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CN-122010561-A - Method for preparing scandium-lutetium co-doped zirconia ceramic ultrafine powder by sol-gel method and application

CN122010561ACN 122010561 ACN122010561 ACN 122010561ACN-122010561-A

Abstract

A method for preparing scandium-lutetium co-doped zirconia ceramic ultrafine powder by using a sol-gel method and application thereof relate to the technical field of advanced ceramic material preparation. The invention aims to solve the problems of poor component uniformity, large grain size, wide distribution, serious hard agglomeration and low conductivity of ceramic powder used by the electrolyte of the existing solid oxide fuel cell. The method comprises the steps of preparing a precursor solution, preparing uniform and transparent sol, step-by-step drying, and calcining. The invention can realize the uniform mixing of the components at the molecular level, effectively inhibit the hard agglomeration of powder and the abnormal growth of crystal grains, and obtain the ultrafine powder with fine crystal grains and uniform grain size distribution. The method has the advantages of simple process, low synthesis temperature, no need of pressurization and low cost. The invention can obtain scandium-lutetium co-doped zirconia ceramic ultrafine powder.

Inventors

  • KE Hua
  • LUO HUIJIADAI
  • LI FANGZHE
  • Ji Dongning

Assignees

  • 哈尔滨工业大学

Dates

Publication Date
20260512
Application Date
20260213

Claims (10)

  1. 1. A method for preparing scandium-lutetium co-doped zirconia ceramic ultrafine powder by using a sol-gel method is characterized by comprising the following steps: 1. Preparing a precursor solution, namely weighing a zirconium source, scandium nitrate and lutetium nitrate according to the stoichiometric ratio of a target product (ZrO 2 ) 1-x-y (Sc 2 O 3 ) x (Lu 2 O 3 ) y , wherein x=0.01-0.10 and y=0.005-0.10), adding the zirconium source, scandium nitrate and lutetium nitrate into glacial acetic acid together, heating and stirring until the zirconium source, scandium nitrate and lutetium nitrate are completely dissolved, and naturally cooling to room temperature to obtain a clear solution; 2. Forming stable sol, namely adding glycol into the clear solution under the condition of continuous stirring, and continuously stirring until the mixture is uniformly mixed to obtain uniform and transparent sol; 3. step drying, namely drying the sol at low temperature, and then raising the temperature to continue drying to obtain xerogel; 4. calcination treatment, grinding xerogel, and then carrying out heat treatment, wherein the heat treatment adopts one of the following two modes: A. the two-step calcination method comprises the steps of firstly raising the temperature to 300-500 ℃, preserving heat, then continuously raising the temperature to 700-900 ℃, preserving heat, and cooling along with a furnace after the calcination is finished; B. the twice calcining method comprises the steps of firstly raising the temperature to 300-500 ℃, preserving heat, then cooling to room temperature along with a furnace, taking out and grinding, raising the temperature of ground powder to 700-900 ℃ from the room temperature, preserving heat, and cooling along with the furnace after calcining is finished, thus obtaining scandium-lutetium co-doped zirconia ceramic ultrafine powder.
  2. 2. The method for preparing scandium lutetium co-doped zirconia ceramic ultra-fine powder according to claim 1, wherein the zirconium source in the first step is zirconyl nitrate or zirconium nitrate.
  3. 3. The method for preparing scandium-lutetium co-doped zirconia ceramic ultra-fine powder according to claim 1, wherein the concentration of the zirconium source in the clarified solution in the first step is 0.3mol/L to 1mol/L.
  4. 4. The method for preparing scandium-lutetium co-doped zirconia ceramic ultrafine powder by using a sol-gel method according to claim 1, wherein the mass fraction of glacial acetic acid in the first step is 99.5% -99.9%, and the mass fraction of ethylene glycol in the second step is 99% -99.8%.
  5. 5. The method for preparing scandium-lutetium co-doped zirconia ceramic ultrafine powder according to claim 1, wherein the volume ratio of glacial acetic acid in the first step to glycol in the second step is (1.5-3.5): 1.
  6. 6. The method for preparing scandium-lutetium co-doped zirconia ceramic ultrafine powder by using a sol-gel method according to claim 1, wherein the temperature of heating and stirring in the first step is 60-80 ℃, the speed of heating and stirring is 150-300 r/min, the time of heating and stirring is 10-15 min, the speed of stirring in the second step is 150-300 r/min, and the time of stirring is 15-60 min.
  7. 7. The method for preparing scandium-lutetium co-doped zirconia ceramic ultrafine powder according to claim 1, wherein in the third step, the sol is dried for 48-96 hours at 40 ℃ and then dried for 72-168 hours at 60 ℃ to obtain xerogel.
  8. 8. The method for preparing scandium-lutetium co-doped zirconia ceramic ultrafine powder by using a sol-gel method according to claim 1, wherein in the fourth step A, the temperature is raised to 300-500 ℃ at a temperature raising rate of 1-5 ℃ per minute, the temperature is kept for 1-3 hours, then the temperature is raised to 700-900 ℃ at a temperature raising rate of 2-6 ℃ per minute, the temperature is kept for 2-4 hours, and the furnace is cooled after the calcination is finished.
  9. 9. The method for preparing scandium-lutetium co-doped zirconia ceramic ultrafine powder by using a sol-gel method according to claim 1, wherein in the fourth step B, the temperature is raised to 300-500 ℃ at a temperature rise rate of 1-5 ℃ per minute, the temperature is kept for 1-3 hours, then the furnace is cooled to room temperature, the ground powder is taken out and ground, the temperature of the ground powder is raised to 700-900 ℃ at a temperature rise rate of 2-6 ℃ per minute again, the temperature is kept for 2-4 hours, and the furnace is cooled after the calcination is finished, so that scandium-lutetium co-doped zirconia ceramic ultrafine powder is obtained.
  10. 10. The application of scandium-lutetium co-doped zirconia ceramic ultra-fine powder prepared by the method according to any one of claims 1-9, which is characterized in that scandium-lutetium co-doped zirconia ceramic ultra-fine powder is used as a solid oxide fuel cell electrolyte.

Description

Method for preparing scandium-lutetium co-doped zirconia ceramic ultrafine powder by sol-gel method and application Technical Field The invention relates to the technical field of advanced ceramic material preparation, in particular to a method for preparing scandium-lutetium co-doped zirconia ceramic ultrafine powder by using a sol-gel method. Background Zirconia (ZrO 2) based ceramics are key electrolyte materials for SOFCs due to their high temperature ionic conductivity and good chemical stability. Pure ZrO 2 has low ionic conductivity, and the crystalline phase thereof is subject to monoclinic (< 1175 ℃), tetragonal (1175-2370 ℃) and cubic (> 2370 ℃) transition with temperature. By doping with divalent or trivalent cations (e.g., Y 3+,Sc3+), oxygen vacancies can be introduced into the lattice and stabilize the high Wen Lifang phase to medium to low temperatures, thereby achieving suitable oxygen ion conductivity. Of the numerous dopants, scandium (Sc 3+) forms Sc 2O3 doped zirconia (ScSZ) with the highest oxygen ion conductivity due to the closest ionic radius (0.087 nm) to zirconium ions (Zr 4+, 0.084 nm). However, studies have demonstrated that 10 mol% Sc 2O3 doped zirconia (10 ScSZ) with optimal conductivity has a reversible phase transition from cubic phase (C-phase) to rhombohedral phase (β -phase) at about 600 ℃. This phase change can lead to abrupt conductivity changes and initiate microcracks in the thermal cycle, severely threatening the long-term reliability of the electrolyte. To suppress the detrimental phase change of 10ScSZ, the prior art proposes strategies to introduce a second phase stabilizer. Among them, cerium oxide (CeO 2) has been widely studied because it has a fluorite structure and can widen a cubic phase stability interval, and a co-doping system such as 10Sc1CeSZ is formed. It is worth noting that in the Sc 2O3-CeO2-ZrO2 system, the 10Sc1CeSZ (i.e., 10 mol% Sc 2O3 doped with 1 mol% CeO 2) component has been reported to have one of the highest oxygen ion conductivities known to date. The addition of CeO 2 does raise the conductivity peak and also further improves the phase stability. However, this solution introduces a new and more difficult technical problem that Ce 4+ is easily reduced to Ce 3+ in a strongly reducing atmosphere at the anode side of the SOFC. This process, accompanied by lattice expansion and additional oxygen vacancy generation, can disrupt the structural integrity of the electrolyte and can cause deleterious electron conduction, leading to accelerated degradation of cell performance. Thus, there is a strong need in the art for a novel co-dopant that is effective in stabilizing the ScSZ cubic phase structure, while maintaining a high degree of chemical stability in a reducing atmosphere. Trivalent lutetium ions (Lu 3+) are highly matched (0.087 nm with a degree of matching better than Ce 4+) with Zr 4+ due to their ionic radius (about 0.085 nm), theoretically, they can reduce lattice strain more effectively, and enhance phase structural stability. Meanwhile, the valence state of Lu 2O3 is stable in a wide oxygen partial pressure range and is not easy to reduce, so that the defect of Ce-based doping agent is hopeful to be overcome. Thus, scandium-lutetium (Sc-Lu) co-doping can be considered as a very potential solution to address the dual challenges of ScSZ-based electrolyte phase instability and chemical reduction instability. However, the realization of high performance Sc-Lu co-doped zirconia materials is highly dependent on powder preparation technology. Although the traditional solid phase method is difficult to realize uniform doping of atomic scale, wet chemical methods such as coprecipitation method and the like can be used, the requirement on process control is extremely high, and the composition segregation and the serious agglomeration of powder are easy to cause. The lack of microscopic uniformity of the powder prepared by the method counteracts the theoretical advantages brought by the co-doping design. Therefore, developing a synthetic method that can achieve high uniform mixing of Sc, lu, zr ions at the molecular/atomic level and can precisely control particle size and morphology of the powder becomes a prerequisite for obtaining the desired high-performance Sc-Lu SZ electrolyte material. Disclosure of Invention The invention aims to solve the problems of poor component uniformity, large grain size, wide distribution, serious hard agglomeration and low conductivity of ceramic powder used by the conventional solid oxide fuel cell electrolyte, and provides a method for preparing scandium-lutetium co-doped zirconia ceramic ultrafine powder by using a sol-gel method and application thereof. The invention provides a sol-gel preparation method which has relatively simple process and uniform components and can effectively inhibit agglomeration and excessive growth of crystal grains. The invention can realize the uniform mixing of the components at the