材料期刊网

通过掺杂摩尔分数为0.3%的稀土Ce³⁺, 制备了BaHfO₃∶Ce闪烁陶瓷, 用XRD, TG--DSC, SEM及TEM表征了BaHfO₃∶Ce物相及形貌, 研究了不同烧结工艺下BaHfO₃∶Ce的致密化及显微组织. 结果表明: 前驱体的晶化转变存在三个阶段, 在900℃煅烧2 h合成出BaHfO₃∶Ce纳米粒子, 形貌为近球状, 粒径尺寸约为15 nm. 经真空烧结与常压烧结的样品致密化和显微组织存在明显差异: 前者在1750℃真空烧结保温1.5 h, 样品基本致密化, 晶粒尺寸在40---50 μm范围内; 而后者晶粒尺寸分布离散性较大. 真空烧结后的闪烁陶瓷和同组分粉体样品在530 nm波长的激发光谱中分别存在380---420 nm紫色和420---450 nm蓝色的发光谱带, 在391, 398和445 nm波长处均出现较强峰值, 对应着Ce³⁺4f→5d能级跃迁的吸收, 这表明该闪烁陶瓷的发光强度高于同组分粉体样品.

BaHfO3 ceramic scintillator dopped by 0.3%Ce³⁺ (molar fraction) was prepared by co–precipitation method. XRD, TG–DSC and TEM were employed to measure the phase transformation and grain morphology of BaHfO₃Ce. The densification and microstructure of BaHfO3Ce ceramic scintillator prepared in different sintering atmospheres were studied. Results show that there are three stages during the crystallization of the precursor. The near spherical BaHfO₃Ce nanoparticles can be obtained after calcining at 900℃ for 2 h, and the grain size is about 15 nm. The densification and microstructure of BaHfO₃Ce have obvious differences under sintering in air and in vacuum. The fully densified sample was obtained by vacuum sintering at 1750℃ for 1.5 h, and the grain size is about 40—50 μm. The sample prepared by sintering in air has the uneven grain size distribution. 380—420 nm purple and 420—450 nm blue bands appear in the wavelength λ=530 nm excitation spectra of the vacuum sintering scintillator and the as–synthesized powders, respectively. And the peaks in the excitation spectra are at 391, 398 and 445 nm corresponding to 4f →5d energy level transition of Ce³⁺. A comparison for the emission spectra prepared by vacuum sintering shows that the ceramic scintillator has the stronger luminescence intensity than the as–synthesized powders.