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 Induced Crystallization In CW Laser-Irradiated Sol-Gel Deposited Titania Films

1993 ◽  
Vol 321 ◽  
Author(s):  
Gregory J. Exarhos ◽  
Nancy J. Hess
Keyword(s):  
Laser Fluence ◽  
Sol Gel ◽  
Film Stress ◽  
Amorphous Films ◽  
Time Resolved ◽  
Cw Laser ◽  
Residual Film ◽  
Titania Films ◽  
Induced Crystallization ◽  
Nanograin Size

AbstractIsothermal annealing of amorphous TiO2 films deposited from acidic sol-gel precursor solutions results in film densification and concomitant increase in refractive index. Subsequent heating above 300°C leads to irreversible transformation to an anatase crystalline phase. Similar phenomena occur when such amorphous films are subjected to focused cw laser irradiation. Controlled variations in laser fluence are used to density or crystallize selected regions of the film. Low fluence conditioning leads to the evolution of a subtle nanograin-size morphology, evident in AFM images, which appears to retard subsequent film crystallization when such regions are subjected to higher laser fluence. Time-resolved Raman spectroscopy has been used to characterize irradiated regions in order to follow the crystallization kinetics, assess phase homogeneity, and evaluate accompanying changes in residual film stress.

scholarly journals Induced Crystallization in CW Laser-Irradiated Sol-Gel Deposited Titania Films

1993 ◽  
Vol 316 ◽  
Author(s):  
Gregory J. Exarhos ◽  
Nancy J. Hess
Keyword(s):  
Laser Fluence ◽  
Sol Gel ◽  
Film Stress ◽  
Amorphous Films ◽  
Time Resolved ◽  
Cw Laser ◽  
Residual Film ◽  
Titania Films ◽  
Induced Crystallization ◽  
Nanograin Size

ABSTRACTIsothermal annealing of amorphous TiO2 films deposited from acidic sol-gel precursor solutions results in film densification and concomitant increase in refractive index. Subsequent heating above 300°C leads to irreversible transformation to an anatase crystalline phase. Similar phenomena occur when such amorphous films are subjected to focused cw laser irradiation. Controlled variations in laser fluence are used to density or crystallize selected regions of the film. Low fluence conditioning leads to the evolution of a subtle nanograin-size morphology, evident in AFM images, which appears to retard subsequent film crystallization when such regions are subjected to higher laser fluence. Time-resolved Raman spectroscopy has been used to characterize irradiated regions in order to follow the crystallization kinetics, assess phase homogeneity, and evaluate accompanying changes in residual film stress.

scholarly journals Bulk modulus of H2O across the ice VII–ice X transition measured by time-resolved x-ray diffraction in dynamic diamond anvil cell experiments

2021 ◽  
Vol 103 (6) ◽  
Author(s):  
A. S. J. Méndez ◽  
F. Trybel ◽  
R. J. Husband ◽  
G. Steinle-Neumann ◽  
H.-P. Liermann ◽  
...  
Keyword(s):  
Bulk Modulus ◽  
Diamond Anvil Cell ◽  
X Ray Diffraction ◽  
Time Resolved ◽  
X Ray ◽  
Diamond Anvil

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.

scholarly journals A new internally heated diamond anvil cell system for time-resolved optical and x-ray measurements

2020 ◽  
Vol 91 (8) ◽  
pp. 085114
Author(s):  
Yimin Mijiti ◽  
Marco Perri ◽  
Jean Coquet ◽  
Lucie Nataf ◽  
Marco Minicucci ◽  
...  
Keyword(s):  
Diamond Anvil Cell ◽  
Cell System ◽  
Time Resolved ◽  
X Ray ◽  
Diamond Anvil

scholarly journals Compression-rate dependence of pressure-induced phase transitions in Bi

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Rachel J. Husband ◽  
Earl F. O’Bannon ◽  
Hanns-Peter Liermann ◽  
Magnus J. Lipp ◽  
Alba S. J. Méndez ◽  
...  
Keyword(s):  
Diamond Anvil Cell ◽  
Nucleation And Growth ◽  
Compression Rate ◽  
X Ray Diffraction ◽  
Phase Boundaries ◽  
Time Resolved ◽  
Future Studies ◽  
X Ray ◽  
Diamond Anvil ◽  
Stress States

AbstractIt is qualitatively well known that kinetics related to nucleation and growth can shift apparent phase boundaries from their equilibrium value. In this work, we have measured this effect in Bi using time-resolved X-ray diffraction with unprecedented 0.25 ms time resolution, accurately determining phase transition pressures at compression rates spanning five orders of magnitude (10–2–103 GPa/s) using the dynamic diamond anvil cell. An over-pressurization of the Bi-III/Bi-V phase boundary is observed at fast compression rates for different sample types and stress states, and the largest over-pressurization that is observed is ΔP = 2.5 GPa. The work presented here paves the way for future studies of transition kinetics at previously inaccessible compression rates.

Time‐resolved stimulated Raman scattering in a diamond anvil cell

1987 ◽  
Vol 86 (4) ◽  
pp. 2423-2427 ◽  
Author(s):  
Michael Baggen ◽  
Martin van Exter ◽  
Ad Lagendijk
Keyword(s):  
Raman Scattering ◽  
Diamond Anvil Cell ◽  
Stimulated Raman Scattering ◽  
Time Resolved ◽  
Diamond Anvil ◽  
Stimulated Raman

scholarly journals Time-Resolved Synchrotron X-ray Diffraction on Pulse Laser Heated Iron in Diamond Anvil Cell

2012 ◽  
Vol 377 ◽  
pp. 012108 ◽  
Author(s):  
Choong-Shik Yoo ◽  
Haoyan Wei ◽  
Ranga Dias ◽  
Guoyin Shen ◽  
Jesse Smith ◽  
...  
Keyword(s):  
Pulse Laser ◽  
Diamond Anvil Cell ◽  
X Ray Diffraction ◽  
Time Resolved ◽  
X Ray ◽  
Diamond Anvil ◽  
Laser Heated

scholarly journals Time-Resolved Reflectivity Measurement of the Pressure-Enhanced Crystallization Rate of Amorphous Si in a Diamond Anvil Cell

1988 ◽  
Vol 100 ◽  
Author(s):  
G. Q. Lu ◽  
E. Nygren ◽  
M. J. Aziz ◽  
D. Turnbull ◽  
C. W. White
Keyword(s):  
Pressure Dependence ◽  
Diamond Anvil Cell ◽  
Activation Volume ◽  
Solid Phase ◽  
Crystallization Rate ◽  
Time Resolved ◽  
Reflectivity Measurement ◽  
Diamond Anvil ◽  
Fluid Argon

ABSTRACTWe have measured the pressure dependence of the solid phase epitaxial growth (SPEG) rate of self-implanted Si (100) by using the in-situ time-resolved reflectivity technique [1] in a hightemperature and high-pressure diamond anvil cell (DAC). With fluid argon as the pressure transmission medium, a clean and perfectly hydrostatic pressure environment is achieved around the sample. The external heating geometry employed in the DAC provides a uniform temperature across the sample. At temperatures in the range of 530 – 550 °C and pressure up to 50 kbars (5 GPa), the growth rate is enhanced by up to a factor of ten over that at 1 atmosphere pressure. The results are characterized by a negative activation volume of approximately −3.0 cm3/mole (−27% of the atomic volume). These preliminary results show a significantly weaker pressure dependence than does the previous work of Nygren et al. [2], who found an activation volume of −8.7 cm3/mole. The implications of these results for the nature of the defect responsible for thermal SPEG and irradiation enhanced SPEG is discussed.

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