Eu3+、Dy3+和Er3+对制备堇青石晶相转变的对比表征

以菱镁矿风化石、工业Al₂O₃和SiO₂微粉为原料, 固相反应烧结合成制备堇青石。通过在反应物中分别加入不同含量的Eu₂O₃、Dy₂O₃和Er₂O₃, 研究分析和对比了Eu³⁺、Dy³⁺和Er³⁺对堇青石晶相组成、晶粒大小、晶胞常数、结晶度及显微结构的影响。采用XRD和SEM表征试样中的晶相和显微结构, 利用X'Pert Plus软件对结晶相的晶胞参数和结晶度进行分析, 采用半定量法对试样晶相组成进行计算, 利用Scherrer公式计算堇青石的晶粒大小。结果表明: 由于Eu₂O₃、Dy₂O₃和Er₂O₃的加入, 通过固相反应烧结所得堇青石试样中出现了莫来石相, Eu³⁺、Dy³⁺和Er³⁺对Mg²⁺的置换作用改变了堇青石相晶格常数和晶胞体积。随着添加剂含量的增加, 堇青石结构中液相量增加, 相对结晶度降低, 常温致密度提高, 堇青石晶粒粒径减小。综合对比分析, Eu₂O₃对堇青石晶相转变的影响程度最弱, Er₂O₃对堇青石晶相转变的影响程度最强, 对提高合成堇青石的烧结性和热震稳定性效果最好。

Characterization comparison of Eu3+, Dy3+ and Er3+ on phasetransition of cordierite

Cordierite was prepared by solid reaction of raw materials including decomposed magnesite, industrial Al₂O₃ and SiO₂ powder. Adding different mass fractions of Eu₂O₃, Dy₂O₃ and Er₂O₃ as additive, the effect of Eu³⁺, Dy³⁺ and Er³⁺ on the composition, grain size, lattice parameters, crystallinity and microstructure of crystalline phases was studied and compared. The crystalline phases and microstructure were determined by XRD and SEM respectively. The lattice parameters and crystallinity of the crystalline phases were estimated by X'Pert plus software. The phase composition was evaluated by semi-quantification method, and the grain size was calculated by Scherrer formula. The results show that the mullite phase is observed in the sintered samples because of the addtion of Eu₂O₃, Dy₂O₃ and Er₂O₃. Due to the substitution of Eu³⁺, Dy³⁺ and Er³⁺ for Mg²⁺, the lattice parameters and lattice volume of cordierite are changed. The liquid phase and density for room temperature increase, while relative crystallinity and grain size of cordierite decrease with addtives increasing. Comprehensive analysis shows that the effect of Eu₂O₃ on the phasetransition is the weakest, while the effect of Eu₂O₃ is the strongest among the three additives. The effect of Eu₂O₃ on sintering property and thermal shock resistance is the best of three additives.