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High‐Temperature Phase Equilibria of the Magnesium–Niobium–Titanate System
Author(s) -
Mangham Robert I.,
Petuskey William T.
Publication year - 2005
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.1551-2916.2005.00584.x
Subject(s) - columbite , isothermal process , phase diagram , solid solution , niobium , solubility , atmospheric temperature range , magnesium , thermodynamics , extrapolation , materials science , phase (matter) , analytical chemistry (journal) , titanate , mineralogy , chemistry , metallurgy , ceramic , mathematical analysis , physics , mathematics , organic chemistry , chromatography
The high‐temperature phase equilibria for the MgO–Nb 2 O 5 –TiO 2 system have been determined in air and at 1 atm O 2 . Three isothermal sections, namely 1450°, 1350°, and 1250°C, were determined experimentally. From this, the 1000°C isothermal section was deduced by extrapolation. Throughout each diagram, most compounds were found to have an extended range of solubility, each exhibiting the same substitutional pattern of the combination 1/3(MgNb 2 ) 4+ replacing Ti 4+ . Furthermore, entropic stabilization because of cation mixing is evident for all phases except for the columbite solid solution, in which case the solid solution range decreased with increasing temperature.