Methods for determining the Curie temperature (Tc) of titanomaghemites from experimental saturation magnetization-temperature (Js-T) data are reviewed. Js-T curves for many submarine basalts and synthetic titanomaghemites are irreversible and determining Curie temperatures from these curves is not a straightforward procedure. Subsequently, differences of sometimes over 100°C in the values of Tc may result just from the method of calculation. Two methods for determining Tc will be discussed: (1) the graphical method, and (2) the extrapolation method. The graphical method is the most common method employed for determining Curie temperatures of submarine basalts and synthetic titanomaghemites. The extrapolation method based on the quantum mechanical and thermodynamic aspects of the temperature variation of saturation magnetization near Tc, although not new to solid state physics, has not been used for estimating Curie temperatures of submarine basalts. The extrapolation method is more objective than the graphical method and uses the actual magnetization data in estimating Tc.
Bibliographical noteFunding Information:
The author wishes to express his thanks to Subir K. Banerjee, whose original suggestion, prompted me to pursue this investigation. Also, I like to thank S. Grommd and an anonymous reviewer, whose comments and suggestions contributed to the final draft. This material is based on research supported by the National Science Foundation under grant OCE-7615255.