Heat capacity near first order phase transitions and the magnetocaloric effect: An analysis of the errors, and a case study of Gd5(Si2Ge2) and Dy

1999 ◽  
Vol 86 (11) ◽  
pp. 6315-6321 ◽  
Author(s):  
V. K. Pecharsky ◽  
K. A. Gschneidner
Keyword(s):  
Heat Capacity ◽  
Phase Transitions ◽  
Magnetocaloric Effect ◽  
First Order ◽  
First Order Phase

scholarly journals Effect of Quenching and Normalizing on the Microstructure and Magnetocaloric Effect of a Cu–11Al–9Zn Alloy with 6.5 wt % Ni–2.5 wt % Fe

2019 ◽  
Vol 5 (3) ◽  
pp. 48 ◽  
Author(s):  
E. J. Gutiérrez Castañeda ◽  
R. E. Barreras Castro ◽  
A. Contreras Briseño ◽  
B. Fernández Arguijo ◽  
A. A. Torres Castillo ◽  
...  
Keyword(s):  
Phase Transitions ◽  
Magnetocaloric Effect ◽  
Electronic Configuration ◽  
Thermal Treatments ◽  
Magnetic Entropy ◽  
Transition Elements ◽  
First Order ◽  
Lanthanide Elements ◽  
Cu Alloys ◽  
First Order Phase

First-order phase transitions (FOPT) and second-order phase transitions (SOPT) are commonly observed in Cu alloys containing lanthanide elements, due to their electronic configuration, and have an important effect on the optimization of their magnetocaloric effect (MCE). Alloys containing rare earths have the best magnetocaloric response; however, these elements are very expensive, due to their obtaining and processing methods. The present work reports the effect of using 3d transition elements and thermal treatments on the microstructure and MCE of Cu–11Al–9Zn alloys with 6.5 wt % Ni and 2.5 wt % Fe. It was found that thermal treatments of quenching and normalizing, as well as the use of Ni and Fe, have an important influence on both the resulting phases and MCE of the investigated alloy. MCE was calculated indirectly from the change in the magnetic entropy (–ΔSm) under isothermal conditions, using Maxwell´s relation; it was found that samples subjected to normalizing presented a higher magnetocaloric effect than samples with quenching, which was related to the greater disorder in the alloy, due to the coexistence of β1 + β phases.

Reversible magnetocaloric effect in materials with first order phase transitions in cyclic magnetic fields: Fe48Rh52 and Sm0.6Sr0.4MnO3

2016 ◽  
Vol 109 (20) ◽  
pp. 202407 ◽  
Author(s):  
A. M. Aliev ◽  
A. B. Batdalov ◽  
L. N. Khanov ◽  
A. P. Kamantsev ◽  
V. V. Koledov ◽  
...  
Keyword(s):  
Phase Transitions ◽  
Magnetic Fields ◽  
Magnetocaloric Effect ◽  
First Order ◽  
First Order Phase

scholarly journals Electric properties of olive oil under pressure

2021 ◽  
Author(s):  
L. T. Pawlicki ◽  
R. M. Siegoczyński ◽  
S. Ptasznik ◽  
K. Marszałek
Keyword(s):  
Molecular Structure ◽  
Phase Transition ◽  
Phase Diagram ◽  
Phase Transitions ◽  
Olive Oil ◽  
Material Parameters ◽  
First Order ◽  
Long Time ◽  
Capacitive Reactance ◽  
First Order Phase

AbstractThe main purpose of the experiment was a thermodynamic research with use of the electric methods chosen. The substance examined was olive oil. The paper presents the resistance, capacitive reactance, relative permittivity and resistivity of olive. Compression was applied with two mean velocities up to 450 MPa. The results were shown as functions of pressure and time and depicted on the impedance phase diagram. The three first order phase transitions have been detected. All the changes in material parameters were observed during phase transitions. The material parameters measured turned out to be the much more sensitive long-time phase transition factors than temperature. The values of material parameters and their dependence on pressure and time were compared with the molecular structure, arrangement of molecules and interactions between them. Knowledge about olive oil parameters change with pressure and its phase transitions is very important for olive oil production and conservation.

scholarly journals Fate of false vacua in holographic first-order phase transitions

2020 ◽  
Vol 2020 (12) ◽  
Author(s):  
Francesco Bigazzi ◽  
Alessio Caddeo ◽  
Aldo L. Cotrone ◽  
Angel Paredes
Keyword(s):  
Phase Transitions ◽  
Chiral Symmetry ◽  
Metastable Phase ◽  
Chiral Symmetry Breaking ◽  
Model Parameters ◽  
Temperature Phase ◽  
Thin Wall ◽  
Critical Temperatures ◽  
First Order ◽  
First Order Phase

Abstract Using the holographic correspondence as a tool, we study the dynamics of first-order phase transitions in strongly coupled gauge theories at finite temperature. Considering an evolution from the large to the small temperature phase, we compute the nucleation rate of bubbles of true vacuum in the metastable phase. For this purpose, we find the relevant configurations (bounces) interpolating between the vacua and we compute the related effective actions. We start by revisiting the compact Randall-Sundrum model at high temperature. Using holographic renormalization, we compute the derivative term in the effective bounce action, that was missing in the literature. Then, we address the full problem within the top-down Witten-Sakai-Sugimoto model. It displays both a confinement/deconfinement and a chiral symmetry breaking/restoration phase transition which, depending on the model parameters, can happen at different critical temperatures. For the confinement/deconfinement case we perform the numerical analysis of an effective description of the transition and also provide analytic expressions using thick and thin wall approximations. For the chiral symmetry transition, we implement a variational approach that allows us to address the challenging non-linear problem stemming from the Dirac-Born-Infeld action.

scholarly journals Charge density waves and their transitions in anisotropic quantum Hall systems

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Yuchi He ◽  
Kang Yang ◽  
Mark Oliver Goerbig ◽  
Roger S. K. Mong
Keyword(s):  
Phase Transitions ◽  
Charge Density ◽  
Density Wave ◽  
Quantum Hall ◽  
Charge Density Waves ◽  
Stripe Phase ◽  
Electron Bubble ◽  
First Order ◽  
Bubble Phase ◽  
First Order Phase

AbstractIn recent experiments, external anisotropy has been a useful tool to tune different phases and study their competitions. In this paper, we look at the quantum Hall charge density wave states in the N = 2 Landau level. Without anisotropy, there are two first-order phase transitions between the Wigner crystal, the 2-electron bubble phase, and the stripe phase. By adding mass anisotropy, our analytical and numerical studies show that the 2-electron bubble phase disappears and the stripe phase significantly enlarges its domain in the phase diagram. Meanwhile, a regime of stripe crystals that may be observed experimentally is unveiled after the bubble phase gets out. Upon increase of the anisotropy, the energy of the phases at the transitions becomes progressively smooth as a function of the filling. We conclude that all first-order phase transitions are replaced by continuous phase transitions, providing a possible realisation of continuous quantum crystalline phase transitions.

scholarly journals Theoretical uncertainties for cosmological first-order phase transitions

2021 ◽  
Vol 2021 (4) ◽  
Author(s):  
Djuna Croon ◽  
Oliver Gould ◽  
Philipp Schicho ◽  
Tuomas V. I. Tenkanen ◽  
Graham White
Keyword(s):  
Phase Transitions ◽  
Standard Model ◽  
Scale Dependence ◽  
Effective Field ◽  
Bubble Nucleation ◽  
Perturbative Approach ◽  
First Order ◽  
The Standard Model ◽  
First Order Phase ◽  
Renormalisation Scale

Abstract We critically examine the magnitude of theoretical uncertainties in perturbative calculations of fist-order phase transitions, using the Standard Model effective field theory as our guide. In the usual daisy-resummed approach, we find large uncertainties due to renormalisation scale dependence, which amount to two to three orders-of-magnitude uncertainty in the peak gravitational wave amplitude, relevant to experiments such as LISA. Alternatively, utilising dimensional reduction in a more sophisticated perturbative approach drastically reduces this scale dependence, pushing it to higher orders. Further, this approach resolves other thorny problems with daisy resummation: it is gauge invariant which is explicitly demonstrated for the Standard Model, and avoids an uncontrolled derivative expansion in the bubble nucleation rate.

scholarly journals Bubble wall velocity at strong coupling

2021 ◽  
Vol 2021 (8) ◽  
Author(s):  
Francesco Bigazzi ◽  
Alessio Caddeo ◽  
Tommaso Canneti ◽  
Aldo L. Cotrone
Keyword(s):  
Phase Transitions ◽  
Steady State ◽  
Friction Force ◽  
Bubble Velocity ◽  
Strongly Coupled ◽  
First Order ◽  
Black Hole Background ◽  
Different Dimensions ◽  
Holographic Description ◽  
First Order Phase

Abstract Using the holographic correspondence as a tool, we determine the steady-state velocity of expanding vacuum bubbles nucleated within chiral finite temperature first-order phase transitions occurring in strongly coupled large N QCD-like models. We provide general formulae for the friction force exerted by the plasma on the bubbles and for the steady-state velocity. In the top-down holographic description, the phase transitions are related to changes in the embedding of $$ Dq\hbox{-} \overline{D}q $$ Dq ‐ D ¯ q flavor branes probing the black hole background sourced by a stack of N Dp-branes. We first consider the Witten-Sakai-Sugimoto $$ D4\hbox{-} D8\hbox{-} \overline{D}8 $$ D 4 ‐ D 8 ‐ D ¯ 8 setup, compute the friction force and deduce the equilibrium velocity. Then we extend our analysis to more general setups and to different dimensions. Finally, we briefly compare our results, obtained within a fully non-perturbative framework, to other estimates of the bubble velocity in the literature.

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