Theory of structural transformations in ferrofluids: chains and "gas-liquid" phase transitions.
Theory of structural transformations in ferrofluids: chains and "gas-liquid" phase transitions.
复制标题
铁磁流体结构转变理论：链和“气-液”相变。
DOI：
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发表时间：
2002
期刊：
影响因子：
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通讯作者：
L. Iskakova
中科院分区：
文献类型：
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作者：
A. Zubarev;L. Iskakova
我们考虑一个铁磁流体由相同的球形粒子与永久磁矩。在假设磁流体中可以出现线性柔性链的情况下，我们估计了链内粒子数的分布函数。分析和简单的表达式的大小分布函数中得到的一个链内的粒子之间的强磁相互作用的渐近。我们研究了在无限强磁场下，线性链对粒子系综中大块“气-液”相变的条件和情景的影响。为了研究链对粒子系综中整体“气-液”相变的影响，在考虑粒子间相互作用的情况下，计算了独立粒子模型和链模型中粒子的化学势μ。当温度足够低时，货车德瓦耳斯环出现在第一个模型中的μ与颗粒的体积浓度φ的图上;函数μ（φ）在第二个模型中对于所有检查的温度单调增加。这意味着冷凝“气-液”相变可以发生在单个颗粒的模型中;然而，在真实的铁磁流体中链的形成阻止了这种转变的出现。
We consider a ferrofluid consisting of identical spherical particles with a permanent magnetic moment. Under the assumption that linear flexible chains can appear in the ferrofluid, we estimate the distribution function of the number of particles inside the chain. The analysis is done and simple expressions for the size distribution function are obtained in asymptotics of a strong magnetic interaction between the particles inside one chain. We studied the influence of the linear chains on conditions and scenarios of bulk "gas-liquid" phase transition in the ensemble of the particles under an infinitely strong magnetic field. In order to study the influence of the chains on bulk "gas-liquid" phase transition in the ensemble of the particles, their chemical potential mu is calculated in the model of separate interacting particles as well as in the model with chains, taking into account the interaction between them. When the temperature is low enough, van der Waals loops appear on the plots of mu versus volume concentration phi of the particles in the first model; function mu(phi) increases monotonically in the second model for all examined temperatures. This means that the condensation "gas-liquid" phase transition can take place in the model of individual particles; however, formation of the chains in real ferrofluids prevents the appearance of this transition.