Phase coexistence in highly deuterated ferroelectric triglycine selenate: Landau description

The phase transition in a 90% deuterated sample of TGSe has been investigated by calorimetric and dielectric measurements. As a consequence of the presence of an internal crack in the sample, the transition takes place in two stages separated by an interval where the paraelectric and the ferroelectric phases coexist without latent heat contribution. From the latent heat, the specific heat excess and the Curie law for the dielectric constant, it is shown that the transition follows a 2-4-6 Landau potential, whose coefficients are determined. This potential describes completely all the data, including those corresponding to the coexistence interval.Dirección General de Investigación Científica y Técnica (DGICYT) FIS2005-0244

Scale-invariant avalanche dynamics in the temperature-driven martensitic transition of a Cu-Al-Be single crystal

We have combined high sensitivity, extra-low differential temperature scanning rate calorimetry, and acoustic emission (AE) measurements to study avalanches during the cubic ↔ 18R martensitic transition of a Cu-Al-Be single crystalline shape memory alloy. Both AE and calorimetry corroborate a good power-law behavior for cooling with an exponent ε 1.6. For heating, a slope is observed in the maximum likelihood curves, which confirms that our data are affected by an exponential cutoff. An effective energy exponent, ε ∼ 1.85, and a cutoff, λ −1 = 0.115(38)E-3 aJ, were determined by fits of power-laws with exponential damping. The long tail observed in the low-temperature region by calorimetric measurements suggests the existence of significant elastic effects that constrain the progress of the transformation at low temperatures. While thermodynamic features such as transformation enthalpy and entropy are those expected for Cu-based shape-memory alloys undergoing a cubic ↔ 18R transition, the critical behavior deviates from the corresponding behavior expected from this symmetry change. These deviations are a consequence of the elastic hardening induced by the interplay of the transformation with dislocation jamming, which has the effect of effectively reducing the number of pathways connecting the parent and martensitic phaseMinisterio de Ciencia,Innovación y Universidades (MAT2016-75823-R)Engineering and Physical Sciences Research Council (EP/P024904/1

Deuteration effect on tricritical phase transition of triglycine selenate: Calorimetric and dielectric measurements analyzed in the framework of Landau theory

The ferroelectric phase transition of three single crystals of TGSe1−x DTGSex has been described by using specific heat, latent heat, and dielectric permittivity measurements. Pure, half-deuterated, and highly-deuterated TGSe single crystals were analyzed. Transition temperature and latent heat increase with increasing deuteration. Irrespective of the degree of deuteration, a 2-4-6 Landau model is suitable to describe the phase transition. The fourth-rank prefactor in Landau potential is found to be very sensitive to deuteration while the second-rank and the sixth-rank prefactors smoothly change with composition. The pyroelectric figure of merit for these materials has also been derived from the theoretical model.Gobierno de España-FIS2006-0404

Dynamic heat flux experiments in Cu67.64Zn 16.71Al15.65: Separating the time scales of fast and ultra-slow kinetic processes in martensitic transformations

Crackling noise and avalanches during the martensite phase transformation of Cu67.64Zn16.71Al15.65 were investigated. Heat flux measurements with extremely slow heating rates of 0.005 Kh -1 allowed sufficient separation between the continuous background and the avalanche jerks. The jerk enthalpy is below 3 of the total transformation enthalpy. The crackling noise follows power law behavior with an energy exponent near ε=1.8. The jerks are almost uncorrelated with approximately a Poisson distribution of the waiting times between jerks. Quantitative analysis showed a scaling behavior with p(wt) ∼ wt (γ-1)exp(-wt/τ)n with γ=0.7 and n ≈ 1.Ministerio de Educación y Ciencia FIS2006-0404

Memory effect in triglycine sulfate induced by a transverse electric field: specific heat measurement

The influence of a transverse electric field on the specific heat of triglycine sulfate (TGS) has been studied. The specific heat of TGS has been measured on heating the sample from the ferroelectric to the paraelectric phase after prolonged application of transverse electric field (i.e. perpendicular to the ferroelectric axis). It is shown that the specific heat of TGS can 'remember' the temperature T(s) at which the transverse field was previously applied.España, Gobierno de España IS-2006-0404

Design and baseline characteristics of the finerenone in reducing cardiovascular mortality and morbidity in diabetic kidney disease trial

Background: Among people with diabetes, those with kidney disease have exceptionally high rates of cardiovascular (CV) morbidity and mortality and progression of their underlying kidney disease. Finerenone is a novel, nonsteroidal, selective mineralocorticoid receptor antagonist that has shown to reduce albuminuria in type 2 diabetes (T2D) patients with chronic kidney disease (CKD) while revealing only a low risk of hyperkalemia. However, the effect of finerenone on CV and renal outcomes has not yet been investigated in long-term trials. Patients and Methods: The Finerenone in Reducing CV Mortality and Morbidity in Diabetic Kidney Disease (FIGARO-DKD) trial aims to assess the efficacy and safety of finerenone compared to placebo at reducing clinically important CV and renal outcomes in T2D patients with CKD. FIGARO-DKD is a randomized, double-blind, placebo-controlled, parallel-group, event-driven trial running in 47 countries with an expected duration of approximately 6 years. FIGARO-DKD randomized 7,437 patients with an estimated glomerular filtration rate >= 25 mL/min/1.73 m(2) and albuminuria (urinary albumin-to-creatinine ratio >= 30 to <= 5,000 mg/g). The study has at least 90% power to detect a 20% reduction in the risk of the primary outcome (overall two-sided significance level alpha = 0.05), the composite of time to first occurrence of CV death, nonfatal myocardial infarction, nonfatal stroke, or hospitalization for heart failure. Conclusions: FIGARO-DKD will determine whether an optimally treated cohort of T2D patients with CKD at high risk of CV and renal events will experience cardiorenal benefits with the addition of finerenone to their treatment regimen. Trial Registration: EudraCT number: 2015-000950-39; ClinicalTrials.gov identifier: NCT02545049

Square modulated differential thermal analysis

KMnF3 and DKDP crystals have been studied around their phase transitions using a conduction calorimetry technique where a long periodical square thermal pulse (0.05 K in amplitude) is superposed to a heating or cooling ramp as low as 0.06 K h−1 . Specific heat data obtained in the dissipation and relaxation semiperiods of the square pulse become different inside the phase transition interval. The electromotive force developed by the heat fluxmeters at the end of the relaxation semiperiod (underlying signal) is compared with the DTA trace obtained in a second run with the same temperature ramp but without the modulated perturbation. The comparison between the DTA trace and specific heat data obtained in the first run allows us to determine the value of the latent heat and to obtain information about the kinetic of the phase transition

Study of Stability and Thermo-magnetic Response of MnCoFeGeSi Mechanically Alloyed Systems

Amorphous precursors with the composition MnCo0.8Fe0.2Ge1-xSix, where x = 0.2, 0.3, 0.4, and 0.6, were obtained through mechanical alloying. These precursors were subsequently subjected to different thermal treatments, resulting in the formation of the austenite Ni2In-type structure for x ≤ 0.4. For the highest Si content (x = 0.6), this phase coexists with the martensite TiNiSi-type structure without apparent partitioning of the elements at the nanoscale. These structures remain stable up to their melting points, but subsequent melting processes exhibit differences compared to the initial solidification at a cooling rate of − 20 K/min. The magnetocaloric effect was investigated through thermomagnetic and heat capacity measurements and simulated using the Arrott-Noakes equation of state, revealing the presence of a distribution of Curie temperatures. Despite the absence of a martensitic transformation, these alloys exhibit a significant magnetocaloric response, which increases as the precursor system's amorphization (i.e., homogenization) is enhanced

Thermo-magnetic characterization of phase transitions in a Ni-Mn-In metamagnetic shape memory alloy

The partially overlapped ferroelastic/martensitic and para-ferromagnetic phase transitions of a Ni50.53Mn33.65In15.82 metamagnetic shape memory alloy have been studied from calorimetric, magnetic and acoustic emission measurement. We have taken advantage of the existence of thermal hysteresis of the first order ferroelastic/martensitic phase transition (~2.5 K) to discriminate the latent heat contribution Delta=H 7.21(15)kJ/kg and the specific heat contribution Delta H_c =216(1)J/kg to the total excess enthalpy of the phase transition. The specific heat was found to follow a step-like behavior at this phase transition. The intermittent dynamics of the ferroelastic/martensitic transition has been characterized as a series of avalanches detected both from acoustic emission and calorimetric measurements. The energy distribution of these avalanche events was found to follow a power law with a characteristic energy exponent 2 which is in agreement with the expected value for a system undergoing a symmetry change from cubic to monoclinic. Finally, the critical behavior of the para-ferromagnetic austenite phase transition that takes place at ~311 K has been studied from the behavior of the specific heat. A critical exponent 0.09 has been obtained, which has been shown to be in agreement with previous values reported for Ni-Mn-Ga alloys but different from the critical divergence reported for pure Ni.European FEDER US-1260179European FEDER P18-RT-746CICYT MAT2016-75823-

Phase transition and polar cluster behavior above Curie temperature in ferroelectric BaTi0.8Zr0.2O3

We study the phase transition behavior of the ferroelectric BaTi0.8Zr0.2O3 in the paraelectric region. The temperature dependencies of thermal, polar, elastic and dielectric properties indicate the presence of local structures above the paraelectric-ferroelectric transition temperature Tc = 292 K. The non-zero remnant polarization is measured up to a characteristic temperature T* ~350 K, which coincides with the temperature where the dielectric constant deviates from Curie-Weiss law. Resonant Piezoelectric Spectroscopy shows that DC field-cooling above Tc using fields smaller than the coercive field leads to an elastic response and remnant piezoelectricity below T*, which likely corresponds to the coherence temperature associated with polar nanostructures in ferroelectrics. The observed remnant effect is attributed to the reorientation of polar nanostructures above Tc.VI Plan Propio de la Universidad de SevillaVII Plan Propio de Investigación de la Universidad de Sevill