ATSUMI Mihoko Kanagawa Dentistry College, School of Dentistry, Assistan, 歯学部, 助手 (70257301)
MATSUBARA Ikuya Kanagawa Dental College, School of Dentistry, Assistant Professor, 歯学部, 講師 (40157342)
|Budget Amount *help
¥3,000,000 (Direct Cost : ¥3,000,000)
Fiscal Year 1998 : ¥1,300,000 (Direct Cost : ¥1,300,000)
Fiscal Year 1997 : ¥1,700,000 (Direct Cost : ¥1,700,000)
When the soft magnetic materials such as permalloy or ferrites including gar*ets are stressed, or under external stimulus or forces, the permeability is gradually or suddenly changed due to a change of domain wall movements. We tried the phenomena *pecially disaccommodation (gradual decrease of permeability with time) to the dentistry field. The objectives are double, one is the analysis of the behaviors of magnetic materials under simulus or occlusion process. The other is an analysis of occlusion process. In this experiment, the former process of magnetic materials is limited, since many obuservations are obtained in relation to this pourpose. Furthemore, light irradiation is found to be equivalent to the mechanical force in the point of the permeability relaxation such as disaccommodation. This reason may be drawn from the photoinduced distortion in an insulating materials, garnets. In addition, a large Balkhausen effect was found under external stress. On the other hands, a usual Balkhausen effect consists of a small discontinuous steps of magnetization, the magnitudes of which depend on the strength of weight, resulting in the crystal local distortion. In the preliminary stage of experiments, the reason why the photoinduced disaccommodation can take place in garnets at low temperatures is a puzzling problem. However, we propose a tentative explanation based on the photoinduced distortion and the induced preferred directions within the domain wall in soft materials create localized potential minima. As these minima become deeper with time, the mobility of the domain wall will decrease, associated with gradual decrease of initial permeability after demagnetization, so called, disaccommodation.