采用溶胶-凝胶法(sol-gel)制备掺0～20mol％Er3+勃姆石(γ-AlOOH)凝胶,X射线衍射和差热分析法研究掺Er3+:γ-AlOOH凝胶在950～1400℃烧结的相变过程.结果表明:Er3+的掺杂降低α相的生长速度,抑制Al2O3的θ→α相变,推迟相变结束温度50～70℃.Er-Al-O系化合物Al10Er6O24和ErAlO3相的析出取决于掺Er~(3+)浓度和烧结温度.在较高烧结温度下,ErAlO3相由掺1～5mol％Er3+:Al2O3中析出;Al10Er6O24相则在掺5～20mol％Er3+:Al2O3中析出,随着烧结温度的升高,在全部掺Er3+:Al2O3中析出.ErAlO3相促进θ→α相变的形核,α相形核起始温度可提前30～50℃,但对α相生长影响不大.Al10Er6O24相对θ→α相变没有显著影响.
The 0～20mol%Er3+-doped γ-AlOOH gels were prepared by using sol-gel methods from the aluminium
isopropoxide [Al(OC3H7)3]-derived Al2O3 sols. The phase structures and these transformation processes of Er3+-doped γ-AlOOH gels
sintered at 950～1400℃ were investigated by using X-ray diffraction (XRD) and differential thermal analysis (DTA). The experimental
results show that Er3+ doping lead to restraining the phase transformation of θ→α for alumina, and decreasing the growth rate of α phase
with an increase of 50～70℃ for the completed transformation temperature. The precipitation of the two Er-Al-O compounds, i.e.
Al10Er6O24 and ErAlO3 phases, is dependent on the Er3+ doping concentration and the sintering temperature. The ErAlO3
phase precipitates in the 1～5mol%Er3+-doped Al2O3 sintered at 1100～1200℃. The Al_{10Er_6O_{24 phase precipitates in the 5～20mol%Er3+-doped Al2O3 sintered at
1000～1100℃, and is in all Er3+-doped Al2O3 with further increasing the sintering temperature. The nucleation of phase
transformation for θ→α is accelerated due to the presence of ErAlO3 phase, resulting in a decrease of 30～50℃ for the beginning temperature of phase transformation correspondingly.
It has no greatly influence on the growth rate of α phase. The Al10Er6O24 phase does not affect the phase transformation for
θ→α
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