Phase transition metal–crown ether coordination compounds tuned by metal ions

2016 ◽  
Vol 45 (3) ◽  
pp. 1000-1006 ◽  
Author(s):  
Qiong Ye ◽  
Hui-Ting Wang ◽  
Lin Zhou ◽  
Li-Hui Kong ◽  
Heng-Yun Ye ◽  
...  
Keyword(s):  
Phase Transition ◽  
Phase Transitions ◽  
Transition Temperature ◽  
Transition Metal ◽  
Crown Ether ◽  
Metal Ions ◽  
Phase Transition Temperature ◽  
Coordination Compounds ◽  
Room Temperature ◽  
Metal Center

(15-Crown-5)(BiCl3) and (15-crown-5)(SbCl3) are discovered to show phase transitions above room temperature, where the phase transition temperature relates to the metal center.

scholarly journals The Effect of Selected Anions on Dipalmitoylphosphatidylcholine Phase Transitions

2002 ◽  
Vol 57 (7-8) ◽  
pp. 712-716 ◽  
Author(s):  
Adriana Przyczyna ◽  
Bożenna Różycka-Roszk ◽  
Marek Langner
Keyword(s):  
Phase Transition ◽  
Phase Transitions ◽  
Transition Temperature ◽  
Phase Transition Temperature ◽  
Salt Concentration ◽  
Half Width ◽  
Main Phase ◽  
Interface Properties ◽  
Transition Enthalpy ◽  
Peak Half Width

The effect of three anions, Cl-, Br- and I-, on the phase transitions of dipalmitoylphosphatidylcholine (DPPC) was measured. Main phase transition was modestly affected by these anions in the salt concentration range 0.2 M. For Cl- and Br- the temperature of main phase transition was lower (by about 0.5 °C), its half-width modestly larger and enthalpy practically unchanged, all three parameters were altered to a much larger degree. Main phase transition temperature was 1.5 °C lower and the peak half-width significantly smaller. These changes were not accompanied by any alteration in main phase transition enthalpy. Iodide shifted the pretransition temperature toward lower values and increased its half-width to such an extent that at concentrations above 100 mm it was practically undetectable. Besides cations, the presence of anions also has a distinct effect on lipid bilayer interface properties.

Temperature dependence of piezoelectric properties of 0.67 Pb(Mg1/3Nb2/3)O3–0.33 PbTiO3 single crystals

2003 ◽  
Vol 18 (2) ◽  
pp. 537-541 ◽  
Author(s):  
Ping-chu Wang ◽  
Xiao-ming Pan ◽  
Dong-lin Li ◽  
Yuan-wei Song ◽  
Hao-su Luo ◽  
...  
Keyword(s):  
Phase Transition ◽  
Transition Temperature ◽  
Temperature Dependence ◽  
Single Crystals ◽  
Phase Transition Temperature ◽  
Room Temperature ◽  
Piezoelectric Properties ◽  
Device Design ◽  
Temperature Range ◽  
Approach Zero

Piezoelectric properties k33 and d33 of 0.67 Pb(Mg1/3Nb2/3)O3–0.33 PbTiO3 single crystals grown by a modified Bridgman method were measured in the temperature range of 20–150 °C. Recoverability of the properties after the samples were heated to 110 °C, above the ferroelectric–ferroelectric (F–F) phase transition temperature of the composition, was found. From 20 to approximately 80 °C, k33 increases slightly, while d33 is almost doubled. Between approximately 90 and 100 °C, k33 decreases sharply to roughly a level of PZT-5 ceramics and d33 decreases to about 700 pC/N. They increase again with further increase of temperature; at 140 °C they attain 0.74 and approximately 1300 pC/N, respectively, and then decrease quickly and approach zero at about 150 °C. When heating to 110 °C followed by cooling to room temperature, the property decay is small. After more than one dozen heating–cooling cycles, k33 and d33 tend to be stable at 0.89 and approximately 1220 pC/N, respectively. The results might be helpful for device design and applications of PMN–PT single crystals.

High-Performance Lead-Free Barium Titanate Piezoelectric Ceramics

2008 ◽  
Vol 54 ◽  
pp. 7-12 ◽  
Author(s):  
Tomoaki Karaki ◽  
Masatoshi Adachi ◽  
Kang Yan
Keyword(s):  
Phase Transition ◽  
Dielectric Constant ◽  
Transition Temperature ◽  
Barium Titanate ◽  
Phase Transition Temperature ◽  
Room Temperature ◽  
Electromechanical Coupling ◽  
Electromechanical Coupling Factor ◽  
Coupling Factor ◽  
Piezoelectric Constants

Barium titanate (BaTiO3) ceramics with a high-density were fabricated by two-step sintering method from hydrothermally synthesized 100 nm BaTiO3 nano-particles. The best specimen with an average grain size of 1.6 μm and a density of 5.91 g/cm3 (98.3% of the theoretical value). The dielectric constant was 4500 and electromechanical coupling factor kp was 45%. Large piezoelectric constants d33 = 460 pC/N and d31 = -185 pC/N were observed in the specimens. This was an important practical result towards obtaining a high d33 in non-lead-based BaTiO3 ceramics manufactured by a low-cost process. These results also indicated the possibility of using BaTiO3 ceramics in piezoelectric devices at room temperature. Temperature dependence of dielectric constant showed two peaks located at 24 and 126 oC, corresponding to orthorhombic-to-tetragonal phase transition temperature Tot and Curie temperature Tc, respectively. Owing to the size effect of nanocrystals, Tot shifted to 24 oC. The maximum of electromechanical coupling factor kp appeared close to the phase transition temperature. It also caused a very large temperature coefficient of resonance frequency from room temperature to 60 oC. Hysteresis curve measurement showed a very low coercive field Ec = 115 V/mm. A large Poisson’s ratio, about 0.38, was determined from the ratio of overtone frequency and resonant frequency in the planar mode. The high Poisson’s ratio and the large dielectric constants are most likely the origin of the high piezoelectric constants in the ceramics.

scholarly journals Martensite Transformation and Mechanical Properties of Polycrystalline Co-Ni-Al Alloys with Gd Doping

Metals ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 848 ◽  
Author(s):  
Jia Ju ◽  
Huan Liu ◽  
Liguo Shuai ◽  
Zhuang Liu ◽  
Yan Kang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Phase Transition ◽  
Compressive Strength ◽  
Transition Temperature ◽  
Phase Transition Temperature ◽  
Martensite Transformation ◽  
Room Temperature ◽  
Al Alloys ◽  
Β Phase

In order to improve the mechanical properties and phase transition temperature, the influence of Gd doping on the microstructure, phase transition temperature and mechanical properties of Co35Ni32Al33 alloy was investigated. The results show that the γ+β phase was observed in the microstructure of the sample with less Gd doping and the γ phase+martensite was found with more Gd content. The phase transition temperature apparently increases with Gd doping and the phase transition temperature goes over room temperature when the Gd is 3 at.% or more. With increasing Gd doping, more γ phase appears in the sample which results in decrease in hardness. The compressive strength decreases from 2274 to 1630 MPa and the ductility increase from 4.2 to 12.9% with increasing Gd content.

Large electrostrictive effect in Sn-doped NBT–BT lead-free relaxor ceramics

2020 ◽  
Vol 34 (11) ◽  
pp. 2050100
Author(s):  
W. P. Cao ◽  
J. Sheng ◽  
Z. Liu ◽  
C. Gao ◽  
Z. H. Wang ◽  
...  
Keyword(s):  
Phase Transition ◽  
Transition Temperature ◽  
Phase Transition Temperature ◽  
Room Temperature ◽  
Relaxor Ferroelectrics ◽  
Lead Free ◽  
Ferroelectric Relaxor ◽  
Pseudocubic Phase ◽  
Further Development ◽  
Electrostrictive Effect

In this work, we design and adjust the composition in [Formula: see text]–[Formula: see text] lead-free relaxor ferroelectrics by doping SnO2 to introduce a relaxor phase and accordingly obtain prominent lead-free electrostrictors. It was found that all the samples exhibited ideal features of relaxor ferroelectrics and the ferroelectric-relaxor phase transition temperature of the ceramics was adjusted to near or below room temperature after doping with a handful of [Formula: see text]. A relatively high electrostrictive coefficient [Formula: see text] of 0.0293 m4/C2 was achieved for the composition with [Formula: see text], which was attributed to the formation of relaxor pseudocubic phase developed by the [Formula: see text] substitution. These results provide some instructive thoughts for the further development of [Formula: see text]-based electrostrictive materials by B-site doping.

scholarly journals Stabilization of model membranes during drying by compatible solutes involved in the stress tolerance of plants and microorganisms

2004 ◽  
Vol 383 (2) ◽  
pp. 277-283 ◽  
Author(s):  
Dirk K. HINCHA ◽  
Martin HAGEMANN
Keyword(s):  
Phase Transition ◽  
Phase Transitions ◽  
Transition Temperature ◽  
Phase Transition Temperature ◽  
Membrane Lipids ◽  
Compatible Solutes ◽  
Stress Conditions ◽  
Lipid Phase ◽  
Cellular Protection ◽  
Solute Leakage

Many organisms accumulate compatible solutes under environmental stress conditions. Cyanobacteria accumulate compatible solutes in response to increased external salinity, with tolerance increasing from Suc (sucrose) or trehalose to 2-O-(α-D-glucopyranosyl)-glycerol and glycinebetaine accumulating species. It is not clear how these different solutes influence salt tolerance. One possible explanation may be a differential ability of these solutes to stabilize membranes under stress conditions. We therefore performed drying experiments with liposomes in the presence of compatible solutes. Suc, trehalose and sorbitol protected liposomes from leakage of a soluble marker and from membrane fusion during drying and rehydration. 2-O-(α-D-glucopyranosyl)-glycerol was less effective and glycinebetaine showed hardly any effect. In combination with Suc, the latter two solutes showed improved protection. Lipid-phase transitions are known to contribute to solute leakage from liposomes. We determined phase transitions in dry membranes in the absence or presence of the solutes, using Fourier-transform infrared spectroscopy. The ability of the solutes to decrease the phase transition temperature corresponded closely to their ability to protect the liposomes against solute leakage. All solutes interacted with the phosphate in the lipid headgroups. The magnitude of the shift in the asymmetric P=O stretching vibration correlated closely with the lipid-phase transition temperature. This indicates that the degree of membrane protection afforded by the solutes is mainly determined by their ability to interact with the membrane lipids. However, this is not a determinant of cellular protection against salt stress, as the solutes show a reverse order when ranked with regard to protection against these stresses.

POSS solid solutions exhibiting orientationally disordered phase transitions

2017 ◽  
Vol 53 (66) ◽  
pp. 9273-9276 ◽  
Author(s):  
Satoshi Morimoto ◽  
Hiroaki Imoto ◽  
Kensuke Naka
Keyword(s):  
Phase Transition ◽  
Phase Transitions ◽  
Transition Temperature ◽  
Phase Transition Temperature ◽  
Solid Solutions ◽  
Single Phase ◽  
Disordered Phase

A mixture of two different monofunctionalized heptaisobutyl-substituted octasilsesquioxanes formed solid solutions showing a single phase-transition temperature, which exhibited orientationally disordered (OD) phases.

Low temperature crystal structure of TbAsO4 and DyAsO4

1977 ◽  
Vol 55 (18) ◽  
pp. 1633-1640 ◽  
Author(s):  
F. G. Long ◽  
C. V. Stager
Keyword(s):  
Phase Transition ◽  
Transition Temperature ◽  
Low Temperature ◽  
Phase Transition Temperature ◽  
Room Temperature ◽  
X Rays ◽  
Single Crystal Diffraction ◽  
Low Temperature Crystal Structure ◽  
Jahn Teller ◽  
Good Agreement

The crystal structures of TbAsO4 and DyAsO4 have been determined by X rays, using single crystal diffraction techniques. The structures have been determined both above and below the co-operative Jahn–Teller phase transition temperature. The structures at room temperature are in good agreement with previous results. The low temperature structures, below the phase transition temperature, are compared to the theory of Elliott, Harley, Hayes, and Smith.

Realizing high thermoelectric performance in GeTe through decreasing the phase transition temperature via entropy engineering

2019 ◽  
Vol 7 (46) ◽  
pp. 26393-26401 ◽  
Author(s):  
Yuting Qiu ◽  
Yang Jin ◽  
Dongyang Wang ◽  
Mengjia Guan ◽  
Wenke He ◽  
...  
Keyword(s):  
Phase Transition ◽  
Phase Transitions ◽  
Transition Temperature ◽  
Phase Transition Temperature ◽  
Thermoelectric Performance

Entropy engineering is one of the powerful approaches to suppress phase transitions.

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