Cubic to tetragonal phase transitions in(NH4)2PtBr6andRb2PtI6

1978 ◽  
Vol 18 (3) ◽  
pp. 1352-1355 ◽  
Author(s):  
Robert G. C. McElroy ◽  
Robin L. Armstrong
Keyword(s):  
Phase Transitions ◽  
Tetragonal Phase

scholarly journals Thickness-dependent electrocaloric effect in mixed-phase Pb 0.87 Ba 0.1 La 0.02 (Zr 0.6 Sn 0.33 Ti 0.07 )O 3 thin films

2016 ◽  
Vol 374 (2074) ◽  
pp. 20160056 ◽  
Author(s):  
T. M. Correia ◽  
Q. Zhang
Keyword(s):  
Thin Films ◽  
Dielectric Constant ◽  
Phase Transitions ◽  
Film Thickness ◽  
Tetragonal Phase ◽  
Sol Gel ◽  
Breakdown Field ◽  
Electrocaloric Effect ◽  
Thickness Increase ◽  
Higher Temperature

Full-perovskite Pb 0.87 Ba 0.1 La 0.02 (Zr 0.6 Sn 0.33 Ti 0.07 )O 3 (PBLZST) thin films were fabricated by a sol–gel method. These revealed both rhombohedral and tetragonal phases, as opposed to the full-tetragonal phase previously reported in ceramics. The fractions of tetragonal and rhombohedral phases are found to be strongly dependent on film thickness. The fraction of tetragonal grains increases with increasing film thickness, as the substrate constraint throughout the film decreases with film thickness. The maximum of the dielectric constant ( ε m ) and the corresponding temperature ( T m ) are thickness-dependent and dictated by the fraction of rhombohedral and tetragonal phase, with ε m reaching a minimum at 400 nm and T m shifting to higher temperature with increasing thickness. With the thickness increase, the breakdown field decreases, but field-induced antiferroelectric–ferroelectric ( E AFE−FE ) and ferroelectric–antiferroelectric ( E FE−AFE ) switch fields increase. The electrocaloric effect increases with increasing film thickness. This article is part of the themed issue ‘Taking the temperature of phase transitions in cool materials’.

Raman Scattering Study of Cubic to Tetragonal Phase Transitions in Mixed SystemAxBa1-xTiO3

1996 ◽  
Vol 35 (Part 1, No. 9B) ◽  
pp. 5192-5195 ◽  
Author(s):  
Seiji Kojima ◽  
Yasuo Ikeuchi ◽  
Huang Zhunchang ◽  
Yin Qingrui
Keyword(s):  
Phase Transitions ◽  
Raman Scattering ◽  
Tetragonal Phase ◽  
Scattering Study

scholarly journals Raman scattering study of thePbZr1−xTixO3system: Rhombohedral-monoclinic-tetragonal phase transitions

2002 ◽  
Vol 66 (13) ◽  
Author(s):  
A. G. Souza Filho ◽  
K. C. V. Lima ◽  
A. P. Ayala ◽  
I. Guedes ◽  
P. T. C. Freire ◽  
...  
Keyword(s):  
Phase Transitions ◽  
Raman Scattering ◽  
Tetragonal Phase ◽  
Scattering Study

Raman Scattering Study of Cubic to Tetragonal Phase Transitions of Ti-rich Pb(ZrxTi1-x)O3

1997 ◽  
Vol 36 (Part 1, No. 5B) ◽  
pp. 2985-2988 ◽  
Author(s):  
Yasuo Ikeuchi ◽  
Seiji Kojima ◽  
Takashi Yamamoto
Keyword(s):  
Phase Transitions ◽  
Raman Scattering ◽  
Tetragonal Phase ◽  
Scattering Study

Phase Transitions in the BIMEVOX Solid Solutions with Me = Ga, Zr

2008 ◽  
Vol 587-588 ◽  
pp. 114-117 ◽  
Author(s):  
V.V. Murasheva ◽  
Elena A. Fortalnova ◽  
Ekaterina D. Politova ◽  
Marina G. Safronenko ◽  
Sergei Yu. Stefanovich ◽  
...  
Keyword(s):  
Phase Transition ◽  
Phase Transitions ◽  
Solid Solutions ◽  
Phase Stability ◽  
Tetragonal Phase ◽  
Room Temperature ◽  
Β Phase ◽  
Α Phase ◽  
Phase Transition Temperatures ◽  
Stability Ranges

The polymorph phase stability ranges have been studied for the Bi4V2-xMexO11-y solid solutions with Me = Ga and Zr at room temperature. The formation of orthorhombic α- (x = 0.0 and 0.05) and β-phases (x = 0.1, 0.15) and tetragonal phase (0.2 ≤ x ≤ 0.3) has been revealed in BIGAVOX solid solutions. In BIZRVOX solid solutions, α-phase exists at x ≤ 0.05, while β-phase exists at 0.1 ≤ x ≤ 0.3. The second order phase transitions at ~ 308°C (BIGAVOX) and ~ 270°C (BIZRVOX) have been revealed for solid solutions with x = 0.05 using the SHG and DSC methods. In both systems, the β↔γ-phase transition temperatures have been found to decrease with increasing x.

scholarly journals Thermal Expansion and Magnetostriction of Laves-Phase Alloys: Fingerprints of Ferrimagnetic Phase Transitions

Materials ◽  
2019 ◽  
Vol 12 (11) ◽  
pp. 1755 ◽  
Author(s):  
Chao Zhou ◽  
Huixin Bao ◽  
Yoshitaka Matsushita ◽  
Tieyan Chang ◽  
Kaiyun Chen ◽  
...  
Keyword(s):  
Phase Transition ◽  
Thermal Expansion ◽  
Phase Transitions ◽  
Tetragonal Phase ◽  
Magnetic Phase ◽  
Coupling Effect ◽  
Rhombohedral Phase ◽  
Laves Phase ◽  
Elastic Coupling ◽  
New Perspective

The magneto–elastic coupling effect correlates to the changes of moment and lattice upon magnetic phase transition. Here, we report that, in the pseudo-binary Laves-phase Tb1-xDyxCo2 system (x = 0.0, 0.7, and 1.0), thermal expansion and magnetostriction can probe the ferrimagnetic transitions from cubic to rhombohedral phase (in TbCo2), from cubic to tetragonal phase (in DyCo2), and from cubic to rhombohedral then to tetragonal phase (in Tb0.3Dy0.7Co2). Furthermore, a Landau polynomial approach is employed to qualitatively investigate the thermal expansion upon the paramagnetic (cubic) to ferrimagnetic (rhombohedral or tetragonal) transition, and the calculated thermal expansion curves agree with the experimental curves. Our work illustrates the correlation between crystal symmetry, magnetostriction, and thermal expansion in ferrimagnetic Laves-phase alloys and provides a new perspective to investigate ferrimagnetic transitions.

Rietveld refinement and diffuse phases transition of Ba1-XBixTi0.8Fe0.2O3 ceramics at x=0.00, 0.05, 0.10 and 0.15 prepared by solid state method.

2020 ◽  
Author(s):  
Najwa Gouitaa ◽  
LAMCHARFI Taj-dine ◽  
Mfadal BOUAYAD ◽  
ABDI Farid ◽  
Mustapha Haddad
Keyword(s):  
Phase Transitions ◽  
Rietveld Refinement ◽  
Tetragonal Phase ◽  
Structural Parameters ◽  
Hexagonal Phase ◽  
Complex Impedance ◽  
Rhombohedral Phase ◽  
Cubic Phase ◽  
Solid State Method ◽  
X Ray

Abstract The effect of substitution of Baryum by Bismut in site A and titanium by iron in site A on structural, physical and electrical properties of Ba1-xBixTi0.80Fe0.20O3 ceramics at (x=0.00, 0.05, 0.10 and 0.15) was investigated by X-ray diffraction, Scaning Electron Microscopy (SEM) as well as dielectric characterizations. The crystal phase was studied by using rietveld refinement. The result of rietveld refinement of X-ray powders diffraction of Ba1-xBixTi0.80Fe0.20O3 shows that these compounds crystallize in tetragonal (P4mm) and hexagonal (P63mmc) for x=0.00 and 0.05 while at x=0.10 and 0.15 the hexagonal phase disappears and the tetragonal phase is stabilized. The structural parameters and the R-factors of these ceramics were succefully determined by the rietveld refinement. The Raman spectra confirms the disappearance of hexagonal phase in benefit of tetragonal phase as the Bi substitution increases. The dielectric measurements as function of temperature are studied and showed tree diffuse phase transitions transition from the ferroelectric rhombohedral phase to the ferroelectric orthorhombic TR-O phase and the second one is from the ferroelectric orthorhombic phase to the ferroelectric TO-T tetragonal phase. While the third one at high temperatures is the phase transition from the ferroelectric tetragonal phase to the paraelectric cubic phase Tm. These phases transition were displaced to the lower temperature with increasing of Bi substitution. And the value of dielectric permittivity increases gradually with increasing of Bi2+ contents. All these phase transitions showed a diffused phenomenon which can be well described by fitting the modified Ushino relation, 1/ε’r = 1/ε’r,max [ 1+ ((T-Tm)/2δ)γ]. The complex impedance Cole–Cole plots showed negative temperature coefficient of resistivity (NTCR) behavior of the Ba1-xBixTi0.80Fe0.20O3 for x=0.05 to 0.15 materials and decrease in grain and grain boundaries resistivity. The relaxation behavior in the test materials is found to be of Debye type.

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