Nucleation and Annihilation of Discommensurations in the First-Order Commensurate-Incommensurate Phase Transition in K2ZnCl4

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.

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Elastic Properties and Energy Loss Related to the Disorder–Order Ferroelectric Transitions in Multiferroic Metal–Organic Frameworks [NH4][Mg(HCOO)3] and [(CH3)2NH2][Mg(HCOO)3]

Materials ◽

10.3390/ma14113125 ◽

2021 ◽

Vol 14 (11) ◽

pp. 3125

Author(s):

Zhiying Zhang ◽

Hongliang Yu ◽

Xin Shen ◽

Lei Sun ◽

Shumin Yue ◽

...

Keyword(s):

Phase Transition ◽

Energy Loss ◽

Elastic Properties ◽

Ferroelectric Phase ◽

Loss Modulus ◽

Structural Phase ◽

Metal Organic Frameworks ◽

First Order ◽

Metal Organic ◽

Elastic Anomalies

Elastic properties are important mechanical properties which are dependent on the structure, and the coupling of ferroelasticity with ferroelectricity and ferromagnetism is vital for the development of multiferroic metal–organic frameworks (MOFs). The elastic properties and energy loss related to the disorder–order ferroelectric transition in [NH4][Mg(HCOO)3] and [(CH3)2NH2][Mg(HCOO)3] were investigated using differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA). The DSC curves of [NH4][Mg(HCOO)3] and [(CH3)2NH2][Mg(HCOO)3] exhibited anomalies near 256 K and 264 K, respectively. The DMA results illustrated the minimum in the storage modulus and normalized storage modulus, and the maximum in the loss modulus, normalized loss modulus and loss factor near the ferroelectric transition temperatures of 256 K and 264 K, respectively. Much narrower peaks of loss modulus, normalized loss modulus and loss factor were observed in [(CH3)2NH2][Mg(HCOO)3] with the peak temperature independent of frequency, and the peak height was smaller at a higher frequency, indicating the features of first-order transition. Elastic anomalies and energy loss in [NH4][Mg(HCOO)3] near 256 K are due to the second-order paraelectric to ferroelectric phase transition triggered by the disorder–order transition of the ammonium cations and their displacement within the framework channels, accompanied by the structural phase transition from the non-polar hexagonal P6322 to polar hexagonal P63. Elastic anomalies and energy loss in [(CH3)2NH2][Mg(HCOO)3] near 264 K are due to the first-order paraelectric to ferroelectric phase transitions triggered by the disorder–order transitions of alkylammonium cations located in the framework cavities, accompanied by the structural phase transition from rhombohedral R3¯c to monoclinic Cc. The elastic anomalies in [NH4][Mg(HCOO)3] and [(CH3)2NH2][Mg(HCOO)3] showed strong coupling of ferroelasticity with ferroelectricity.

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Gravitational wave signals of dark matter freeze-out

Journal of High Energy Physics ◽

10.1007/jhep02(2021)022 ◽

2021 ◽

Vol 2021 (2) ◽

Cited By ~ 3

Author(s):

Danny Marfatia ◽

Po-Yan Tseng

Keyword(s):

Phase Transition ◽

Dark Matter ◽

Gravitational Waves ◽

Order Phase Transition ◽

First Order ◽

Stochastic Background ◽

First Order Phase Transition ◽

Relic Abundance ◽

First Order Phase ◽

Freeze Out

Abstract We study the stochastic background of gravitational waves which accompany the sudden freeze-out of dark matter triggered by a cosmological first order phase transition that endows dark matter with mass. We consider models that produce the measured dark matter relic abundance via (1) bubble filtering, and (2) inflation and reheating, and show that gravitational waves from these mechanisms are detectable at future interferometers.

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Dark Matter production from relativistic bubble walls

Journal of High Energy Physics ◽

10.1007/jhep03(2021)288 ◽

2021 ◽

Vol 2021 (3) ◽

Author(s):

Aleksandr Azatov ◽

Miguel Vanvlasselaer ◽

Wen Yin

Keyword(s):

Phase Transition ◽

Dark Matter ◽

Electroweak Phase Transition ◽

First Order ◽

Matter Production ◽

First Order Phase Transition ◽

Relic Abundance ◽

Higgs Portal ◽

First Order Phase ◽

Gravitational Background

Abstract In this paper we present a novel mechanism for producing the observed Dark Matter (DM) relic abundance during the First Order Phase Transition (FOPT) in the early universe. We show that the bubble expansion with ultra-relativistic velocities can lead to the abundance of DM particles with masses much larger than the scale of the transition. We study this non-thermal production mechanism in the context of a generic phase transition and the electroweak phase transition. The application of the mechanism to the Higgs portal DM as well as the signal in the Stochastic Gravitational Background are discussed.

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The Madelung constant and bonding angle as “sensors” of the high-pressure induced amorphization and first-order isostructural phase transition in Mg(OH)2 and Ca(OH)2

Journal of Solid State Chemistry ◽

10.1016/j.jssc.2021.121993 ◽

2021 ◽

Vol 296 ◽

pp. 121993

Author(s):

Valeri S. Harutyunyan

Keyword(s):

Phase Transition ◽

High Pressure ◽

Madelung Constant ◽

First Order ◽

Isostructural Phase Transition

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Electroweak-like baryogenesis with new chiral matter

Journal of High Energy Physics ◽

10.1007/jhep07(2021)224 ◽

2021 ◽

Vol 2021 (7) ◽

Author(s):

Kohei Fujikura ◽

Keisuke Harigaya ◽

Yuichiro Nakai ◽

Ruoquan Wang

Keyword(s):

Phase Transition ◽

Gauge Symmetry ◽

Cp Violation ◽

Standard Model ◽

Dipole Moments ◽

Dark Matter Candidate ◽

Lepton Asymmetry ◽

First Order ◽

The Standard Model ◽

Concrete Realization

Abstract We propose a framework where a phase transition associated with a gauge symmetry breaking that occurs (not far) above the electroweak scale sets a stage for baryogenesis similar to the electroweak baryogenesis in the Standard Model. A concrete realization utilizes the breaking of SU(2)R× U(1)X→ U(1)Y. New chiral fermions charged under the extended gauge symmetry have nonzero lepton numbers, which makes the B − L symmetry anomalous. The new lepton sector contains a large flavor-dependent CP violation, similar to the Cabibbo-Kobayashi-Maskawa phase, without inducing sizable electric dipole moments of the Standard Model particles. A bubble wall dynamics associated with the first-order phase transition and SU(2)R sphaleron processes generate a lepton asymmetry, which is transferred into a baryon asymmetry via the ordinary electroweak sphaleron process. Unlike the Standard Model electroweak baryogenesis, the new phase transition can be of the strong first order and the new CP violation is not significantly suppressed by Yukawa couplings, so that the observed asymmetry can be produced. The model can be probed by collider searches for new particles and the observation of gravitational waves. One of the new leptons becomes a dark matter candidate. The model can be also embedded into a left-right symmetric theory to solve the strong CP problem.

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Nucleation is more than critical: A case study of the electroweak phase transition in the NMSSM

Journal of High Energy Physics ◽

10.1007/jhep03(2021)055 ◽

2021 ◽

Vol 2021 (3) ◽

Author(s):

Sebastian Baum ◽

Marcela Carena ◽

Nausheen R. Shah ◽

Carlos E. M. Wagner ◽

Yikun Wang

Keyword(s):

Phase Transition ◽

Parameter Space ◽

Local Minima ◽

Critical Temperatures ◽

Electroweak Phase Transition ◽

First Order ◽

Vacuum Structure ◽

The Universe ◽

Scalar Sector

Abstract Electroweak baryogenesis is an attractive mechanism to generate the baryon asymmetry of the Universe via a strong first order electroweak phase transition. We compare the phase transition patterns suggested by the vacuum structure at the critical temperatures, at which local minima are degenerate, with those obtained from computing the probability for nucleation via tunneling through the barrier separating local minima. Heuristically, nucleation becomes difficult if the barrier between the local minima is too high, or if the distance (in field space) between the minima is too large. As an example of a model exhibiting such behavior, we study the Next-to-Minimal Supersymmetric Standard Model, whose scalar sector contains two SU(2) doublets and one gauge singlet. We find that the calculation of the nucleation probabilities prefers different regions of parameter space for a strong first order electroweak phase transition than the calculation based solely on the critical temperatures. Our results demonstrate that analyzing only the vacuum structure via the critical temperatures can provide a misleading picture of the phase transition patterns, and, in turn, of the parameter space suitable for electroweak baryogenesis.

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