| Budget Amount *help |
¥2,400,000 (Direct Cost: ¥2,400,000)
Fiscal Year 1986: ¥300,000 (Direct Cost: ¥300,000)
Fiscal Year 1985: ¥2,100,000 (Direct Cost: ¥2,100,000)
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| Research Abstract |
A.C. magnetic susceptibility measurements have been performed on the superfine Ni metallic particles prepared inside the cavities of X zeolites. The measurements were carried out in the temperature range 4.2-300 K by using a Hokusan SQUID magnetometer, model HS-1R on the samples,A,B,and C which have different particle diameters. The magnetic susceptibilities of the sample A increases with decreasing temperature from room temperature down to 50 K, and then decreases rapidly. The temperature dependence and the value of Curie constant may be described within the Neel model of superparamagnetism. But the blocking temperature <T_f> of these systems is inversely proportional to the particle size. So our experimental results on Ni fine particles in X zeolite differ from other one. In order to understand the observations, an attempt has been made to caluculate the temperature dependence of the magnetic susceptibility using a Hamiltonian of the form H=-2 <mu_B> N. <S_z> ・H-D・ <S_z2> where N is number of atoms per particle, S is spin quantum number,and H is the external magnetic field. It is found that the calculation has been successful to explain the temperature dependence of the A.C. magnetic susceptibilities for Ni superfine particle systems with the fitting parameter D = 75, 330, and 470 K coresponding to the sample,A,B,and C respectively. In coclusion, we have observed new superparamagnetism for the superfine Ni particles formed in X zeolites.
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