scholarly journals Tailoring the phase transition temperature to achieve high-performance cubic GeTe-based thermoelectrics

2020 ◽  
Vol 8 (36) ◽  
pp. 18880-18890 ◽  
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.

scholarly journals Phase-transition temperature suppression to achieve cubic GeTe and high thermoelectric performance by Bi and Mn codoping

2018 ◽  
Vol 115 (21) ◽  
pp. 5332-5337 ◽  
Author(s):  
Zihang Liu ◽  
Jifeng Sun ◽  
Jun Mao ◽  
Hangtian Zhu ◽  
Wuyang Ren ◽  
...  
Keyword(s):  
Phase Transition ◽  
Transition Temperature ◽  
Phase Transition Temperature ◽  
High Performance ◽  
Hole Concentration ◽  
Rhombohedral Structure ◽  
Germanium Telluride ◽  
Strong Point ◽  
Bi Doping ◽  
Valence Bands

Germanium telluride (GeTe)-based materials, which display intriguing functionalities, have been intensively studied from both fundamental and technological perspectives. As a thermoelectric material, though, the phase transition in GeTe from a rhombohedral structure to a cubic structure at ∼700 K is a major obstacle impeding applications for energy harvesting. In this work, we discovered that the phase-transition temperature can be suppressed to below 300 K by a simple Bi and Mn codoping, resulting in the high performance of cubic GeTe from 300 to 773 K. Bi doping on the Ge site was found to reduce the hole concentration and thus to enhance the thermoelectric properties. Mn alloying on the Ge site simultaneously increased the hole effective mass and the Seebeck coefficient through modification of the valence bands. With the Bi and Mn codoping, the lattice thermal conductivity was also largely reduced due to the strong point-defect scattering for phonons, resulting in a peak thermoelectric figure of merit (ZT) of ∼1.5 at 773 K and an average ZT of ∼1.1 from 300 to 773 K in cubic Ge0.81Mn0.15Bi0.04Te. Our results open the door for further studies of this exciting material for thermoelectric and other applications.

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

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.

The structure of membranes and membrane proteins embedded in amorphous ice

1992 ◽  
Vol 50 (1) ◽  
pp. 432-433
Author(s):  
Uwe Lücken ◽  
Joachim Jäger
Keyword(s):  
Phase Transition ◽  
Transition Temperature ◽  
Membrane Proteins ◽  
Phase Transition Temperature ◽  
Lipid Vesicles ◽  
Freezing Stress ◽  
Amorphous Ice ◽  
Different Temperatures ◽  
Band Pass ◽  
Lipid Polymorphism

TEM imaging of frozen-hydrated lipid vesicles has been done by several groups Thermotrophic and lyotrophic polymorphism has been reported. By using image processing, computer simulation and tilt experiments, we tried to learn about the influence of freezing-stress and defocus artifacts on the lipid polymorphism and fine structure of the bilayer profile. We show integrated membrane proteins do modulate the bilayer structure and the morphology of the vesicles.Phase transitions of DMPC vesicles were visualized after freezing under equilibrium conditions at different temperatures in a controlled-environment vitrification system. Below the main phase transition temperature of 24°C (Fig. 1), vesicles show a facetted appearance due to the quasicrystalline areas. A gradual increase in temperature leads to melting processes with different morphology in the bilayer profile. Far above the phase transition temperature the bilayer profile is still present. In the band-pass-filtered images (Fig. 2) no significant change in the width of the bilayer profile is visible.

scholarly journals Study of physical properties of a ferrimagnetic spinel Cu1.5Mn1.5O4: spin dynamics, magnetocaloric effect and critical behavior

RSC Advances ◽  
2021 ◽  
Vol 11 (41) ◽  
pp. 25664-25676
Author(s):  
Abir Hadded ◽  
Jalel Massoudi ◽  
Sirine Gharbi ◽  
Essebti Dhahri ◽  
A. Tozri ◽  
...  
Keyword(s):  
Phase Transition ◽  
Transition Temperature ◽  
Physical Properties ◽  
Magnetocaloric Effect ◽  
Phase Transition Temperature ◽  
Magnetic Phase Transition ◽  
Critical Behavior ◽  
Magnetic Phase ◽  
Spin Dynamics ◽  
Critical Behaviour

The present work reports a detailed study of the spin dynamics, magnetocaloric effect and critical behaviour near the magnetic phase transition temperature, of a ferrimagnetic spinel Cu1.5Mn1.5O4.

scholarly journals Modulating the phase transition temperature of giant magnetocaloric thin films by ion irradiation

2017 ◽  
Vol 1 (6) ◽  
Author(s):  
S. Cervera ◽  
M. Trassinelli ◽  
M. Marangolo ◽  
C. Carrétéro ◽  
V. Garcia ◽  
...  
Keyword(s):  
Thin Films ◽  
Phase Transition ◽  
Transition Temperature ◽  
Phase Transition Temperature ◽  
Ion Irradiation

Determination of ferroelastic phase transition temperature in BiVO4 by Raman spectroscopy

2021 ◽  
Vol 291 ◽  
pp. 129519
Author(s):  
Yuwaraj K. Kshetri ◽  
Bina Chaudhary ◽  
Takashi Kamiyama ◽  
Tae-Ho Kim ◽  
Federico Rosei ◽  
...  
Keyword(s):  
Phase Transition ◽  
Raman Spectroscopy ◽  
Transition Temperature ◽  
Phase Transition Temperature ◽  
Ferroelastic Phase Transition
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