Local order in CVD diamond films : Comparative Raman, x-ray-diffraction, and x-ray-absorption near-edge studies

1998 ◽  
Vol 57 (22) ◽  
pp. 14123-14132 ◽  
Author(s):  
L. Fayette ◽  
B. Marcus ◽  
M. Mermoux ◽  
G. Tourillon ◽  
K. Laffon ◽  
...  
Keyword(s):  
Diamond Films ◽  
Cvd Diamond ◽  
Local Order ◽  
X Ray Diffraction ◽  
X Ray ◽  
X Ray Absorption

Grain Impingement and Intrinsic Stresses in CVD Diamond

1997 ◽  
Vol 505 ◽  
Author(s):  
S. Nijhawan ◽  
J. Rankin ◽  
B. L Walden ◽  
B. W. Sheldon
Keyword(s):  
Tensile Strain ◽  
Diamond Films ◽  
Cvd Diamond ◽  
Intermediate Annealing ◽  
X Ray Diffraction ◽  
Entire Sample ◽  
X Ray ◽  
Pole Figures ◽  
Annealing Step ◽  
Film Microstructure

ABSTRACTIntrinsic stresses in polycrystalline CVD diamond films have been related to restructuring at grain boundaries. It is speculated that reducing the interfacial energy induces an elastic tensile strain. There appears to be a correlation between the evolution of macroscopic stresses in the entire sample and localized, non-homogeneous stresses in the microstructure based on Raman Spectroscopy and x-ray diffraction pole figures. A multistep processing sequence developed previously can help reduce these stresses substantially, by using an intermediate annealing step when the diamond grains are partially coalesced. Our results suggest that small changes in the film microstructure due to annealing can reduce both homogeneous and non-homogeneous stresses.

ESR and X-ray diffraction studies of the CVD diamond films

1997 ◽  
Vol 12 (1) ◽  
pp. 53-59 ◽  
Author(s):  
K. Fabisiak ◽  
F. Rozpłoch
Keyword(s):  
Diamond Films ◽  
Cvd Diamond ◽  
X Ray Diffraction ◽  
X Ray

X-ray diffraction characterization of epitaxial CVD diamond films with natural and isotopically modified compositions

2016 ◽  
Vol 61 (6) ◽  
pp. 979-986 ◽  
Author(s):  
I. A. Prokhorov ◽  
A. E. Voloshin ◽  
V. G. Ralchenko ◽  
A. P. Bolshakov ◽  
D. A. Romanov ◽  
...  
Keyword(s):  
Diamond Films ◽  
Cvd Diamond ◽  
X Ray Diffraction ◽  
X Ray

Local atomic structure in tetragonal pure ZrO2nanopowders

2010 ◽  
Vol 43 (2) ◽  
pp. 227-236 ◽  
Author(s):  
Leandro M. Acuña ◽  
Diego G. Lamas ◽  
Rodolfo O. Fuentes ◽  
Ismael O. Fábregas ◽  
Márcia C. A. Fantini ◽  
...  
Keyword(s):  
Tetragonal Phase ◽  
Local Structure ◽  
X Ray Diffraction ◽  
X Ray ◽  
Atomic Structures ◽  
Crystallite Sizes ◽  
Exafs Study ◽  
The Difference ◽  
X Ray Absorption ◽  
Good Agreement

The local atomic structures around the Zr atom of pure (undoped) ZrO2nanopowders with different average crystallite sizes, ranging from 7 to 40 nm, have been investigated. The nanopowders were synthesized by different wet-chemical routes, but all exhibit the high-temperature tetragonal phase stabilized at room temperature, as established by synchrotron radiation X-ray diffraction. The extended X-ray absorption fine structure (EXAFS) technique was applied to analyze the local structure around the Zr atoms. Several authors have studied this system using the EXAFS technique without obtaining a good agreement between crystallographic and EXAFS data. In this work, it is shown that the local structure of ZrO2nanopowders can be described by a model consisting of two oxygen subshells (4 + 4 atoms) with different Zr—O distances, in agreement with those independently determined by X-ray diffraction. However, the EXAFS study shows that the second oxygen subshell exhibits a Debye–Waller (DW) parameter much higher than that of the first oxygen subshell, a result that cannot be explained by the crystallographic model accepted for the tetragonal phase of zirconia-based materials. However, as proposed by other authors, the difference in the DW parameters between the two oxygen subshells around the Zr atoms can be explained by the existence of oxygen displacements perpendicular to thezdirection; these mainly affect the second oxygen subshell because of the directional character of the EXAFS DW parameter, in contradiction to the crystallographic value. It is also established that this model is similar to another model having three oxygen subshells, with a 4 + 2 + 2 distribution of atoms, with only one DW parameter for all oxygen subshells. Both models are in good agreement with the crystal structure determined by X-ray diffraction experiments.

The Relative Merits of Oxides of Hafnium, Cerium and Thorium as Surrogates for Plutonium Oxide in Calcium Phosphate Ceramics

2009 ◽  
Vol 1193 ◽  
Author(s):  
B. L. Metcalfe ◽  
S. K. Fong ◽  
L. A. Gerrard ◽  
I. W. Donald ◽  
E. S. Welch ◽  
...  
Keyword(s):  
Calcium Phosphate ◽  
Calcination Temperature ◽  
Cerium Oxide ◽  
Absorption Spectroscopy ◽  
Hafnium Oxide ◽  
Intermediate Level ◽  
X Ray Diffraction ◽  
X Ray ◽  
X Ray Absorption ◽  
Additional Phase

AbstractThe choice of surrogate for plutonium oxide for use during the initial stages of research into the immobilization of intermediate level pyrochemical wastes containing plutonium andamericium oxides in a calcium phosphate host has been investigated by powder X-ray diffraction and X-ray absorption spectroscopy. Two non-radioactive surrogates, hafnium oxide and cerium oxide, together with radioactive thorium oxide were compared. Similarities in behaviour were observed for all three surrogates when calcined at the lowest temperature, 750°C but differences became more pronounced as the calcination temperature was increased to 950°C. Although some reaction occurred between all the surrogates and the host to form a substituted whitlockite phase, increasing the temperature led to a significant increase in the cerium reaction and the formation of an additional phase, monazite. Additionally it was observed that the cerium became increasingly trivalent at higher temperatures.

Sign in / Sign up

Export Citation Format

Share Document