This paper prepared a series of Eu³⁺ doped Gd₂Zr₂O₇ transparent ceramics by a vacuum sintering method, and charaterized the density and optical transmittance of cubic phase Gd₂Zr₂O₇. The effects of doping ions and their concentration on the crystal structure, optical transmittance, fluorescence performance, and scintillation performance were investigated. The results show that the prepared transparent ceramic samples have a good optical transmittance. The spectral characterization reveals that 20% Eu³⁺ doped Gd₂Zr₂O₇ has optimum fluorescence and irradiated luminescence intensity, and the most intense emission peak is located at 630 nm. The X-ray imaging shows that Gd_1.8Eu_0.2Zr₂O₇ transparent ceramics have an X-ray imaging resolution of up to 11 lp·mm^-1, having a potential for the imaging applications.

High purity gadolinium oxide, europium oxide and zirconia (purity 4N) as raw materials were mixed according to a stoichiometric ratio (Gd³⁺,Eu³⁺)∶Zr⁴⁺ of 1∶1. The mixed raw materials were ground in anhydrous ethanol and polyethylene glycol (PEG) in a planetary mill with zirconia grinding chamber and ballsat a ball∶material mass ratio of 27∶1 for 72 h. Afterwards, the ground mixture slurry was washed with anhydrous ethanol after drying. Gd_2-xEu_xZr₂O₇ could be obtained via sintering in a box furnace at 1 400 ℃ according to the reaction: Gd_2-XEu_XZr₂O₇

The ceramic blank was formed via dry pressing and cold isostatic pressing, sintered in a vacuum tungsten furnace at 1 800 ℃ for 10 h, and then annealed in a box furnace in air at 1 250 ℃ for 6 h. Finally, a transparent ceramic with 1 mm thickness was obtained after double-sided polishing.

A ceramic powder prepared by ball grinding was sintered in a vacuum tungsten wire furnace to prepare transparent ceramics with a high light transmission rate. The XRD results show that when 20% Eu³⁺ is added to Gd₂Zr₂O₇, the crystal structure of Gd_1.8Eu_0.2Zr₂O₇ appears some superlattice diffraction peaks (331) of pyrochlore. The crystal structure changes from defective fluorite to pyrochlore. The optical transmittance spectra indicate that the optical transmittance decreases from 76% to 65% (@1 500 nm) when the doping content of Eu³⁺ increases from 0 to 28%. There exist 6 distinct excitation peaks between 230 nm and 500 nm. A wide excitation peak at 267 nm is attributed to the charge transfer band of O^2-—Eu³⁺. In addition, five excitation peaks at 362, 382, 393, 414 nm and 465 nm correspond to 4f-4f energy level transitions ⁷F₀→⁵D₄, ⁵G_J, ⁵L₆, 5D₃ and ⁵D₂ in Eu³⁺, respectively. Among six excitation peaks, a wide excitation peak at 267 nm has the most intense intensity. All the excitation peak intensities increase when Eu³⁺ concentration increases from 4% to 20%. When Eu³⁺ doping amount is 20%, the maximum excitation peak intensity appears. The further characterization of the scintillation properties of ceramic samples indicates that the X-ray irradiation intensity is a maximum value when the doping amount is 20%. At 630 nm, the radiation luminescence intensity value is 1.1×10⁴, and the material has an X-ray absorption capacity equivalent to that of BGO crystals, and also has a good anti-radiation damage ability. Finally, X-ray imaging tests on Gd_1.8Eu_0.2Zr₂O₇ ceramic samples of different materials show that the Gd_1.8Eu_0.2Zr₂O₇ ceramic sample can clearly distinguish metal and plastic materials, and has a limit spatial resolution of 11 1p·mm^-1, indicating that the modified material is a potential X-ray detection material.

A series of Eu³⁺ doped transparent ceramics were prepared by a vacuum sintering method. The crystal structure of Gd_2-xEu_xZr₂O₇ was gradually changed from defective fluorite to pyrochlore via adjusting the doping amount of Eu³⁺. At 630 nm, the Gd_2-xEu_xZr₂O₇ transparent ceramic sample showed the optimum fluorescence emission and X-ray irradiation intensity, and the material had a limit spatial resolution of 11 1p·mm^-1, which could clearly distinguish metal and plastic materials, confirming an application potential of the A₂B₂O₇ series of scintillating transparent ceramics X-ray imaging.