Repozytorium Uniwersytetu Jagiellońskiego
Magnetocaloric effect in M-pyrazole-[Nb(CN)_{8}] (M=Ni, Mn) molecular compounds
Magnetocaloric effect in M-pyrazole-[Nb(CN)_{8}] ...
Opis pozycji
| tytuł: | Magnetocaloric effect in M-pyrazole-[Nb(CN)_{8}] (M=Ni, Mn) molecular compounds |
| autor: | Fitta Magdalena, Bałanda Maria, Mihalik Marian, Pinkowicz Dawid  , Sieklucka Barbara , Zentkova Maria, Pełka Robert |
| tytuł czasopisma: | Journal of Physics. Condensed Matter |
| tom: | 24 |
| numer: | 50 |
| data wydania: | 2012 |
| article ID: | 506002 |
| ISSN: |
0953-8984 |
| eISSN: |
1361-648X |
| DOI: | |
| język: | angielski |
| język czasopisma: | angielski |
| abstrakt w j. angielskim: | We report a study of magnetocaloric effect (MCE) in cyanido-bridged {[MII(pyrazole)4]2[NbIV(CN)8]⋅4H2O}n molecular compounds where M = Ni, Mn, pyrazole = C3H4N2. The substances show a sharp phase transition to a long range magnetically ordered state, with ferromagnetic coupling between M and Nb sublattices in the case of the Ni-based sample 1 (Tc = 13.4 K) and ferrimagnetic coupling for the Mn-based sample 2 (Tc = 23.8 K). The magnetic entropy change ΔS due to applied field change ΔH as a function of temperature was determined by the magnetization and heat capacity measurements. The maximum value of ΔS at μ0ΔH = 5 T is 6.1 J mol−1 K−1 (5.9 J kg−1 K−1) for 1 at T = 14 K and 6.7 J mol−1 K−1 (6.5 J kg−1 K−1) for 2 at T = 25 K. MCE data at different applied fields have been presented as one universal curve, which confirms magnetic transitions in 1 and 2 to be of second order. The temperature dependences of the n exponent characterizing the dependence of ΔS on ΔH have been obtained. The n(Tc) values, consistent with the shape of the magnetization curves, pointed to the 3D Heisenberg behaviour for 2 and some anisotropy, probably of the XY type, for 1. The (H/Tc)2/3 dependence of the maximum entropy change has been tested in the ferrimagnetic Mn2–L–[Nb(CN)8] (L = C3H4N2, C4H4N2) series. |
| punktacja wydziałowa: | 30 |
| wydział:instytut/zakład/katedra: | Wydział Chemii : Zakład Chemii Nieorganicznej |
| typ: | artykuł w czasopiśmie |
| podtyp: | artykuł |
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