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Phase Relations in the Ternary Systems Nd─B─N, Sm─B─N, and Gd─B─N
Author(s) -
Klesnar Helmuth,
Rogl Peter
Publication year - 1992
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.1992.tb05511.x
Subject(s) - ternary operation , phase (matter) , boron , rare earth , lanthanide , ternary numeral system , nitride , chemistry , crystallography , materials science , analytical chemistry (journal) , mineralogy , nanotechnology , ion , organic chemistry , layer (electronics) , computer science , programming language , chromatography
Phase relations and phase stabilities have been derived for the ternary systems RE─B─N (RE = Nd, Sm, or Gd) at elevated temperatures (1400°C and above) by means of X‐ray powder analysis. Under the experimental conditions selected, various ternary compounds are found to be stable: Nd 3 B 2 N 4 with the Ce 3 B 2 N 4 type and (Nd,Sm,Gd)BN 2 with the PrBN 2 type. Phase equilibria at 1400°C and under 10 5 Pa of argon are mainly characterized by the incompatibility of the RE metals Nd, Sm, and Gd with BN due to the competing equilibria between the RE tetraborides and the RE mononitrides. Each of the ternary compounds, however, is found to be in a two‐phase equilibrium with hex ‐BN. Because of the different thermodynamic stabilities within the various structure series of ternary rare‐earth boron nitrides RE 3 B 2 N 4 and REBN 2 , the compound Nd 3 B 2 N 4 is observed only at temperatures below 1800°C and under 10 5 Pa of Ar, whereas GdBN 2 is found to be stable only at temperatures above 1400°C under a partial pressure of 10 5 Pa of N 2 .