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The System Bi 2 O,—B 2 O 3
Author(s) -
LEVIN ERNEST M.,
MCDANIEL CLYDE L.
Publication year - 1962
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.1151-2916.1962.tb11168.x
Subject(s) - liquidus , phase diagram , molality , melting point , ionic radius , analytical chemistry (journal) , phase (matter) , chemistry , mineralogy , thermodynamics , materials science , crystallography , ion , physics , chromatography , organic chemistry , aqueous solution
The phase diagram for the system Bi 2 O 3 ‐B 2 O 3 has been determined experimentally. The melting point of Bi 2 O 3 has been redetermined as 825° C with an estimated overall uncertainty of about ±3°C, and the molal heat of fusion of Bi 2 O 3 , calculated from the slope of the liquidus curve, is 2050 cal per mole. The system contains a body‐centered cubic phase of approximate composition 12Bi 2 O 3 ·B 2 O 3 , which melts incongruently at 632°C. Four congruently melting compounds exist in the system: 2Bi 2 O 3 · B 2 O 3 ·5B 2 O 3 , Bi 2 O 3 ·3B 2 O 3 , and Bi 2 O 3 ·4B 2 O 3 , with melting points, respectively, of 675°, 722°, 708°, and 715°C. The Bi 2 O 3 ·4B 2 O 3 compound exhibits a sluggish transformation at 696°C. Compositions containing up to 97.5 wt% (85 mole %) Bi 2 O 3 can be partly or totally quenched to glass. Indices of the quenched glasses are greater than 1.74. A region of liquid immiscibility extends at 709°C from almost pure B 2 O 3 to 19.0 mole % Bi 2 O 3 . The extent of immiscibility theoretically calculated agrees with the experimentally determined value when 1.20 A is used for the ionic radius of Bi 3+ .