摘要
The subsolidus phase relationships in the systems R_2O_3-AlN-Al_2O_3 (R=Ce, Pr, Nd.and Sm) and the isothermal section at 1700℃ of the Nd_2O_3-AlN-Al_2O_3 system have beendetermined. A nitrogen-containing R-β-alumina phase RAl_(12)O_(18)N has been identified. Theformation of the β-alumina phase occurring at both the compositions RAl_(12)O_(18)N and R_2O_3·11Al_2O_3 was explored in a series of light rare-earth systems. Single-phase N-containing β-aluminas can be obtained with the compositions RAl_(12)O_(18)N (R=La, Ce, Pr, Nd, Sm, andEu). However, La, Ce, Pr and Eu can also form β-alumina phase as the main phase at thecompositions of R_2O_3·11Al_2O_3, which form continuous solid solutions with RAl_(12)O_(18)N. Theunit cell dimensions of RAl_(12)O_(18)N have been determined to be α=5.557 (A) and c=22.00 (A) and there appears no deviation among the different R-β-aluminas (R=Ce→Sm)that can be detected. At 1700℃, an extensive liquid region exists in the triangle Nd_2O_3-Nd_2AlO_3N-NdAlO_3.
The subsolidus phase relationships in the systems R<sub>2</sub>O<sub>3</sub>-AlN-Al<sub>2</sub>O<sub>3</sub> （R=Ce, Pr, Nd.and Sm） and the isothermal section at 1700℃ of the Nd<sub>2</sub>O<sub>3</sub>-AlN-Al<sub>2</sub>O<sub>3</sub> system have beendetermined. A nitrogen-containing R-β-alumina phase RAl<sub>12</sub>O<sub>18</sub>N has been identified. Theformation of the β-alumina phase occurring at both the compositions RAl<sub>12</sub>O<sub>18</sub>N and R<sub>2</sub>O<sub>3</sub>·11Al<sub>2</sub>O<sub>3</sub> was explored in a series of light rare-earth systems. Single-phase N-containing β-aluminas can be obtained with the compositions RAl<sub>12</sub>O<sub>18</sub>N （R=La, Ce, Pr, Nd, Sm, andEu）. However, La, Ce, Pr and Eu can also form β-alumina phase as the main phase at thecompositions of R<sub>2</sub>O<sub>3</sub>·11Al<sub>2</sub>O<sub>3</sub>, which form continuous solid solutions with RAl<sub>12</sub>O<sub>18</sub>N. Theunit cell dimensions of RAl<sub>12</sub>O<sub>18</sub>N have been determined to be α=5.557 （A） and c=22.00 （A） and there appears no deviation among the different R-β-aluminas （R=Ce→Sm）that can be detected. At 1700℃, an extensive liquid region exists in the triangle Nd<sub>2</sub>O<sub>3</sub>-Nd<sub>2</sub>AlO<sub>3</sub>N-NdAlO<sub>3</sub>.
基金
Project supported by the National Natural Scieuce Foundation of China.
