Magnetic Entropy Change by Mean-Field Theory for the Second-Order Phase Transition Manganite Nd0.6Sr0.3Ca0.1Mn0.975Fe0.025O3

2016 ◽  
Vol 29 (5) ◽  
pp. 1151-1157 ◽  
Author(s):  
M. R. Laouyenne ◽  
Sa. Mahjoub ◽  
M. Baazaoui ◽  
E. K. Hlil ◽  
M. Oumezzine
Keyword(s):  
Field Theory ◽  
Phase Transition ◽  
Order Phase Transition ◽  
Magnetic Entropy Change ◽  
Mean Field Theory ◽  
Mean Field ◽  
Entropy Change ◽  
Second Order ◽  
Magnetic Entropy ◽  
Second Order Phase Transition

Electrolytic Hydriding of La(Fe, Si)13 Based Materials and its Magnetocaloric Effect

2014 ◽  
Vol 809-810 ◽  
pp. 443-448 ◽  
Author(s):  
Kun Yang ◽  
Na Tian ◽  
Cai Yin You
Keyword(s):  
Phase Transition ◽  
Magnetic Properties ◽  
External Field ◽  
Curie Temperature ◽  
Surface Morphology ◽  
Order Phase Transition ◽  
Magnetic Entropy Change ◽  
Entropy Change ◽  
Magnetic Entropy ◽  
Second Order Phase Transition

In this paper, the hydriding of La (Fe, Fe)13 based alloys was realized by the electrolytic method and the effect of electrolytic temperature on the hydriding was investigated. The phase components and surface morphology were analyzed by XRD and SEM. The magnetic properties of samples were characterized using VSM. Results showed that the electrolytic hydriding process was enhanced by increasing the electrolytic temperature. The Curie temperature was increased from 196 K to 325 K. Through Arrot-plot analyses, it was found that the phase transition of samples tends to be a second order phase transition. The magnetic entropy change was reduced from 8.03 J/(kg•K) to 2.03 J/(kg•K) under a maximum external field of 1.5 T.

scholarly journals Modeling the Magnetocaloric Effect of Nd0.67Ba0.33Mn0.98 Fe0.02O3 by the Mean Field Theory

2020 ◽  
Author(s):  
Mohamed Hsini ◽  
Sadok Zemni
Keyword(s):  
Field Theory ◽  
Phase Transition ◽  
Magnetic Properties ◽  
Magnetic Fields ◽  
Magnetocaloric Effect ◽  
Mean Field Theory ◽  
Mean Field ◽  
Entropy Change ◽  
Magnetization Curves ◽  
The Mean

In this paper, we have exploited the mean field theory combined with the Bean-Rodbell model to justify the magnetocaloric effect (MCE) in Nd0.67Ba0.33Mn0.98Fe0.02O3 sample. The simulation of some magnetic properties has been investigated. Modeling magnetization curves have been successfully achieved using this model. The second-order ferromagnetic-paramagnetic (FM-PM) phase transition of our system has been verified through the value of the parameter which controls the transition nature in the Bean-Rodbell model. Theoretical and experimental expressions, which have rated the magnetic entropy change ( − ∆ S M ) under various magnetic fields, have been derived. Theoretical ( − ∆ S M ) curves have been compared to the experimental ones.

Exothermic effect of entropy change in second-order phase transition ferroelectrics

2018 ◽  
Vol 45 (4-6) ◽  
pp. 66-75
Author(s):  
Shao H. Qu ◽  
Ming Mei ◽  
Wan Q. Cao ◽  
Rui K. Pan ◽  
Ya J. Qi ◽  
...  
Keyword(s):  
Phase Transition ◽  
Order Phase Transition ◽  
Entropy Change ◽  
Second Order ◽  
Exothermic Effect ◽  
Second Order Phase Transition

Magnetic entropy calculation for a second-order ferromagnetic phase transition

2014 ◽  
Vol 28 (08) ◽  
pp. 1450059
Author(s):  
Lei Zhang ◽  
Jiyu Fan ◽  
Yuheng Zhang
Keyword(s):  
Phase Transition ◽  
Calculation Method ◽  
Magnetic Entropy Change ◽  
Entropy Change ◽  
Transition System ◽  
Second Order ◽  
Ferromagnetic Phase ◽  
Magnetic Entropy ◽  
Conventional Calculation ◽  
Ferromagnetic Phase Transition

In this paper, we present a new calculation method of magnetic entropy in an arbitrary second-order ferromagnetic phase transition system. Based on the Arrott–Noakes relation (H/M)1/γ = (T-TC)/TC+(M/M1)1/β, the Gibbs energy can be rewritten as a new form where the critical exponents are naturally included. Correspondingly, the magnetic entropy (SM) is presented as: [Formula: see text]. Thus, the magnetic entropy change (ΔSM) can be deduced as [Formula: see text] which is consistent exactly with the previous report [V. Franco et al., Appl. Phys. Lett.89 (2006) 222512]. In addition, the conventional calculation method of magnetic entropy can be treated as a particular form of this calculation method. Furthermore, the obtained magnetic entropy change from experimental measurement are consistent with the theoretical value deduced from the present method.

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