Surface modified cerium dioxide powder as well as preparation method and application thereof

Abstract

The invention discloses surface modified cerium dioxide powder as well as a preparation method and application thereof, and the preparation method comprises the following steps: 1) modifying cerium dioxide with the particle size of 0.55-2.5 mu m with KH550 to obtain KH550 modified cerium dioxide powder; 2) mixing the KH550 modified cerium oxide powder obtained in the step 1) with C1-C3 alkyl alcohol and C1-C3 alkyl acid, and then reacting at 45-75 DEG C for 0.5-2.5 hours to obtain an initial reaction mixture; 3) adding polyethylene glycol carboxylic acid with the molecular weight of 350-2000 into the initial reaction mixture at the temperature of 45-75 DEG C, and continuously reacting for 3-8 hours to obtain a final reactant; 4) cooling the final reactant, carrying out solid-liquid separation, washing the separated solid, and drying the washed solid to obtain surface modified cerium dioxide powder; wherein the mass ratio of the KH550 modified cerium oxide powder to the polyethylene glycol carboxylic acid is 6: (0.6-3.7). According to the preparation method, the surface modified cerium dioxide powder with smaller particle size, better dispersity and larger Zeta potential absolute value can be obtained.

Description

Technical Field

[0001] The present invention relates to a surface-modified cerium dioxide powder and its preparation method and application. Background Art

[0002] With the rapid development of communication technology, the size of electronic devices is getting smaller and smaller, and the requirements for the flatness of semiconductor chips and high-performance optical surfaces are also getting higher and higher. Chemical Mechanical Polishing (CMP) technology is a commonly used technology that can achieve global planarization of the wafer surface in integrated circuit manufacturing at present, and can reach atomic-level ultra-high flatness, and its effect affects the final quality and yield of the chip. In order to obtain a surface with ultra-high precision, the requirements for the formulation and production of polishing materials are also continuously increasing. Cerium dioxide (CeO 2 ) as an efficient polishing material is widely used in high-precision polishing. The main disadvantages of existing polishing materials are poor dispersibility, wide particle size distribution, and many large particles, which seriously affect the application of rare earth polishing materials in China.

[0003] The addition of a dispersant can effectively improve the dispersibility of cerium dioxide particles. Commonly used dispersants include inorganic salt dispersants, organic polymer dispersants, and surfactants, etc. The purpose of dispersion is achieved through electrostatic repulsion and steric hindrance stabilization mechanisms.

[0004] A literature discloses a preparation method of a modified nano-cerium oxide, including: dissolving silane coupling agent KH550 in water and mixing it with nano-cerium oxide powder to prepare a dispersion liquid with a cerium oxide weight percentage of 1-10%; then stirring evenly with a magnetic stirrer and subjecting it to ultrasonic treatment to obtain a cerium oxide dispersion liquid; heating the above dispersion liquid to a reaction temperature of 70-100 °C and reacting for 1-12 hours; after the reaction is completed, centrifuging, purifying, and drying to obtain cerium oxide abrasive grains modified by KH550. In this literature, before modification, the nano-cerium oxide powder agglomerates severely, and after modification, the dispersibility is improved.

[0005] Another literature discloses a surface-modified cerium oxide particle, which is obtained by modifying with a modifier containing silicon and oxygen. This literature provides a modified cerium oxide for the problem that existing cerium oxide abrasive grains are prone to agglomeration, resulting in damage to the surface of the workpiece after polishing.

[0006] The dispersion effect of the technical solutions recorded in the above literatures still needs to be further improved. Summary of the Invention

[0007] An object of the present invention is to provide a preparation method of a surface-modified cerium dioxide powder, which can disperse cerium dioxide with a particle size of 0.55-2.5 μm well, and can obtain a surface-modified cerium dioxide powder with better dispersibility and a larger absolute value of Zeta potential.

[0008] Another object of the present invention is to provide a surface-modified cerium dioxide powder prepared by the above preparation method.

[0009] Another object of the present invention is to provide a use of a surface-modified cerium dioxide powder as a polishing material.

[0010] The present invention adopts the following technical solutions to achieve the above objects.

[0011] On the one hand, the present invention provides a preparation method of a surface-modified cerium dioxide powder, comprising the following steps:

[0012] 1) Modify cerium dioxide with a particle size of 0.55 - 2.5 μm with KH550 to obtain KH550-modified cerium oxide powder;

[0013] 2) Mix the KH550-modified cerium oxide powder obtained in step 1) with a C1 - C3 alkyl alcohol and a C1 - C3 alkyl acid, and then react at 45 - 75 °C for 0.5 - 2.5 h to obtain an initial reaction mixture;

[0014] 3) At 45 - 75 °C, add a polyethylene glycol carboxylic acid with a molecular weight of 350 - 2000 to the initial reaction mixture and continue to react for 3 - 8 h to obtain a final reactant;

[0015] 4) Cool the final reactant, perform solid-liquid separation, wash the separated solid, and dry the washed solid to obtain a surface-modified cerium dioxide powder;

[0016] Wherein, the mass ratio of the KH550-modified cerium oxide powder to the C1 - C3 organic acid is 1:8 - 13; the volume ratio of the C1 - C3 alkyl alcohol to the C1 - C3 alkyl acid is 1 - 2:1;

[0017] Wherein, the mass ratio of the KH550-modified cerium oxide powder to the polyethylene glycol carboxylic acid is 6:0.6 - 3.7.

[0018] The present invention discovers that for cerium dioxide with a particle size of 0.55 - 2.5 μm, first modify it with KH550 and then react and modify it with a polyethylene glycol carboxylic acid with a certain molecular weight, a surface-modified cerium dioxide powder with smaller particle size, better dispersibility, and a larger absolute value of Zeta potential can be obtained.

[0019] The present invention believes that covalently grafting the high molecular chain of the dispersant onto the surface of the cerium dioxide particles makes the hydrophilic groups face outwards, has good compatibility with the dispersion medium, and forms a polymer layer on the surface of the particles. When surrounding particles approach the particles, the polymer layer is squeezed, the number of molecular chain configurations decreases, the configurational entropy decreases, resulting in an increase in the free energy of the system, generating a repulsive potential energy for the approaching particles, and thus achieving a good dispersion effect.

[0020] In the present invention, the particle size of the raw material cerium dioxide is 0.55 - 2.5 μm, preferably 0.55 - 1.5 μm, and more preferably 0.75 - 1 μm. KH550 is γ-aminopropyltriethoxysilane.

[0021] In step 2), the mass ratio of the KH550-modified cerium oxide powder to the C1 - C3 organic acid can be 1:8 - 13, preferably 1:9 - 12, and more preferably 1:9 - 10. The volume ratio of the C1 - C3 alkyl alcohol to the C1 - C3 alkyl acid can be 1 - 2:1, preferably 1 - 1.5:1. The reaction temperature can be 45 - 75 °C, preferably 50 - 70 °C, and more preferably 55 - 60 °C. The reaction time can be 0.5 - 2.5 h, preferably 1.5 - 2 h.

[0022] In step 2), preferably, the KH550-modified cerium oxide powder, the C1 - C3 alkyl alcohol, and the C1 - C3 alkyl acid can be mixed under stirring, then ultrasonicated for 10 - 20 min, preferably ultrasonicated for 10 - 15 min, and then reacted at 45 - 75 °C for 0.5 - 2.5 h to obtain an initial reaction mixture.

[0023] In step 3), the molecular weight of the polyethylene glycol carboxylic acid can be 350 - 2000, preferably 450 - 2000, and more preferably 500 - 2000, such as 500, 550, 600, 650, 700, 750, 800, 900, 1000, 1500, 2000. The present invention finds that controlling the molecular weight of the polyethylene glycol carboxylic acid within the above range can further reduce the particle size and improve the dispersibility of the obtained surface-modified cerium dioxide. If it is greater than or less than this range, the technical effects of the present invention cannot be achieved.

[0024] The mass ratio of the KH550-modified cerium oxide powder to the polyethylene glycol carboxylic acid can be 6:0.6 - 3.7, preferably 6:0.7 - 3.6, more preferably 6:0.8 - 3.5, and still more preferably 6:0.9 - 3.5. According to a specific embodiment of the present invention, the mass ratio of the KH550-modified cerium oxide powder to the polyethylene glycol carboxylic acid is 6:0.9 - 3.44. According to another specific embodiment of the present invention, the mass ratio of the KH550-modified cerium oxide powder to the polyethylene glycol carboxylic acid is 6:0.9 - 1.3. The reaction temperature can be 45 - 75 °C, preferably 50 - 70 °C, and more preferably 55 - 60 °C. The reaction time can be 3 - 8 h, preferably 5 - 7 h, such as 6 h. This is beneficial to further reducing the particle size of cerium dioxide and improving the dispersibility of cerium dioxide.

[0025] In step 4), the final reactant can be cooled to room temperature, and then filtered or centrifuged for solid-liquid separation.

[0026] According to the preparation method of the present invention, preferably, step 1) includes the following specific steps:

[0027] (1) Mix a C6-C8 hydrocarbon solvent and KH550, and then heat up to 60-85 °C to obtain an initial mixture;

[0028] (2) At 60-85 °C, add cerium dioxide with a particle size of 0.55-2.5 μm to the initial mixture and react for 5-10 h;

[0029] (3) After the reaction is completed, cool down and perform solid-liquid separation. Wash and dry the separated solid to obtain KH550-modified cerium oxide powder;

[0030] Among them, the mass ratio of KH550 to cerium dioxide is 1:3-6. This is beneficial to the preliminary modification of cerium dioxide with a particle size of 0.55-2.5 μm.

[0031] In step (1), mix the C6-C8 hydrocarbon solvent and KH550 under stirring, then ultrasonicate for 10-20 min, preferably ultrasonicate for 10-15 min, and then heat up to 60-85 °C, preferably 70-85 °C, to obtain an initial mixture.

[0032] In step (2), the mass ratio of KH550 to the raw material cerium dioxide can be 1:3-6, preferably 1:4-5. The reaction temperature can be 60-85 °C, preferably 70-85 °C. The reaction time can be 5-10 h, preferably 7-9 h, for example 8 h.

[0033] In step (3), after the reaction is completed, cool down to room temperature and perform solid-liquid separation by filtration or centrifugation.

[0034] According to the preparation method of the present invention, preferably, in step (1), the C6-C8 hydrocarbon solvent is selected from at least one of n-hexane, n-heptane, n-octane, cyclohexane, toluene, and ethylbenzene, and the mass ratio of KH550 to the C6-C8 hydrocarbon solvent is 1:10-30. This is beneficial to the grafting of KH550 onto the surface of cerium dioxide particles. The C6-C8 hydrocarbon solvent is preferably one of n-hexane, n-heptane, n-octane, cyclohexane, toluene, and ethylbenzene, more preferably toluene. The mass ratio of KH550 to the C6-C8 hydrocarbon solvent is preferably 1:14-25.

[0035] According to the preparation method of the present invention, preferably, in step (3), the separated solid is washed with acetone and alcohol, and the washed solid is dried; wherein, the drying temperature is 50-80 °C and the drying time is 4-8 h. This is beneficial to the next graft modification. In this step, the alcohol can be selected from one of methanol, ethanol, and isopropanol, preferably ethanol. According to a specific embodiment of the present invention, the separated solid is washed with acetone and ethanol in sequence. Toluene and other impurities are removed by washing. The drying temperature can be 50-80 °C, preferably 60-70 °C. The drying time can be 4-8 h, preferably 6-7 h.

[0036] According to the preparation method of the present invention, preferably, in step 2), the C1-C3 alkyl alcohol can be selected from at least one of methanol, ethanol, and isopropanol. Preferably, the C1-C3 alkyl alcohol is selected from one of methanol, ethanol, and isopropanol, more preferably ethanol.

[0037] According to the preparation method of the present invention, preferably, in step 2), the C1-C3 alkyl acid can be selected from at least one of formic acid, acetic acid, and propionic acid. Preferably, the C1-C3 alkyl acid is selected from one of formic acid, acetic acid, and propionic acid, more preferably acetic acid. This is beneficial to the reaction of polyethylene glycol carboxylic acid with KH550-modified cerium oxide powder.

[0038] According to the preparation method of the present invention, preferably, in step 3), the molecular weight of the polyethylene glycol carboxylic acid is 550-2000. In some embodiments, the molecular weight of the polyethylene glycol carboxylic acid is 550-750. In some other embodiments, the molecular weight of the polyethylene glycol carboxylic acid is 550-950. In still some other embodiments, the molecular weight of the polyethylene glycol carboxylic acid is 1000-1400. In yet some other embodiments, the molecular weight of the polyethylene glycol carboxylic acid is 1500-2000.

[0039] According to the preparation method of the present invention, preferably, in step 4), the separated solid is washed with water and alcohol, and the washed solid is dried at 50-80 °C for 4-8 h. In this step, the alcohol can be selected from one of methanol, ethanol, and isopropanol, preferably ethanol. According to a specific embodiment of the present invention, in step 4), the separated solid is washed with water and ethanol in sequence. Acetic acid and other impurities are removed by washing. The drying temperature can be 50-80 °C, preferably 60-70 °C. The drying time can be 4-8 h, preferably 6-7 h.

[0040] On the other hand, the present invention also provides a surface-modified cerium dioxide powder, which is prepared by the preparation method described above. The preparation method of the surface-modified cerium dioxide of the present invention grafts KH550 and polyethylene glycol carboxylic acid hydrophilic polymer chains onto the surface of cerium dioxide, breaks the hard agglomeration of the powder, effectively controls the particle size of the cerium dioxide particles and achieves the effect of improving the dispersibility.

[0041] On yet another aspect, the present invention also provides an application of the surface-modified cerium dioxide powder as described above in polishing materials.

[0042] The preparation method of the present invention can better disperse cerium dioxide with a particle size of 0.55 - 2.5 μm, and obtain a surface-modified cerium dioxide powder with smaller particle size, better dispersibility and a larger absolute value of Zeta potential. According to the preferred technical solution of the present invention, by first modifying the raw material cerium dioxide with KH550 and then grafting and modifying it with polyethylene glycol carboxylic acid of a certain molecular weight, a surface-modified cerium dioxide powder with better dispersibility and smaller particle size can be obtained. This preparation method can be extended to other polishing material systems, providing new ideas for the preparation of high-performance rare earth polishing materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 It is a schematic diagram of the process mechanism of the surface modification of cerium dioxide in the present invention.

[0044] Figure 2 It is an infrared spectrogram of the raw material cerium dioxide, KH550-modified cerium oxide and surface-modified cerium dioxide in Example 1.

[0045] Figure 3 It is a mass spectrogram of the raw material cerium dioxide, KH550-modified cerium oxide and surface-modified cerium dioxide in Example 1.

[0046] Figure 4 It is an XRD pattern of the raw material cerium dioxide, KH550-modified cerium oxide and surface-modified cerium dioxide in Example 1.

[0047] Figure 5(a) is an SEM image of the raw material cerium dioxide in Example 1.

[0048] Figure 5(b) is an SEM image of the KH550-modified cerium oxide in Example 1.

[0049] Figure 5(c) is an SEM image of the surface-modified cerium dioxide in Example 1. DETAILED DESCRIPTION OF THE INVENTION

[0050] <Analysis Method>

[0051] Infrared spectrum: Tested by the reflection mode of a Bruker Alph infrared spectrometer, and the test range is 500 - 4000 cm-1 。

[0052] SEM scanning test: Tested with a Zeiss Sigma500 field emission scanning electron microscope from Germany.

[0053] XRD: Tested with an X’Pert PRO X-ray diffractometer.

[0054] Mass spectrometry: Tested with a Thermo Fisher Scientific Nicolet iS20 time-of-flight secondary ion mass spectrometer (TOF-SIMS) from the United States.

[0055] Zeta potential and particle size: Tested with a Baxter 90PLUS ZETA potential analyzer.

[0056] The raw materials used in the examples and comparative examples are introduced below:

[0057] Polyethylene glycol carboxylic acid (PEG-COOH) with a molecular weight of 550 or 2000, both purchased from Sinobioway Biotechnology Co., Ltd.

[0058] γ-Aminopropyltriethoxysilane (KH550): Purchased from Bidepharm reagents.

[0059] Example 1

[0060] Stir and mix 300 mL of toluene and 15 g of KH550 (γ-aminopropyltriethoxysilane), then sonicate for 10 min, and then heat up to 78 °C to obtain an initial mixture. At 78 °C, add 60 g of cerium dioxide with a particle size of 0.792 μm to the initial mixture and react for 8 h. After the reaction, cool to room temperature (about 25 °C), and perform centrifugal separation. Wash the separated solid successively with acetone and ethanol (specifically, wash with 50 mL of acetone and 100 mL of ethanol successively, recorded as 1 washing time, and the total number of washing times is 3 times). Dry the washed solid in a vacuum at 60 °C for 6 h to obtain KH550-modified cerium oxide powder, denoted as CeO 50 -NH 2 -NH 2 。

[0061] Mix 6 g of the obtained KH550-modified cerium oxide powder, 60 mL of ethanol, and 60 mL of acetic acid under stirring, then sonicate for 10 min, and then react at 55 °C for 1.5 h to obtain an initial reaction mixture.

[0062] At 55 °C, add 0.94 g of polyethylene glycol carboxylic acid (PEG-COOH) with a molecular weight of 550 to the initial reaction mixture and continue to react for 6 h to obtain the final reactant.

[0063] The final reactant was cooled to room temperature (about 25 °C), centrifuged, and the separated solid was washed successively with water and ethanol (specifically, washed successively with 100 mL of water and 100 mL of ethanol, recorded as 1 washing time, and the total number of washing times was 3 times). The washed solid was dried in vacuo at 60 °C for 6 h to obtain surface-modified cerium oxide powder, denoted as CeO 2 -PEG.

[0064] The mechanism of the surface modification process is shown in Figure 1 .

[0065] Example 2

[0066] 300 mL of toluene and 15 g of KH550 (γ-aminopropyltriethoxysilane) were stirred and mixed, then sonicated for 10 min, and then heated to 78 °C to obtain an initial mixture. At 78 °C, 60 g of D 50 Cerium oxide with a particle size of 0.792 μm was added to the initial mixture and reacted for 8 h. After the reaction, it was cooled to room temperature (about 25 °C), centrifuged, and the separated solid was washed successively with acetone and ethanol (specifically, washed successively with 50 mL of acetone and 100 mL of ethanol, recorded as 1 washing time, and the total number of washing times was 3 times). The washed solid was dried in vacuo at 60 °C for 6 h to obtain KH550-modified cerium oxide powder, denoted as CeO 2 -NH 2 .

[0067] The obtained 6 g of KH550-modified cerium oxide powder, 60 mL of ethanol, and 60 mL of acetic acid were mixed under stirring, then sonicated for 10 min, and then reacted at 55 °C for 1.5 h to obtain an initial reaction mixture.

[0068] At 55 °C, 3.42 g of polyethylene glycol carboxylic acid (PEG-COOH) with a molecular weight of 2000 was added to the initial reaction mixture and reacted for another 6 h to obtain the final reactant. Denoted as CeO 2 -PEG-2000.

[0069] The final reactant was cooled to room temperature (about 25 °C), centrifuged, and the separated solid was washed successively with water and ethanol (specifically, washed successively with 100 mL of water and 100 mL of ethanol, recorded as 1 washing time, and the total number of washing times was 3 times). The washed solid was dried in vacuo at 60 °C for 6 h to obtain surface-modified cerium oxide powder, denoted as CeO 2 -PEG-2000.

[0070] The obtained surface-modified cerium oxide powder (CeO 2The particle size and dispersibility of (-PEG-2000) were also improved, but the particle size was slightly larger than that of Example 1, and the dispersibility was slightly worse than that of Example 1. See Table 1. This should be due to the entanglement between the longer PEG chains, which makes the cerium dioxide particles more likely to aggregate, forming larger aggregates, and thus showing a larger particle size and slightly worse dispersibility.

[0071] Comparative Example 1

[0072] 300 mL of water and 15 g of KH550 (γ-aminopropyltriethoxysilane) were stirred and mixed, then ultrasonicated for 10 min, and then heated to 78 °C to obtain an initial mixture. At 78 °C, 60 g of D 50 Cerium dioxide with a particle size of 0.792 μm was added to the initial mixture and stirred for 8 h. It was found that KH550 was basically not reduced and hardly reacted.

[0073] Experimental Example

[0074] (I) Infrared test

[0075] The raw materials CeO of Example 1 were characterized by a Fourier transform infrared spectrometer 2 The obtained KH550-modified cerium oxide (CeO 2 -NH 2 ) and the obtained surface-modified cerium dioxide (CeO 2 -PEG). The infrared test results are shown in Figure 2 .

[0076] It can be seen from Figure 2 that in the infrared spectrum of CeO 2 -NH 2 , obvious peaks were detected at 1490 cm -1 , 2931 cm -1 and 2845 cm -1 . The peak at 1490 cm -1 is the stretching vibration peak of -C-N, and the peaks at 2931 cm -1 and 2845 cm -1 are the stretching vibration peaks of -CH 2 . It can be seen that the short chain containing amino groups was successfully grafted onto the surface of CeO 2 . In the infrared spectrum of CeO 2 -PEG, the C=O stretching vibration peak at 1700 cm -1 indicates the formation of urethane bonds, and the -OH stretching vibration peak at 3500 cm -1 indicates the successful grafting of the PEG chain.

[0077] (II) Mass spectrometry test

[0078] The raw material CeO of Example 1 was analyzed by time-of-flight secondary particle mass spectrometry. 2 The obtained KH550 modified cerium oxide (CeO 2 -NH 2 ) and the resulting surface-modified cerium dioxide (CeO 2 -PEG) was characterized, and the results are shown in Figure 3 .

[0079] Depend on Figure 3 It can be seen that in CeO 2 CN, CNO, Si 2 O 5 H and Si 3 O 7 H and other fragment peaks. This further proves that the amino short chain and PEG chain have been successfully grafted onto CeO 2 surface.

[0080] (III) XRD test

[0081] The raw material CeO 2 The obtained KH550 modified cerium oxide (CeO 2 -NH 2 ) and the resulting surface-modified cerium dioxide (CeO 2 -PEG) was tested by XRD, and the results are shown in Figure 4 .Depend on Figure 4 It can be seen that the amino short chain and PEG chain are grafted to CeO 2 The surface does not affect CeO 2 of the crystal structure.

[0082] (IV) SEM scanning test

[0083] The raw material CeO 2 The obtained KH550 modified cerium oxide (CeO 2 -NH 2 ) and the resulting surface-modified cerium dioxide (CeO 2 -PEG) were tested by SEM, and the results are shown in Figure 5(a), Figure 5(b), and Figure 5(c). 2 After the surface, CeO 2 The dispersibility of the particles is improved. PEG chains are grafted to CeO 2 -NH 2 After the surface, CeO 2 The dispersibility of particles is further improved.

[0084] (V) Particle size and potential test

[0085] The results are shown in Table 1.

[0086] Table 1

[0087]

[0088] As can be seen from Table 1, after the amino short chain is grafted onto the surface of CeO 2 the particle size of CeO 2 particles decreases, and the Zeta potential increases. After the PEG chain is grafted onto the surface of KH550-modified cerium oxide (CeO 2 -NH 2 ), the particle size of CeO 2 particles further decreases, and the Zeta potential further increases. The greater the absolute value of the Zeta potential, the greater the charge repulsion force between particles, and the less likely the particles are to agglomerate. These results indicate that after the polymer is grafted onto the surface of CeO 2 the dispersibility of CeO 2 particles can be effectively improved. It can also be seen from Example 1 and Example 2 that controlling the molecular weight of poly(ethylene glycol) carboxylic acid within a specific range is more conducive to controlling the particle size and dispersibility of the obtained surface-modified cerium oxide powder.

[0089] The present invention is not limited to the above embodiments. Without departing from the essence of the present invention, any deformation, improvement, or replacement that can be conceived by those skilled in the art falls within the scope of the present invention.

Claims

1. A method for preparing surface-modified cerium dioxide powder, characterized in that: The following steps are involved: 1) modifying cerium dioxide with a particle size of 0.55 to 2.5 μm with KH550 to obtain KH550-modified cerium oxide powder; 2) mixing the KH550 modified cerium oxide powder obtained in step 1) with C1-C3 alkyl alcohol and C1-C3 alkyl acid, and then reacting at 45-75° C. for 0.5-2.5 h to obtain an initial reaction mixture; 3) adding polyethylene glycol carboxylic acid having a molecular weight of 350 to 2000 to the initial reaction mixture at 45 to 75° C. and continuing the reaction for 3 to 8 hours to obtain a final reactant; 4) cooling the final reactant, separating the solid from the liquid, washing the separated solid, and drying the washed solid to obtain a surface-modified cerium dioxide powder; The mass ratio of KH550 modified cerium oxide powder to C1-C3 organic acid is 1:8-13; the volume ratio of C1-C3 alkyl alcohol to C1-C3 alkyl acid is 1-2:1; Wherein, the mass ratio of KH550 modified cerium oxide powder to polyethylene glycol carboxylic acid is 6:0.6-3.

7.

2. The preparation method according to claim 1, characterized in that: Step 1) includes the following specific steps: (1) mixing a C6-C8 hydrocarbon solvent and KH550, and then heating the mixture to 60-85° C. to obtain an initial mixture; (2) adding cerium dioxide having a particle size of 0.55 to 2.5 μm to the initial mixture at 60 to 85° C. and reacting for 5 to 10 hours; (3) cooling after the reaction, separating the solid and the liquid, washing and drying the separated solid to obtain KH550 modified cerium oxide powder; Among them, the mass ratio of KH550 to cerium dioxide is 1:3-6.

3. The preparation method according to claim 2, characterized in that: In step (1), the C6-C8 hydrocarbon solvent is selected from at least one of n-hexane, n-heptane, n-octane, cyclohexane, toluene and ethylbenzene; and the mass ratio of KH550 to the C6-C8 hydrocarbon solvent is 1:10-30.

4. The preparation method according to claim 2, characterized in that: In step (3), the separated solid is washed with acetone and alcohol, and the washed solid is dried; wherein the drying temperature is 50 to 80° C. and the drying time is 4 to 8 hours.

5. The preparation method according to claim 1, characterized in that: In step 2), the C1-C3 alkyl alcohol is selected from at least one of methanol, ethanol and isopropanol.

6. The preparation method according to claim 1, characterized in that: In step 2), the C1-C3 alkyl acid is selected from at least one of formic acid, acetic acid and propionic acid.

7. The preparation method according to claim 1, characterized in that: In step 3), the molecular weight of the polyethylene glycol carboxylic acid is 550-2000.

8. The preparation method according to claim 1, characterized in that: In step 4), the separated solid is washed with water and alcohol, and the washed solid is dried at 50-80° C. for 4-8 hours.

9. A surface-modified cerium dioxide powder, characterized in that: It is prepared according to the preparation method according to any one of claims 1 to 8.

10. Use of the surface-modified cerium dioxide powder according to claim 9 in polishing materials.

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