Influence of Interfaces on the Phase Stability in Nanostructured Thin Film Multilayers

2002 ◽  
Vol 727 ◽  
Author(s):  
G.B. Thompson ◽  
R. Banerjee ◽  
S.A. Dregia ◽  
H.L. Fraser
Keyword(s):  
Thin Film ◽  
Phase Stability ◽  
Interfacial Energy ◽  
Structural Component ◽  
Volume Fraction ◽  
Stability Diagram ◽  
Dislocation Network ◽  
Classical Thermodynamic ◽  
Nanostructured Thin Film ◽  
Phase Stability Diagram

AbstractNanostructured thin film multilayers, comprising of alternating A/B layers, can exhibit metastable structures in one or both layers. From a classical thermodynamic viewpoint, the reduction interfacial energy is primarily responsible for this stabilizing effect. Based on this idea, a model has been constructed in which phase stability regions are represented as functions of both the bilayer thickness and volume fraction of the one the layers. Applying this classical thermodynamic model to a single, previously reported hcp to bcc transformation in Zr for Zr/Nb multilayers, a phase stability diagram was proposed. Various Zr/Nb multilayers with different bilayer thicknesses and volume fractions have been sputtered deposited. hcp to bcc transformations in the Zr layer were confirmed by x-ray and electron diffraction. Furthermore the Zr/Nb stability diagram predicted a novel hcp Nb phase which was subsequently verified experimentally. Using Zr/Nb as a guide, a similar phase stability diagram was constructed and experimentally determined for Ti/Nb multilayers. For each multilayer system, the reduction in interfacial energy was calculated from the experimentally determined diagram. These values were then compared to estimations of the structural component of the interfacial energy. The structural component was based on the energy per unit area of a misfit dislocation network constructed by an o-lattice. This simple assesment suggests that the reduction of the structural component of the interfacial energy is sufficient to drive the transformation.

Phase stability diagram program for personal computers

Calphad ◽  
1988 ◽  
Vol 12 (2) ◽  
pp. 185-190 ◽  
Author(s):  
W.C. Russell ◽  
N. Shah ◽  
H. Alan Fine
Keyword(s):  
Phase Stability ◽  
Stability Diagram ◽  
Personal Computers ◽  
Phase Stability Diagram

First-principles studies of polar perovskite KTaO3 surfaces: structural reconstruction, charge compensation, and stability diagram

2018 ◽  
Vol 20 (27) ◽  
pp. 18515-18527 ◽  
Author(s):  
Yaqin Wang ◽  
Jianli Cheng ◽  
Maziar Behtash ◽  
Wu Tang ◽  
Jian Luo ◽  
...  
Keyword(s):  
Phase Stability ◽  
First Principles ◽  
Charge Compensation ◽  
Stability Diagram ◽  
First Principles Calculations ◽  
Surface Phase ◽  
Phase Stability Diagram

First-principles calculations predict a surface phase stability diagram for the polar perovskite KTaO3.

A Thermodynamic Approach in Tuning Phase Stability in Nanocomposite Multilayers

2003 ◽  
Vol 788 ◽  
Author(s):  
G. B. Thompson ◽  
R. Banerjee ◽  
H. L. Fraser
Keyword(s):  
Functional Properties ◽  
Phase Stability ◽  
Volume Fraction ◽  
Stability Diagram ◽  
Free Energies ◽  
Two Phase ◽  
New Type ◽  
Interfacial Free Energies ◽  
Stabilizing Element ◽  
Good Agreement

ABSTRACTChanges in the crystallographic phase stability of individual layers in a multilayered thin film stack are expected to have a significant influence upon the functional properties of the structure. The ability to predict and tune these phase stability states is of relevant importance in order to maximize the functional properties of the multilayer. A classical thermodynamic methodology, based upon competitive volumetric and interfacial free energies, has been used in the prediction and subsequent confirmation of the hcp to bcc phase stability in a Ti/Nb multilayer. An outcome of this model is a new type of phase stability diagram that can be used to predict the hcp Ti and bcc Ti phase stability as a function of length scale and volume fraction. The Ti layers were subsequently alloyed with a bcc-stabilizing element. The alloyed sputtered deposited Ti layers were able to stabilize the bcc Ti phase to a larger layer thickness as compared to the unalloyed Ti/Nb multilayers. The percentage of alloying element added to the Ti layer in controlling the critical transition thickness between the two phase states had good agreement with the predictions proposed by the thermodynamic model.

Raman Studies of Stress-Induced Phase Transformations in Titania Films

1991 ◽  
Vol 230 ◽  
Author(s):  
Gregory J. Exarhos ◽  
Nancy J. Hess
Keyword(s):  
Diamond Anvil Cell ◽  
Phonon Frequency ◽  
Volume Fraction ◽  
Sol Gel ◽  
Stability Diagram ◽  
Film Stress ◽  
Time Resolved ◽  
Phase Stability Diagram ◽  
Diamond Anvil ◽  
Titania Films

AbstractTime-resolved micro-Raman spectroscopy is used to follow the amorphous to crystalline phase transformation in sol-gel deposited titania films induced thermally or through the action of applied hydrostatic pressure in a diamond anvil cell. Time-dependent phonon intensities intrinsic to the growing phase are related to the volume fraction of crystallite present at any time. The sigmoidally generated curves can be modeled in terms of modified Avrami ingrowth kinetics in which diffusion of the amorphous phase to the nucleation center is restricted by the morphology of the evolving phase. Phonon frequency and linewidth measurements during the course of the transformation probe changes in film stress and particle size which are used to understand the mechanistics of the transformation. Raman measurements also are used to derive a phase stability diagram for titania films.

scholarly journals Phase Stability Diagrams for Nanostructured Thin Film Multilayers

2003 ◽  
Vol 9 (S02) ◽  
pp. 292-293
Author(s):  
G. B. Thompson ◽  
R. Banerjee ◽  
H. L. Fraser
Keyword(s):  
Thin Film ◽  
Phase Stability ◽  
Stability Diagrams ◽  
Nanostructured Thin Film

The relaxation of compressive biaxial strains in SOS via microtwins

1989 ◽  
Vol 47 ◽  
pp. 608-609
Author(s):  
M. E. Twigg ◽  
E. D. Richmond ◽  
J. G. Pellegrino
Keyword(s):  
Thin Film ◽  
Chemical Vapor Deposition ◽  
Molecular Beam Epitaxy ◽  
Compressive Stress ◽  
Vapor Deposition ◽  
Partial Dislocation ◽  
Molecular Beam ◽  
Volume Fraction ◽  
Chemical Vapor ◽  
Silicon Thin Film

For heteroepitaxial systems, such as silicon on sapphire (SOS), microtwins occur in significant numbers and are thought to contribute to strain relief in the silicon thin film. The size of this contribution can be assessed from TEM measurements, of the differential volume fraction of microtwins, dV/dν (the derivative of the microtwin volume V with respect to the film volume ν), for SOS grown by both chemical vapor deposition (CVD) and molecular beam epitaxy (MBE).In a (001) silicon thin film subjected to compressive stress along the [100] axis , this stress can be relieved by four twinning systems: a/6[211]/( lll), a/6(21l]/(l1l), a/6[21l] /( l1l), and a/6(2ll)/(1ll).3 For the a/6[211]/(1ll) system, the glide of a single a/6[2ll] twinning partial dislocation draws the two halves of the crystal, separated by the microtwin, closer together by a/3.

Dip Coating From Density Mismatching Mixture

2021 ◽  
Author(s):  
Bashir Khoda ◽  
AMM Nazmul Ahsan ◽  
SM Abu Shovon
Keyword(s):  
Thin Film ◽  
Particle Size ◽  
Volume Fraction ◽  
Steel Wire ◽  
Cost Effective ◽  
Dip Coating ◽  
Solid Loading ◽  
Heterogeneous Mixture ◽  
Inorganic Particles ◽  
Inorganic Particle

Abstract Solid transfer technology from mixtures is gaining ever-increasing attention from materials scientists and production engineers due to their high potential in near net-shaped production of cost-effective engineering components. Dip coating, a wet deposition method, is an effective and straightforward way of thin-film/layers formation. The dipping mixtures are often embedded with inorganic fillers, nanoparticles, or clusters (d<30 nm) that produce a thin film ranging from nm to couple microns. An increase in the volume of solid transfer by the dipping process can open-up a novel 3D near-net-shape production. However, adding larger inorganic particle size (>1µm) or adding a higher solid fraction will increase the solid transfer but may result in a multi-phase heterogeneous mixture. In this work, the physical mechanism of an increased volume of solid transfer with a larger spherical particle size (>5 µm) is investigated. Polymer-based glue and evaporating solvent are mixed to construct the liquid carrier system (LCS). Moderate volume fraction of inorganic particles (20% < ?p < 50%) are added into the LCS solution as solid loading. Three levels of binder volume fraction are considered to investigate the effect of the solid transfer. Cylindrical AISI 304 steel wire with dia 0.81 mm is dipped and the coating thickness, weight, and the surface packing coverage by the particles are measured in our lab. The results presented the influence of volume fraction of inorganic particle and glue composition on the solid transfer from the heterogeneous mixture.

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