The Phase Diagram of K3FeF6 to 35 kbar and 600 °C

1977 ◽  
Vol 32 (4) ◽  
pp. 413-415 ◽  
Author(s):  
P. W. Richter ◽  
J. B. Clark
Keyword(s):  
Phase Transition ◽  
Phase Diagram ◽  
Temperature Region ◽  
Tetragonal Phase ◽  
Cubic Phase ◽  
Small Temperature ◽  
Effect Of Pressure ◽  
Low Pressures ◽  
New Phase

The effect of pressure on the tetragonal/cubic phase transition in K3FeF6 was studied to 35 kbar. A new phase which also occurs in K3TiF6, exists over a small temperature region at low pressures. A strong possibility exists that the K3FeF6 tetragonal phase is isostructural with the corresponding phase found for the K3XF6 (X = Ln, Y) compounds.

High-temperature X-ray powder diffraction study of the tetragonal-cubic phase transition in nanocrystalline, compositionally homogeneous ZrO2–CeO2 solid solutions

2008 ◽  
Vol 23 (S1) ◽  
pp. S70-S74 ◽  
Author(s):  
L. M. Acuña ◽  
R. O. Fuentes ◽  
D. G. Lamas ◽  
I. O. Fábregas ◽  
N. E. Walsöe de Reca ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Phase Transition ◽  
High Temperature ◽  
Powder Diffraction ◽  
Solid Solutions ◽  
Tetragonal Phase ◽  
Room Temperature ◽  
Cubic Phase ◽  
X Ray ◽  
First Order

Crystal structure of compositionally homogeneous, nanocrystalline ZrO2–CeO2 solutions was investigated by X-ray powder diffraction as a function of temperature for compositions between 50 and 65 mol % CeO2. ZrO2-50 and 60 mol % CeO2 solid solutions, which exhibit the t′-form of the tetragonal phase at room temperature, transform into the cubic phase in two steps: t′-to-t″ followed by t″-to-cubic. But the ZrO2-65 mol % CeO2, which exhibits the t″-form, transforms directly to the cubic phase. The results suggest that t′-to-t″ transition is of first order, but t″-to-cubic seems to be of second order.

scholarly journals Transient Phases and their Transition Temperatures of A-Si in Non-Isothermal Processes

1993 ◽  
Vol 321 ◽  
Author(s):  
Masakuni Suzuki ◽  
Akio Kitagaffa
Keyword(s):  
Phase Transition ◽  
Phase Diagram ◽  
Glass Transition ◽  
Transition Temperature ◽  
Heating Rate ◽  
Random Networks ◽  
Transition Temperatures ◽  
Isothermal Processes ◽  
Transient Phases ◽  
New Phase

ABSTRACTThe heating rate dependence of the phase transition temperature was formulated based on the temperature dependence of nucleation of a new phase. The glass transition temperature of a-Si was explained in terms of van der Waals fluid of a-Si pseudo-Molecules which are produced by the fragmentation of continuous random networks of Si atoms. Transient phases and their transition temperatures as a function of the heating rate are summarized in the phase diagram.

Temperature and Electric Field Dependent Phase Transformations in [001] PMN-PT Single Crystal

2021 ◽  
Vol 875 ◽  
pp. 55-59
Author(s):  
Ghulam Shabbir ◽  
Ahmad H. Qureshi
Keyword(s):  
Phase Transition ◽  
Phase Diagram ◽  
Electric Field ◽  
Single Crystal ◽  
Cubic Phase ◽  
Zero Field ◽  
Field Phase ◽  
Phase Transition Temperatures ◽  
Field Dependent ◽  
Oriented Single Crystal

The capacitance of (1-x)Pb(Mg1/3Nb2/3)O3-xPbTiO3 (PMN-xPT) [001]-oriented single crystal was examined as a function of temperature and applied external dc electric field. The phase transition temperatures under the applied electric field were measured upon cooling the crystal (zero-field heating field-cooling condition) from paraelectric cubic phase. From these data, temperature versus electric field phase diagram of PMN-xPT crystal have been constructed and discussed.

Laser effects on phase transition for cubic Sb2O3 microcrystals under high pressure

2017 ◽  
Vol 5 (22) ◽  
pp. 5451-5457 ◽  
Author(s):  
Zhilei Sui ◽  
Shuhe Hu ◽  
Hao Chen ◽  
Chan Gao ◽  
Hao Su ◽  
...  
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
Laser Irradiation ◽  
Amorphous Phase ◽  
Tetragonal Phase ◽  
Cubic Phase ◽  
Ambient Conditions

Laser irradiation transforms Sb2O3 from the tetragonal phase into an HD-amorphous phase under high pressure and back to cubic phase from LD-amorphous phase at ambient conditions.

scholarly journals PIN–PMN–PT piezoelectric crystals with increased rhombohedral-to-tetragonal phase transition temperature

2014 ◽  
Vol 04 (01) ◽  
pp. 1450001 ◽  
Author(s):  
Jun Luo ◽  
Shujun Zhang ◽  
Wesley Hackenberger ◽  
Thomas R. Shrout
Keyword(s):  
Phase Transition ◽  
Tetragonal Phase ◽  
The Self ◽  
Cubic Phase ◽  
High Quality ◽  
Piezoelectric Crystals ◽  
Phase Transition Temperatures ◽  
Tetragonal Phase Transition

In this work, crystal growth and characterization of PIN–PMN–PT (29–59% PIN and 28–35% PT) were conducted to understand how PIN ratio in the PIN–PMN–PT system impacts its phase stability during crystallization. High-quality PIN–PMN–PT crystals with 36% PIN were obtained using the self-seeded Bridgman process, even though the cubic phase In 2 O 3 formed at the very beginning of solidification. The melt became more unstable when the PIN ratio in the PIN–PMN–PT system increased to 49% and above, which affected the composition and quality of the as-grown crystals significantly. By increasing the PIN to 36% in PIN–PMN–PT crystal, the rhombohedral-to-tetragonal phase transition temperatures and the coercive field reached 115–135°C and 4.5~5.6 kV/cm, respectively, that greatly expanded the operation domains compared to PMN–PT crystals.

First-Principles Calculations of Structural Changes Induced by Oxygen Vacancies in Tetragonal Phase BaTiO3

2011 ◽  
Vol 485 ◽  
pp. 19-22
Author(s):  
Yoshiki Iwazaki ◽  
Tatsuo Sakashita ◽  
Toshimasa Suzuki ◽  
Youichi Mizuno ◽  
Shinji Tsuneyuki
Keyword(s):  
Phase Transition ◽  
Density Functional Theory ◽  
First Principles ◽  
Tetragonal Phase ◽  
Density Functional ◽  
Oxygen Vacancies ◽  
Structural Changes ◽  
Cubic Phase ◽  
First Principles Calculations ◽  
Functional Theory

Structural changes induced by oxygen vacancies in tetragonal phase BaTiO3are studied with first principles calculations within density functional theory. In our calculations, the incorporation of oxygen vacancies greatly decreases c/a ratio of the tetragonal phase BaTiO3, and a phase transition from tetragonal to cubic phase occurs when the incorporation of the oxygen vacancies reaches about 4%. Our results also shows that the generation of the oxygen vacancies slightly increases the volume of BaTiO3, and the increases are typically less than 0.5% even in heavily reduced conditions.

SPIN EFFECTS IN THE PHASE TRANSITION OF THE νT = 1 BILAYER ELECTRON SYSTEM

2009 ◽  
Vol 23 (12n13) ◽  
pp. 2587-2595
Author(s):  
KOJI MURAKI ◽  
PAULA GIUDICI ◽  
NORIO KUMADA
Keyword(s):  
Phase Transition ◽  
Phase Diagram ◽  
Phase Boundary ◽  
Field Experiments ◽  
Quantum Hall ◽  
Decisive Role ◽  
Electron System ◽  
Spin Effects ◽  
Magnetic Length ◽  
New Phase

We present tilted-field experiments on a bilayer electron system at νT = 1 with negligible tunneling and demonstrate that the spin degree of freedom plays a decisive role in the ground-state phase diagram of the system. We observe that the phase boundary separating the incompressible quantum Hall state and a compressible state at d/ℓB = 1.90 (d: interlayer distance, ℓB: magnetic length) in a perpendicular field shifts to higher densities with tilt until it saturates at d/ℓB = 2.33. We develop a model describing the energies of the competing phases and show that the observed shift of the phase boundary reflects the spin-polarization dependence of the Coulomb and Zeeman energies of the compressible state. A new phase diagram as a function of d/ℓB and the Zeeman energy is established and its implications as to the nature of the phase transition are discussed.

Temperature Dependent Raman Scattering and Dielectric Permittivity Measurements of Pb1−x Srx TiO3 Films

2003 ◽  
Vol 784 ◽  
Author(s):  
V. M. Naik ◽  
M. Smith ◽  
H. Dai ◽  
P. Talagala ◽  
R. Naik ◽  
...  
Keyword(s):  
Phase Transition ◽  
Dielectric Permittivity ◽  
Raman Spectra ◽  
Tetragonal Phase ◽  
Room Temperature ◽  
Cubic Phase ◽  
X Ray Diffraction ◽  
Phonon Modes ◽  
X Ray ◽  
Permittivity Measurements

ABSTRACTPb1-x Srx TiO3 (x = 0 to 1.0) films of thickness ∼ 4 μ m have been prepared on sapphire and Pt substrates by metalorganic decomposition (MOD) method. X-ray diffraction results show that the films are polycrystalline with a perovskite tetragonal phase at room temperature for x < 0.5 and a cubic phase for x > 0.5. Room temperature Raman spectra show a systematic variation of lattice vibrational modes with x. The most notable changes in the Raman spectra with x are the decrease in the splitting of A1(3TO) and E(3TO) modes and the disappearance of E(3TO) mode at x ∼ 0.6. Although the x-ray diffraction peaks for films with x > 0.5 show a cubic phase at room temperature, the Raman spectra show the characteristic phonon modes of a tetragonal phase even at x = 0.7. The dielectric permittivity versus temperature measurements for films with x ≤ 0.7 show a broad dielectric anomaly corresponding to a diffuse ferroelectric to paraelectric phase transition. The phase transition temperature (Tc) values are consistently lower than the corresponding bulk ceramic alloys. Furthermore, Tc are also determined by monitoring the temperature dependence of the splitting between E(3TO) and A1(3TO) phonon modes in the Raman spectra of Pb1-x Srx TiO3 films for x ≤ 0.6. There has been good agreement between the two methods.

Orientational ordering in solid ortho–para H2 mixtures and analogy with a spin glass

1985 ◽  
Vol 63 (1) ◽  
pp. 3-23 ◽  
Author(s):  
A. Brooks Harris ◽  
Horst Meyer
Keyword(s):  
Phase Transition ◽  
Spin Glass ◽  
Electric Quadrupole ◽  
Experimental Investigations ◽  
Cubic Phase ◽  
Hexagonal Close Packed ◽  
Quadrupole Interactions ◽  
Orientational Ordering ◽  
Low Pressures ◽  
Quadrupolar Glass

A review is presented of our understanding of the orientational ordering in solid hydrogen, where ortho-H2 molecules are subject to anisotropic electric quadrupole–quadrupole interactions. This review pertains to solid H2 at low pressures and is concerned mostly with NMR experiments. After a discussion of the phase transition from the disordered hexagonal close-packed (hep) to the long-range ordered cubic phase, a description is given of experimental investigations of the ordering in the hep phase for ortho concentrations X < 0.53. This ordering appears to take place continuously as the temperature decreases. The question as to whether or not this phase is to be called a quadrupolar glass phase is addressed, and comparison is made with the orientational freezing in other compounds. A theoretical analysis is given to show that the ortho–para mixture is the analog of a spin glass in a random field for which no phase transition is expected.

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