Phase Transition Temperature of Ferroelectric Thin Film Evaluated by Four-State Potts Model

2005 ◽  
Vol 902 ◽  
Author(s):  
Wing Yee Winnie Chung ◽  
Veng Cheong Lo
Keyword(s):  
Thin Film ◽  
Phase Transition ◽  
Boundary Condition ◽  
Transition Temperature ◽  
Potts Model ◽  
Domain Walls ◽  
Ferroelectric Thin Film ◽  
Two Dimensional ◽  
Thermally Activated ◽  
Phase Transition Temperatures

AbstractAn epitaxial ferroelectric thin film can be modeled by a two-dimensional array of dipoles. The orientation of each dipole is assigned to one of the four possible states which are mutually perpendicular to each other. Consequently, the whole film can be divided into domains with both 90° and 180° domain walls. The dominant switching mechanism for individual dipole is implemented by a 90° rotation. Two different conditions have been considered. For the first one (model A), every dipole inside the film is allowed to rotate, provided that it is thermally activated. For the second (model B), only the dipole rotation is restricted to those at the domain walls. The phase transition temperatures under these two models have been evaluated. Furthermore, the effects of sample size and boundary condition are discussed.

COMBINED EFFECT OF THE ELECTRODE AND SURFACE TRANSITION LAYER ON THE PROPERTIES OF A FERROELECTRIC THIN FILM

2012 ◽  
Vol 19 (06) ◽  
pp. 1250058 ◽  
Author(s):  
LIAN CUI ◽  
ZHAOAN LI ◽  
YUNFENG DONG ◽  
ZHIYOU HAN ◽  
XU XU ◽  
...  
Keyword(s):  
Thin Film ◽  
Phase Transition ◽  
Transition Temperature ◽  
Transition Layer ◽  
Paraelectric Phase ◽  
Ferroelectric Thin Film ◽  
Phenomenological Theory ◽  
Combined Effect ◽  
Ginzburg Landau ◽  
Surface Transition

Within the framework of the modified Ginzburg–Landau–Devonshire phenomenological theory, we study the properties of a ferroelectric thin film with surface transition layer, considering the effect of electrodes. The combined effect of the electrode and surface transition layer on the properties (including the polarization, transition temperature and coercive filed) of a ferroelectric thin film is discussed in detail. The results show that the surface transition layer and the electrode can induce the phase transition from ferroelectric to paraelectric phase.

INDUCED CHANGES OF THERMOTROPIC PROPERTIES OF PHASE TRANSITIONS BETWEEN SMECTIC A MESOPHASE AND ISOTROPIC LIQUID: EFFECT OF SURFACES

2006 ◽  
Vol 20 (14) ◽  
pp. 821-833 ◽  
Author(s):  
ARIF NESRULLAJEV ◽  
ŞENER OKTIK
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Phase Transition ◽  
Phase Transitions ◽  
Isotropic Liquid ◽  
Smectic A ◽  
Phase Transition Temperatures ◽  
Smectic A Phase ◽  
Induced Changes ◽  
Thermotropic Properties

In this work, the effect of thin films on the thermotropic and thermo-optical properties and peculiarities of the phase transitions between the smectic A and isotropic liquid have been investigated. Peculiarities of the heterophase regions of the straight smectic A-isotropic liquid and reverse isotropic liquid-smectic A phase transitions have been studied. Change of morphologic properties of the heterophase regions, shift of the phase transition temperatures and the change of temperature widths of these heterophase regions under thin film influence have been observed.

Phase transition of a two-dimensional, multiplicatively coupledXY–Potts model

2009 ◽  
Vol 42 (22) ◽  
pp. 225001 ◽  
Author(s):  
Marcel Hellmann ◽  
Youjin Deng ◽  
Matthias Weiss ◽  
Dieter W Heermann
Keyword(s):  
Phase Transition ◽  
Potts Model ◽  
Two Dimensional

scholarly journals Influence of dimensionality on phase transition in VO2 nanocrystals

2013 ◽  
Vol 45 (3) ◽  
pp. 305-311 ◽  
Author(s):  
V.A. Blagojevic ◽  
N. Obradovic ◽  
N. Cvjeticanin ◽  
D.M. Minic
Keyword(s):  
Phase Transition ◽  
Activation Energy ◽  
Transition Temperature ◽  
Apparent Activation Energy ◽  
Phase Transition Temperature ◽  
Bulk Material ◽  
Two Dimensional ◽  
Lower Phase ◽  
One Dimensional ◽  
Simultaneous Movement

Hydrothermally synthesized one-dimensional and two-dimensional nanocrystals of VO2 undergo phase transition around 65?C, where temperature and mechanism of phase transition are dependent on dimensionality of nanocrystals. Both nanocrystalline samples exhibit depression of phase transition temperature compared to the bulk material, the magnitude of which depends on the dimensionality of the nanocrystal. One-dimensional nanoribbons exhibit lower phase transition temperature and higher values of apparent activation energy than two-dimensional nanosheets. The phase transition exhibits as a complex process with somewhat lower value of enthalpy than the phase transition in the bulk, probably due to higher proportion of surface atoms in the nanocrystals. High values of apparent activation energy indicate that individual steps of the phase transition involve simultaneous movement of large groups of atoms, as expected for single-domain nanocrystalline materials.

Change of Phase Transition Temperature in Band Engineered Ferroelectric Lanthanum-Modified Bismuth Titanates

2020 ◽  
Vol 20 (11) ◽  
pp. 7135-7139
Author(s):  
Rui Tang ◽  
Sangmo Kim ◽  
Chung Wung Bark
Keyword(s):  
Phase Transition ◽  
Dielectric Constant ◽  
Transition Temperature ◽  
Phase Transition Temperature ◽  
Ferroelectric Properties ◽  
Solar Spectrum ◽  
Ferroelectric Material ◽  
Transition Temperatures ◽  
Phase Transition Temperatures ◽  
Increasing Temperature

The ferroelectric material chosen for a solar cell has to absorb as much of the solar spectrum as possible, therefore a low band gap is desirable, but it is rarely known for phase transition temperature on the bandgap engineered ferroelectric materials. The phase transition temperature of a ferroelectric material can be determined by monitoring its dielectric constant with increasing temperature, as the dielectric constant changes abruptly at the phase transition temperature. Here, we inform the measurement of the phase transition temperature of the ferroelectric complex oxide Bi3.25La0.75Ti3O12 as well as cobalt and iron doped Bi3.25La0.75Ti3O12 bulk ceramics for photovoltaic cells based on dielectric monitoring with changing temperature. We synthesized lanthanum-modified bismuth-titanate-based ceramics with various doping concentrations transition metal to Ti. X-ray diffraction analysis revealed that all the compounds crystallized in an orthorhombic structure. Their morphologies and size distributions were observed using scanning electron microscopy. From the ultraviolet-visible spectroscopy absorption spectra of the synthesized powder, bandgaps were checked. An inductance-capacitance-resistance meter was used to obtain the relationship between dielectric responses and the temperature of the targets in a tube furnace. We observed that the dielectric constant increases gradually with increasing temperature, until the transition temperature and subsequently decreases, and we were able to determine the phase transition temperatures of the tested materials. Furthermore, the results revealed that all the doped bismuth titanates keep their phase transition temperatures, which were sufficiently high, to maintain their ferroelectric properties above room temperature.

FERROELECTRIC THIN-FILM BASED TWO-DIMENSIONAL ELECTROMAGNETIC BANDGAP STRUCTURES

2006 ◽  
Vol 86 (1) ◽  
pp. 67-76
Author(s):  
UMAIR KHAN ◽  
GURU SUBRAMANYAM ◽  
SPARTAK GEVORGIAN ◽  
ANDREI VOROBIEV
Keyword(s):  
Thin Film ◽  
Ferroelectric Thin Film ◽  
Two Dimensional ◽  
Electromagnetic Bandgap
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