scholarly journals Synthesis, microstructure and effect of high pressures on transport properties of GdBaCo2O5,5

2021 ◽  
Vol 12 (2-2021) ◽  
pp. 247-252
Author(s):  
T. N. Tarasenko ◽  
◽  
T. S. Sivachenko ◽  
I. Yu. Reshidova ◽  
V. V. Burkhovetskii ◽  
...  
Keyword(s):  
Phase Transition ◽  
Transition Temperature ◽  
Hysteresis Loop ◽  
High Pressures ◽  
Strong Dependence ◽  
Thermal Relaxation ◽  
Temperature Hysteresis ◽  
First Order ◽  
M Phase ◽  
Layered Cobaltite

In polycrystalline samples of double layered cobaltite GdBaCo2O5.5 the structure and resistivity at the first order “insulator-metal” (I-M) phase transition were studied at normal and high pressures. The strong dependence of the shape of the temperature hysteresis loop on the rate of temperature change indicates an infra-slow thermal relaxation of conductivity. Baric studies have shown an increase in the transition temperature ТIM at increasing pressure P with baric coefficient dТIM/dP ≈ 10 K/GPa. The spin blockade model is used to explain the observed effects.

scholarly journals Спектры пропускания монокристаллов гибридных перовскитов MAPbI-=SUB=-3-=/SUB=- вблизи края фундаментального поглощения

2022 ◽  
Vol 130 (1) ◽  
pp. 116
Author(s):  
В.Е. Аникеева ◽  
К.Н. Болдырев ◽  
О.И. Семенова ◽  
М.Н. Попова
Keyword(s):  
Phase Transition ◽  
Absorption Edge ◽  
Structural Phase ◽  
Fundamental Absorption Edge ◽  
Orthorhombic Phase ◽  
Temperature Hysteresis ◽  
First Order ◽  
Hybrid Perovskite ◽  
First Order Phase Transition ◽  
First Order Phase

The paper presents the transmission spectra of hybrid perovskite MAPbI3 single crystals near the fundamental absorption edge in a wide temperature range. The absorption coefficient α of the single crystal samples is estimated at a temperature T = 150 K for the light with a photon energy E = 1.6 eV and at T = 40 K for E = 1.8 eV. The obtained values turned out to be several orders of magnitude smaller than the values of α for thin-film samples known from the literature. A sharp shift of the fundamental absorption edge by ~ 100 meV was observed at a temperature T1 = 160 K of the structural phase transition from the tetragonal to the orthorhombic phase. The temperature hysteresis of the shift of the fundamental absorption edge near T1 was recorded, which is characteristic of a first-order phase transition.

Lattice expansion of α-bis-(N-methylsalicylaldiminato)-copper(II)

1981 ◽  
Vol 154 (3-4) ◽  
Author(s):  
W. Adlhart ◽  
V. K. Syal
Keyword(s):  
Phase Transition ◽  
Transition Temperature ◽  
Monoclinic Phase ◽  
Lattice Expansion ◽  
X Rays ◽  
First Order

Abstract.The lattice expansion of α-bis-(N-methylsalicylaldiminato)copper(II) powder was measured by X-rays with the focussing Guinier method from 90 – 320 K. The orthorhombic-monoclinic phase transition is of first order and its transition temperature is 237 ± 2 K.

CRITICAL BEHAVIOR OF THE SPECIFIC HEAT IN THE VICINITY OF THE TRANSITION TEMPERATURE FOR S-TRIAZINE

2009 ◽  
Vol 23 (09) ◽  
pp. 2253-2259 ◽  
Author(s):  
M. KURT ◽  
H. YURTSEVEN
Keyword(s):  
Experimental Data ◽  
Phase Transition ◽  
Transition Temperature ◽  
Critical Exponent ◽  
Specific Heat ◽  
Power Law ◽  
Order Phase Transition ◽  
Critical Behavior ◽  
First Order ◽  
Second Order Phase Transition

The critical behavior of the specific heat is studied in s-triazine ( C 3 N 3 H 3). Using the experimental data for the CP, the temperature dependence of the specific heat is analyzed according to a power-law formula and the values of the critical exponent for CP are extracted in the vicinity of the transition temperature (TC=198.07 K ). It is indicated that s-triazine undergoes a weakly first order (quasi-continuous) or second order phase transition.

FIRST ORDER PHASE TRANSITIONS, WHEN AND FROM WHERE DO THEY EMERGE? —THE CASE OF GELS

1995 ◽  
Vol 09 (07) ◽  
pp. 737-749 ◽  
Author(s):  
KEN SEKIMOTO
Keyword(s):  
Phase Transition ◽  
Transition Temperature ◽  
Transition Point ◽  
The Other ◽  
Basic Fact ◽  
Theoretical Understanding ◽  
First Order ◽  
First Order Phase Transition ◽  
The One ◽  
First Order Phase

We briefly review the recent theoretical understanding of the first order phase transition undergone by gels with an emphasis on physical concepts, deliberately excluding details of modeling and analytic methods. The density of a gel changes discontinuously at the transition point. A variety of features of the transition result from the basic fact that the inhomogeneity of the density of the gel inevitably causes shear deformation. This deformation, on the one hand, reflects the geometry of the sample and, on the other hand, may alter the transition temperature.

Size-dependent ultrahigh electrocaloric effect near pseudo-first-order phase transition temperature in barium titanate nanoparticles

RSC Advances ◽  
2015 ◽  
Vol 5 (47) ◽  
pp. 37476-37484 ◽  
Author(s):  
Hong-Hui Wu ◽  
Jiaming Zhu ◽  
Tong-Yi Zhang
Keyword(s):  
Phase Transition ◽  
Transition Temperature ◽  
Order Phase Transition ◽  
Electrocaloric Effect ◽  
First Order ◽  
Size Dependent ◽  
First Order Phase Transition ◽  
Pseudo First Order ◽  
Barium Titanate Nanoparticles ◽  
First Order Phase

The proposed Pseudo-First-Order Phase Transition in a ferroelectric nanoparticle occurs at a temperature lower than its paraelectric/ferroelectric transition Curie temperature and is associated with an ultrahigh electrocaloric effect.

scholarly journals Thermoresponsive Behavior of Magnetic Nanoparticle Complexed pNIPAm-co-AAc Microgels

2018 ◽  
Vol 8 (10) ◽  
pp. 1984 ◽  
Author(s):  
Su-Kyoung Lee ◽  
Yongdoo Park ◽  
Jongseong Kim
Keyword(s):  
Phase Transition ◽  
Transition Temperature ◽  
Magnetic Nanoparticles ◽  
Phase Transition Temperature ◽  
Functional Materials ◽  
Inorganic Nanoparticles ◽  
Temperature Hysteresis ◽  
Volume Phase Transition ◽  
Volume Phase ◽  
Volume Phase Transition Temperature

Characterization of responsive hydrogels and their enhancement with novel moieties have improved our understanding of functional materials. Hydrogels coupled with inorganic nanoparticles have been sought for novel types of responsive materials, but the efficient routes for the formation and the responsivity of complexed materials remain for further investigation. Here, we report that responsive poly(N-isopropylacrylamide-co-acrylic acid) (pNIPAm-co-AAc) hydrogel microparticles (microgels) are tunable by varying composition of co-monomer and crosslinker as well as by their complexation with magnetic nanoparticles in aqueous dispersions. Our results show that the hydrodynamic diameter and thermoresponsivity of microgels are closely related with the composition of anionic co-monomer, AAc and crosslinker, N,N′-Methylenebisacrylamide (BIS). As a composition of hydrogels, the higher AAc increases the swelling size of the microgels and the volume phase transition temperature (VPTT), but the higher BIS decreases the size with no apparent effect on the VPTT. When the anionic microgels are complexed with amine-modified magnetic nanoparticles (aMNP) via electrostatic interaction, the microgels decrease in diameter at 25 °C and shift the volume phase transition temperature (VPTT) to a higher temperature. Hysteresis on the thermoresponsive behavior of microgels is also measured to validate the utility of aMNP-microgel complexation. These results suggest a simple, yet valuable route for development of advanced responsive microgels, which hints at the formation of soft nanomaterials enhanced by inorganic nanoparticles.

Phase Transitions by Dilatometry, Part I: Synthesis, Characterisation and Isotropic to Smectic-A and Smectic-A to Smectic-B Transitions in Two Liquid Crystalline Higher Homologues of N-(p-n-nonyloxybenzylidene) p-n-alkylanilines

2004 ◽  
Vol 59 (9) ◽  
pp. 537-542 ◽  
Author(s):  
C. Rama Chandra Prabhu ◽  
S. Lakshminarayana ◽  
V. G. K. M. Pisipatia
Keyword(s):  
Phase Transition ◽  
Differential Scanning Calorimetry ◽  
Transition Temperature ◽  
Liquid Crystalline ◽  
Scanning Calorimetry ◽  
First Order ◽  
Smectic A ◽  
M 12 ◽  
Phase Variants ◽  
Enthalpy Data

Two higher homologues of N(p-n-nonyloxybenzylidene)p-n-alkylanilines, viz. the 9O.m series with m = 12 and 16, are synthesised and characterised by thermal microscopy, differential scanning calorimetry and density studies. The compounds exhibit the phase variants smectic-A, smectic-B and smectic-G. Density studies reveal the first order nature of the isotropic to smectic-A and smectic-A to smectic-B transitions. An estimate of the pressure dependence of the phase transition temperature, using volume and enthalpy data, is presented. A comparison of these results with those reported on nO.m and other liquid crystalline compounds is presented.

scholarly journals Protonic Conduction of Partially-Substituted CsH2PO4 and the Applicability in Electrochemical Devices

Membranes ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 49 ◽  
Author(s):  
Navarrete ◽  
Andrio ◽  
Escolástico ◽  
Moya ◽  
Compañ ◽  
...  
Keyword(s):  
Phase Transition ◽  
Transition Temperature ◽  
Low Temperatures ◽  
High Pressures ◽  
Proton Conductor ◽  
Partial Substitution ◽  
Cubic Phase ◽  
Protonic Conduction ◽  
Stable Production ◽  
Electrochemical Devices

CsH2PO4 is a proton conductor pertaining to the acid salts group and shows a phase transition from monoclinic to cubic phase at 232 ± 2 °C under high-steam atmospheres (>30%). This cubic phase gives rise to the so-called superprotonic conductivity. In this work, the influence of the partial substitution of Cs by Ba and Rb, as well as the partial substitution of P by W, Mo, and S in CsH2PO4 on the phase transition temperature and electrochemical properties is studied. Among the tested materials, the partial substitution by Rb led to the highest conductivity at high temperature. Furthermore, Ba and S-substituted salts exhibited the highest conductivity at low temperatures. CsH2PO4 was used as electrolyte in a fully-assembled fuel cell demonstrating the applicability of the material at high pressures and the possibility to use other materials (Cu and ZnO) instead of Pt as electrode electrocatalyst. Finally, an electrolyzer cell composed of CsH2PO4 as electrolyte, Cu and ZnO as cathode and Pt and Ag as anode was evaluated, obtaining a stable production of H2 at 250 °C.

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