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研究了R_2O_3-AlN-Al_2O_3(R=Ce,Pr,Nd和Sm)三元系固相线下的相关系及Nd_2O_3-AlN—Al_2O_3系统在1700℃的等温截面.发现存有一个组成为RAl_(12)O_(18)N的新相,其结构同β—Al_2O_3.本文对其它轻稀土元素可否形成新相也作了探讨.发现从La到Eu(除了Pm未测外)都能在组成RAl_(12)O_(18)N处形成含N的β-Al_2O_3相.经测定它们的单相区范围为:当R=Nd和Sm时,含Nβ-Al_2O_3相只发生在RAl_(12)O_(18)N组成处;而其它稀土的含Nβ-Al_2O_3相的组成都扩大到纯氧化物一端,即R_2O_3:11Al_2O_3处.经测定RAl_(12)O_(18)N的晶胞常数(a=5.557和c=22.00)几乎不随R而变化.1700℃时,在Nd_2O_3-Nd_2AlO_3N-NdAlO_3三角形区域中存有一个很大液相区.
The phase relationship of R_2O_3-AlN-Al_2O_3 (R = Ce, Pr, Nd and Sm) ternary system solidus and the isothermal cross section of Nd_2O_3-AlN-Al_2O_3 system at 1700 ℃ were investigated. 12) O_ (18) N, the structure of which is the same as that of β-Al_2O_3.In this paper, it is also discussed whether other LREEs can form a new phase.It is found that La to Eu (except Pm) (12) O_ (18) N, the β-Al_2O_3 phase containing N was formed.The range of single-phase region was determined as follows: when R = Nd and Sm, the N_β_Al_2O_3 phase only occurred in the region of RAl_ (12) O_ 18) N, while the composition of other rare earths containing Nβ-Al_2O_3 phase extended to one side of pure oxide, namely R_2O_3: 11Al_2O_3. The unit cell constants (a = 5.557) of RAl_ (12) O_ And c = 22.00) hardly changed with R. At 1700 ℃, there was a large liquid region in the Nd_2O_3-Nd_2AlO_3N-NdAlO_3 triangle.