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High‐Temperature Phase Transition of Y 4 Al 2 O 9
Author(s) -
Yamane Hisanori,
Omori Mamoru,
Okubo Akira,
Hirai Toshio
Publication year - 1993
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.1151-2916.1993.tb07783.x
Subject(s) - differential scanning calorimetry , monoclinic crystal system , phase transition , materials science , enthalpy , phase (matter) , hysteresis , transition temperature , diffraction , analytical chemistry (journal) , crystallography , thermodynamics , chemistry , crystal structure , condensed matter physics , optics , physics , superconductivity , organic chemistry , chromatography
Reversible thermal phase transition was observed for Y 4 Al 2 O 9 at 1377°C with a hysteresis width of 78°C using differential scanning calorimetry. The enthalpy of the transition (Δ H ) was about 300 cal/mol. Powder X‐ray diffraction peaks of the high‐temperature phase, as well as the peaks of the low‐temperature phase, were characterized with a monoclinic unit cell. Thermal hysteresis was also confirmed by the temperature dependence of the lattice parameter. The unit cell volume of the high‐temperature phase was 0.5% smaller than that of the low‐temperature phase at 1400°C.