Vallone Steven P, Tantillo Anthony N, Dos Santos António M, Molaison Jamie J, Kulmaczewski Rafal, Chapoy Antonin, Ahmadi Pezhman, Halcrow Malcolm A, Sandeman Karl G
Department of Physics, Brooklyn College, CUNY, 2900 Bedford Avenue, Brooklyn, NY, 11210, USA.
Physics Program, The Graduate Center, CUNY, 365 Fifth Avenue, New York, NY, 10016, USA.
Adv Mater. 2019 Jun;31(23):e1807334. doi: 10.1002/adma.201807334. Epub 2019 Apr 15.
The first experimental evidence for a giant, conventional barocaloric effect (BCE) associated with a pressure-driven spin crossover transition near room temperature is provided. Magnetometry, neutron scattering, and calorimetry are used to explore the pressure dependence of the SCO phase transition in polycrystalline samples of protonated and partially deuterated [FeL ][BF ] [L = 2,6-di(pyrazol-1-yl)pyridine] at applied pressures of up to 120 MPa (1200 bar). The data indicate that, for a pressure change of only 0-300 bar (0-30 MPa), an adiabatic temperature change of 3 K is observed at 262 K or 257 K in the protonated and deuterated materials, respectively. This BCE is equivalent to the magnetocaloric effect (MCE) observed in gadolinium in a magnetic field change of 0-1 Tesla. The work confirms recent predictions that giant, conventional BCEs will be found in a wide range of SCO compounds.
首次提供了与室温附近压力驱动的自旋交叉转变相关的巨大常规巴氏效应（BCE）的实验证据。利用磁强计、中子散射和量热法，在高达120兆帕（1200巴）的外加压力下，研究了质子化和部分氘代的[FeL][BF] [L = 2,6-二（吡唑-1-基）吡啶]多晶样品中SCO相变的压力依赖性。数据表明，对于仅0 - 300巴（0 - 30兆帕）的压力变化，在质子化和氘代材料中，分别在262 K或257 K时观察到3 K的绝热温度变化。这种BCE相当于在钆中0 - 1特斯拉磁场变化时观察到的磁热效应（MCE）。这项工作证实了最近的预测，即在广泛的SCO化合物中会发现巨大的常规BCE。
