非简谐振动对纳米铁磁粒子表面能的影响

在考虑到原子作非简谐振动的情况下,先求出在均匀外磁场中单轴铁磁粒子原子振动的简谐系数、非简谐系数和粒子的自由能.再以球状纳米铁磁粒子作计算,以探讨粒子表面能随温度和粒径变化的规律以及原子非简谐振动对粒子表面能的影响.结果表明:铁磁纳米微粒的表面能随温度的升高和粒径的减小而减小,作者认为纳米微粒的小尺寸效应以及由此产生的晶格振动的非简谐效应和晶格振动软化,对纳米铁磁粒子的表面能有重要影响.

Influence of Anharmonic Vibration on Surface Energy of Nanometer Ferromagnetic Granule

Considering atomic anharmonic vibration, the authors figure out the free energy of granule and the harmonic parameter and anharmonic parameter of atomic vibration of single-domain ferromagnetic in uniform external field. With spheroidal nanometer granule, the authors discuss the influence of atomic anharrnonic vi- bration on the surface energy of granule and the law of the surface energy of granule changing with temperature and granule-radius. As a result, the surface energy of nanometer ferromagnetic granule will decrease with the increasing temperature and the decreasing granule-radius; The small size effect of nanometer granule, anharmonic effect of lattice vibration and its mollescence of lattice vibration have an important influence on the surface energy of nanometer ferromagnetic granule.