The crystal structure, magnetic and magnetocaloric properties of(Ho_(1-x) Y_(0.5))_5 Pd_2 compounds are investigated. All the compounds crystallize in a cubic Dy_5 Pd_2-type structure with the space group Fd3 m and un...The crystal structure, magnetic and magnetocaloric properties of(Ho_(1-x) Y_(0.5))_5 Pd_2 compounds are investigated. All the compounds crystallize in a cubic Dy_5 Pd_2-type structure with the space group Fd3 m and undergo a second order transition from spin glass(SG) state to paramagnetic(PM) state. The spin glass transition temperatures T_g decrease from 26 K for x = 0 to 13 K for x = 0.5. In the PM region, the reciprocal susceptibilities for all the compounds obey the Curie–Weiss law. The paramagnetic Curie temperatures(θp) for Ho_5 Pd_2,(Ho_(0.75) Y_(0.25)_5 Pd_2, and(Ho_(0.5) Y_(0.5))_5 Pd_2 are determined to be 32 K, 30 K, and 22 K, respectively, and the corresponding effective magnetic moments(μeff) are10.8 μB/Ho, 10.3 μB/RE, and 7.5 μB/RE, respectively. Magnetocaloric effect(MCE) is anticipated according to the Maxwell relation, based on the isothermal magnetization curves. For a magnetic field change of 0–5 T, the maximum values of the isothermal magnetic entropy change-?SMof the(Ho_(1-x)Y_x)_5 Pd_2(x = 0, 0.25, and 0.5) compounds are determined to be 11.5 J·kg^(-1)·K^(-1), 11.1 J·kg^(-1)·K^(-1), and 8.9 K J·kg^(-1)·K^(-1), with corresponding refrigerant capacity values of 382.3 J·kg^(-1), 336.2 J·kg^(-1), and 242.5 J·kg^(-1), respectively.展开更多
The lantern-shaped cage Pd_(2)L_(4)and tweezer-like PdL_(2)can be synthesized from the trans-and cis-isomer of an azobenzene-containing ligand,respectively,which were characterized by^(1)H,^(13)C,^(1)H-^(1)H COSY,DOSY...The lantern-shaped cage Pd_(2)L_(4)and tweezer-like PdL_(2)can be synthesized from the trans-and cis-isomer of an azobenzene-containing ligand,respectively,which were characterized by^(1)H,^(13)C,^(1)H-^(1)H COSY,DOSY NMR spectroscopies,high-resolution ESI-MS and density function theory(DFT)calculations.The interconversion of Pd_(2)L_(4)and PdL_(2)can be achieved via the cis-trans isomerization of the azobenzene unit on the ligand upon alternative irradiation of light 365 nm or 420 nm.展开更多
基金Project supported by the National Basic Research Program of China(Grant No.2014CB643703)the National Key Research and Development Program of China(Grant No.2016YFB0700901)+1 种基金the National Natural Science Foundation of China(Grant Nos.51261004 and 51761007)Guangxi Natural Science Foundation,China(Grant No.2018GXNSFAA294051)
文摘The crystal structure, magnetic and magnetocaloric properties of(Ho_(1-x) Y_(0.5))_5 Pd_2 compounds are investigated. All the compounds crystallize in a cubic Dy_5 Pd_2-type structure with the space group Fd3 m and undergo a second order transition from spin glass(SG) state to paramagnetic(PM) state. The spin glass transition temperatures T_g decrease from 26 K for x = 0 to 13 K for x = 0.5. In the PM region, the reciprocal susceptibilities for all the compounds obey the Curie–Weiss law. The paramagnetic Curie temperatures(θp) for Ho_5 Pd_2,(Ho_(0.75) Y_(0.25)_5 Pd_2, and(Ho_(0.5) Y_(0.5))_5 Pd_2 are determined to be 32 K, 30 K, and 22 K, respectively, and the corresponding effective magnetic moments(μeff) are10.8 μB/Ho, 10.3 μB/RE, and 7.5 μB/RE, respectively. Magnetocaloric effect(MCE) is anticipated according to the Maxwell relation, based on the isothermal magnetization curves. For a magnetic field change of 0–5 T, the maximum values of the isothermal magnetic entropy change-?SMof the(Ho_(1-x)Y_x)_5 Pd_2(x = 0, 0.25, and 0.5) compounds are determined to be 11.5 J·kg^(-1)·K^(-1), 11.1 J·kg^(-1)·K^(-1), and 8.9 K J·kg^(-1)·K^(-1), with corresponding refrigerant capacity values of 382.3 J·kg^(-1), 336.2 J·kg^(-1), and 242.5 J·kg^(-1), respectively.
基金financially supported by the National Natural Science Foundation of China(No.21572063)Shanghai Municipal Science and Technology Major Project(No.2018SHZDZX03)the Fundamental Research Funds for the Central Universities。
文摘The lantern-shaped cage Pd_(2)L_(4)and tweezer-like PdL_(2)can be synthesized from the trans-and cis-isomer of an azobenzene-containing ligand,respectively,which were characterized by^(1)H,^(13)C,^(1)H-^(1)H COSY,DOSY NMR spectroscopies,high-resolution ESI-MS and density function theory(DFT)calculations.The interconversion of Pd_(2)L_(4)and PdL_(2)can be achieved via the cis-trans isomerization of the azobenzene unit on the ligand upon alternative irradiation of light 365 nm or 420 nm.
