Octanuclear [NiII4LnIII4] complexes. Synthesis, crystal structures and magnetocaloric properties

Magnetocaloric properties of compounds Gd(Ni0.98Si0.02), Dy(Ni0.95Si0.05) and their hydrides Gd(Ni0.98Si0.02)H3, Dy(Ni0.95Si0.05)H4 were investigated in the temperature range 2 – 100K. It was found that partial substitution of Ni atoms by Si atoms, as well as subsequent hydrogenation can lead to a significant change in the Curie temperature (TC), the magnetocaloric effect, and the temperature at which the maximum MCE (Tmax) is observed. It is shown that the TC and Tmax of the hydrides are shifted by several degrees to the low temperature region with increasing or maintaining the MCE, which can significantly expand the application of such materials in cryogenic engineering.

Download Full-text

The distribution of minerals in hyper-agpaitic rocks in terms of symmetry: evolution of views on the number and symmetry of minerals

Geological Survey of Denmark and Greenland Bulletin ◽

10.34194/ggub.v190.5176 ◽

2001 ◽

pp. 73-82 ◽

Cited By ~ 2

Author(s):

Alexander P. Khomyakov

Keyword(s):

Crystal Structures ◽

21St Century ◽

Special Interest ◽

Periodic Table ◽

Mineral Species ◽

Original Series ◽

Temperature Range ◽

The Earth ◽

High Alkalinity ◽

Low Symmetry

NOTE: This article was published in a former series of GEUS Bulletin. Please use the original series name when citing this article, for example: Khomyakov, A. P. (2001). The distribution of minerals in hyper-agpaitic rocks in terms of symmetry: evolution of views on the number and symmetry of minerals. Geology of Greenland Survey Bulletin, 190, 73-82. https://doi.org/10.34194/ggub.v190.5176 _______________ Among the unique mineral localities of the Earth the complexes of nepheline syenites with hyper-agpaitic differentiates are of special interest due to their extreme diversity of mineral species. The four best studied complexes of this type – Khibina, Lovozero, Ilímaussaq and Mont Saint-Hilaire – have yielded more than 700 mineral species of which about 200 are new. The great mineral diversity is due to the combination of several factors, the most important of which is the extremely high alkalinity of agpaitic magmas, causing about half of the elements of the periodic table to be concentrated together. Minerals from hyper-agpaitic rocks are characterised by the predominance of highly ordered, low-symmetry crystal structures resulting, in particular, from the markedly extended temperature range of crystallisation. Generalisation of available data for unique mineral localities underpins the hypothesis that there is no natural limit to the number of mineral species. It is predicted that by the middle of the 21st century, the overall number of minerals recorded in nature will exceed 10 000, with the proportion of triclinic species increasing from the present 9% to 14.5%, and that of cubic species decreasing from 10% to 5%.

Download Full-text

Improvement of magnetocaloric properties over a large temperature range in 0.5La0.7Ca0.2Sr0.1MnO3/0.5La0.7Ca0.15Sr0.15MnO3 composite

Journal of Alloys and Compounds ◽

10.1016/j.jallcom.2017.07.092 ◽

2017 ◽

Vol 724 ◽

pp. 851-858 ◽

Cited By ~ 4

Author(s):

A. Ezaami ◽

N. Ouled nasser ◽

W. Cheikhrouhou-Koubaa ◽

A. Cheikhrouhou

Keyword(s):

Large Temperature ◽

Temperature Range ◽

Magnetocaloric Properties

Download Full-text

The Effect of Different Atomic Substitution at Mn Site on Magnetocaloric Effect in Ni50Mn35Co2Sn13 Alloy

Crystals ◽

10.3390/cryst8080329 ◽

2018 ◽

Vol 8 (8) ◽

pp. 329 ◽

Cited By ~ 3

Author(s):

Chengfen Xing ◽

Hu Zhang ◽

Kewen Long ◽

Yaning Xiao ◽

Hanning Zhang ◽

...

Keyword(s):

Magnetocaloric Effect ◽

Parent Phase ◽

Martensitic Transition ◽

Martensitic Transformation Temperature ◽

Low Field ◽

Transition Metal Element ◽

Magnetocaloric Properties ◽

Metal Element ◽

Mn Content ◽

Atomic Substitution

The effect of different atomic substitutions at Mn sites on the magnetic and magnetocaloric properties in Ni50Mn35Co2Sn13 alloy has been studied in detail. The substitution of Ni or Co for Mn atoms might lower the Mn content at Sn sites, which would reduce the d-d hybridization between Ni 3d eg states and the 3d states of excess Mn atoms at Sn sites, thus leading to the decrease of martensitic transformation temperature TM in Ni51Mn34Co2Sn13 and Ni50Mn34Co3Sn13 alloys. On the other hand, the substitution of Sn for Mn atoms in Ni50Mn34Co2Sn14 would enhance the p-d covalent hybridization between the main group element (Sn) and the transition metal element (Mn or Ni) due to the increase of Sn content, thus also reducing the TM by stabilizing the parent phase. Due to the reduction of TM, a magnetostructural martensitic transition from FM austenite to weak-magnetic martensite is realized in Ni51Mn34Co2Sn13 and Ni50Mn34Co2Sn14, resulting in a large magnetocaloric effect around room temperature. For a low field change of 3 T, the maximum ∆SM reaches as high as 30.9 J/kg K for Ni50Mn34Co2Sn14. A linear dependence of ΔSM upon μ0H has been found in Ni50Mn34Co2Sn14, and the origin of this linear relationship has been discussed by numerical analysis of Maxwell’s relation.

Download Full-text

Magnetocaloric properties in cryogenic temperature range of ferromagnetic CeSi1.3Ga0.7 alloy

Journal of Magnetism and Magnetic Materials ◽

10.1016/j.jmmm.2021.168886 ◽

2021 ◽

pp. 168886

Author(s):

K. Synoradzki ◽

P. Skokowski ◽

Ł. Fra¸ckowiak ◽

M. Koterlyn ◽

T. Toliński

Keyword(s):

Cryogenic Temperature ◽

Temperature Range ◽

Magnetocaloric Properties

Download Full-text

79Br, 127I NQR of Diammoniumalkyl Halides and Piperazinium Halides. Crystal Structure of Piperazinium Dibromide Monohydrate and Piperazinium Monoiodide

Zeitschrift für Naturforschung A ◽

10.1515/zna-1989-0109 ◽

1989 ◽

Vol 44 (1) ◽

pp. 41-55 ◽

Cited By ~ 1

Author(s):

Jutta Hartmann ◽

Shi-Qi Dou ◽

Alarich Weiss

Keyword(s):

Crystal Structure ◽

Phase Transitions ◽

Hydrogen Bonds ◽

Crystal Structures ◽

Monoclinic Space Group ◽

Orthorhombic Space Group ◽

Space Group ◽

Temperature Range

Abstract The 79Br and 127I NQR spectra were investigated for 1,2-diammoniumethane dibromide, -diiodide, 1,3-diammoniumpropane dibromide, -diiodide, piperazinium dibromide monohydrate, and piperazinium monoiodide in the temperature range 77 ≦ T/K ≦ 420. Phase transitions could be observed for the three iodides. The temperatures for the phase transitions are: 400 K and 404 K for 1,2-diammoniumethane diiodide, 366 K for 1,3-diammoniumpropane diiodide, and 196 K for piperazinium monoiodide.The crystal structures were determined for the piperazinium compounds. Piperazinium dibromide monohydrate crystallizes monoclinic, space group C2/c, with a= 1148.7 pm, 0 = 590.5 pm, c= 1501.6pm, β = 118.18°, and Z = 4. For piperazinium monoiodide the orthorhombic space group Pmn 21 was found with a = 958.1 pm, b = 776.9 pm, c = 989.3 pm, Z = 4. Hydrogen bonds N - H ... X with X = Br, I were compared with literature data.

Download Full-text

Unveiling a Scaling and Universal Behavior for the Magnetocaloric Effect in Cubic Crystal Structures: A Monte Carlo Simulation

Scientific Reports ◽

10.1038/s41598-019-41321-y ◽

2019 ◽

Vol 9 (1) ◽

Cited By ~ 2

Author(s):

J. D. Alzate-Cardona ◽

J. S. Salcedo-Gallo ◽

D. F. Rodríguez-Patiño ◽

C. D. Acosta-Medina ◽

E. Restrepo-Parra

Keyword(s):

Monte Carlo Simulation ◽

Monte Carlo ◽

Magnetocaloric Effect ◽

Crystal Structures ◽

Cubic Crystal ◽

Universal Behavior

Download Full-text

The Influence of Cold Rolling on Magnetocaloric Properties of Gd100-xYx (x = 0, 5, 10, 15) Alloys

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.233-234.238 ◽

2015 ◽

Vol 233-234 ◽

pp. 238-242 ◽

Cited By ~ 6

Author(s):

Sergey Taskaev ◽

Konstantin Skokov ◽

Dmitriy Karpenkov ◽

Vladimir V. Khovaylo ◽

Vasiliy D. Buchelnikov ◽

...

Keyword(s):

Cold Rolling ◽

Magnetocaloric Effect ◽

High Temperature Heat Treatment ◽

Magnetic Cooling ◽

A Value ◽

Magnetocaloric Properties ◽

Cooling Devices ◽

Cold Rolled ◽

Magnetocaloric Materials ◽

Temperature Heat Treatment

In this work we report the results of investigation of the magnetocaloric effect in Gd100-xYx (x= 0, 5, 10, 15) cold rolled ribbons. It is shown that the magnetocaloric effect exists within a wide temperature interval 258-295 K and it is comparable with the magnetocaloric effect observed in bulk samples of pure gadolinium. The value of the magnetocaloric effect in the rolled samples is reduced in comparison with the bulk samples and strongly depends on a degree of plastic deformation. High temperature heat treatment can restore a value of the magnetocaloric effect in the cold rolled ribbons up to initial ones. Thus, cold rolling is proposed to be a promising technique for producing thin forms of magnetocaloric materials for heat exchangers of magnetic cooling devices.

Download Full-text

Magnetic Properties and Magnetocaloric Effect in Gd100-xCox Thin Films

Crystals ◽

10.3390/cryst9060278 ◽

2019 ◽

Vol 9 (6) ◽

pp. 278 ◽

Cited By ~ 1

Author(s):

Mohamed Tadout ◽

Charles-Henri Lambert ◽

Mohammed El Hadri ◽

Abdelilah Benyoussef ◽

Mohammed Hamedoun ◽

...

Keyword(s):

Thin Films ◽

Magnetocaloric Effect ◽

Magnetic Entropy Change ◽

Entropy Change ◽

Magnetic Thin Films ◽

Critical Parameters ◽

Cooling Power ◽

Magnetocaloric Properties ◽

Co Concentration ◽

Key Parameter

We investigated the magnetic and magnetocaloric properties of Gd100-xCox ( x = 40 to 56) thin films fabricated by the sputtering technique. Under an applied field change Δ H = 20 kOe , the magnetic entropy change ( Δ S m ) decreases from 2.64 Jkg−1K−1 for x = 44 to about 1.27 Jkg−1K−1 for x = 56. Increasing the Co concentration from x = 40 to 56 shifts the Curie temperature of Gd100-xCox ( x = 40 to 56) thin films from 180 K toward 337 K. Moreover, we extracted the values of critical parameters Tc, β, γ, and δ by using the modified Arrott plot methods. The results indicate the presence of a long-range ferromagnetic order. More importantly, we showed that the relative cooling power (RCP), which is a key parameter in magnetic refrigeration applications, is strongly enhanced by changing the Co concentration in the Gd100-xCox thin films. Our findings help pave the way toward the enhancement of the magnetocaloric effect in magnetic thin films.

Download Full-text