Rhombohedral and Monoclinic Phases of PZT near the Antiferroelectric and the Morphotropic Boundaries

2012 ◽  
Vol 184 ◽  
pp. 333-338 ◽  
Author(s):  
Francesco Cordero ◽  
Francesco Trequattrini ◽  
Floriana Craciun ◽  
Carmen Galassi
Keyword(s):  
Phase Transition ◽  
Phase Diagram ◽  
Curie Temperature ◽  
Structural Studies ◽  
M Phase ◽  
Frequency Independent ◽  
The Common ◽  
Two Phases ◽  
New Phase ◽  
Large Frequency

Anelastic and dielectric spectroscopy measurements are presented, which, together with previous measurements [1], clarify some controversial aspects of the phase diagram of PbZr1xTixO3close to the border with the antiferroelectric (AFE) phase, and at the morphotropic phase boundary (MPB). No evidence is found of a border separating monoclinic (M) from rhombohedral (R) phases, supporting recent structural studies according to which the two phases coexist, with the fraction of M prevailing near the MPB. A large frequency independent softening at the MPB indicates a genuine M phase over only finely twinned R phase. A new phase transition is found in both the anelastic and dielectric spectra atx= 0.1, at a temperatureTITbetween the Curie temperatureTCand the boundaryTTto the phases with tilted octahedra. Such a diffuse transition is interpreted as onset of disordered tilts, which finally become ordered belowTT. In this manner, the phase diagram of PZT is rationalised with respect to the common tendency of perovskites to undergo tilting when the mismatch between the cation sizes exceeds a threshold.

Conductivities of Binary Molten Alkalihalide/Silverhalide Mixtures

1991 ◽  
Vol 46 (1-2) ◽  
pp. 206-210
Author(s):  
H.-P. Boßmann ◽  
J. Richter ◽  
N. Struck
Keyword(s):  
Phase Transition ◽  
Phase Diagram ◽  
Melting Point ◽  
Temperature Coefficients ◽  
The Common ◽  
Common Anion

AbstractThe electric conductivities of molten (Na, Ag)Cl, (Rb.Ag)Cl, (Na,Ag)Br, (Rb. Ag)Br, and (Cs, Ag)Br are determined as functions of composition and temperature from the melting point to 1100 K. The relation of the temperature coefficients to the phase diagram of the systems (K.Ag)Cl, (Rb. Ag)Cl, (Cs, Ag)Cl, and (Cs, Ag)I near and at the phase transition (liquid-solid) is studied. The molar conductivities and mobilities of the cations with reference to the common anion are evaluated.

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.

scholarly journals Phase Transition of Ice at High Pressures and Low Temperatures

Molecules ◽  
2020 ◽  
Vol 25 (3) ◽  
pp. 486
Author(s):  
Jinjin Xu ◽  
Jinfeng Liu ◽  
Jinyun Liu ◽  
Wenxin Hu ◽  
Xiao He ◽  
...  
Keyword(s):  
Phase Transition ◽  
Phase Diagram ◽  
High Pressures ◽  
Structural Phase ◽  
Extreme Conditions ◽  
Dispersion Interactions ◽  
Many Body ◽  
Two Phases ◽  
Moller Plesset ◽  
The Many

The behavior of ice under extreme conditions undergoes the change of intermolecular binding patterns and leads to the structural phase transitions, which are needed for modeling the convection and internal structure of the giant planets and moons of the solar system as well as H2O-rich exoplanets. Such extreme conditions limit the structural explorations in laboratory but open a door for the theoretical study. The ice phases IX and XIII are located in the high pressure and low temperature region of the phase diagram. However, to the best of our knowledge, the phase transition boundary between these two phases is still not clear. In this work, based on the second-order Møller–Plesset perturbation (MP2) theory, we theoretically investigate the ice phases IX and XIII and predict their structures, vibrational spectra and Gibbs free energies at various extreme conditions, and for the first time confirm that the phase transition from ice IX to XIII can occur around 0.30 GPa and 154 K. The proposed work, taking into account the many-body electrostatic effect and the dispersion interactions from the first principles, opens up the possibility of completing the ice phase diagram and provides an efficient method to explore new phases of molecular crystals.

A strain-induced new phase diagram and unusually high Curie temperature in manganites

2017 ◽  
Vol 5 (31) ◽  
pp. 7813-7819 ◽  
Author(s):  
Yunfang Kou ◽  
Tian Miao ◽  
Hui Wang ◽  
Lin Xie ◽  
Yanmei Wang ◽  
...  
Keyword(s):  
Phase Diagram ◽  
Critical Temperature ◽  
Curie Temperature ◽  
Functional Materials ◽  
Strongly Correlated Systems ◽  
High Curie Temperature ◽  
Strongly Correlated ◽  
Correlated Systems ◽  
Physical Phenomena ◽  
New Phase

Raising the critical temperature of functional materials is a major challenge for the exploitation of many exciting physical phenomena in strongly correlated systems.

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.

ROUGHNESS INFLUENCE ON SURFACE MELTING

2001 ◽  
Vol 08 (06) ◽  
pp. 599-608 ◽  
Author(s):  
FRAY DE LANDA CASTILLO ALVARADO ◽  
MARGARITO CRUZ PINEDA ◽  
JERZY H. RUTKOWSKI ◽  
LESZEK WOJTCZAK
Keyword(s):  
Field Theory ◽  
Phase Transition ◽  
Phase Diagram ◽  
Order Parameter ◽  
Surface Melting ◽  
Density Fluctuations ◽  
Solid Model ◽  
Van Der Waals Equation ◽  
Liquid Phases ◽  
Two Phases

The influence of surface roughness on surface melting phase transition is discussed within the molecular field theory. The roughness is characterized by the surface order parameter averaged over all the density fluctuations whose description corresponds to the discrete Gaussian solid-on-solid model. The potential governing the transition between the rough surface and the surface melting is considered in terms of the modified van der Waals equation of state. Its effective shape represents two intersecting parabolas with nonequal curvatures for the solid and liquid phases. The phase diagram shows the coexistence of two phases with rough and wet surfaces.

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.

scholarly journals Electric properties of olive oil under pressure

2021 ◽  
Author(s):  
L. T. Pawlicki ◽  
R. M. Siegoczyński ◽  
S. Ptasznik ◽  
K. Marszałek
Keyword(s):  
Molecular Structure ◽  
Phase Transition ◽  
Phase Diagram ◽  
Phase Transitions ◽  
Olive Oil ◽  
Material Parameters ◽  
First Order ◽  
Long Time ◽  
Capacitive Reactance ◽  
First Order Phase

AbstractThe main purpose of the experiment was a thermodynamic research with use of the electric methods chosen. The substance examined was olive oil. The paper presents the resistance, capacitive reactance, relative permittivity and resistivity of olive. Compression was applied with two mean velocities up to 450 MPa. The results were shown as functions of pressure and time and depicted on the impedance phase diagram. The three first order phase transitions have been detected. All the changes in material parameters were observed during phase transitions. The material parameters measured turned out to be the much more sensitive long-time phase transition factors than temperature. The values of material parameters and their dependence on pressure and time were compared with the molecular structure, arrangement of molecules and interactions between them. Knowledge about olive oil parameters change with pressure and its phase transitions is very important for olive oil production and conservation.

scholarly journals Time Dependent Lyotropic Chromonic Textures in Microfluidic Confinements

Crystals ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 35 ◽  
Author(s):  
Anshul Sharma ◽  
Irvine Lian Hao Ong ◽  
Anupam Sengupta
Keyword(s):  
Phase Transition ◽  
Aspect Ratio ◽  
Temporal Dynamics ◽  
Initial Conditions ◽  
Flow Behavior ◽  
Medical Diagnostics ◽  
Time Dependent ◽  
Disodium Cromoglycate ◽  
M Phase ◽  
Static Conditions

Nematic and columnar phases of lyotropic chromonic liquid crystals (LCLCs) have been long studied for their fundamental and applied prospects in material science and medical diagnostics. LCLC phases represent different self-assembled states of disc-shaped molecules, held together by noncovalent interactions that lead to highly sensitive concentration and temperature dependent properties. Yet, microscale insights into confined LCLCs, specifically in the context of confinement geometry and surface properties, are lacking. Here, we report the emergence of time dependent textures in static disodium cromoglycate (DSCG) solutions, confined in PDMS-based microfluidic devices. We use a combination of soft lithography, surface characterization, and polarized optical imaging to generate and analyze the confinement-induced LCLC textures and demonstrate that over time, herringbone and spherulite textures emerge due to spontaneous nematic (N) to columnar M-phase transition, propagating from the LCLC-PDMS interface into the LCLC bulk. By varying the confinement geometry, anchoring conditions, and the initial DSCG concentration, we can systematically tune the temporal dynamics of the N- to M-phase transition and textural behavior of the confined LCLC. Overall, the time taken to change from nematic to the characteristic M-phase textures decreased as the confinement aspect ratio (width/depth) increased. For a given aspect ratio, the transition to the M-phase was generally faster in degenerate planar confinements, relative to the transition in homeotropic confinements. Since the static molecular states register the initial conditions for LC flows, the time dependent textures reported here suggest that the surface and confinement effects—even under static conditions—could be central in understanding the flow behavior of LCLCs and the associated transport properties of this versatile material.

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