The effect of temperature is discussed on the magnetic-alignment process of micron-sized particles dispersed in a fluid medium, based on the experimental data compiled on various non-ferromagnetic materials having different concentrations of paramagnetic impurity ion. The fieldintensity required to achieve alignment decreased with temperature following the relation calculated from the Langevin theory, when the diamagnetic particles were free of paramagnetic ions. The rotational Brownian motion was considered to randomize the direction of the microcrystals in the theory. The above-mentioned temperature dependence was expected to occur for most of the diamagnetic oxides, since the oxides were expected to posses a finite amount of diamagnetic anisotropy according to a model proposed recently to explain the origin of anisotropy. The decease of temperature caused additional reduction on the field-intensity to achieve alignment, when finite amount of paramagnetic ion was contained in the particle. This was because the paramagnetic anisotropy increased which the reduction of temperature. The doping of paramagnetic ion on non-ferromagnetic materials in the course of processing a material expected to reduce the field intensity to achieve magnetic alignment at room temperature. The above findings, concerned with the reduction of field intensity to achieve magnetic alignment, may increase the possibility of practical applications of the phenomena of magnetic alignment. (Received June 20, 2003; Accepted November 14, 2003) Keywords: diamagnetic anisotropy, magnetic alignment at low magnetic field, temperature dependence of magnetic alignment, magnetic alignment of micron-sized particle, magneto-rotation, Curie temperature dependence of paramagnetic anisotropy, doping of paramagnetic ion, ceramic material, kaolinite, graphite
The reduction of field intensity to achieve magnetic alignment of micron-sized nonferromagnetic particles caused by the variations of various parameters was studied systematically, based on the experimental data obtained for various non ferromagnetic materials. The field intensity where the order parameter reached <m>=0.8, denoted by B s, was proportional to the square root of temeprature for graphite crystals free of paramagnetic ions. The relationship was consistent with the Langevin theory on magnetic alignment. The majority of inorganic oxides is expected to possess diamagnetic anisotropy, since their origin can be explained quantitatively by assuming a constant anisotropy on the individual bonding orbital composing the material. B s is expected to decrease with the temperature for these oxides, in the same manner observed for the graphite grains. Experiments on talc and kaolinite particles including paramagnetic ions revealed that B s was proportional to temperature when the paramagnetic concentration was high, since the paramagnetic anisotropy followed the Curie law.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.