Accelerating solid diffusion and suppressing phase transition in LiV3O8via calcium doping at lithium sites

Nanoscale ◽  
2020 ◽  
Vol 12 (18) ◽  
pp. 10205-10215
Author(s):  
Yinsheng Xu ◽  
Xiaoxiao Wang ◽  
Zhengnan Wang ◽  
Shengping Wang ◽  
Xiaoyan Zhu ◽  
...  
Keyword(s):  
Phase Transition ◽  
Structural Change ◽  
Concentration Polarization ◽  
Β Phase ◽  
Solid Diffusion ◽  
Α Phase ◽  
Charge Process ◽  
Calcium Doping ◽  
Capacity Decay

The phase transition of LiV3O8 from α phase to β phase during discharge/charge process leads to drastic structural change and rapid capacity decay, and consequent sluggish Li+ solid diffusion results in serious concentration polarization.

Brillouin scattering near the α–β phase transitions of N2 and CO

1988 ◽  
Vol 66 (4) ◽  
pp. 541-548 ◽  
Author(s):  
V. Askarpour ◽  
H. Klefte ◽  
M. J. Clouter
Keyword(s):  
Phase Transition ◽  
Single Crystals ◽  
Elastic Constants ◽  
Brillouin Scattering ◽  
X Ray Diffraction ◽  
X Ray ◽  
Β Phase ◽  
Α Phase ◽  
Mode Softening ◽  
Cubic Structure

The technique of high resolution Brillouin spectroscopy has been used to determine the adiabatic elastic constants of single crystals of β-N2 and β-CO as a function of temperature, in an effort to study the α–β phase transition. For all elastic constants, there is an increase of approximately 1%/K on cooling and there is no evidence of further mode softening, even within 0.5 K of the phase transition. Three large single crystals of α-CO were grown. The orientations were determined, by Laue X-ray diffraction, and correlated to the orientations of the parent β-crystals. The β-phase hexagonal basal planes appear to transform to planes of the form {110} in the α-phase cubic structure.

scholarly journals Phase transition and structures of the twinned low-temperature phases of (Et4N)[ReS4]

2020 ◽  
Vol 76 (3) ◽  
pp. 231-235
Author(s):  
Eduard Bernhardt ◽  
Regine Herbst-Irmer
Keyword(s):  
Phase Transition ◽  
Low Temperature ◽  
Title Compound ◽  
Room Temperature ◽  
Monoclinic Space Group ◽  
Rapid Cooling ◽  
Space Group ◽  
Disordered Structure ◽  
Β Phase ◽  
Α Phase

The title compound, tetraethylammonium tetrathiorhenate, [(C2H5)4N][ReS4], has, at room temperature, a disordered structure in the space group P63 mc (Z = 2, α-phase). A phase transition to the monoclinic space group P21 (Z = 2, γ-phase) at 285 K leads to a pseudo-merohedral twin. The high deviation from the hexagonal metric causes split reflections. However, the different orientations could not be separated, but were integrated using a large integration box. Rapid cooling to 110–170 K produces a metastable β-phase (P63, Z = 18) in addition to the γ-phase. All crystals of the β-phase are contaminated with the γ-phase. Additionally, the crystals of the β-phase are merohedrally twinned. In contrast to the α-phase, the β- and γ-phases do not show disorder.

scholarly journals Investigation of phase transformation in Fe microalloyed Ti6Al4V alloy during continuous heating process

2020 ◽  
Vol 321 ◽  
pp. 12010
Author(s):  
Changliang Wang ◽  
Feng Li ◽  
Can Ding ◽  
Hui Chang ◽  
Lian Zhou
Keyword(s):  
Phase Transition ◽  
Phase Transformation ◽  
Expansion Method ◽  
Ti6al4v Alloy ◽  
Continuous Heating ◽  
Heating Process ◽  
Β Phase ◽  
Α Phase ◽  
Phase Transition Temperatures ◽  
Evolution Of Microstructure

The phase transformation and dilatometric curves in Fe microalloyed Ti6Al4V alloy (Ti6Al4V-Fe) during continuous heating at 1 ℃ /min heating rate had been studied by dilatometer and metallographic methods, and β phase transition temperatures of alloy were obtained. In order to validate the accuracy of these β phase transition temperature and microstructure evolution, the relative phase concentration and the evolution of microstructure which were acquired by cooling after tempering were analyzed by metallographic microscope. The results illuminated that the expansion method was able to accurately measure the β transformation temperature of Ti6Al4V-Fe alloy. The lathy-shaped α phase decreased significantly disappeared in the range of 838℃ to 988℃, and the α→β phase transformation occurred.

Stretching Induced Crystalline-Phase Transition in Energy-Conversion Poly(Vinylidene Fluoride) (PVDF) Films

2014 ◽  
Vol 1070-1072 ◽  
pp. 589-593
Author(s):  
Fei Peng Wang ◽  
Zheng Yong Huang ◽  
Jian Li
Keyword(s):  
Phase Transition ◽  
Crystalline Phase ◽  
High Speed ◽  
Vinylidene Fluoride ◽  
X Ray Diffraction ◽  
X Ray ◽  
Β Phase ◽  
Α Phase ◽  
Poly Vinylidene Fluoride ◽  
Crystalline Phase Transition

Commercial poly (vinylidene fluoride) (PVDF) films are uniaxially stretched with varying rates at 110 °C in order to endow PVDF piezo-and pyroelectric by crystalline-phase transition from α to β during the stretching. The crystalline phases are determined by infrared spectroscopy. The β-phase content and its fraction in films increase as a result of stretching with high rates. In addition, higher stretching rates yield a slight increase of γ phase. The crystallite size is evaluated by means of X-ray diffraction. It is found that the β-phase crystallites become smaller with fast stretching, whereas the α-phase crystallites are cracked and disappear at high-speed stretching of 2.5 /min.

Phase Transitions in the BIMEVOX Solid Solutions with Me = Ga, Zr

2008 ◽  
Vol 587-588 ◽  
pp. 114-117 ◽  
Author(s):  
V.V. Murasheva ◽  
Elena A. Fortalnova ◽  
Ekaterina D. Politova ◽  
Marina G. Safronenko ◽  
Sergei Yu. Stefanovich ◽  
...  
Keyword(s):  
Phase Transition ◽  
Phase Transitions ◽  
Solid Solutions ◽  
Phase Stability ◽  
Tetragonal Phase ◽  
Room Temperature ◽  
Β Phase ◽  
Α Phase ◽  
Phase Transition Temperatures ◽  
Stability Ranges

The polymorph phase stability ranges have been studied for the Bi4V2-xMexO11-y solid solutions with Me = Ga and Zr at room temperature. The formation of orthorhombic α- (x = 0.0 and 0.05) and β-phases (x = 0.1, 0.15) and tetragonal phase (0.2 ≤ x ≤ 0.3) has been revealed in BIGAVOX solid solutions. In BIZRVOX solid solutions, α-phase exists at x ≤ 0.05, while β-phase exists at 0.1 ≤ x ≤ 0.3. The second order phase transitions at ~ 308°C (BIGAVOX) and ~ 270°C (BIZRVOX) have been revealed for solid solutions with x = 0.05 using the SHG and DSC methods. In both systems, the β↔γ-phase transition temperatures have been found to decrease with increasing x.

Deformation-induced ambient temperature α-to-β phase transition and nanocrystallization in (α + β) titanium alloy

2009 ◽  
Vol 24 (11) ◽  
pp. 3439-3445 ◽  
Author(s):  
Yong Han ◽  
Huaye Zhuang ◽  
Jian Lu
Keyword(s):  
Phase Transition ◽  
Titanium Alloy ◽  
Ambient Temperature ◽  
Surface Mechanical Attrition Treatment ◽  
Aged Alloy ◽  
Lattice Instability ◽  
Β Phase ◽  
Α Phase ◽  
Diffusion Controlled ◽  
Mechanical Attrition

Ambient temperature α-to-β phase transition and nanocrystallization in the aged Ti–25Nb–3Mo–3Zr–2Sn titanium alloy was achieved by surface mechanical attrition treatment (SMAT). The phase transition occurs at α/β interfaces and extends to α phase interiors with increasing strain. It is irreversible and diffusion controlled. The stress-induced increase of Gibbs energy and enrichment of Nb may cause a high order of lattice instability of the α phase adjacent to the α/β interfaces and compel the α phase to β phase. The presence of fine α needles in the aged alloy and the phase transition from α to β with increasing strain are viewed to play a crucial role in the subsequent nanostructuring.

Thermal Expansion of Lithium Sulphate

1983 ◽  
Vol 38 (12) ◽  
pp. 1396-1399 ◽  
Author(s):  
B. E. Meilander ◽  
L. Nilsson
Keyword(s):  
Phase Transition ◽  
Thermal Expansion ◽  
Linear Thermal Expansion ◽  
X Ray Diffraction ◽  
First Order ◽  
Β Phase ◽  
Α Phase ◽  
First Order Phase Transition ◽  
Lithium Sulphate ◽  
First Order Phase

Abstract The thermal expansion of the α and β phases of lithium sulphate has been studied using dilatometric and X-ray diffraction techniques. In the α-phase the coefficient of linear thermal expansion is 4.6·10-5 K-1 while in the β-phase the coefficient of linear thermal expansion increases from 0.9·10-5K-1 at room temperature up to 3.4·10-5 K-1 close to the first order phase transition at 575 °C. The volume expansion at the phase transition is 3.2%. In the α-phase the thermal Grüneisen parameter has been calculated to be 0.63 at 705 °C.

scholarly journals Crystal structure across the β to α phase transition in thermoelectric Cu2−xSe

IUCrJ ◽  
2017 ◽  
Vol 4 (4) ◽  
pp. 476-485 ◽  
Author(s):  
Espen Eikeland ◽  
Anders B. Blichfeld ◽  
Kasper A. Borup ◽  
Kunpeng Zhao ◽  
Jacob Overgaard ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Phase Transition ◽  
Structural Changes ◽  
Negative Thermal Expansion ◽  
Structural Rearrangement ◽  
High Performing ◽  
Β Phase ◽  
Α Phase ◽  
Starting Point ◽  
Cu Migration

The crystal structure uniquely imparts the specific properties of a material, and thus provides the starting point for any quantitative understanding of thermoelectric properties. Cu2−xSe is an intensely studied high performing, non-toxic and cheap thermoelectric material, and here for the first time, the average structure of β-Cu2−xSe is reported based on analysis of multi-temperature single-crystal X-ray diffraction data. It consists of Se–Cu layers with additional copper between every alternate layer. The structural changes during the peculiarzTenhancing phase transition mainly consist of changes in the inter-layer distance coupled with subtle Cu migration. Just prior to the transition the structure exhibits strong negative thermal expansion due to the reordering of Cu atoms, when approached from low temperatures. The phase transition is fully reversible and group–subgroup symmetry relations are derived that relate the low-temperature β-phase to the high-temperature α-phase. Weak superstructure reflections are observed and a possible Cu ordering is proposed. The structural rearrangement may have a significant impact on the band structure and the Cu rearrangement may also be linked to an entropy increase. Both factors potentially contribute to the extraordinaryzTenhancement across the phase transition.

Phase Transition in Poly(Vinylidene Fluoride) Investigated with Micro-Raman Spectroscopy

2005 ◽  
Vol 59 (3) ◽  
pp. 275-279 ◽  
Author(s):  
C. J. L. Constantino ◽  
A. E. Job ◽  
R. D. Simões ◽  
J. A. Giacometti ◽  
V. Zucolotto ◽  
...  
Keyword(s):  
Phase Transition ◽  
Raman Spectroscopy ◽  
Vinylidene Fluoride ◽  
Raman Band ◽  
X Ray Diffraction ◽  
X Ray ◽  
Micro Raman Spectroscopy ◽  
Β Phase ◽  
Α Phase ◽  
Poly Vinylidene Fluoride

The phase transition from the non-polar α-phase to the polar β-phase of poly(vinylidene fluoride) (PVDF) has been investigated using micro-Raman spectroscopy, which is advantageous because it is a nondestructive technique. Films of α-PVDF were subjected to stretching under controlled rates at 80 °C, while the transition to β-PVDF was monitored by the decrease in the Raman band at 794 cm−1 characteristic of the α-phase, along with the concomitant increase in the 839 cm−1 band characteristic of the β-phase. The α→β transition in our PVDF samples could be achieved even for the sample stretched to twice (2×-stretched) the initial length and it did not depend on the stretching rate in the range between 2.0 and 7.0 mm/min. These conclusions were corroborated by differential scanning calorimetry (DSC) and X-ray diffraction experiments for PVDF samples processed under the same conditions as in the Raman scattering measurements. Poling with negative corona discharge was found to affect the α-PVDF morphology, improving the Raman bands related to this crystalline phase. This effect is minimized for films stretched to higher ratios. Significantly, corona-induced effects could not be observed with the other experimental techniques, i.e., X-ray diffraction and infrared spectroscopy.

Further Investigations of Crystal-to-Crystal Phase Transition of a [2]Pseudorotaxane Composed of Ferrocene-terminated Dialkylammonium and Dibenzo[24]crown-8-ether

CrystEngComm ◽  
2021 ◽  
Author(s):  
Yuji Suzaki ◽  
Yugo Fukuchi ◽  
Hiroko Tadami ◽  
Take-aki Koizumi ◽  
Kohtaro Osakada ◽  
...  
Keyword(s):  
Phase Transition ◽  
Low Temperature ◽  
Crystalline Phase ◽  
Crystal Phase ◽  
Β Phase ◽  
Α Phase ◽  
Crystal Phase Transition ◽  
Crystalline Phase Transition

[2]Pseudorotaxane [(FcCH2NH2CH2C6H4-4-Me)(DB24C8)][PF6] ([1][PF6]; Fc = ferrocenyl, DB24C8 = dibenzo[24]crown-8-ether) undergoes crystalline phase transition at 128 °C upon heating and at 106 °C upon cooling (α-phase at low temperature; β-phase at...

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