Preparation And Properties Of Nanostructured Sc³⁺:Y₂O₃ Solid Solution Transparent Ceramics

As an excellent optical material,yttria ceramic has various potential applications in high temperature window,transparent domes,infrared lens,microwave dielectric substrates,infrared generator shell due to its features of high optical transparency,high melting point,good corrosion resistance,high dielectric constant,high thermal conductivity,small thermal expansion coefficient,low thermal emission rate,etc.Conventional sintering methods usually lead to grain growth which results in reduced strength of yttria ceramics and then failing to meet the requirements of practical application.In this paper,Sc2O3 was added to enhance the strength by solid solution strengthening.Meanwhile,spark plasma sintering(SPS)can effectively limit the grain growth and enhance the strength by fine grain strengthening,so high transparent and high strength yttria ceramics can be obtained.Firstly,0-30 at.%doped nanocrystalline Sc3+:Y2O3 solid solution powders were prepared by low temperature combustion method.And the best sintering condition of SPS was determined by changing the sintering temperature and holding time.In addition,transparent Sc3+:Y2O3 ceramics with various Sc3+ doping concentrations were prepared by SPS.Then analyze the effect of Sc2O3 content on the mechanical properties and optical properties of the ceramics.10 at.%Sc3+:Y2O3 ceramics were treated at high temperatures in order to explore the microstructure evolution.The results show that the microstructure,mechanical properties and optical properties of transparent 10 at.%Sc3+:Y2O3 ceramics are greatly influenced by the sintering temperature and holding time of SPS.With the increasing of sintering temperature,the grain size initially decreases and then increases,the hardness decreases,the transmittance firstly increases and then decreases in the wavelength of 1.5-6.5?m.With the extension of holding time,the grain size increases,the hardness decreases,the transmittance increases and then decreases in the same range.The obtained optimum sintering condition is 1300? 10 min,the average grain size of the sample is 320 nm,the hardness is 8.86 GPa,and the transmittance is 80.6%around 5.3 ?m.Transparent Sc3+:Y2O3 ceramics prepared by SPS can improve the strength of yttria body.Transparent Sc3+:Y2O3 solid solution ceramics are prepared by doping various Sc3+ to enhance the strength of ceramics.When doping with 20 at.%Sc3+,the hardness of the ceramic is 9.18 GPa,and the transmittance reaches 82.2%around 5.3 ?m.In addition,that increasing the amount of Sc3+ can effectively inhibit the grain growth to enhance the strength and improve the transmittance.When the dopant amount reaches 30 at.%,other phases are produced in matrix leading to rapid decrease of the strength and transmittance.After high temperature treatment,the grain size of 10 at.%Sc3+:Y2O3 ceramics become quite large accompanied with decreased density,and the grain size increases with the rising of treated temperature.