A detailed structural analysis and phase‐stabilization study of tetragonal (t‐) ZrO2 in α‐Al2O3–ZrO2 composites has been performed via Rietveld refinement of X‐ray powder diffraction data and Fourier ...transform infrared (FTIR) spectroscopy. It is observed that the tetragonal distortion (δ) of t‐ZrO2 in the composites is similar to that of pure t‐ZrO2. Although the average Zr—O bond distances are similar to those of other cation‐doped zirconias, the X‐ray and FTIR study gave no indication of Al2O3–ZrO2 solid‐solution formation. It is concluded that other factors, such as oxygen vacancies, play a significant role in the stabilization process. It may be argued that size‐stabilized t‐ZrO2 is actually an oxygen‐deficient form.
We report here the draft genome sequence of the filamentous nitrogen-fixing cyanobacterium Tolypothrix boutellei strain VB521301. The organism is lipid rich and hydrophobic and produces ...polyunsaturated fatty acids which can be harnessed for industrial purpose. The draft genome sequence assembled into 11,572,263 bp with 70 scaffolds and 7,777 protein coding genes.
The variation of hardness on (1
0
0) faces of orthorhombic ammonium sulphate crystals, AS (NH
4)
2SO
4, with load were studied. Vickers hardness numbers,
H
v, were found to increase with the increase ...in load. Work-hardening index ‘
n’ was found to be greater than 2 showing soft-material characteristics. Kick’s law has been satisfied after making a correction in the observed diagonal length of the indentation impression. The fracture toughness values ‘
K
c’, determined from measurements of crack lengths, were estimated to be 0.078 and 0.073
MN
m
−3/2 for (1
0
0) faces at 90 and 100
g, respectively. The brittleness indices ‘
B
i’ were estimated as 1.79 and 2.04
μm
−1/2 for the same faces at same loads. Using Wooster’s empirical relation, elastic stiffness coefficient,
c
11, has been calculated from hardness value.
α‐Al2O3 prepared by combustion technique was ball‐milled in a planetary ball‐mill for several hours. A detail microstructural characterization of the ball‐milled samples was performed by X‐ray line ...broadening analysis. X‐ray diffraction patterns from the milled materials showed super‐Lorentzian peak shapes for the α‐Al2O3 peak profiles, attributed to a bimodal size distribution of the α‐Al2O3 crystallites, one type of crystallites having spherical and the other having cylindrical morphology. Rietveld analysis using two different phase fractions of α‐Al2O3 with different microstructural features yielded a low goodness‐of‐fit of the X‐ray data, indicating the suitability of the assumed model.
α-Al
2
O
3
prepared by combustion technique was ball-milled in a planetary ball-mill for several hours. A detail microstructural characterization of the ball-milled samples was performed by X-ray ...line broadening analysis. X-ray diffraction patterns from the milled materials showed super-Lorentzian peak shapes for the α-Al
2
O
3
peak profiles, attributed to a bimodal size distribution of the α-Al
2
O
3
crystallites, one type of crystallites having spherical and the other having cylindrical morphology. Rietveld analysis using two different phase fractions of α-Al
2
O
3
with different microstructural features yielded a low goodness-of-fit of the X-ray data, indicating the suitability of the assumed model.
A detailed structural analysis and phase-stabilization study of tetragonal (
t
-) ZrO
2
in α-Al
2
O
3
–ZrO
2
composites has been performed
via
Rietveld refinement of X-ray powder diffraction data and ...Fourier transform infrared (FTIR) spectroscopy. It is observed that the tetragonal distortion (δ) of
t
-ZrO
2
in the composites is similar to that of pure
t
-ZrO
2
. Although the average Zr—O bond distances are similar to those of other cation-doped zirconias, the X-ray and FTIR study gave no indication of Al
2
O
3
–ZrO
2
solid-solution formation. It is concluded that other factors, such as oxygen vacancies, play a significant role in the stabilization process. It may be argued that size-stabilized
t
-ZrO
2
is actually an oxygen-deficient form.
A detailed structural analysis and phase-stabilization study of tetragonal (t -) ZrO2 in alpha-Al2O3-ZrO2 composites has been performed via Rietveld refinement of X-ray powder diffraction data and ...Fourier transform infrared (FTIR) spectroscopy. It is observed that the tetragonal distortion (delta) of t -ZrO2 in the composites is similar to that of pure t -ZrO2. Although the average Zr--O bond distances are similar to those of other cation-doped zirconias, the X-ray and FTIR study gave no indication of Al2O3-ZrO2 solid-solution formation. It is concluded that other factors, such as oxygen vacancies, play a significant role in the stabilization process. It may be argued that size-stabilized t -ZrO2 is actually an oxygen-deficient form.
alpha-Al2O3 prepared by combustion technique was ball-milled in a planetary ball-mill for several hours. A detail microstructural characterization of the ball-milled samples was performed by X-ray ...line broadening analysis. X-ray diffraction patterns from the milled materials showed super-Lorentzian peak shapes for the alpha-Al2O3 peak profiles, attributed to a bimodal size distribution of the alpha-Al2O3 crystallites, one type of crystallites having spherical and the other having cylindrical morphology. Rietveld analysis using two different phase fractions of alpha-Al2O3 with different microstructural features yielded a low goodness-of-fit of the X-ray data, indicating the suitability of the assumed model. PUBLICATION ABSTRACT
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