Botello-Zubiate María E, Grijalva-Castillo María C, Soto-Parra Daniel, Sáenz-Hernández Renee J, Santillán-Rodríguez Carlos R, Matutes-Aquino José A
Centro de Investigación en Materiales Avanzados, S.C., Miguel de Cervantes 120, Complejo Industrial Chihuahua, Chihuahua 31136, Mexico.
CONACYT-Centro de Investigación en Materiales Avanzados, S.C., Miguel de Cervantes 120, Complejo Industrial Chihuahua, Chihuahua 31136, Mexico.
Materials (Basel). 2019 Jan 19;12(2):309. doi: 10.3390/ma12020309.
Manganites of the family LaCaSrMnO₃ were fabricated by four preparation methods: (a) the microwave-assisted sol-gel Pechini method; (b) sol-gel Pechini chemical synthesis; (c) solid-state reaction with a planetary mill; and (d) solid-state reaction with an attritor mill, in order to study the effect of the preparation route used on its magnetocaloric and magnetic properties. In addition, the manganites manufactured by the Pechini sol-gel method were compacted using Spark Plasma Sintering (SPS) to determine how the consolidation process influences its magnetocaloric properties. The Curie temperatures of manganites prepared by the different methods were determined in ~295 K, with the exception of those prepared by a solid-state reaction with an attritor mill which was 301 K, so there is no correlation between the particle size and the Curie temperature. All samples gave a positive slope in the Arrot plots, which implies that the samples underwent a second order Ferromagnetic (FM)⁻Paramagnetic (PM) phase transition. Pechini sol-gel manganite presents higher values of Relative Cooling Power (RCP) than the solid-state reaction manganite, because its entropy change curves are smaller, but wider, associated to the particle size obtained by the preparation method. The SPS technique proved to be easier and faster in producing consolidated solids for applications in active magnetic regenerative refrigeration compared with other compaction methods.
通过四种制备方法合成了LaCaSrMnO₃系列锰氧化物：(a) 微波辅助溶胶 - 凝胶佩琴尼法；(b) 溶胶 - 凝胶佩琴尼化学合成法；(c) 行星式球磨机固态反应法；(d) 搅拌磨固态反应法，目的是研究制备方法对其磁热和磁性能的影响。此外，使用放电等离子烧结（SPS）对通过佩琴尼溶胶 - 凝胶法制备的锰氧化物进行压实，以确定固结过程如何影响其磁热性能。除了通过搅拌磨固态反应制备的锰氧化物居里温度为301 K外，通过不同方法制备的锰氧化物居里温度在约295 K测定，因此粒径与居里温度之间没有相关性。所有样品在阿罗特图中都呈现正斜率，这意味着样品经历了二级铁磁（FM）-顺磁（PM）相变。佩琴尼溶胶 - 凝胶锰氧化物的相对冷却功率（RCP）值高于固态反应锰氧化物，因为其熵变曲线较小但更宽，这与制备方法获得的粒径有关。与其他压实方法相比，SPS技术在生产用于主动磁再生制冷应用的固结固体方面被证明更容易、更快。
