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Fabrication And Properties Of Yttrium Oxide-based Transparent Optical Functional Ceramics

Posted on:2020-02-28Degree:MasterType:Thesis
Country:ChinaCandidate:X ZhangFull Text:PDF
GTID:2381330596997030Subject:Materials engineering
Abstract/Summary:PDF Full Text Request
The 21st century is the era of information economy,which is the era of great integration of science and technology with photon computer as the beginning and light as the medium.Under the background of this era,the application of light and the development of optical-functional material are particularly important.As a new favorite in the field of modern optical-functional materials,transparent ceramics will find more and more applications in many fields,including industry,military,exploration,medical,etc.Yttrium oxide transparent ceramics with cubic structure have received extensive attention in the field of optical-functional material due to their excellent physical and chemical properties.Pure Y2O3 transparent ceramics are considered as brilliant high-temperature windows and infrared dome materials due to their wide optical transmittance and low infrared spontaneous emissivity.Y2O3 transparent ceramics doped with rare earth ions are considered to have great application prospects in femtosecond lasers and irradiation detection materials due to their advantages such as high absorption efficiency,high thermal conductivity,low phonon energy and strong irradiation resistance.Based on the above background,the preparations and performances of Y2O3 and RE?Yb or Eu?:Y2O3 transparent ceramics were studied and optimized.Nano-RE:Y2O3 powders with high dispersion and high sinter-ability were successfully synthesized by co-precipitation method,and then high optical quality Y2O3 based transparent ceramics were prepared by vacuum sintering combined with hot isostatic pressing?HIP?treatment.The spectral properties of yttrium oxide transparent ceramics doped with different rare earth ions were also studied.The main contents of the thesis are as follows:1.Y2O3 nanopowders were prepared by precipitation method.The influences of calcination temperature on the particle size,morphology and agglomeration of Y2O3 nanopowders were preliminarily investigated.The Y2O3 transparent ceramics were successfully fabricated by vacuum pre-sintering combined with HIP post-treatment from the powders calcined at 1100oC.The influences of pre-sintering temperature on the density,microstructure and optical quality of Y2O3 ceramics before and after HIP treatment were studied.The sample pre-sintered at 1500oC for 2 h with HIP post-treating at 1550oC for 3 h had the highest in-line transmittance.The mechanical properties of Y2O3 ceramics were also studied.2.5at.%Yb:Y2O3 nanopowders were prepared by co-precipitation method.The influences of R value?molar ratio of ammonium hydrogen carbonate to metal ions?on the properties of Yb:Y2O3precursors,calcined powders and ceramics were investigated.The nanopowders with R=4.0showed weak agglomeration.With the increase of R value,the transmittance of ceramics increased firstly and then decreased,in which the Yb:Y2O3 ceramics with R=4.0 had the highest transmittance.In the case of selecting R value of 4.0,the influences of calcination temperature on the composition and morphology of the powders were investigated.The results showed that the Yb:Y2O3 powders calcined at different temperatures were pure Y2O3 phase.The Yb:Y2O3powders calcined at low temperature showed weak agglomeration,while the powders calcined at a high temperature tended to form sintering necks,which would make agglomeration more serious and was not conducive to fabricating ceramics.The powders calcined at 1150oC had good dispersion and sintering activity,and the sintered ceramics had the highest optical transmittance.3.The influences of sintering temperature?vacuum pre-sintering temperature and HIP post-treatment temperature?on microstructure and optical quality of 5at.%Yb:Y2O3 ceramics were studied.It was found that the optimal vacuum pre-sintering temperature and HIP post-treatment temperature were 1450oC and 1550oC,respectively.The obtained ceramics had the highest in-line transmittance of 81.4%at the 1100 nm,which was close to the theoretical transmittance.4.The absorption cross section,emission cross section and gain cross section of the5at.%Yb:Y2O3 ceramics were calculated.The prepared 5at.%Yb:Y2O3 transparent ceramics have a wide absorption and emission band,which are considered to be a promising gain medium for ultrashort pulse lasers.5.4at.%Eu:Y2O3 scintillation ceramics were prepared by solid-phase ball milling and co-precipitation,respectively.The Eu:Y2O3 ceramics were poor in optical quality due to the agglomeration of the initial ball milling powders,while the Eu:Y2O3 ceramics had a higher optical transmittance from highly dispersive co-precipitated powders.The 4at.%Eu:Y2O3transparent ceramics prepared by the co-precipitation method have high optical output and are considered as a very promising scintillating material.
Keywords/Search Tags:RE:Y2O3, nanopowders, transparent ceramics, co-precipitation method, hot isostatic pressing(HIP), spectral characteristics
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