scholarly journals Determination of Phase Transition and Critical Behavior of the As-Cast GdGeSi-(X) Type Alloys (Where X = Ni, Nd and Pr)

Materials ◽  
2021 ◽  
Vol 14 (1) ◽  
pp. 185
Author(s):  
Piotr Gębara ◽  
Mariusz Hasiak
Keyword(s):  
Phase Transition ◽  
Order Phase Transition ◽  
Critical Behavior ◽  
Critical Exponents ◽  
Second Order ◽  
Experimental Result ◽  
First Order Phase Transition ◽  
First Order Phase ◽  
Second Order Phase Transition

The aim of the paper is to present a study of the magnetocaloric effect and the nature of phase transition in the Gd80Ge15Si5 (S1), Gd75Ge15Si5Ni5 (S2), Gd75Ge15Si5Pr5 (S3) and Gd75Ge15Si5Nd5 (S4) alloys. The magnetic entropy changes determined for studied samples, under external magnetic field ~3T, were 11.91, 12.11, 5.08 and 4.71 J/(kg K) for S1, S2, S3 and S4, respectively. The values of refrigerant capacity (under ~3T) were 164, 140, 160 and 140 J/kg for S1, S2, S3 and S4, respectively. The first order phase transition was detected for samples S1 and S2, while specimens S3 and S4 manifested the second order phase transition at the Curie point (TC). The analysis of temperature evolution of the exponent n (ΔSM = C·(Bmax)n) showed the validity of this method in detecting either the first or the second order phase transition and the structural transition. The analysis of critical behavior was carried out for samples S3 and S4. The critical exponents and precise TC values were calculated. The ascertained critical exponents were used to determine the theoretical value of the exponent n, which corresponded well with experimental result.

scholarly journals Holographic Phase Transition Probed by Nonlocal Observables

2016 ◽  
Vol 2016 ◽  
pp. 1-13 ◽  
Author(s):  
Xiao-Xiong Zeng ◽  
Li-Fang Li
Keyword(s):  
Phase Transition ◽  
Black Hole ◽  
Order Phase Transition ◽  
Entanglement Entropy ◽  
Second Order ◽  
Stable Phase ◽  
First Order ◽  
First Order Phase Transition ◽  
First Order Phase ◽  
Second Order Phase Transition

From the viewpoint of holography, the phase structure of a 5-dimensional Reissner-Nordström-AdS black hole is probed by the two-point correlation function, Wilson loop, and entanglement entropy. As the case of thermal entropy, we find for all the probes that the black hole undergoes a Hawking-Page phase transition, a first-order phase transition, and a second-order phase transition successively before it reaches a stable phase. In addition, for these probes, we find that the equal area law for the first-order phase transition is valid always and the critical exponent of the heat capacity for the second-order phase transition coincides with that of the mean field theory regardless of the size of the boundary region.

scholarly journals The Effect of Fe Doping on the Magnetic and Magnetocaloric Properties of Mn5−xFexGe3

2017 ◽  
Vol 2017 ◽  
pp. 1-7 ◽  
Author(s):  
Jeffrey Brock ◽  
Nathanael Bell-Pactat ◽  
Hong Cai ◽  
Timothy Dennison ◽  
Tucker Fox ◽  
...  
Keyword(s):  
Phase Transition ◽  
Order Phase Transition ◽  
Room Temperature ◽  
Entropy Change ◽  
Second Order ◽  
Ferromagnetic Transition ◽  
Fe Doping ◽  
First Order Phase Transition ◽  
Magnetocaloric Properties ◽  
First Order Phase

The magnetic and magnetocaloric properties of a series of minutely doped Mn5-xFexGe3 compounds that exhibit the D88-type hexagonal crystal structure at room temperature have been investigated. For all Fe concentrations, the alloys are ferromagnetic and undergo a second-order ferromagnetic-to-paramagnetic transition near room temperature. Although the small Fe doping had little effect on the ferromagnetic transition temperatures of the system, changes in the saturation magnetization and magnetic anisotropy were observed. For x≤0.15, all compounds exhibit nearly the same magnetic entropy change of ~7 J/kg K, for a field change of 50 kOe. However, the magnitude of the refrigerant capacities increased with Fe doping, with values up to 108.5 J/kg and 312 J/kg being observed for field changes of 20 kOe and 50 kOe, respectively. As second-order phase transition materials, the Mn5-xFexGe3 compounds are not subject to the various drawbacks associated with first-order phase transition materials yet exhibit favorable magnetocaloric effects.

scholarly journals Geometric Curvatures of Plane Symmetry Black Hole

2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
Shao-Wen Wei ◽  
Yu-Xiao Liu ◽  
Chun-E. Fu ◽  
Hai-Tao Li
Keyword(s):  
Phase Transition ◽  
Black Hole ◽  
Order Phase Transition ◽  
Semiclassical Approximation ◽  
Second Order ◽  
Plane Symmetry ◽  
First Order ◽  
First Order Phase Transition ◽  
Transition Points ◽  
First Order Phase

We study the properties and thermodynamic stability of the plane symmetry black hole from the viewpoint of geometry. We find that the Weinhold curvature gives the first-order phase transition atN=1, whereNis a parameter of the plane symmetry black hole while the Ruppeiner one shows first-order phase transition points for arbitraryN≠1. Considering the Legendre invariant proposed by Quevedo et al., we obtain a unified geometry metric, which contains the information of the second-order phase transition. So, the first-order and second-order phase transitions can be both reproduced from the geometry curvatures. The geometry is also found to be curved, and the scalar curvature goes to negative infinity at the Davie phase transition points beyond semiclassical approximation.

scholarly journals Magnetocaloric effect and critical behavior near the first to second-order phase transition of La0.7Ca0.3−xSnxMnO3 compounds

2020 ◽  
Vol 7 (4) ◽  
pp. 046101
Author(s):  
Dao Son Lam ◽  
Nguyen Thi Dung ◽  
Tran Dang Thanh ◽  
Dinh Chi Linh ◽  
Wen-Zhe Nan ◽  
...  
Keyword(s):  
Phase Transition ◽  
Magnetocaloric Effect ◽  
Order Phase Transition ◽  
Critical Behavior ◽  
Second Order ◽  
Second Order Phase Transition

scholarly journals First- and second-order phase transitions in RE6Co2Ga (RE = Ho, Dy or Gd) cryogenic magnetocaloric materials

2021 ◽  
Author(s):  
Dan Guo ◽  
Luis M. Moreno-Ramírez ◽  
Carlos Romero-Muñiz ◽  
Yikun Zhang ◽  
Jia-Yan Law ◽  
...  
Keyword(s):  
Phase Transition ◽  
Phase Transitions ◽  
Order Phase Transition ◽  
Density Functional ◽  
Magnetic Ordering ◽  
Density Functional Theory Calculations ◽  
Entropy Change ◽  
Second Order ◽  
First Order Phase Transition ◽  
First Order Phase

AbstractRare-earth (RE) rich intermetallics crystallizing in orthorhombic Ho6Co2Ga-type crystal structure exhibit peculiar magnetic properties that are not widely reported for their magnetic ordering, order of magnetic phase transition, and related magnetocaloric behavior. By tuning the type of RE element in RE6Co2Ga (RE = Ho, Dy or Gd) compounds, metamagnetic anti-to-paramagnetic (AF to PM) phase transitions could be tuned to ferro-to-paramagnetic (FM to PM) phase transitions. Furthermore, the FM ground state for Gd6Co2Ga is confirmed by density functional theory calculations in addition to experimental observations. The field dependence magnetocaloric and Banerjee’s criteria demonstrate that Ho6Co2Ga and Dy6Co2Ga undergo a first-order phase transition in addition to a second-order phase transition, whereas only the latter is observed for Gd6Co2Ga. The two extreme alloys of the series, Ho6Co2Ga and Gd6Co2Ga, show maximum isothermal entropy change (∣ΔS iso max (5 T)∣) of 10.1 and 9.1 J kg−1K−1 at 26 and 75 K, close to H2 and N2 liquefaction, respectively. This outstanding magnetocaloric effect performance makes the RE6Co2Ga series of potential for cryogenic magnetic refrigeration applications.

Critical Behavior of Antiphase Boundaries in Fe-A127% Close to the D03→B2 Order Phase Transition

1995 ◽  
Vol 398 ◽  
Author(s):  
D. Le Floc'h ◽  
A. Loiseau
Keyword(s):  
Electron Microscopy ◽  
Phase Transition ◽  
Transmission Electron Microscopy ◽  
Quantitative Determination ◽  
Order Phase Transition ◽  
Critical Behavior ◽  
Antiphase Boundaries ◽  
Transmission Electron ◽  
Second Order Phase Transition

ABSTRACTIn this paper, we present the first quantitative determination of the divergence law of the correlation length ξ, when approaching the second order phase transition DO3→B2, by studying the behaviour of the APBs by transmission electron microscopy.

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