Nanophase Composite Materials for Magnetic Refrigeration

该计划的目标是（1）生成 含有Fe和Cr的相对单分散的纳米颗粒， 激光诱导气相颗粒形成过程，（2）至 通过表面放电/液体有效地去除颗粒 氮电极组件，（3）以固结纳米颗粒 纳米复合材料，并测量它们的增强 在变化的外部磁场下的磁热效应， （4）将实验数据与理论进行比较， 最大磁热制冷量 三种技术被用于产生纳米- 大小的颗粒：激光烧蚀，光解解离，和 热解 对于激光消融和光解 解离实验，准分子激光器在 将使用紫外频率范围。 反应 腔室配置、气体压力和流动模式将被 优化用于控制单分散的生成 纳米粒子 利用CO2的光解热解技术 激光器将被开发用于最终的大规模生产 的纳米复合材料。 利用CO2激光诱导 热解过程中，所提出的新的纳米复合材料可以 为建造...大量准备 近室运行的磁制冷机样机 温度 纳米复合制冷剂颗粒的气体- 相成核过程及其固结成 具有增强磁矩的超顺磁性材料 将导致显著的材料， 磁热效应

The objectives of the proposed program are (1) to generate relatively monodispersed nanoparticles containing Fe and Cr by laser-induced gas-phase particle formation processes, (2) to effectively remove particles by a surface discharge/liquid nitrogen electrode assembly , (3) to consolidate nanoparticles into nanophase composites and measure their enhanced magnetocaloric effect under varying external magnetic field, and (4) to compare the experimental data with theory for maximum magnetocaloric refrigerating capacity. Three techniques are used for the generation of nanometer- sized particles: laser ablation, photolytic dissociation, and pyrolysis. For both the laser ablation and photolytic dissociation experiments, excimer lasers operating in the ultraviolet frequency range will be used. The reaction chamber configuration, gas pressure and flow patterns will be optimized for controlled generation of monodispersed nanoparticles. The photolytic pyrolysis technique using CO2 lasers will be developed for the eventual scale-up production of nanocomposite at high rates. Using CO2 laser-induced pyrolytic process, the proposed new nanocomposite material may be prepared in large quantities for the construction of prototype magnetic refrigerators operating near room temperature. The creation of nanocomposite refrigerant particles by gas- phase nucleation processes and their consolidation into superparamagnetic materials with enhanced magnetic moments will result in significant materials with increases of the magnetocaloric effect.