Studies of the surface magnetic state of the Sr-M hexagonal ferrites near the phase transition at the Curie temperature

1999 ◽  
Vol 41 (3) ◽  
pp. 420-425 ◽  
Author(s):  
A. S. Kamzin ◽  
V. L. Rozenbaum
Keyword(s):  
Phase Transition ◽  
Curie Temperature ◽  
Magnetic State ◽  
Hexagonal Ferrites

Magnetic Concentration Phase Transitions in Ultrathin Films

2013 ◽  
Vol 683 ◽  
pp. 69-72 ◽  
Author(s):  
Leonid Afremov ◽  
Ilia Ilyushin
Keyword(s):  
Phase Transition ◽  
Phase Transitions ◽  
Ising Model ◽  
Curie Temperature ◽  
Percolation Threshold ◽  
Ultrathin Films ◽  
Magnetic State ◽  
Critical Concentration ◽  
Magnetic Moments ◽  
Nearest Neighbors

Modeling study of magnetic and concentration phase transition in ultrathin films of diluted magnet has been carried out under approximation of random interaction between atomic magnetic moments of nearest neighbors and within the framework of Ising model. The dependence of Curie temperature on concentration of magnetic atoms was formed. It is shown that with increasing of thickness of ultrathin film the critical concentration of transition from unordered to ordered magnetic state decreases down to the value equal to the percolation threshold.

scholarly journals Hopkinson Effect Study in Spinel and Hexagonal Ferrites

2011 ◽  
Vol 62 (4) ◽  
pp. 239-243 ◽  
Author(s):  
Jozef Sláma ◽  
Martin Šoka ◽  
Anna Grusková ◽  
Alvaro Gonzalez ◽  
Vladimír Jančárik
Keyword(s):  
Magnetic Susceptibility ◽  
Curie Temperature ◽  
Magnetic State ◽  
Spinel Ferrite ◽  
Effect Study ◽  
Paramagnetic Relaxation ◽  
Spinel Ferrites ◽  
Blocking Temperature ◽  
Hexagonal Ferrites ◽  
Sem Micrographs

Hopkinson Effect Study in Spinel and Hexagonal Ferrites The magnetic susceptibility shows a Hopkinson peak just below the Curie temperature TC when heating the selected hexagonal and spinel ferrite samples. It is proposed that this peak can be associated with a transition from stable magnetic state to super-paramagnetic relaxation above the blocking temperature up to the TC. The Hopkinson effect results are compared with SEM micrographs of both studied hexagonal and spinel ferrites.

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.

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

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
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