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Multicaloric and coupled-caloric effects
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作者 郝嘉政 胡凤霞 +11 位作者 尉紫冰 沈斐然 周厚博 高怡红 乔凯明 李佳 张丞 梁文会 王晶 何峻 孙继荣 沈保根 《Chinese Physics B》 SCIE EI CAS CSCD 2020年第4期31-40,共10页
The multicaloric effect refers to the thermal response of a solid material driven by simultaneous or sequential application of more than one type of external field.For practical applications,the multicaloric effect is... The multicaloric effect refers to the thermal response of a solid material driven by simultaneous or sequential application of more than one type of external field.For practical applications,the multicaloric effect is a potentially interesting strategy to improve the efficiency of refrigeration devices.Here,the state of the art in multi-field driven multicaloric effect is reviewed.The phenomenology and fundamental thermodynamics of the multicaloric effect are well established.A number of theoretical and experimental research approaches are covered.At present,the theoretical understanding of the multicaloric effect is thorough.However,due to the limitation of the current experimental technology,the experimental approach is still in progress.All these researches indicated that the thermal response and effective reversibility of multiferroic materials can be improved through multicaloric cycles to overcome the inherent limitations of the physical mechanisms behind single-field-induced caloric effects.Finally,the viewpoint of further developments is presented. 展开更多
关键词 multicaloric EFFECT coupled-caloric EFFECT SOLID-STATE REFRIGERATION MAGNETOCALORIC EFFECT
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First neutron Bragg-edge imaging experimental results at CSNS
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作者 陈洁 谭志坚 +12 位作者 刘玮强 邓司浩 王声翔 王立毅 郑海彪 卢怀乐 沈斐然 郝嘉政 周晓娟 周健荣 孙志嘉 何伦华 梁天骄 《Chinese Physics B》 SCIE EI CAS CSCD 2021年第9期45-48,共4页
The neutron Bragg-edge imaging is expected to be a new non-destructive energy-resolved neutron imaging technique for quantitatively two-dimensional or three-dimensional visualizing crystallographic information in a bu... The neutron Bragg-edge imaging is expected to be a new non-destructive energy-resolved neutron imaging technique for quantitatively two-dimensional or three-dimensional visualizing crystallographic information in a bulk material,which could be benefited from pulsed neutron source.Here we build a Bragg-edge imaging system on the General Purpose Powder Diffractometer at the China Spallation Neutron Source.The residual strain mapping of a bent Q235 ferrite steel sample has been achieved with a spectral resolution of 0.15%by the time-of-flight neutron Bragg-edge imaging on this system.The results show its great potential applications in materials science and engineering. 展开更多
关键词 neutron Bragg-edge imaging China Spallation Neutron Source
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巨磁热材料相变过程晶格熵变和自旋熵变符号问题研究 被引量:1
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作者 郝嘉政 胡凤霞 +9 位作者 尉紫冰 沈斐然 周厚博 高怡红 乔凯明 梁文会 张丞 王晶 孙继荣 沈保根 《中国科学:物理学、力学、天文学》 CSCD 北大核心 2021年第6期178-188,共11页
基于磁热效应的固态制冷技术由于绿色环保、高效节能等优势具有广阔的应用前景.具有巨大磁热效应的一级相变材料的共同特征是磁相变伴随晶胞参数或晶体对称性的不连续变化,其中一些材料体系在铁磁(FM)-顺磁(PM)相变过程中伴随晶格的负... 基于磁热效应的固态制冷技术由于绿色环保、高效节能等优势具有广阔的应用前景.具有巨大磁热效应的一级相变材料的共同特征是磁相变伴随晶胞参数或晶体对称性的不连续变化,其中一些材料体系在铁磁(FM)-顺磁(PM)相变过程中伴随晶格的负热膨胀.通常地,较大晶格体积相的声子振动模较软,进而具有较大的晶格熵.但实验和理论研究表明不同负热膨胀材料的声子振动模演化机制存在巨大差异.特别地,声子振动模在材料发生磁相变时的强化或软化决定相变时的晶格熵变的大小和符号.因此,具有负热膨胀特点的巨磁热材料相变过程中的晶格熵变和自旋熵变的符号相同还是相反一直存在争议.我们结合前人核共振非弹性X射线散射(NRIXS)等相关研究,并利用热流测量和德拜理论计算澄清了具有负热膨胀特点的巨磁热La(Fe, Si)_(13)基化合物和六角MM′X合金(M, M′=过渡族元素、X=主族元素)的晶格熵变和自旋熵变的符号问题.结果表明, La(Fe, Si)_(13)基化合物和MM′X合金在磁有序相变过程中晶格熵变和自旋熵变的符号始终相同,符合熵增原理.这项工作有助于全面理解具有负热膨胀行为的磁晶耦合材料巨磁热效应的内在物理机制及其多场调控原理. 展开更多
关键词 晶格熵变符号 自旋熵变符号 相变 负热膨胀 磁热效应
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