【作者】 张哲；

【导师】 李继光； 李晓东；

【作者基本信息】 东北大学 ， 材料工程（专业学位）， 2023， 硕士

【摘要】 Y2O3具有宽带隙(5.6eV)、高热导率(13.6 W·(m·K)-1)、高热稳定性、低声子能量、良好的耐腐蚀性和抗热震性等优良性能,可用于制备透明窗口、闪烁体基质材料而获得广泛研究。然而,关于Y2O3透明陶瓷的制备还存在诸多问题。首先,如何解决采用沉淀法制备纳米氧化钇粉体过程中出现的团聚体问题仍不全面。其次,如何在不引入杂质前提下提升纳米粉体的分散性、烧结活性并降低团聚度的研究仍处于空白阶段。国内外对于不同种类烧结助剂对于粉体合成及烧结活性的研究仍不全面。最后,制备高烧结活性纳米粉体对于(Y,Gd,Zr,Eu)2O3+δ(YGO:Eu)粉体及陶瓷发光性能的影响仍需探索。因此,本文以氧化钇粗粉为原料,依次从粉体分散、成型和烧结的角度出发,就如何制备出高烧结活性粉体进行了系统研究,通过XRD、BET、FT-IR、FE-SEM、粒度分析、透过率等测试手段,对Y2O3粉体、坯体和陶瓷进行表征。实验结果为Y2O3透明陶瓷制备所需初始粉体,尤其是作为闪烁体材料的研究发展提供了可靠的制备工艺。主要研究结果如下:以提高粉体分散性和烧结活性为目标,采用沉淀法制备工艺,利用正交试验,选择合适的碳酸氢铵与钇离子摩尔比(1.00:1)、煅烧温度(1100℃)及煅烧保温时间(2h),确定最佳沉淀法制备工艺和煅烧工艺,通过对比三种分散剂:TAC(柠檬酸三铵)、PAA(聚丙烯酸)、PEI(聚乙烯亚胺)对粉体分散性和烧结活性的影响,发现PEI加入量为1 wt%时,粉体团聚度仅为1.137,粒度分布最窄且具有较高烧结活性;对于合成的粉体,干压后在冷等静压200MPa下保压2min,在空气气氛下1500℃预烧7h,1550℃、200 MPa热等静压烧结2 h可直接得到平均晶粒尺寸为310 nm且直线透过率极高的Y2O3透明陶瓷,厚度为1.5 mm样品在波长800nm处的透过率达到78.9%,为实现离子掺杂奠定扎实理论基础。针对烧结助剂掺杂的问题,从粉体合成角度着手,通过已开发的沉淀法制备工艺成功制备出Y2O3粉体,探究了烧结助剂种类及掺杂含量对于粉体分散性和烧结活性的影响。烧结助剂的掺杂对于粉体的形貌及颗粒尺寸没有明显影响。发现二价烧结助剂(Ca2+、Mg2+)会加速晶界迁移速率并降低烧结温度,随着二价烧结助剂含量增加,陶瓷晶粒尺寸迅速增加(～1.30 μm),陶瓷烧结体致密度增加(～96.1%),致密化速率过快,易形成晶内孔隙。而四价烧结助剂(Zr4+)加入,会极大程度的抑制晶界迁移速率,同时随着四价烧结助剂含量增加,陶瓷晶粒尺寸变化不明显,但在高温条件下抑制晶界迁移速率,有效降低孔隙率,有助于真空烧结制备Y2O3透明陶瓷。采用共沉淀法制备工艺结合空气烧结,通过组分设计和制备工艺优化,对于YGO:Eu粉体分散性、烧结活性及立方相YGO:Eu固溶体发光性能进行研究。发现适量Gd3+(25～50 at.%)的掺杂可促进烧结时离子扩散和晶粒的生长。当Gd3+的掺杂含量为0.5 at.%,煅烧温度为1100℃,空气气氛烧结温度为1500℃时制备的YGO:Eu固溶体相对密度可达～96.9%。Gd3+的低电负性使得陶瓷电荷迁移带(CTB)发生红移,陶瓷可被275 nm紫外光、396 nm近紫外光、466 nm蓝光有效激发实现红光发射,作为红光材料经真空烧结后可有望应用于白光LED领域。更多还原

【Abstract】 Y2O3 has excellent properties such as broadband gap(5.6 eV),high thermal conductivity(13.6 W·(m·K)-1),high thermal stability.low phonon energy,good corrosion resistance and thermal shock resistance,and can be widely studied for the preparation of transparent window and scintillator matrix materials.However.there are still many issues regarding the preparation of Y2O3 transparent ceramics.Firstly,it is still not comprehensive how to solve the problem of agglomerates that occur during the preparation of nano yttrium oxide powders using the precipitation method.Secondly,how to improve the dispersity.sintering activity and reduce the degree of agglomeration of nano powders without introducing impurities is still in the blank stage.The research on different types of sintering aids for powder synthesis and sintering activity is still not comprehensive both domestically and internationally.Finally,high sintering activity nano powder was prepared for(Y.Gd.Zr.Eu)2O3+δ The influence of(YGO:Eu)powder and ceramic luminescent properties still needs to be explored.Therefore,this article takes crude yttrium oxide powder as the raw material.and systematically studies how to prepare high sintering active powder from the perspectives of powder dispersion,molding,and sintering.Y2O3 powder,green body,and ceramics are characterized through testing methods such as XRD,BET.FT-IR,FESEM.particle size analysis.transmittance,and porosity.The experimental results provide a reliable preparation process for the initial powder required for the preparation of Y2O3 transparent ceramics,especially for the research and development of scintillator materials.The main research content is as follows:With the goal of improving powder dispersibility and sintering activity,a precipitation method was used to prepare the powder.Orthogonal experiments were conducted to select the appropriate molar ratio of ammonium bicarbonate to yttrium ion,calcination temperature,and holding time to determine the optimal precipitation method preparation process and calcination process.By comparing the effects of three dispersants:TAC(triammonium citrate),PAA(polyacrylic acid),and PEI(polyethylene imine)on powder dispersibility and sintering activity,It was found that when the addition of PEI was 1 wt%,the agglomeration degree of the powder was only 1.137.the particle size distribution was the narrowest and the sintering activity was higher;For the preparation of powders,after dry pressing,the Y2O3 transparent ceramics with an average grain size of 310 nm and extremely high linear transmittance can be directly obtained by holding them under cold isostatic pressure of 200 MPa for 2 minutes,pre firing them under air atmosphere at 1500℃ for 7 hours.and sintering them under hot isostatic pressure of 1550℃ and 200 MPa for 2 hours.The sample with a thickness of 1.5 mm has a transmittance of 78.9%at a wavelength of 800 nm,laying a solid theoretical foundation for ion doping.In response to the issue of doping sintering additives.Y2O3 was successfully prepared from the perspective of powder synthesis by developing a precipitation method preparation process The influence of sintering additives and doping content on powder dispersion and sintering activity was investigated.It was found that divalent sintering aids(Ca2+,Mg2+)can accelerate grain boundary migration rate and lower sintering temperature.As the content of divalent sintering aids increases,the ceramic grain size rapidly increases(～1.30 μm)The density of ceramic sintered body increases(～97.1%).The addition of tetravalent sintering additives(Zr4+)greatly suppresses the grain boundary migration rate.At the same time,as the content of tetravalent sintering additives increases,the change in ceramic grain size is not significant.However,it effectively reduces porosity under high temperature conditions,which helps to prepare Y2O3 transparent ceramics through vacuum sintering.The dispersion and sintering activity of YGO:Eu powder and the luminescence properties of cubic YGO:Eu solid solution were studied by using the coprecipitation method combined with air sintering,through the composition design and preparation process optimization.It was found that moderate doping of Gd3+(25-50 at.%)can promote ion diffusion and grain growth during sintering.When the doping content of Gd3+is 50 at.%,the calcination temperature is 1100℃,and the air atmosphere sintering temperature is 1500℃,the relative density of YGO:Eu solid solution can reach 96.9%.The low electronegativity of Gd3+makes the charge transfer band(CTB)of ceramics red shifted.Ceramics can be effectively excited by 275 nm ultraviolet light,396 nm near ultraviolet light,and 466 nm blue light to achieve red light emission.As a red light material,it is expected to realize white LED after vacuum sintering.更多还原