Preparation And Properties Of Gd_2-xM_xZr₂O₇?M=Nd?Sm?Transparent Ceramics

Cubic pyrochlore-type transparent ceramics are a new material appearing in the context of exploring new inorganic scintillators.They not only have a cubic structure,a wide solid solution range,high refractive index,high effective atomic number,but also have excellent characteristics such as phase stability,corrosion resistance,and strong radiation absorption.It is an ideal rare-earth-doped matrix material and has potential applications in optical photography,scintillator matrix materials,and solid-state laser materials.In this thesis,Gd₂Zr₂O₇ nanopowders were synthesized by combustion method and solvothermal method.After molding and vacuum sintering,high optical quality Gd₂Zr₂O₇ transparent ceramics were obtained at a relatively low sintering temperature.Finally,Gd₂Zr₂O₇ transparent ceramics were used as matrix materials to explore the possibility and regularity of Nd³⁺and Sm³⁺ions.The specific research results are as follows:Firstly,Gd₂Zr₂O₇ nanopowders with good dispersibility and high sintering activity were prepared by the combustion method.The best calcination temperature of the powders is1200?,and the particle size of the powders is about 80 nm.Gd₂Zr₂O₇ transparent ceramic with the best density and highest transmittance was prepared by vacuum sintering at 1825?,and the ceramic grain size was about 80?m.Gd₂Zr₂O₇ transparent ceramic has high transmittance in the wavelength range of 800 nm⁵?m,and the transmittance can reach 77.3%at 1300 nm.Gd₂Zr₂O₇ nanopowder was prepared by solvothermal method.The nano-powder calcined at 800?showed good dispersibility and sintering activity,and the particle size of the powder was about 15 nm.The samples sintered under vacuum at 1800?showed the highest density and transmittance,with a density of 99.4%and a transmittance of 72.3%at 800 nm.Gd_2-xNd_xZr₂O₇?x=0.4-2.0?powders and transparent ceramics were prepared by combustion and vacuum sintering.All the powders show the defective fluorite structure,which is transformed into pyrochlore structure after sintering.All samples showed characteristic absorption peaks belonging to Nd³⁺ions,and the samples with x=0.4 had the highest transmittance,which can reach 78%at 1000 nm.Under the excitation of 808 nm laser,strong emission peaks were observed at 520 nm and 1067 nm,but the corresponding fluorescence lifetime could not be measured.Therefore,Nd:Gd₂Zr₂O₇(Nd³⁺ions doping amount:1%¹0%)powders and transparent ceramics were prepared.The powders showed the defective fluorite structure,and the ceramics were transformed into a pyrochlore structure.7%of the samples showed the highest transmission,up to 71%at 950 nm.It was confirmed from the excitation and absorption spectra that the samples had strong luminescence at 1062 nm under the excitation of 808 nm.Theirs lifetime is about 0.6?s,and no concentration quenching phenomenon is found.Sm³⁺ions doped Gd₂Zr₂O₇ nano-powders and transparent ceramics were prepared by a combustion method and vacuum sintering.When the Sm³⁺ions doping amount is 1%³%,the powder has a defective fluorite structure with a particle size of about 30 nm.After sintering,the ceramic is transformed into pyrochlore structure,and the diffraction peak shifts to a low angle as the Sm³⁺ions doping concentration increases.The 3%sample has the highest transmission,reaching 74.7%at 1000 nm.All samples had similar absorption peaks,and strengthened with increasing Sm³⁺ions doping concentration.Four main emission peaks can be observed under 404 nm excitation,of which the emission peak intensity is the largest at615 nm,indicating that the sample can be effectively excited by ultraviolet light and emit orange-red light.All samples have a millisecond fluorescence lifetime at 404 nm excitation and 615 nm,and the concentration quenching occurs when the doping concentration reaches10%.