Structural Evolution of TiO2 Precipitates in Ti‐DopedSapphire (α‐Al2O3)
Structural Evolution of TiO2 Precipitates in Ti‐DopedSapphire (α‐Al2O3)
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掺钛蓝宝石 (α-Al2O3) 中 TiO2 沉淀的结构演化
DOI：
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发表时间：
2011
期刊：
影响因子：
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通讯作者：
A. Heuer
中科院分区：
文献类型：
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作者：
J. He;K. Lagerlöf;A. Heuer
建立了一个随时间变化的相稳定性图，描述了ti掺杂蓝宝石（α-Al2O3）中TiO2析出物的结构演变。在1200℃~ 1300℃退火后，掺钛蓝宝石中形成具有α-PbO2结构的高压TiO2相（α-TiO2）；在这些温度下延长退火时间导致孪晶颗粒，孪晶使析出的基体失配应变能最小化。孪晶α-TiO2最终转变为金红石结构，与蓝宝石基体的相干性丧失一致。金红石在1350℃以上退火的蓝宝石中直接成核。金红石主要以半相干孪晶析出，孪晶在析出序列中出现较早。
A time-dependent phase stability diagram has been developed describing the structural evolution of TiO2 precipitates in Ti-doped sapphire (α-Al2O3). A high-pressure TiO2 phase with the α-PbO2 structure (α-TiO2) forms as a coherent precipitate in Ti-doped sapphire annealed at 1200°–1300°C; extended annealing times at these temperatures result in twinned particles, the twinning minimizing the precipitate–matrix misfit strain energy. Twinned α-TiO2 eventually transforms to the rutile structure, coincident with the loss of coherency with the sapphire matrix. Rutile nucleates directly in sapphire annealed at temperatures at 1350°C and above. Rutile is present mainly as semicoherent and twinned precipitates, the twinning occurring relatively early in the precipitation sequence.