder is obtained.

[0071] Example 12

[0072] The difference from Example 7 is that ammonia water is used to adjust the pH value to 7, and finally CeO2 rare earth polishing powder is obtained.

[0073] Example 13

[0074] The difference from Example 7 is that ammonia water is used to adjust the pH value to 8, and finally CeO2 rare earth polishing powder is obtained.

[0075] Example 14

[0076] The difference from Example 7 is that ammonia water is used to adjust the pH value to 9, and finally CeO2 rare earth polishing powder is obtained.

[0077] Example 15

[0078] The difference from Example 7 is that ammonia water is used to adjust the pH value to 10, and finally CeO2 rare earth polishing powder is obtained.

[0079] Example 16

[0080] The difference from Example 7 is that ammonia water is used to adjust the pH value to 11, and finally CeO2 rare earth polishing powder is obtained.

[0081] Example 17

[0082] The cerium carbonate solid is calcined at 400°C in an oxygen atmosphere for 4 hours, and then crushed and classified to obtain a calcined product, which is then dispersed in an ammonia solution and hydrothermally heated at 100°C for 48 hours. The hydrothermal product is then filtered, washed, and dried to obtain a rare earth polishing powder with the chemical formula CeO2.

[0083] Example 18

[0084] Cerium nitrate solution, lanthanum nitrate solution and ammonium bicarbonate solution were mixed in a stoichiometric ratio, and the precipitate was filtered, washed and dried to obtain a cerium-containing compound. After calcining it at 900°C in an oxygen atmosphere for 48 hours, the calcined product was crushed and classified to obtain a calcined product, which was dispersed in a hydrogen peroxide solution and hydrothermally heated at 120°C for 24 hours. The hydrothermal product was then filtered, washed and dried to obtain a cerium-containing compound having the chemical formula Ce. 0.5 La 0.5 O 1.75 Rare earth polishing powder.

[0085] Example 19

[0086] Cerium nitrate, praseodymium nitrate, lanthanum nitrate solution and ammonium bicarbonate solution were mixed in a stoichiometric ratio, and the precipitate was filtered, washed and dried to obtain a cerium-containing compound. After calcining it at 300°C in an oxygen atmosphere for 1 hour, the calcined product was crushed and classified to obtain a calcined product, which was dispersed in an ammonia solution and hydrothermally heated at 150°C for 12 hours. The hydrothermal product was then filtered, washed and dried to obtain a compound with the chemical formula Ce. 0.8 Pr 0.1 La 0.1 O 1.9 Rare earth polishing powder.

[0087] Example 20

[0088] Cerium nitrate solution and ammonium bicarbonate solution are mixed in a stoichiometric ratio to obtain a precursor slurry, which is then wet-fluorinated with hydrofluoric acid. The fluorinated product is filtered, washed, and dried to obtain a cerium-containing compound. The product is calcined at 1000°C in an oxygen atmosphere for 24 hours, crushed and classified to obtain a calcined product, which is dispersed in hydrogen peroxide and hydrothermally heated at 180°C for 1 hour. The hydrothermal product is then filtered, washed, and dried to obtain a product with the chemical formula CeO 1.7 F 0.6 Rare earth polishing powder.

[0089] Example 21

[0090] Cerium chloride, lanthanum chloride, neodymium chloride solution and ammonium bicarbonate solution were mixed in a stoichiometric ratio, and the precipitate was filtered, washed and dried to obtain a cerium-containing compound. After calcining it at 700°C in air atmosphere for 12 hours, the calcined product was crushed and classified to obtain a calcined product, which was dispersed in ammonia water and hydrothermally heated at 200°C for 3 hours. The hydrothermal product was then filtered, washed and dried to obtain a cerium-containing compound with the chemical formula Ce. 0.4 La 0.3 Nd 0.3 O 1.7 Rare earth polishing powder.

[0091] Example 22

[0092] Cerium oxalate, lanthanum oxalate and ammonium bicarbonate solution are mixed in a stoichiometric ratio to obtain a precursor slurry, which is then wet-fluorinated with hydrofluoric acid. The fluorinated product is filtered, washed and dried to obtain a cerium-containing compound. The product is calcined at 500°C in an air atmosphere for 6 hours, crushed and classified to obtain a calcined product, which is dispersed in a sodium metabisulfite solution and hydrothermally heated at 220°C for 8 hours. The hydrothermal product is then filtered, washed and dried to obtain a product with the chemical formula Ce. 0.9 La 0.1 O 1.5 F 0.9 Rare earth polishing powder.

[0093] Example 23

[0094] A cerium nitrate solution and ammonia water are mixed in a stoichiometric ratio, and the precipitate is filtered, washed, and dried to obtain a cerium-containing compound. This precipitate is then calcined at 600°C in an oxygen atmosphere for 8 hours, crushed and classified to obtain a calcined product, which is then dispersed in a mixed solution of ammonia water and hydrogen peroxide and hydrothermally heated at 250°C for 15 hours. The hydrothermal product is then filtered, washed, and dried to obtain a rare earth polishing powder with the chemical formula CeO2.

[0095] Example 24

[0096] Cerium nitrate solution, ammonia water, and sodium hexametaphosphate were mixed in a stoichiometric ratio, and the precipitate was filtered, washed, and dried to obtain a cerium-containing compound. After calcining it at 600°C in an oxygen atmosphere for 8 hours, the calcined product was crushed and classified to obtain a calcined product, which was dispersed in a mixed solution of ammonia water / hydrogen peroxide and hydrothermaled at 250°C for 15 hours and 250°C for 15 hours. The hydrothermal product was then filtered, washed, and dried to obtain a cerium-containing compound having the chemical formula Ce. 0.9 P 0.1 O2 rare earth polishing powder.

[0097] Example 25

[0098] The difference from Example 23 is that after crushing and grading, the calcined product is obtained, which is dispersed in a mixed solution of ammonia water / hydrogen peroxide and hydrothermally heated at 100°C for 15 hours to finally obtain rare earth polishing powder with the chemical formula CeO2.

[0099] Example 26

[0100] The difference from Example 23 is that after crushing and grading, the calcined product is obtained, which is dispersed in a mixed solution of ammonia water / hydrogen peroxide and hydrothermally heated at 120°C for 15 hours to finally obtain rare earth polishing powder with the chemical formula CeO2.

[0101] Example 27

[0102] The difference from Example 23 is that after crushing and grading, the calcined product is obtained, which is dispersed in a mixed solution of ammonia water / hydrogen peroxide and hydrothermally heated at 150°C for 15 hours to finally obtain rare earth polishing powder with the chemical formula CeO2.

[0103] Example 28

[0104] The difference from Example 23 is that after crushing and grading, the calcined product is obtained, which is dispersed in a mixed solution of ammonia water / hydrogen peroxide and hydrothermally heated at 180°C for 15 hours to finally obtain rare earth polishing powder with the chemical formula CeO2.

[0105] Example 29

[0106] The difference from Example 23 is that after crushing and grading, the calcined product is obtained, which is dispersed in a mixed solution of ammonia water / hydrogen peroxide and hydrothermally heated at 200°C for 15 hours to finally obtain rare earth polishing powder with the chemical formula CeO2.

[0107] Example 30

[0108] The difference from Example 23 is that after crushing and grading, the calcined product is obtained, which is dispersed in a mixed solution of ammonia water / hydrogen peroxide and hydrothermally heated at 220°C for 15 hours to finally obtain rare earth polishing powder with the chemical formula CeO2.

[0109] Comparative Example 1

[0110] Cerium nitrate solution and ammonium bicarbonate solution are mixed in a stoichiometric ratio to obtain a precursor slurry, which is then wet-fluorinated with hydrofluoric acid. The fluorinated product is filtered, washed, and dried to obtain a cerium-containing compound. The fluorinated product is calcined at 1000°C in a hydrogen atmosphere for 24 hours, and then crushed and classified to obtain a product with the chemical formula CeO 1.7 F 0.6 Rare earth polishing powder.

[0111] Comparative Example 2

[0112] The cerium nitrate solution and ammonia water are mixed in a stoichiometric ratio, and the precipitate is filtered, washed, and dried to obtain a cerium-containing compound. This compound is then calcined at 600°C in an oxygen atmosphere for 8 hours and crushed and classified to obtain a rare earth polishing powder with the chemical formula CeO2.

[0113] The D50 particle size of the rare earth polishing powders obtained in Examples 1 to 30 and Comparative Examples 1 and 2 was measured using a dynamic laser particle size analyzer, the trivalent cerium content in the surface layer was measured by XPS, and the content of trivalent cerium in the total cerium was measured by EDTA titration. The test data and the chemical formula of the rare earth polishing powder are listed in Table 1.

[0114] Application Examples 1 to 30, Application Comparative Examples 1 and 2

[0115] Take the rare earth polishing powder prepared in Examples 1 to 30 and Comparative Examples 1 and 2 respectively, disperse them in deionized water, add sodium hexametaphosphate as a surfactant, and disperse them mechanically at high speed (2000 rpm) for 30 minutes to prepare a polishing slurry. Use the prepared rare earth polishing slurry to polish K9 glass (80 mm × 100 mm × 0.5 mm) or polish silicon oxide wafers (4 inches in diameter), with a polishing pressure of 4.95 psi, a polishing disc and a stage with rotation speeds of 45 and 15 rpm / min, respectively, and a polishing time of 20 minutes. The polishing rate was measured, and the surface roughness Sa of the glass before and after polishing was measured using a non-contact surface profiler. The polishing slurry was recycled, and the number of cycles was defined as the number when the polishing rate was reduced to 80% of the initial polishing rate, and the test results are listed in Table 2.

[0116] Table 1

[0117] Table 2

[0118] From the above description, it can be seen that the above embodiments of the present invention achieve the following technical effects:

[0119] The bulk phase of the rare earth polishing powder described herein is primarily tetravalent cerium, with trivalent cerium concentrated on the surface of the rare earth polishing powder particles. This surface enrichment of trivalent cerium facilitates the formation of Ce-O-Si bonds, thereby increasing the polishing rate of the rare earth polishing powder. Furthermore, it helps prevent the presence of trivalent cerium in the bulk phase from disrupting the face-centered cubic structure of cerium oxide, resulting in a highly stable structure. This results in excellent polishing rates and service life, and allows for the production of extremely low-roughness surfaces.

[0120] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A rare earth polishing powder, characterized in that: The chemical formula of the rare earth polishing powder is Ce 1-x M x O y D z , wherein 0≤x≤0.6, 1.2≤y≤2.0, 0≤z≤0.9; the mass percentage of trivalent cerium in the total cerium in the rare earth polishing powder is ≤10%, and the mass percentage of trivalent cerium in the surface area of ​​the rare earth polishing powder particles in the total cerium in the surface area of ​​the rare earth polishing powder particles is ≥20%, wherein the surface area refers to the area 1 to 5 nm close to the surface of the rare earth polishing powder particles; M is selected from any one or more of transition metal elements, alkaline earth metal elements, aluminum elements, silicon elements, alkali metal elements and rare earth elements except cerium, and D is selected from any one or more of fluorine, chlorine, phosphorus and sulfur.

2. A rare earth polishing powder according to claim 1, characterized in that: The cerium oxide phase contained in the rare earth polishing powder is a cubic fluorite phase.

3. The rare earth polishing powder according to claim 1 or 2, characterized in that: The mass percentage of the trivalent cerium in the surface layer of the rare earth polishing powder particles in the total cerium in the surface layer of the rare earth polishing powder particles is ≥25%.

4. The rare earth polishing powder according to any one of claims 1 to 3, characterized in that 0≤x≤0.4, preferably 1.5≤y≤2, preferably 0≤z≤0.6; preferably, M is selected from any one or more of lanthanum, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, thulium, ytterbium, yttrium, zirconium, iron, magnesium, sodium, calcium, and silicon, and preferably, D is fluorine and / or phosphorus.

5. The rare earth polishing powder according to any one of claims 1 to 4, characterized in that: The median particle size D of the rare earth polishing powder 50 It is 0.01 to 5 μm, preferably 0.01 to 2 μm.

6. A method for preparing the rare earth polishing powder according to any one of claims 1 to 5, characterized in that: The preparation method comprises: Step S1, calcining a raw material including a cerium compound in an oxidizing atmosphere to obtain a calcined product; Step S2, subjecting the calcined product to hydrothermal treatment in a solution to obtain the rare earth polishing powder.

7. The preparation method according to claim 6, characterized in that: In step S1, the cerium-containing compound is selected from any one or more of cerium-containing carbonates, fluorocarbonates, oxalates, and hydroxides; the cerium-containing compound is preferably synthesized by any one or more of a coprecipitation method, a sol-gel method, a microemulsion method, a combustion method, and a solid phase method; Preferably, the oxidizing atmosphere in step S1 is oxygen or air; Preferably, the calcination temperature in step S2 is 300-1000° C., preferably 500-900° C.; preferably, the calcination time is 1-48 h, preferably 1-24 h.

8. The preparation method according to claim 6 or 7, characterized in that: In the step S2, the temperature of the hydrothermal treatment is 100 to 250°C, preferably 120 to 200°C; the time of the hydrothermal treatment is preferably 1 to 48 hours, preferably 3 to 24 hours.

9. The preparation method according to any one of claims 6 to 8, characterized in that: In step S2, the solution is an aqueous solution with a pH value of 4 to 12, preferably an aqueous solution with a pH value of 5 to 10, and the pH value of the solution is preferably adjusted to be within the above range using sodium hydroxide and / or potassium hydroxide.

10. The preparation method according to any one of claims 6 to 8, characterized in that: In step S2, the solution includes a reducing substance, and the reducing substance is selected from any one or more of ammonia water, hydrogen peroxide, potassium sulfite, potassium bisulfite, and potassium pyrosulfite. Preferably, the amount of the reducing substance is ≤ 30wt% of the mass of the roasting product.

11. A polishing slurry comprising rare earth polishing powder, a surfactant, a pH regulator and water, characterized in that: The rare earth polishing powder is the rare earth polishing powder according to any one of claims 1 to 5.

12. The polishing slurry according to claim 11, characterized in that In terms of mass percentage, the content of the rare earth polishing powder in the polishing slurry is ≤20%, preferably ≤10%; preferably, the content of the surfactant in the polishing slurry is ≤5%, preferably ≤1%, and preferably, the surfactant is selected from any one or more of sodium hexametaphosphate, sodium polyacrylate, sodium salt of maleic acid-acrylic acid copolymer, and sodium pyrophosphate; preferably, the pH value of the polishing slurry is 4 to 10.

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