Phase Equilibrium Relations in the Binary System Bismuth Sesquioxide-Niobium Pentoxide
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[Gaithersburg, MD] : U.S. Dept. of Commerce, National Institute of Standards and Technology,
Date of publication, distribution, etc.
1962.
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/pmc/articles/PMC5324962/
520 ## - SUMMARY, ETC.
Summary, etc.
The phase equilibrium diagram for the binary system bismuth sesquioxide-niobium pentoxide has been constructed from observations of fusion characteristics and X-ray diffraction data. In the system five binary compounds were observed with Bi(2)O(3):Nb(2)O(5) ratios of 5:3, 1:1, 4:9, 1:5, and 1:6. The 1:1 compound was found to transform irreversibly (in laboratory time) from the orthorhombic bismutotantalite type structure to a triclinic form at about 1,020 °C and melt congruently at 1,245 °C. The 5:3 compound melts incongruently at 1,193 °C the 4:9 at 1,183 °C and the 1:6 at 1,242 °C. The 1:5 compound has a maximum temperature of stability at 1,095 °C and the 4:9 and 1:6 compounds have minimum temperatures of stability at 1,070 °C and 1,002 °C respectively. Nb(2)O(5) was found to enter into solid solution in Bi(2)O(3), up to about 23.5 mole percent Nb(2)O(5). The melting point is increased and the monoclinic-cubic phase transformation temperature is decreased. A morphotropic phase change occurrs at about 19.5 mole percent Nb(2)O(5) from the cubic to a pseudocubic structure.
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The Journal of Research of the National Bureau of Standards Section A is a publication of the U.S. Government. The papers are in the public domain and are not subject to copyright in the United States. Articles from J Res may contain photographs or illustrations copyrighted by other commercial organizations or individuals that may not be used without obtaining prior approval from the holder of the copyright.
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en
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