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Immiscibility and the System Lanthanum Oxide–Boric Oxide
Author(s) -
LEVIN ERNEST M.,
ROBBINS CARL R.,
WARING JON L.
Publication year - 1961
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.1151-2916.1961.tb15356.x
Subject(s) - aragonite , phase diagram , lanthanum , oxide , boron , mineralogy , diagram , thermodynamics , analytical chemistry (journal) , materials science , chemistry , inorganic chemistry , crystallography , phase (matter) , calcite , metallurgy , physics , organic chemistry , statistics , mathematics
The phase equilibrium diagram for the system La 2 O 3 ‐B 2 O 3 has been determined experimentally. The compounds La 2 O 3 ‐3B 2 O 3 and La 2 O 3 ‐B 2 O 3 melt congruently at 1141°± 5°C. and 1660°± 15°C, respectively. At 1488°± 5°C, La 2 O 3 ‐B 2 O 3 inverts from the aragonite‐type structure to a high‐temperature form. Trilanthanum borate, 3La 2 O 3 B 2 O 3 , melts incongruently at 1386°± 5°C. to give liquid and La 2 O 3 . No solid solutions exist in the system. A region of liquid immiscibility exists in the system and extends at 1136°± 5°C. from almost pure B 2 O 3 to 21.5 mole % La 2 O 3 . The experimental value for the extent of immiscibility agrees with that calculated from theoretical considerations. A second method for estimating immiscibility in the system is demonstrated, which requires experimentally only the determination of the index of refraction of the modifier‐rich liquid. Principles governing immiscibility are discussed.