Thermodynamics of Epitaxial Ferroelectric Films.

1995 ◽  
Vol 401 ◽  
Author(s):  
S. B. Desu ◽  
V. P. Dudkevich ◽  
P. V. Dudkevich ◽  
I. N. Zakharchenko ◽  
G. L. Kushlyan
Keyword(s):  
Thermal Expansion ◽  
Phase Transitions ◽  
Misfit Dislocations ◽  
Ferroelectric Films ◽  
Growth Stresses ◽  
Substrate Interaction ◽  
Thermal Expansion Coefficients ◽  
Expansion Coefficients ◽  
The Difference ◽  
Film Substrate

AbstractThe problem of phase transitions and physical properties of the BaTiO3-type films on the (001) single-crystal substrates of the cubic syngony was solved in the limits of the Landau- Devonshire thermodynamics. The thermoelastic film-substrate interaction caused by the difference between thermal expansion coefficients was strictly taken into consideration. The model was based on the following assumptions: 1) the film is closely conjugated with the substrate; 2) the film is sufficiently “thick”to find itself unstrained at the growth temperature Ts, ( growth stresses were compensated by misfit dislocations ), and 3) the film is sufficiently “thin, and the stresses arising at the temperatures T>Ts may be considered to be uniform.

Athermal Motion of Grain Boundaries, Twins and Triple Junctions in Zn

2004 ◽  
Vol 467-470 ◽  
pp. 801-806 ◽  
Author(s):  
Vera G. Sursaeva
Keyword(s):  
Thermal Expansion ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Triple Junction ◽  
Triple Junctions ◽  
Thermal Expansion Coefficients ◽  
Expansion Coefficients ◽  
The Difference ◽  
The Individual ◽  
Individual Grains

When a bicrystal or polycrystal are subjected to a change in temperature, the individual responses of the two adjoining crystals may differ in a manner, which tends to produce a dilatational mismatch along grain boundaries. If compatibility is to be retained along the interface, an additional set of stresses must then be generated in order to conserve this compatibility. ‘Compatibility stresses’ will also be generated whenever a polycrystal is heated or cooled and the thermal expansion coefficients of the individual grains are different due to thermal expansion anisotropy. In such cases adjacent grains will attempt to change dimensions and develop mismatches by amounts controlled by the parameter Δa*ΔΤ, where Δa is the difference between the thermal expansion coefficients in the appropriate directions, and ΔΤ is the temperature change. These ‘compatibility stresses’ may be relieves if grain boundary motion, triple junction migration and grain growth are possible. These ‘compatibility stresses’ may play important role in the kinetic behavior of the microstructure ranging from influencing the behavior of lattice dislocations near the grain boundaries to promoting grain boundary and triple junction dragging or moving. The motion of the ‘special’ grain boundaries, triple junctions with ‘special’ grain boundaries and twins under the influence of internal mechanical stresses is the main subject of this paper.

Study of the Ti-Mn-Al-Si-O-S Complex Inclusions Inducing Intragranular Acicular Ferrite

2012 ◽  
Vol 535-537 ◽  
pp. 620-627 ◽  
Author(s):  
Chengwei Yang ◽  
Min Jiang ◽  
Xinhua Wang ◽  
Tie Ou
Keyword(s):  
Thermal Expansion ◽  
Confocal Laser ◽  
Complex Inclusion ◽  
Inclusion Formation ◽  
The Core ◽  
Thermal Expansion Coefficients ◽  
Intragranular Acicular Ferrite ◽  
Expansion Coefficients ◽  
The Difference ◽  
Confocal Laser Microscope

High temperature confocal laser microscope, FE-SEM-EDS and EPMA were utilized to study the Ti-Mn-Al-Si-O-S complex inclusion inducing IAF in Ti deoxidized steel. FactStage was also used to calculate the thermodynamics of inclusion formation. It was demonstrated that when the cooling rate is fixed to 5°C/s, IAF can be induced by complex inclusions which act as the core of IAF at 609°C. Microstructure of the complex inclusions is complicated. These inclusions are consisted of the TiOx-MnO core which is surrounded by MnO-Al2O3-SiO2 complex inclusions and small amount of MnS. The reason that Ti-Mn-Al-Si-O-S complex inclusions can induce IAF is that a Mn-depleted zone is formed by the core TiOx-MnO and the MnS around it. Meanwhile, the difference between MnO-Al2O3-SiO2 and austenite thermal expansion coefficients is tremendous is another principle element for the IAF formation.

High-temperature X-ray diffraction study of Ag2S-Cu2S system

2020 ◽  
pp. 2150018
Author(s):  
Y. G. Asadov ◽  
Y. I. Aliyev ◽  
A. O. Dashdemirov ◽  
S. H. Jabarov ◽  
T. G. Naghiyev
Keyword(s):  
Thermal Expansion ◽  
Phase Transitions ◽  
High Temperature ◽  
X Ray Diffraction ◽  
X Ray ◽  
Thermal Expansion Coefficients ◽  
Cubic Phases ◽  
Temperature Ranges ◽  
Expansion Coefficients ◽  
Xrd Method

Single crystals of AgCuS, [Formula: see text], [Formula: see text] and [Formula: see text] compounds were synthesized using the Bridgman method. The crystal structures and phase transitions were studied by X-ray diffraction (XRD) method in the high temperature ranges. The monoclinic, orthorhombic, hexagonal and cubic phases were observed in the temperature range of [Formula: see text]. Thermal expansion coefficients were calculated for different phases according to the lattice parameters. It was determined that the values of thermal expansion coefficients differ in different planes depending on the space group and symmetry.

Thermophysical Properties of Gd2O3 Doped SrHfO3 Ceramic

2015 ◽  
Vol 816 ◽  
pp. 237-241 ◽  
Author(s):  
Wen Ma ◽  
Yi Ren ◽  
Xi Long Jin ◽  
Ya Hong Liang ◽  
Bao Dong Chen ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Thermal Expansion ◽  
Phase Transitions ◽  
High Temperature ◽  
Solid State ◽  
Solid State Reaction Method ◽  
Reaction Method ◽  
Long Period ◽  
Thermal Expansion Coefficients ◽  
Expansion Coefficients

Gd2O3 (10mol%) doped SrHfO3 (Sr (Hf0.9Gd0.1)O2.95) was synthesized by solid state reaction method. The phase stability of the synthesized Sr (Hf0.9Gd0.1)O2.95 powder at high temperature of 1450 oC for a long period and in a temperature range of RT-1400 oC was characterized by XRD and DSC, respectively. The thermal expansion coefficients (TECs) of bulk Sr (Hf0.9Gd0.1)O2.95 were recorded by a high-temperature dilatometer, indicating that the phase transitions of SrHfO3 are suppressed remarkably by doping Gd2O3. The thermal conductivity of bulk Sr (Hf0.9Gd0.1)O2.95 at 1000 oC is ~1.95 W/m·K, which is ~11% lower than that of bulk 8YSZ.

A Study on Metal-Ceramic Thermal Expansion Compatibility

2014 ◽  
Vol 216 ◽  
pp. 85-90
Author(s):  
Marian Miculescu ◽  
Mihai Branzei ◽  
Florin Miculescu ◽  
Daniela Meghea ◽  
Marin Bane
Keyword(s):  
Thermal Expansion ◽  
Bonding Strength ◽  
Linear Thermal Expansion ◽  
Metal Bonding ◽  
Thermal Expansion Coefficients ◽  
Metal Ceramic ◽  
Thermal Compatibility ◽  
Expansion Coefficients ◽  
The Difference ◽  
Dental Applications

Push rod method for determining linear thermal expansion using vertical differential dilatometer was used in the study of the thermal compatibility of metal-ceramic systems for dental applications. The purpose of this study consisted in evaluating the effectiveness of dental coating by determining the ceramic metal bonding strength of metal-ceramic couples (Ni-Cr and Co-Cr alloy coated with dental ceramic) and correlation with the difference of linear thermal expansion coefficients of metals and ceramics.

Thermal Stability of the Structural and Electronic Properties of Strain Symmetrized Sim Gen Superlattices and Ungraded, Nearly Relaxed Si1−x Gex

1992 ◽  
Vol 281 ◽  
Author(s):  
P. A. Dafesh ◽  
P. M. Adams ◽  
V. Arbet-Engels ◽  
K. L. Wang
Keyword(s):  
Thermal Expansion ◽  
Energy Shift ◽  
Buffer Layers ◽  
X Ray ◽  
Lattice Constants ◽  
Thermal Expansion Coefficients ◽  
Structural And Electronic Properties ◽  
Expansion Coefficients ◽  
The Difference ◽  
Anneal Temperature

ABSTRACTIn this study, photoreflectance (PR) spectroscopy and x-ray rocking curves measurements were used to study the variation in strain configuration, defect propagation, structural properties and direct electronic transition energies in Sim Gen superlattices (SL) and nearly relaxed Si1−x Gex buffer layers grown on < 100 > Si as a function of annealing temperature. The in-plane (a│) and perpendicular (a┴) lattice constants of the alloy buffer layers are found to vary only slightly with anneal temperature, TA, up to a temperature To. For TA To, the in-plane strain changed from roughly zero a│ ≈ a┴ (relaxed) or a┴ > a│ (compressive) to a┴ > a│ (tensile). This change in strain configuration is believed to be caused by the difference in thermal expansion coefficients between the epilayer and the Si substrate. The anneal temperature T0 is also correlated with the disappearance of higher order x-ray harmonics from the SL. This point was also correlated with a large energy shift and broadening of the PR spectra from the SL. The shift in energy of the PR spectra is explained in terms of the interdiffusion of Si and Ge at SL heterointerfaces, and to a lesser degree, the strain induced by the above mentioned difference in thermal expansion coefficients. The PR spectra of the alloy E0 transitions are also observed to shift to higher energy with increasing TA.

Defect Reduction by Thermal Cyclic Growth in GaAs Grown on Si by Movpe

1993 ◽  
Vol 325 ◽  
Author(s):  
W. KÜrner ◽  
R. Dieter ◽  
K. Zieger ◽  
F. Goroncy ◽  
A. DÖrnen ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Thermal Stress ◽  
Dislocation Density ◽  
Lattice Mismatch ◽  
Gaas Layer ◽  
Defect Reduction ◽  
Thermal Expansion Coefficients ◽  
Related Defect ◽  
Expansion Coefficients ◽  
The Difference

AbstractThe growth of GaAs epilayers on Si should combine the advantages of both materials. The lattice mismatch and the difference in thermal expansion coefficients, however, result in the yet unsolved problems of high dislocation density and thermal stress in the GaAs layer. Recently, considerable improvements have been achieved by a ‘thermal cyclic growth’ (TCG) process. In this study we focus on the reduction of high defect concentration and dislocation density. The improvement of the epilayer quality is verified by DLTS, PL and DCXD. Results of TEM and DLTS measurements lead to the identification of a dislocation related defect.

scholarly journals Деформация тонких пленок полуметаллов методом купольного изгиба подложки

2022 ◽  
Vol 56 (2) ◽  
pp. 178
Author(s):  
А.В. Суслов ◽  
В.А. Герега ◽  
В.М. Грабов ◽  
Е.В. Демидов ◽  
В.А. Комаров
Keyword(s):  
Thermal Expansion ◽  
Plane Deformation ◽  
X Ray Diffraction ◽  
Temperature Expansion ◽  
X Ray ◽  
Deformation Control ◽  
Thermal Expansion Coefficients ◽  
Bismuth Films ◽  
Expansion Coefficients ◽  
Film Substrate

The results of a study of the semimetal films deformation produced by dome bending of the substrate are presented. Deformation control was carried out by means of X-ray diffraction analysis. It is shown that the dome bending method can be used to study films under planar deformation in a film-substrate system with different thermal expansion coefficients. The maximum in-plane deformation for bismuth films of 1 mkm thickness order was found. It was shown that the deformation created by the dome bending of the substrate in combination with the use of substrates with different temperature expansion makes it possible to obtain a relative in-plane deformation of bismuth films up to 0.8% at 300 K.

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