scholarly journals Effects of temperature and concentration of La in the form of A1 transverse optical phonon in the PbTiO3 system

Cerâmica ◽  
2012 ◽  
Vol 58 (347) ◽  
pp. 313-316 ◽  
Author(s):  
M. R. Joya ◽  
J. J. Barba-O ◽  
P. S. Pizani
Keyword(s):  
Phase Transition ◽  
Curie Temperature ◽  
High Temperatures ◽  
Wide Temperature Range ◽  
Lead Titanate ◽  
Vibrational Mode ◽  
Structural Phase ◽  
Anomalous Behavior ◽  
Effects Of Temperature ◽  
Curie Temperature Tc

The structural phase transition from ferroelectric to paraelectric was studied by Raman scattering in the ceramic lead titanate (PbTiO3) doped with lanthanum (La). A1 vibrational mode contains some sub-peaks that have been associated in literature with PbTiO3 concentration (Ca, Ba), and effects of high temperatures as it approaches the Curie temperature (Tc). Raman new study shows that the anomalous behavior of the A1 mode is not only caused by the effects of concentration or temperature near Tc, but by anharmonicity and defects in the network in the PbTiO3 thermodynamically are inevitable. This effect was studied by a wide temperature range from 10 K to Tc in each sample (La = 0, 5, 10, 15, 20%), showing that the effect depends not only on the high temperatures in the pure PT.

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.

Magnetic Properties and Magnetostriction of ZnxNi1-x MnSb Alloys

2005 ◽  
Vol 475-479 ◽  
pp. 1715-1718
Author(s):  
S.K. Ren ◽  
G.B. Ji ◽  
Song Ling Huang ◽  
Q.Q. Cao ◽  
Feng Ming Zhang ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Curie Temperature ◽  
Structural Phase ◽  
Solid State Reaction Method ◽  
Experimental Result ◽  
Xrd Pattern ◽  
Zn Concentration ◽  
Magnetostriction Coefficient ◽  
The Relationship ◽  
Curie Temperature Tc

We have investigated the magnetic properties and magnetostriction of ZnxNi1-xMnSb compounds prepared by solid state reaction method. It is found that for x less than 0.6 the magnetization of ZnxNi1-xMnSb almost remains unchanged. However, when x is larger than 0.6 the magnetization starts to drop linearly. Experimental result indicates that at low Zn concentrations, x < 0.7, the Curie temperature (TC) decreases with increasing Zn concentration x. However, when x > 0.7, the Curie temperature increases distinctly with increasing x. The Zn concentrartion dependence of magnetostrictive ceofficient is also studied. The experimental curve shows that when x < 0.6 the value of magnetostriction coefficient for ZnxNi1-xMnSb decreases linearly with the increasing Zn concentration x. However, when x is above 0.6, the magnetostrictive ceofficient raises distinctly. By analyzing the XRD pattern, the structures of the materials are examined and the relationship between the properties and the structures are discussed. A structural phase transition is observed. It has been indicated that the structure plays an important role in the magnetic and magnetostrictive properties of the system.

The resistivity and structural phase transition of YBa2Cu3O7−x at high temperatures

1990 ◽  
Vol 167 (1-2) ◽  
pp. 49-52 ◽  
Author(s):  
Zhishuang Gao ◽  
Zhijian Hou ◽  
Baoshi Du ◽  
Dexuan Zhang ◽  
Guoliang Wang ◽  
...  
Keyword(s):  
Phase Transition ◽  
High Temperatures ◽  
Structural Phase Transition ◽  
Structural Phase

Holmium induced enhanced functionality at room temperature and structural phase transition at high temperature in bismuth ferrite nanoparticles

2016 ◽  
Vol 4 (4) ◽  
pp. 780-792 ◽  
Author(s):  
Smita Chaturvedi ◽  
Rabindranath Bag ◽  
Vasant Sathe ◽  
Sulabha Kulkarni ◽  
Surjeet Singh
Keyword(s):  
Phase Transition ◽  
High Temperature ◽  
High Temperatures ◽  
Structural Phase Transition ◽  
Room Temperature ◽  
Bismuth Ferrite ◽  
Structural Phase ◽  
Ferrite Nanoparticles ◽  
High Coercivity ◽  
Remnant Magnetization

Ho-doped sample simultaneously exhibits high-coercivity and enhanced remnant magnetization with a polar R3c symmetry at room temperature. The onset of R3c to Pnma phase transition is observed at high temperatures in the Ho-doped samples.

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

Structural phase transition, depolarization and enhanced pyroelectric properties of (Pb1−1.5xLax)(Zr0.66Sn0.23Ti0.11)O3 solid solution

2016 ◽  
Vol 4 (29) ◽  
pp. 7110-7118 ◽  
Author(s):  
Fangping Zhuo ◽  
Qiang Li ◽  
Jinghan Gao ◽  
Yujie Wang ◽  
Qingfeng Yan ◽  
...  
Keyword(s):  
Phase Transition ◽  
Solid Solution ◽  
Solid State ◽  
Wide Temperature Range ◽  
Structural Phase ◽  
Solid State Method ◽  
Pyroelectric Properties ◽  
Conventional Solid State Method ◽  
System P ◽  
State Method

(Pb1−1.5xLax)(Zr0.66Sn0.23Ti0.11)O3 ceramics were fabricated using the conventional solid-state method. Enhanced and wide temperature range tunable pyroelectric properties were achieved in this system.

scholarly journals Structural, Magnetic and Transport Properties of Ni-Fe-Al Alloys

2009 ◽  
Vol 635 ◽  
pp. 111-116
Author(s):  
S.N. Kaul ◽  
A.C. Abhyankar ◽  
D.V. Sridhar Rao ◽  
K. Muraleedharan ◽  
A.K. Nigam ◽  
...  
Keyword(s):  
Phase Transition ◽  
Curie Temperature ◽  
Magnetocrystalline Anisotropy ◽  
Al Alloys ◽  
Martensitic Transition ◽  
Atomic Order ◽  
First Order ◽  
Melt Spun ◽  
Melt Spun Ribbons ◽  
Curie Temperature Tc

Melt spun ribbons (MSR) of the Ni55Fe20Al25 alloy exhibit a first-order martensitic transition (MT) in the vicinity of a second-order ferromagnetic-to-paramagnetic phase transition. Contrasted with a sharp, complete and thermoelastic MT in MSR, a partial, sluggish and non-thermoelastic MT occurs in annealed Ni55Fe20Al25 alloy that possesses a much higher degree of atomic order. However, the annealed samples have stronger local magnetocrystalline anisotropy and higher Curie temperature (TC) than MSR. Negative magnetoresistance, || / , is two times larger in MSR than in the annealed case. || /  vs. H isotherms in MSR change curvature from concave-upwards to concave-downwards as the temperature is raised through TC whereas concave-downward curvature persists over the entire temperature range in the annealed counterpart.

scholarly journals Anomalous behavior above the Curie temperature in (Nd1−xGdx)0.55Sr0.45MnO3 (x = 0, 0.1, 0.3 and 0.5)

RSC Advances ◽  
2019 ◽  
Vol 9 (47) ◽  
pp. 27541-27548 ◽  
Author(s):  
R. Kamel ◽  
A. Tozri ◽  
E. Dhahri ◽  
E. K. Hlil
Keyword(s):  
Phase Transition ◽  
Magnetic Properties ◽  
Curie Temperature ◽  
Anomalous Behavior

Magnetic properties were studied just above the ferromagnetic–paramagnetic (FM–PM) phase transition of (Nd1−xGdx)0.55Sr0.45MnO3 with x = 0, 0.1, 0.3 and 0.5.

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