Neutron Diffraction Study of the Pseudo-Macro Residual Stresses in ZrO2(CeO2)/Al2O3 Ceramic Composites

1992 ◽  
Vol 36 ◽  
pp. 499-504
Author(s):  
Xun-Li Wang ◽  
C. R. Hubbard ◽  
K. B. Alexander ◽  
P. F. Becher ◽  
J. A. Fernandez-Baca ◽  
...  
Keyword(s):  
Neutron Diffraction ◽  
Residual Stresses ◽  
Volume Fraction ◽  
Structure Refinement ◽  
Ceramic Composites ◽  
Neutron Diffraction Study ◽  
Neutron Powder Diffraction ◽  
The Other ◽  
Al2o3 Ceramic ◽  
Sintering Time

AbstractNeutron powder diffraction techniques have been used to characterize the pseudo-macro (PM) residual stresses in ZrO2(CeO2)/Al2O3 ceramic composites as a function of ZrO2(CeO2) volume fraction and fabrication procedures. The diffraction data were analyzed using the Rietveld structure refinement technique. From the refinement, we found that the CeO2 stabilized tetragonal ZrO2 particles were in tension and the Al2O3 matrix was in compression. Different sintering time had little impact on the PM stresses. On the other hand, the magnitude of the PM stresses in both ZrO2 and Al2O3 decreased linearly with the increase of their volume fractions.

Neutron Diffraction Study of the Pseudo-Macro Residual Stresses in ZrO2 (CeO2) /Al2O3 Ceramic Composites

1993 ◽  
pp. 499-504
Author(s):  
Xun-Li Wang ◽  
C. R. Hubbard ◽  
K. B. Alexander ◽  
P. F. Becher ◽  
J. A. Fernandez-Baca ◽  
...  
Keyword(s):  
Neutron Diffraction ◽  
Residual Stresses ◽  
Diffraction Study ◽  
Ceramic Composites ◽  
Neutron Diffraction Study ◽  
Al2o3 Ceramic

Residual stresses in Al2O3/Y-TZP Ceramic Laminates Fabricated by Tape and Slip Casting

2008 ◽  
Vol 571-572 ◽  
pp. 327-332 ◽  
Author(s):  
Jesus Ruiz-Hervias ◽  
Giovanni Bruno ◽  
Jonas Gurauskis ◽  
A.J. Sanchez-Herencia ◽  
C. Baudin
Keyword(s):  
Residual Stress ◽  
Neutron Diffraction ◽  
Residual Stresses ◽  
Volume Fraction ◽  
Tape Casting ◽  
Slip Casting ◽  
Ceramic Composites ◽  
Processing Route ◽  
Alumina Matrix ◽  
Stress Profiles

Residual stress profiles were measured by neutron diffraction in Al2O3/Y-TZP ceramic composites containing 5 and 40 vol.% Y-TZP fabricated by conventional slip casting and by a novel tape casting route. Residual stresses in the zirconia are tensile and increase as its volume fraction decreases. For the alumina matrix, residual stress is compressive and increases with the zirconia volume fraction. In the composite with 5 vol.% zirconia, the processing route does not have an influence on residual stresses. However, in the composite with 40 vol.% zirconia, residual stresses are different in the samples obtained by both processing routes.

Hydrogen-bond network in cyclodecaamylose hydrate at 20 K; neutron diffraction study of novel structural motifs band-flip and kink in α-(1→4)-D-glucoside oligosaccharides

2001 ◽  
Vol 57 (6) ◽  
pp. 833-841 ◽  
Author(s):  
K. Imamura ◽  
O. Nimz ◽  
J. Jacob ◽  
D. Myles ◽  
S. A. Mason ◽  
...  
Keyword(s):  
Hydrogen Bonds ◽  
Neutron Diffraction ◽  
Diffraction Study ◽  
Structure Refinement ◽  
Neutron Diffraction Study ◽  
The Other ◽  
Water Molecules ◽  
Hydroxyl Groups ◽  
Neutron Density ◽  
Asymmetric Unit

A single-crystal neutron diffraction study of cyclodecaamylose (CA10) was carried out at 20 K. CA10 crystallizes with 27.18 water molecules [(C6H10O5)10·27.18H2O] in space group C2 with unit-cell constants a = 29.31 (5), b = 9.976 (10), c = 19.34 (2) Å, β = 121.07 (2)°. The asymmetric unit contains a half molecule of CA10 and 13.59 water molecules, the other half being related by a crystallographic twofold rotation axis. All H atoms except two water H atoms could be located from difference neutron-density maps; structure refinement converged at R = 0.635. Two of the five CH2—O6 groups and one of the 15 O2, O3 hydroxyl groups of CA10 are twofold orientationally disordered. A total of 13.59 water molecules in the asymmetric unit are distributed over 23 positions; 20 of which are in the CA10 cavity, and the other three occupy intermolecular interstices. Of the 123 symmetry-independent hydrogen bonds, 25 (= 20%) are three-centered and 7 (= 6%) are four-centered. Water molecules and O—H groups of CA10 form an extended network with cooperative O—H...O—H...O—H hydrogen bonds. They are arranged in 11 polygons with three, four, five, six and eight O—H bonds and in homodromic, antidromic and heterodromic arrangements. Nine polygons are located within the cavity and the others are outside.

Neutron Diffraction Study on Intermetallic Er5Mg24 and Tm5Mg24

2004 ◽  
Vol 443-444 ◽  
pp. 263-266 ◽  
Author(s):  
Wolfgang Schäfer ◽  
K.H.J. Buschow
Keyword(s):  
Neutron Diffraction ◽  
Powder Diffraction ◽  
Room Temperature ◽  
Neutron Diffraction Study ◽  
Neutron Powder Diffraction ◽  
Magnetic Exchange ◽  
Lattice Constants ◽  
Group I ◽  
Temperature Lattice ◽  
Curie Temperatures

Neutron powder diffraction on the binary intermetallics Er5Mg24 and Tm5Mg24 confirms their isostructural and pure crystallization in the Ti5Re24-type structure (space group I 4 3m, Z = 2)with rare earths located in 2a(0,0,0) and 8c(x,x,x) and Mg in two different 24g(x,y,x) sites. Room temperature lattice constants are 11.263(2) Å and 11.215(1) Å for the Er and Tm compound, respectively. Atomic positions have been refined. Both compounds order ferromagnetically below Curie temperatures of 17.5(5) K and 7.5(5) K for Er5Mg24 and Tm5Mg24, respectively. The magnitudes of the Er moments at 4.2 K are 7.5(2) µB and 4.4(2)µB on the 2a and the 8c sites, respectively. The Tm moments which have been refined from 2 K measurements amount to 3.0(3)µB and 2.8(2) µB, respectively. The temperature dependencies of the magnetic Bragg intensities reveal distinct deviations from Brillouin curves for J = 15/2 (Er) and J = 6 (Tm) systems and indicate a complex magnetic exchange.

scholarly journals Fe-Mn cation ordering in fayalite–tephroite (FexMn1−x)2SiO4 olivines: a neutron diffraction study

1998 ◽  
Vol 62 (5) ◽  
pp. 607-615 ◽  
Author(s):  
S. A. T. Redfern ◽  
K. S. Knight ◽  
C. M. B. Henderson ◽  
B. J. Wood
Keyword(s):  
Solid Solution ◽  
Neutron Diffraction ◽  
Powder Diffraction ◽  
Metal Cation ◽  
Composition Dependence ◽  
Neutron Diffraction Study ◽  
Neutron Powder Diffraction ◽  
Cation Ordering ◽  
The Difference ◽  
Cation Sites

AbstractTime-of-flight neutron powder diffraction has been employed to determine precise occupancies of the M1 and M2 metal cation sites in synthetic olivines of compositions (Fe0.3Mn0.7)2SiO4, (Fe0.5Mn0.5)2−SiO4, and (Fe0.7Mn0.3)2SiO4. The distribution coefficient for Fe-Mn exchange in these samples has values of 4.864, 3.976, and 4.078, reflecting the preference of Mn2+ for the M2 site, over Fe2+. These results, and the behaviour of the difference in mean bond lengths of the two sites, indicate that, while showing a tendency towards ordering, the composition-dependence of the solid solution is near ideal.

Neutron powder diffraction and theory-aided structure refinement of rubidium and cesium ureate

2016 ◽  
Vol 71 (5) ◽  
pp. 431-438 ◽  
Author(s):  
Kjersti B. Sterri ◽  
Volker L. Deringer ◽  
Andreas Houben ◽  
Philipp Jacobs ◽  
Chogondahalli M.N. Kumar ◽  
...  
Keyword(s):  
Powder Diffraction ◽  
Structure Refinement ◽  
Neutron Diffraction Study ◽  
Neutron Powder Diffraction ◽  
Alkaline Metal ◽  
Hydrogen Atoms ◽  
Neutron Data ◽  
Framework Materials ◽  
Anisotropic Displacement Parameters ◽  
Hydrogen Bonding Networks

AbstractUrea (CN2H4O) is a fundamental biomolecule whose derivatives are abundant throughout chemistry. Among the latter, rubidium ureate (RbCN2H3O) and its cesium analog (CsCN2H3O) have been described only very recently and form the first structurally characterized salts of deprotonated urea. Here, we report on a neutron diffraction study on the aforementioned alkaline-metal ureates, which affords the positions for all hydrogen atoms (including full anisotropic displacement tensors) and thus allows us to gain fundamental insights into the hydrogen-bonding networks in the title compounds. The structure refinements of the experimental neutron data proceeded successfully using starting parameters from ab initio simulations of atomic positions and anisotropic displacement parameters. Such joint experimental-theoretical refinement procedures promise significant practical potential in cases where complex solids (organic, organometallic, framework materials) are studied by powder diffraction.

High Temperature Neutron Diffraction Study of the Formation Reaction of Bismuth Superconductors

1989 ◽  
Vol 169 ◽  
Author(s):  
Mary F. Garbauskas ◽  
Ronald H. Arendt ◽  
James D. Jorgensen ◽  
Richard L. Hitterman
Keyword(s):  
High Temperature ◽  
Transition Temperature ◽  
Neutron Diffraction ◽  
Diffraction Study ◽  
Partial Melting ◽  
Powder Diffraction ◽  
Neutron Diffraction Study ◽  
Neutron Powder Diffraction ◽  
Formation Reaction ◽  
Synthetic Reaction

AbstractHigh temperature neutron powder diffraction has been used to study the formation of the 110K transition temperature material, Bi2Ca2Sr2Cu3Ox (2223), both from synthetic reaction mixtures and after partial melting. The results indicate that the 80K transition temperature material, Bi2CaSr2Cu2Ox (2122), is the precursor to the (2223) material. The reaction to form the (2122) occurs rapidly at 860°C, while the conversion of this material to the (2223) is much slower.

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