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The MgTiO (sub 3) -FeTiO (sub 3) join at high pressure and temperature

Jennifer A. Linton, Yingwei Fei and Alexandra Navrotsky
The MgTiO (sub 3) -FeTiO (sub 3) join at high pressure and temperature
American Mineralogist (October 1999) 84 (10): 1595-1603


The phase relations at high pressure and high temperature for the FeTiO (sub 3) -MgTiO (sub 3) join were determined using several different experimental methods. Through a series of multi-anvil experiments, a phase boundary with a negative slope was observed between MgTiO (sub 3) I (ilmenite structure) and a high pressure phase with the MgTiO (sub 3) II (lithium niobate structure) after quenching. The enthalpy of transformation of MgTiO (sub 3) I to MgTiO (sub 3) II was determined through transposed-temperature-drop calorimetry to be 28.78+ or -1.45 kJ/mol. The enthalpy of transformation from ilmenite to lithium niobate structure was also determined for three intermediate compositions on the FeTiO (sub 3) -MgTiO (sub 3) join, Fe (sub 0.2) Mg (sub 0.8) TiO (sub 3) , Fe (sub 0.5) Mg (sub 0.5) TiO (sub 3) and Fe (sub 0.8) Mg (sub 0.2) TiO (sub 3) , and confirmed for FeTiO (sub 3) , and was found to be a linear function of composition. These experiments represent one of the first successful calorimetric measurements on small samples (1 to 3 mg) synthesized at high pressures (15 to 21 GPa). X-ray analysis during compression of Fe (sub 0.5) Mg (sub 0.5) TiO (sub 3) II in a diamond cell confirmed a room temperature transition at 28 GPa to Fe (sub 0.5) Mg (sub 0.5) TiO (sub 3) III (a GdFeO (sub 3) -type perovskite structure), similar to the transitions previously observed in FeTiO (sub 3) and MnTiO (sub 3) . The Fe (sub 0.5) Mg (sub 0.5) TiO (sub 3) sample was heated to 802 degrees C at 21 GPa, and it was observed that the stable high temperature, high pressure phase is perovskite, Fe (sub 0.5) Mg (sub 0.5) TiO (sub 3) III. The above data combined confirm the stability of a continuous perovskite solid solution at high pressure and temperature for the FeTiO (sub 3) -MgTiO (sub 3) join.

ISSN: 0003-004X
EISSN: 1945-3027
Serial Title: American Mineralogist
Serial Volume: 84
Serial Issue: 10
Title: The MgTiO (sub 3) -FeTiO (sub 3) join at high pressure and temperature
Affiliation: Princeton University, Department of Geosciences, Princeton, NJ, United States
Pages: 1595-1603
Published: 199910
Text Language: English
Publisher: Mineralogical Society of America, Washington, DC, United States
References: 30
Accession Number: 2000-002179
Categories: Geophysics of minerals and rocks
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 5 tables
Secondary Affiliation: Carnegie Institution of Washington, USA, United StatesUniversity of California at Davis, USA, United States
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2018, American Geosciences Institute.
Update Code: 200001
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