The Temperature Dependence of the Preferential Magnetic Alignment of the Magnetically Stable Axes Observed for Small Oxide Crystals Dispersed in a Fluid Medium

Abstract

Temperature dependences were measured between T=223 K and 341 K on magnetic alignment processes of micron-sized talc crystals dispersed in liquid medium. The field intensity required for achieving alignment decreased with temperature, because of an increase in paramagnetic anisotropy and a decrease in the thermal rotational energy. The diamagnetic anisotropies estimated at infinite temperature were -3.3 ×10-4 and -1.2 ×10-4 emu/mol for two different kinds of talc samples. The order of magnitude of diamagnetic anisotropy as well as the direction of the magnetically stable axis of a material can be estimated from the measurement, even if the material contains paramagnetic ions and is too small for torque measurements.