Protonic Conduction of Partially-Substituted CsH2PO4 and the Applicability in 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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Tailoring the phase transition temperature to achieve high-performance cubic GeTe-based thermoelectrics

Journal of Materials Chemistry A ◽

10.1039/d0ta06013e ◽

2020 ◽

Vol 8 (36) ◽

pp. 18880-18890 ◽

Cited By ~ 2

Author(s):

Ady Suwardi ◽

Jing Cao ◽

Lei Hu ◽

Fengxia Wei ◽

Jing Wu ◽

...

Keyword(s):

Phase Transition ◽

Transition Temperature ◽

Phase Transition Temperature ◽

High Performance ◽

Cubic Phase

The rhombohedral–cubic phase transition temperature of GeTe can be tailored via Sn-alloying, leading to high performance thermoelectric GeTe.

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THORIUM-DOPING INDUCED HIGH-Tc SUPERCONDUCTIVITY IN Dy1-xThxFeAsO

International Journal of Modern Physics B ◽

10.1142/s0217979212502074 ◽

2012 ◽

Vol 26 (32) ◽

pp. 1250207 ◽

Cited By ~ 3

Author(s):

YONGKANG LUO ◽

XIAO LIN ◽

YUKE LI ◽

QIAN TAO ◽

LINJUN LI ◽

...

Keyword(s):

Phase Transition ◽

Transition Temperature ◽

Solid State ◽

Low Temperature ◽

Ambient Pressure ◽

Magnetic Moments ◽

Structural Phase ◽

Parent Compound ◽

Partial Substitution ◽

High Tc

Parent compound of DyFeAsO was successfully synthesized by solid-state reaction under ambient pressure and superconductivity was induced by partial substitution of trivalent Dy 3+ ions with tetravalent Th 4+ in Dy 1-x Th x FeAsO . In the undoped parent compound, an anomaly in the resistivity appears around 140 K which corresponds to the structural phase transition and/or antiferromagnetic (AFM) order of the magnetic moments of Fe 2+ ions. At low temperature, another AFM order associated with the magnetic moments of Dy 3+ ions occurs at TN of 9.55 K. The AFM order around 140 K has significant influence on the transport properties, which can be interpreted by opening of partial gap on Fermi surface. Th doping suppresses the AFM order related to the Fe 2+ ions and the midpoint transition temperature [Formula: see text] of 49.3 K is observed for x = 0.3. Our results also indicate that the [ Ln 2 O 2]2+ layer has influence on the magnetism of [ Fe 2 As 2]2- layer.

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Piezoelectric and pyroelectric properties of Mn-doped 0.36Pb(In1/2Nb1/2)O3-0.36Pb(Mg1/3Nb2/3)O3-0.28PbTiO3 ceramics

10.21203/rs.3.rs-25347/v1 ◽

2020 ◽

Author(s):

Xiaoli Huang ◽

Yanxue Tang ◽

Feifei Wang ◽

Xiangyong Zhao ◽

Zhihua Duan ◽

...

Keyword(s):

Phase Transition ◽

Transition Temperature ◽

Phase Transition Temperature ◽

Electromechanical Coupling ◽

Electromechanical Coupling Factor ◽

Coupling Factor ◽

Pyroelectric Coefficient ◽

Cubic Phase ◽

Pyroelectric Properties ◽

Mn Doped

Abstract Piezoelectric and pyroelectric properties as well as strain behavior of 0.5 mol% Mn-doped 0.36Pb(In1/2Nb1/2)O3-0.36Pb(Mg1/3Nb2/3)O3-0.28PbTiO3 (Mn-PIMNT) ceramics were studied. High piezoelectric coefficient of d33 = 235 pC/N, planar electromechanical coupling factor of kp = 43.1% and the high-power Figure of Merit (FOM = 60160 pC/N) were achieved in Mn-PIMNT ceramics. Furthermore, the ceramics exhibited high pyroelectric coefficient of p = 4.8×10-4 Cm-2K-1, figures of merit for the current responsivity of Fi = 1.92×10-10 mV-1, the voltage responsivity of Fv = 0.028 m2C-1, and the detectivity of Fd = 2.317×10-5 Pa-1/2 at room temperature. The excellent piezoelectric and pyroelectric properties together with high ferroelectric rhombohedral to tetragonal phase transition temperature of Trt = 146 ℃ and ferroelectric tetragonal to cubic phase transition temperature of TC = 188 ℃ make the Mn-PIMNT ceramics suitable for high-temperature piezoelectric and pyroelectric devices.

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Proton conduction mechanism and phase transition of (Rb,K)3H(SeO4)2

Acta Crystallographica Section A Foundations and Advances ◽

10.1107/s2053273314086409 ◽

2014 ◽

Vol 70 (a1) ◽

pp. C1359-C1359

Author(s):

Ryoji Kiyanagi ◽

Yasumitsu Matsuo ◽

Yoshihisa Ishikawa ◽

Yukio Noda ◽

Takashi Ohhara ◽

...

Keyword(s):

Phase Transition ◽

High Temperature ◽

Transition Temperature ◽

Hydrogen Bonds ◽

Neutron Diffraction ◽

Structural Phase ◽

Proton Conduction ◽

Proton Density ◽

Conduction Path ◽

Protonic Conduction

The materials represented as M3H(XO4)2 (M = alkaline metal, X = S or Se) are known to exhibit high protonic conductivities at moderately high temperature. The high protonic conductivity emerges upon a structural phase transition and hydrogen bonds become directionally disordered. The protonic conduction is presumably realized through the disordered hydrogen bonds, but no experimental evidence has been reported. Meanwhile, although the mechanism of the protonic conduction is considered to be the same among this group of materials, the transition temperature (Tc) varies depending on the elements of M and X. For example, the material with M = Rb and X = Se undergoes the transition at 440 K while with M = K and X = Se the transition occurs at 390 K. Since the chemical characteristics of Rb and K are, as a principal, the same, some structural features may play crucial roles in triggering the phase transition. In order to clarify the mechanism of the proton conduction in the superprotonic phase and the relation between the crystal structure and Tc, structural studies on Rb3H(SeO4)2 at high temperature and solid solutions of Rb3H(SeO4)2 and K3H(SeO4)2 (Rb3-xKxH(SeO4)2, x=0,1,2,3) were conducted by means of single crystal neutron diffraction at FONDER at JRR-3M and SENJU at J-PARC/MLF. The proton density distribution map obtained from the high temperature neutron diffraction experiment clearly demonstrates 2-dimensional continuous spread of the proton distribution, which is considered to be the proton conduction path (figure). The structure analyses of Rb3-xKxH(SeO4)2 revealed that K ions tend to occupy one of two possible sites. As the concentration of K ion increases, the distortion of SeO4 appears to be enhanced. The variation of the distortion is consistent with the variation of the transition temperature, suggesting the close relationship between the distortion and the phase transition temperature.

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X-Ray Diffraction Study of the Phase Transition of the ${\rm Si}(111)(\sqrt{3} \times \sqrt{3})\mbox{-Ag}$ Surface

Surface Review and Letters ◽

10.1142/s0218625x03005050 ◽

2003 ◽

Vol 10 (02n03) ◽

pp. 519-524 ◽

Cited By ~ 11

Author(s):

Toshio Takahashi ◽

Hiroo Tajiri ◽

Kazushi Sumitani ◽

Koichi Akimoto ◽

Hiroshi Sugiyama ◽

...

Keyword(s):

Phase Transition ◽

Transition Temperature ◽

Low Temperatures ◽

Diffuse Scattering ◽

Room Temperature ◽

Bragg Reflection ◽

Grazing Incidence ◽

X Ray Diffraction ◽

X Ray ◽

Displacive Phase Transition

The structure of the [Formula: see text] surface was studied at both room temperature and a low temperature of 50 K using grazing incidence X-ray diffraction. At low temperatures diffuse scattering was observed in addition to Bragg reflection. Least squares analyses for Bragg reflections using anisotropic Debye–Waller factors show that the structure at 50 K is consistent with an inequivalent triangle (IET) model, while the structure at room temperature is explained by a honeycomb-chained triangle (HCT) model with strong anisotropic Debye–Waller factors. From the temperature dependence of diffuse scattering, the phase transition temperature Tc and critical exponent β were determined to be about 150 K and 0.27. Some Bragg intensities showed discontinuous changes in their first derivatives at Tc. The results favor a displacive phase transition rather than an order–disorder one.

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Low Temperature and High-Pressure Study of Bending L-Leucinium Hydrogen Maleate Crystals

Crystals ◽

10.3390/cryst11121575 ◽

2021 ◽

Vol 11 (12) ◽

pp. 1575

Author(s):

Kseniya D. Skakunova ◽

Denis A. Rychkov

Keyword(s):

Phase Transition ◽

High Pressure ◽

Low Temperatures ◽

High Pressures ◽

Solid Phase ◽

Extreme Conditions ◽

Pressure Impact ◽

Solid Phase Transition ◽

High Pressure Study ◽

Crystal Fracture

The polymorphism of molecular crystals is a well-known phenomenon, resulting in modifications of physicochemical properties of solid phases. Low temperatures and high pressures are widely used to find phase transitions and quench new solid forms. In this study, L-Leucinium hydrogen maleate (LLHM), the first molecular crystal that preserves its anomalous plasticity at cryogenic temperatures, is studied at extreme conditions using Raman spectroscopy and optical microscopy. LLHM was cooled down to 11 K without any phase transition, while high pressure impact leads to perceptible changes in crystal structure in the interval of 0.0–1.35 GPa using pentane-isopentane media. Surprisingly, pressure transmitting media (PTM) play a significant role in the behavior of the LLHM system at extreme conditions—we did not find any phase change up to 3.05 GPa using paraffin as PTM. A phase transition of LLHM to amorphous form or solid–solid phase transition(s) that results in crystal fracture is reported at high pressures. LLHM stability at low temperatures suggests an alluring idea to prove LLHM preserves plasticity below 77 K.

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The Development of Novel Electrolyte Membrane with High Proton Conductivity at Medium Temperatures

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.472-475.2819 ◽

2012 ◽

Vol 472-475 ◽

pp. 2819-2823

Author(s):

Xue Dan Wang ◽

Le Bin Yang ◽

Jia Bin Liu ◽

Yue Xiang Huang ◽

Hang Yan Shen ◽

...

Keyword(s):

Phase Transition ◽

Transition Temperature ◽

Proton Conductivity ◽

Chemical Stability ◽

Wide Temperature Range ◽

Proton Conductor ◽

Dramatic Improvement ◽

High Proton Conductivity ◽

Electrolyte Membrane ◽

High Proton

A novel electrolyte membrane PVDF-Al2O3-CsHSO4 usable at medium temperatures was prepared by composite of PVDF and an inorganic proton conductor Al2O3-CsHSO4. The membrane has a steep increase in proton conductivity around 90°C and retains the high conductivity, about 10-3 S•cm-1, up to 200°C. The incorporation of Al2O3-CsHSO4 with PVDF leads to a dramatic improvement of the properties of PVDF, including widen the phase transition temperature of CsHSO4, improve proton conductivity and enhance chemical stability over wide temperature range.

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Nuclear quantum effects on the liquid–liquid phase transition of a water-like monatomic liquid

Physical Chemistry Chemical Physics ◽

10.1039/c7cp08505b ◽

2018 ◽

Vol 20 (12) ◽

pp. 8210-8217 ◽

Cited By ~ 2

Author(s):

Binh Nguyen ◽

Gustavo E. Lopez ◽

Nicolas Giovambattista

Keyword(s):

Phase Transition ◽

Liquid Phase ◽

Low Temperatures ◽

High Pressures ◽

Quantum Effects ◽

Liquid Phase Transition ◽

Nuclear Quantum Effects

The liquid–liquid phase transition of a classical monatomic liquid shifts towards low-temperatures and high-pressures when nuclear quantum effects are included.

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Martensite-austenite and Ferromagnetic-paramagnetic Transformations in Ni2-xAxMn1-yByGa1-zCz (A, B=Co; C=Al) Heusler Alloys

Revista de Chimie ◽

10.37358/rc.08.12.2058 ◽

2009 ◽

Vol 59 (12) ◽

Author(s):

Mihail-Liviu Craus ◽

Viorel Dobrea ◽

Mihai Lozovan

Keyword(s):

Magnetic Field ◽

Transition Temperature ◽

Martensitic Transformation ◽

Low Temperatures ◽

Room Temperature ◽

Heusler Alloys ◽

Partial Substitution ◽

Martensitic Transition ◽

Cscl Type ◽

Curie Temperatures

Ni2MnGa Heusler alloy is known as a potential smart material. At room temperature it has a L21 type structure, undergoing a martensitic transition (TM) at low temperatures. Some authors have classified Ni-Mn-Ga Heusler alloys on the values of martensitic transformation and Curie temperatures: first group formed by alloys with TM below room temperature and TC, second group with TM around room temperature and third group with TM]TC. The partial substitution of Ni with Mn leads to an increase of the transition temperature and a decrease of the Curie temperature. The Ni2-xMn1+xGa alloys have a complex tetragonal structure at room temperature. The substitution of Ga with Al can change the crystalline and magnetic structure of Heusler alloys: Ni2MnAl is antiferromagnetic for a B2 (CsCl type, with Mn and Al randomly distributed in the center of the cube) structure and ferromagnetic for a L21 (BiF3 type with Mn and Al ordered distributed in the cube center) structure. We intend to put in evidence a dependence between the applied magnetic field on a side, and the transition temperature, on other side, for the Ni2-xAxMn1-yByGa1-zCz (A, B=Co; C=Al) Heusler alloys.

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