scholarly journals Unprecedentedly Wide Curie-Temperature Windows as Phase-Transition Design Platform for Tunable Magneto-Multifunctional Materials

2015 ◽  
Vol 1 (7) ◽  
pp. 1500076 ◽  
Author(s):  
Zhi-Yang Wei ◽  
En-Ke Liu ◽  
Yong Li ◽  
Gui-Zhou Xu ◽  
Xiao-Ming Zhang ◽  
...  
Keyword(s):  
Phase Transition ◽  
Curie Temperature ◽  
Multifunctional Materials

Ferroelectricity of trimethylammonium bromide below room temperature

2020 ◽  
Vol 8 (17) ◽  
pp. 5868-5872 ◽  
Author(s):  
Zhangran Gao ◽  
Yuying Wu ◽  
Zheng Tang ◽  
Xiaofan Sun ◽  
Zixin Yang ◽  
...  
Keyword(s):  
Phase Transition ◽  
Curie Temperature ◽  
Ferroelectric Phase Transition ◽  
Room Temperature ◽  
Ferroelectric Phase ◽  
First Order

Ferroelectricity of trimethylammonium bromide was discovered near room temperature, which undergoes a first-order paraelectric–ferroelectric phase transition at the Curie temperature around 286 K.

The temperature dependence of the photoinduced soft mode in Sn2P2S6 crystal

2019 ◽  
Vol 33 (08) ◽  
pp. 1950061
Author(s):  
K. A. Brekhov ◽  
N. A. Ilyin ◽  
E. D. Mishina ◽  
P. A. Prudkovskii ◽  
G. Kh. Kitaeva
Keyword(s):  
Phase Transition ◽  
Femtosecond Laser ◽  
Curie Temperature ◽  
Temperature Dependence ◽  
Oscillation Frequency ◽  
Phonon Mode ◽  
Soft Mode ◽  
Laser Pulses ◽  
Femtosecond Laser Pulses ◽  
Curie Temperature Tc

In this paper, we present the results of the temperature dependence studies of the photoinduced phonon mode which appears in a ferroelectric-semiconductor Sn2P2S6 (SPS) crystal under the influence of femtosecond laser pulses. We show that its behavior reminds the soft mode one near the phase transition. However, the observed decrease in the oscillation frequency in the vicinity of Curie temperature Tc is much weaker than previously reported. This can be explained by the shadowing of the pure soft mode by its interaction with other photoinduced modes.

Improved Curie Temperature of Li-Doped Lead-Free (K,Na)NbO3 Ceramics Analysis

2014 ◽  
Vol 1061-1062 ◽  
pp. 91-95
Author(s):  
Rui Zhu Zhang ◽  
Wen Peng Guo ◽  
Gao Lei Zhao
Keyword(s):  
Phase Transition ◽  
Curie Temperature ◽  
Electromechanical Coupling ◽  
Piezoelectric Coefficient ◽  
Electromechanical Coupling Factor ◽  
Coupling Factor ◽  
Lead Free ◽  
Tetragonal Symmetry ◽  
Negative Effects ◽  
Li Content

(K,Na)NbO3(KNN)-based lead-free piezoelectric ceramic could be fabricated by ordinary solid sintering method.This paper reported preferable properties of solid solutions (1-x)(Na0.535K0.480)NbO3-xLiNbO3(x=0.050,0.055,0.060,0.065 and 0.070 successively) all sintered at 1060°C.The nonconservation of charge suppressed negative effects caused by evaporations of K&Na and doped Li occupied A sites in ABO3perovskite structure lattices led to the intensification of lattice distortion.XRD result showd phase transition from coexistence of orthorhombic and tetragonal symmetry to tetragonal.Polymorphic phase boundary could be observed when 0.050≤ x≤ 0.060.Coexistence of orthorhombic and tetragonal phases brought improvements of piezoelectric coefficient d33and electromechanical coupling factor kp,whose top values were 162 pC/N and 28.1% in this paper. Positive correlation between the Curie temperature and Li content proved that a distorted crystal lattice needed more energy to accomplish its phase transition from tetragonal to cubic than a normal one.

Depression of Curie temperature by surface structural phase transition

2007 ◽  
Vol 90 (14) ◽  
pp. 142505 ◽  
Author(s):  
H. Y. Ho ◽  
Y. J. Chen ◽  
E. J. Hwang ◽  
S. K. Yu ◽  
C. S. Shern
Keyword(s):  
Phase Transition ◽  
Curie Temperature ◽  
Structural Phase Transition ◽  
Structural Phase

First Principles Study of the Phase Transitions of MnAs

2006 ◽  
Vol 941 ◽  
Author(s):  
Ivan Rungger ◽  
Stefano Sanvito
Keyword(s):  
Phase Transition ◽  
Curie Temperature ◽  
Cell Volume ◽  
Order Phase Transition ◽  
Structural Changes ◽  
Mean Field ◽  
Field Approximation ◽  
Mean Field Approximation ◽  
First Order Phase Transition ◽  
The Stability

ABSTRACTThe magnetic and structural properties of MnAs are investigated by mapping ab initio total energies onto a Heisenberg Hamiltonian. We study the dependence of the Curie temperature over the unit cell volume and an orthorhombic distortion by using the mean field approximation, and find that for orthorhombically distorted cells the Curie temperature is much smaller than for hexagonal cells. We provide an explanation for the structural changes of both the first order phase transition at 318 K and the second order phase transition at 400 K, with the cell volume driving the stability of the different structures in the paramagnetic state. The stable cell is found to be orthorhombic up to a critical lattice constant of about 3.7 Å, above which it remains hexagonal.

Phase Transition and Pyroelectric Properties of La-Modified PbTiO3 Thin Films

1997 ◽  
Vol 493 ◽  
Author(s):  
Kenji Iijima ◽  
Koichi Niihara
Keyword(s):  
Thin Films ◽  
Phase Transition ◽  
Curie Temperature ◽  
Electric Properties ◽  
Rich Region ◽  
Pyroelectric Properties

ABSTRACTPhase transition and related electric properties of La-modified PbTiO3 (PLT) thin films were investigated. Curie temperature of the films decreased and the diffuseness of the phase transition increased with increasing La content. Simultaneously, it was losing a ferroelectricity and pyroelectric properties degraded in La-rich region. This is considered to be due to the increase of a defect in the film by exchanging Pb2+ ions to La3+ ions. Compensation of the defect by the addition of Mn ion improve the ferroelectricity of the PLT and the films showed an extremely large pyroelectric properties.

Cation distribution dependent magnetic properties in CoCr2−xFexO4 (x = 0.1 to 0.5): EXAFS, Mössbauer and magnetic measurements

2017 ◽  
Vol 46 (31) ◽  
pp. 10300-10314 ◽  
Author(s):  
D. Kumar ◽  
A. Banerjee ◽  
A. Mahmoud ◽  
Chandana Rath
Keyword(s):  
Phase Transition ◽  
Magnetic Properties ◽  
Curie Temperature ◽  
Cation Distribution ◽  
Magnetic Measurements ◽  
Magnetic Transitions ◽  
Ferrimagnetic Phase ◽  
Evolution Of Structure ◽  
Lock In

Evolution of structure and rich magnetic transitions such as paramagnetic to ferrimagnetic phase transition at Curie temperature (TC), spiral ordering temperature (TS) and lock-in temperature (TL) have been discussed in CoCr2O4 spinel multiferroic after substituting Fe.

scholarly journals High Temperature XRD of Phase Transition in Piezoelectric PbNb2O6 across its Curie Temperature

2016 ◽  
Vol 13 (1) ◽  
pp. 14-20 ◽  
Author(s):  
Udayan De ◽  
Kriti Ranjan Sahu ◽  
Keka R Chakraborty
Keyword(s):  
Phase Transition ◽  
High Temperature ◽  
Curie Temperature ◽  
Piezoelectric Materials ◽  
Orthorhombic Phase ◽  
X Ray Diffraction ◽  
Lead Metaniobate ◽  
High Temperature Xrd ◽  
Pure Phase ◽  
Xrd Techniques

Orthorhombic phase of lead metaniobate (PbNb2O6) is piezoelectric with a high Curie temperature (>570°C) with high potential of wide use in important high temperature applications that cannot be covered by the popular piezoelectric materials based on BT and PZT. Difficulty of preparing it in pure phase hindered full characterisation and wide use of this long known piezoelectric material. Here,PbNb2O6 pellets have been prepared in pure orthorhombic phase and first characterised by room temperature TEM and XRD techniques, with a satisfying agreement of the two results. Next, we carried out high temperature x-ray diffraction study of its ferroelectric to paraelectric phase transition on heating across the Curie temperature, and also trace the cooling path.On heating the sample to 590°C and cooling back, there is a significant increase of cell volume.

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