Author
Vladimír Sechovský
Bio: Vladimír Sechovský is an academic researcher from Charles University in Prague. The author has contributed to research in topics: Magnetization & Antiferromagnetism. The author has an hindex of 24, co-authored 442 publications receiving 3465 citations.
Papers published on a yearly basis
Papers
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TL;DR: Comprehensive study provides compelling evidence that anion templates are the main driving force in the formation of two novel nanoscale lanthanide hydroxide clusters, characterized by single-crystal X-ray crystallography, infrared spectroscopy, and magnetic measurements.
Abstract: The comprehensive study reported herein provides compelling evidence that anion templates are the main driving force in the formation of two novel nanoscale lanthanide hydroxide clusters, {Gd38(ClO4)6} (1) and {Gd48Cl2(NO3)} (2), characterized by single-crystal X-ray crystallography, infrared spectroscopy, and magnetic measurements {Gd38(ClO4)6}, encapsulating six ClO4(-) ions, features a cage core composed of twelve vertex-sharing {Gd4} tetrahedrons and one Gd⋅⋅⋅Gd pillar When Cl(-) and NO3(-) were incorporated in the reaction instead of ClO4(-), {Gd48Cl2(NO3)} is obtained with a barrel shape constituted by twelve vertex-sharing {Gd4} tetrahedrons and six {Gd5} pyramids What is more, the cage-like {Gd38} can be dynamically converted into the barrel-shaped {Gd48} upon Cl(-) and NO3(-) stimulus To our knowledge, it is the first time that the linear M-O-M' fashion and the unique μ8-ClO4(-) mode have been crystallized in pure lanthanide complex, and complex 2 represents the largest gadolinium cluster Both of the complexes display large magnetocaloric effect in units of J kg(-1) K(-1) and mJ cm(-3) K(-1) on account of the weak antiferromagnetic exchange, the high N(Gd)/M(W) ratio (magnetic density), and the relatively compact crystal lattice (mass density)
148 citations
TL;DR: The magnetocaloric effect of a coordination polymeric material with a repeating unit of Gd(OH)CO3 has been studied experimentally using isothermal magnetization and heat capacity measurements as mentioned in this paper.
Abstract: The magnetocaloric effect of a coordination polymeric material with a repeating unit of Gd(OH)CO3 has been studied experimentally using isothermal magnetization and heat capacity measurements. The maximum entropy change, −ΔSm, reaches 66.4 J kg−1 K−1 or 355 mJ cm−3 K−1 for ΔH = 7 T and T = 1.8 K. Density functional theory (DFT) calculations show weak and competing antiferromagnetic interactions between the metal centres.
148 citations
TL;DR: In this paper, the crystal structure, magnetic susceptibility and isothermal magnetization for the inorganic framework material GdF3 were measured, and the isothermal entropy change was evaluated up to 9 T.
Abstract: The use of paramagnetic molecules as cryogenic coolants usually requires relatively large fields to obtain a practical cooling effect. Thus, research into magnetic molecular materials with larger MCEs in fields of ≤2 T is the main focus in this area. In this work, the crystal structure, magnetic susceptibility and isothermal magnetization for the inorganic framework material GdF3 were measured, and the isothermal entropy change was evaluated up to 9 T. Thanks to the combination of the large isotropic spin of Gd3+, the dense structure and weak ferromagnetic interaction, an extremely large −ΔSm for GdF3 was observed up to 528 mJ cm−3 K−1 for Δμ0H = 9 T, proving it to be an exceptional cryogenic magnetic coolant.
111 citations
TL;DR: Two kinds of inorganic gadolinium(III)-hydroxy "ladders", [2×n] and [3×n], were successfully trapped in succinate (suc) coordination polymers, which give very large volumetric MCEs up to 120 and 144 mJ cm(-3) K(-1) for complexes 1 and 2, respectively.
Abstract: Two kinds of inorganic gadolinium(III)-hydroxy "ladders", [2×n] and [3×n], were successfully trapped in succinate (suc) coordination polymers, [Gd2(OH)2(suc)2(H2O)]n·2nH2O (1) and [Gd6(OH)8(suc)5(H2O)2 ]n·4n H2O (2), respectively. Such coordination polymers could be regarded as alternating inorganic-organic hybrid materials with relatively high density. Magnetic and heat capacity studies reveal a large cryogenic magnetocaloric effect (MCE) in both compounds, namely (ΔH=70 kG) 42.8 J kg(-1) K(-1) for complex 1 and 48.0 J kg(-1) K(-1) for complex 2. The effect of the high density is evident, which gives very large volumetric MCEs up to 120 and 144 mJ cm(-3) K(-1) for complexes 1 and 2, respectively.
90 citations
TL;DR: The transformation of Mn(II) glycolates between the three-dimensional coordination polymer and discrete mononuclear phase can be reversibly switched by water molecules, revealing that the effect of magnetic coupling on MCE plays a dominant role over other factors such as magnetic density for 3d-type magnetic refrigerants.
Abstract: The transformation of Mn(II) glycolates (glc) between the three-dimensional coordination polymer [Mn(glc)2]n (1) and discrete mononuclear phase [Mn(glc)2 (H2O)2] (2) can be reversibly switched by water molecules, which dramatically change the magnetocaloric effect (MCE) of Mn(II) glycolates from the maximum of 6.9 J kg(-1) K(-1) in 1 to 60.3 J kg(-1) K(-1) in 2. This case example reveals that the effect of magnetic coupling on MCE plays a dominant role over that of other factors such as magnetic density for 3d-type magnetic refrigerants.
60 citations
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Journal Article•
28,685 citations
TL;DR: The recent literature concerning the magnetocaloric effect (MCE) has been reviewed and correlations have been made comparing the behaviours of the different families of magnetic materials which exhibit large or unusual MCE values.
Abstract: The recent literature concerning the magnetocaloric effect (MCE) has been reviewed. The MCE properties have been compiled and correlations have been made comparing the behaviours of the different families of magnetic materials which exhibit large or unusual MCE values. These families include: the lanthanide (R) Laves phases (RM2, where M = Al, Co and Ni), Gd5(Si1−xGex)4 ,M n(As1−xSbx), MnFe(P1−xAsx), La(Fe13−xSix) and their hydrides and the manganites (R1−xMxMnO3, where R = lanthanide and M = Ca, Sr and Ba). The potential for use of these materials in magnetic refrigeration is discussed, including a comparison with Gd as a near room temperature active magnetic regenerator material. (Some figures in this article are in colour only in the electronic version)
3,002 citations
01 Sep 1955
TL;DR: In this paper, the authors restrict their attention to the ferrites and a few other closely related materials, which are more closely related to anti-ferromagnetic substances than they are to ferromagnetics in which the magnetization results from the parallel alignment of all the magnetic moments present.
Abstract: In this chapter, we will restrict our attention to the ferrites and a few other closely related materials. The great interest in ferrites stems from their unique combination of a spontaneous magnetization and a high electrical resistivity. The observed magnetization results from the difference in the magnetizations of two non-equivalent sub-lattices of the magnetic ions in the crystal structure. Materials of this type should strictly be designated as “ferrimagnetic” and in some respects are more closely related to anti-ferromagnetic substances than they are to ferromagnetics in which the magnetization results from the parallel alignment of all the magnetic moments present. We shall not adhere to this special nomenclature except to emphasize effects, which are due to the existence of the sub-lattices.
2,659 citations
TL;DR: The magnetocaloric effect and its most straightforward application, magnetic refrigeration, are topics of current interest due to the potential improvement of energy efficiency of cooling and temperature control systems, in combination with other environmental benefits associated to a technology that does not rely on the compression/expansion of harmful gases.
941 citations
TL;DR: In this paper, a review of the magnetocaloric response of materials for magnetic refrigeration close to room temperature is presented, focusing on the main families of materials suitable for this application and the procedures proposed to predict their response.
Abstract: In the past 20 years, there has been a surge in research on the magnetocaloric response of materials, due mainly to the possibility of applying this effect for magnetic refrigeration close to room temperature. This review is devoted to the main families of materials suitable for this application and to the procedures proposed to predict their response. Apart from the possible technological applications, we also discuss the use of magnetocaloric characterization to gain fundamental insight into the nature of the underlying phase transition.
910 citations