Dolomite Decomposition to (Ca,Mg)O Solid Solutions: An X-Ray Diffraction Study.Part II.

1984 ◽  
Vol 39 (10) ◽  
pp. 981-985 ◽  
Author(s):  
G. Spinolo ◽  
U. Anselmi Tamburini
Keyword(s):  
Free Energy ◽  
Low Temperatures ◽  
Particle Sizes ◽  
Diffusional Process ◽  
X Ray Diffraction ◽  
High Iron Content ◽  
X Ray ◽  
Energy Of Mixing ◽  
Free Energy Of Mixing ◽  
Low Pressures

Abstract The full decomposition of dolomites with low and high iron content at low temperatures and low pressures is discussed with reference to the free energy of mixing of the ternary system Ca. Fe, Mg/O. The actual products of the primary step are a couple of rock salt structured oxides close to the spinodal compositions and with very small particle sizes. A subsequent diffusional process can produce large crystallites with equilibrium compositions, but it is effective only when either a low-iron dolomite is used as starting material or higher temperatures are employed.

Amorphous Cu-Zr and Fe-Ti Compositionally Modulated Films Produced by Sputtering from Elemental Targets

1985 ◽  
Vol 58 ◽  
Author(s):  
E. Chason ◽  
H. Kondo ◽  
T. Mizoguchi ◽  
R.C. Cammarata ◽  
F. Spaepen ◽  
...  
Keyword(s):  
Free Energy ◽  
Interdiffusion Coefficient ◽  
Ion Bombardment ◽  
Sputter Deposition ◽  
Modulation Amplitude ◽  
X Ray ◽  
Energy Of Mixing ◽  
Free Energy Of Mixing

ABSTRACTAmorphous compositionally modulated films of Cu-Zr and Fe-Ti have been prepared by sequential sputter deposition of the elemental metals. For Cu-Zr, a critical modulation amplitude has been found, below which the samples are entirely amorphous. The effective interdiffusion coefficient during deposition has been estimated, and found to be assisted by the free energy of mixing and the ion bombardment. X-ray studies of the modulation peaks, using grid scans, reveal a sharp mosaic, and asymmetrical peaks in some samples.

Structure, Composition, and Properties of Mocvd ZrO2 Thin Films

1989 ◽  
Vol 168 ◽  
Author(s):  
Seshu B. Desu ◽  
Tian Shi ◽  
Chi K. Kwok
Keyword(s):  
Vapor Deposition ◽  
Low Temperatures ◽  
Electron Spectroscopy ◽  
Chemical Vapor ◽  
Silicon Substrates ◽  
X Ray Diffraction ◽  
X Ray ◽  
Fine Grained ◽  
Low Pressures ◽  
Constant Refractive Index

AbstractZrO2 films were deposited on silicon substrates at temperatures from 350 to 550 °C by metallorganic chemical vapor deposition (MOCVD) using zirconium acetylacetonates. Depositions were carried out at both atmospheric and low pressures. The optical properties, structure, microstructure, and composition of these films were characterized by Ellipsometer, X-ray diffraction, scanning electron microscopy (SEM), and electron spectroscopy for chemical analysis (ESCA), respectively. The deposition was kinetically controlled at low temperatures and mass transfer controlled at high temperatures. Use of zirconium (IV) acetylacetonate resulted in cubic ZrO2 with some carbon contamination whereas, tetragonal pure ZrO2 were obtained with the precursor zirconium (IV) trifluroacetylacetonate. The tetragonal ZrO2 films are fine grained and showed preferential orientation. The measured values of dielectric constant, refractive index, and electrical resistivity of ZrO2 films are 18, 2.0, and 5E13 Ohm.cm, respectively.

The Evaluation of TiTe2 as a Diffusion Barrier in the Formation of Low Thermal Conductivity Nanolaminates with Bi2Te3 and Sb2Te3

2010 ◽  
Vol 74 ◽  
pp. 38-47
Author(s):  
Clay Mortensen ◽  
Paul Zschack ◽  
David C. Johnson
Keyword(s):  
Thermal Conductivity ◽  
Diffusion Barrier ◽  
Self Assembly ◽  
Low Temperatures ◽  
Annealing Temperature ◽  
The Self ◽  
High Angle ◽  
X Ray Diffraction ◽  
Amorphous Precursor ◽  
X Ray

The evolution of designed [(Ti-Te)]x[(Sb-Te)]y, [(Bi-Te)]x[(Sb-Te)]y, [(Ti-Te)]w[(Bi-Te)]x[(Sb-Te)]y and [(Ti-Te)]w[(Bi-Te)]x[(Ti-Te)]y[(Sb-Te)]z precursors were followed as a function of annealing temperature and time using both low and high angle x-ray diffraction techniques to probe the self assembly into nanolaminate materials. The [(Bi-Te)]x[(Sb-Te)]y precursors were found to interdiffuse at low temperatures to form a (BixSb1-x)2Te3 alloy. The [(Ti-Te)]x[(Bi-Te)]y and [(Ti-Te)]x[(Sb-Te)]y precursors formed ordered nanolaminates [{(TiTe2)}1.35]x[Bi2Te3]y and [{(TiTe2)}1.35]x[Sb2Te3]y respectively. The [(Ti-Te)]w[(Bi-Te)]x[(Sb-Te)]x precursors formed [{(TiTe2)}1.35]w[(Bi0.5Sb0.5)2Te3]2x nanolaminates on annealing, as the bismuth and antimony layers interdiffused. Over the range of TiTe2 thicknesses used in [(Ti-Te)]w[(Bi-Te)]x[(Ti-Te)]y[(Sb-Te)]z precursors, Bi and Sb were found to interdiffuse through the 2-4 nm thick Ti-Te layers, resulting in the formation of (BixSb1-x)2Te3 alloy layers as part of the final nanolaminated products. When the Bi-Te and Sb-Te thicknesses were equal in the amorphous precursors, symmetric [{(TiTe2)}1.35]m[(Bi0.5Sb0.5)2Te3]n nanolamiantes were formed. When the thicknesses of Bi-Te and Sb-Te layers were not equal in the amorphous precursor, asymmetric [(TiTe2)1.35]m[(BixSb1-x)2Te3]n[(TiTe2)1.35]m[(BixSb1-x)2Te3]p nanolaminates were formed. These results imply that to form (A)w(B)x(C)y nanolaminates using designed layered precursors all three components must be immiscible. To form (A)x(B)y(A)x(C)z nanolaminates, the components must be immiscible or the precursor to the A component and the A component itself must be an effective interdiffusion barrier preventing B and C from mixing.

scholarly journals Adsorption of malic acid at the hydroxyapatite/aqueous NaCl solution interface

2021 ◽  
Author(s):  
Władysław Janusz ◽  
Ewa Skwarek
Keyword(s):  
Zeta Potential ◽  
Malic Acid ◽  
Particle Sizes ◽  
Nacl Solution ◽  
X Ray Diffraction ◽  
Radioisotope Method ◽  
X Ray ◽  
Solution Interface ◽  
Adsorption Desorption ◽  
Kinetics Of

AbstractThe aim of the study was the basic incidence on the phenomenon of adsorption that occurs at the hydroxyapatite/malic acid interface, leading to a change in the surface properties of hydroxyapatite, Analytical methods used in the research: X-ray diffraction (XRD) as well as by the, adsorption–desorption of nitrogen (ASAP), potentiometric titration. The specific adsorption of malic acid ions at the hydroxyapatite interface was investigated by means of the radioisotope method. The zeta potential of hydroxyapatite dispersions was determined by electrophoresis with Zetasizer Nano ZS90 by Malvern. The particle sizes of hydroxyapatite samples were analyzed using Masteriszer 2000 Malvern. Studies on the kinetics of malic acid on hydroxyapatite from a solution with an initial concentration of 1 mmol/dm3 have shown that the adsorption process is initially fast, followed by a slow adsorption step. An increase in the pH of the solution causes a decrease in the malic acid adsorption as a result of competition with hydroxyl ions. The presence of adsorbed malic acid was confirmed by the FTIR measurements. The effect of malic acid adsorption on the zeta potential and particle size distribution of hydroxyapatite in the NaCl solution was investigated.

Higher Order Conditional Probabilities and Thermodynamics of Binary Molten Alloys

1997 ◽  
Vol 11 (02n03) ◽  
pp. 93-106 ◽  
Author(s):  
O. Akinlade
Keyword(s):  
Free Energy ◽  
Experimental Evidence ◽  
Cluster Model ◽  
Excess Free Energy ◽  
Higher Order ◽  
Thermodynamic Quantities ◽  
Equiatomic Composition ◽  
Conditional Probabilities ◽  
Energy Of Mixing ◽  
Free Energy Of Mixing

The recently introduced four atom cluster model is used to obtain higher order conditional probabilities that describe the atomic correlations in some molten binary alloys. Although the excess free energy of mixing for all the systems studied are almost symmetrical about the equiatomic composition, most other thermodynamic quantities are not and thus, the study enables us to explain the subtle differences in their physical characteristics required to describe the mechanism of the observed strong heterocoordination in Au–Zn or homocoordination in Cu–Ni within the same framework. More importantly, we obtain all calculated quantities for the whole concentration range thus complimenting experimental evidence.

An X-ray scattering study on inverted Ge–Si huts grown at low temperatures

2004 ◽  
Vol 19 (4) ◽  
pp. 347-351
Author(s):  
J. Xu ◽  
X. S. Wu ◽  
B. Qian ◽  
J. F. Feng ◽  
S. S. Jiang ◽  
...  
Keyword(s):  
Low Temperatures ◽  
Lattice Strain ◽  
Lattice Mismatch ◽  
Grazing Incidence ◽  
X Ray Diffraction ◽  
X Ray ◽  
X Ray Scattering ◽  
Transmission Electron ◽  
Large Lattice ◽  
Scattering Study

Ge–Si inverted huts, which formed at the Si∕Ge interface of Si∕Ge superlattice grown at low temperatures, have been measured by X-ray diffraction, grazing incidence X-ray specular and off-specular reflectivities, and transmission electron microscopy (TEM). The surface of the Si∕Ge superlattice is smooth, and there are no Ge–Si huts appearing on the surface. The roughness of the surfaces is less than 3 Å. Large lattice strain induced by lattice mismatch between Si and Ge is found to be relaxed because of the intermixing of Ge and Si at the Si∕Ge interface.

PREPARATION OF ANTIMONY-PLATINUM SURFACE ALLOY ELECTRODE BY ATOM DIFFUSION IN THE SOLID PHASE

2006 ◽  
Vol 20 (25n27) ◽  
pp. 3999-4004
Author(s):  
HIROSHI MATSUI ◽  
KAZUFUMI WATANABE
Keyword(s):  
Diffraction Pattern ◽  
Low Temperatures ◽  
Solid Phase ◽  
Electrochemical Measurement ◽  
X Ray Diffraction ◽  
Platinum Surface ◽  
X Ray ◽  
Atom Diffusion ◽  
Heat Treated ◽  
Titanium Substrates

Antimony-platinum bilayers were prepared on titanium substrates by the two-step electrodeposition in the usual baths, and then surface alloys were formed by the atom diffusion in the solid phase. The simple antimony layer was little influenced by the substrate in both the measurements of X-ray diffraction and the i - E characteristic in a sulfuric acid solution. Regarding the bilayers, the catalytic activity in hydrogen evolution reaction was very sensitive to the presence of platinum, while the hydrogen adsorbability was quite insensitive. An interaction between antimony and platinum was confirmed by the appearance of a new dissolution wave in the electrochemical measurement and the occurrence of a new diffraction in the X-ray diffraction pattern after the heat-treatment of about 400°C. Although the new diffraction disagreed with any of the reported alloys, clear diffraction pattern of PtSb 2 alloy was observed, when the bilayers were heat-treated at about 600°C for one hour. Considering the penetration depth of X-ray, the alloying of antimony and platinum seems to occur also at low temperatures at least at the top surface.

Effect of Particle Size of ZrO2(Y2O3) Powders on the Shrinkage of the Sintered Substrate with Coloring Gradient

2014 ◽  
Vol 87 ◽  
pp. 162-168
Author(s):  
Paula Cipriano da Silva ◽  
Roberto de Oliveira Magnago ◽  
Camila Aparecida Araujo da Silva ◽  
Bianca de Almeida Fortes ◽  
Claudinei dos Santos
Keyword(s):  
White Layer ◽  
Linear Shrinkage ◽  
Particle Sizes ◽  
X Ray Diffraction ◽  
X Ray ◽  
Particles Size Distribution ◽  
Cad Cam ◽  
Effect Of Particle Size ◽  
Cam Systems ◽  
Zirconia Powders

ZrO2(Y2O3)-based ceramics with coloring gradient can facilitate the development of dental prosthesis by the improvement of esthetic properties. In this work, ZrO2 powders with different particle sizes were investigated. White and yellow zirconia powders (TOSOH Corporation-Japan) were characterized by particles size distribution using nanoSight-LM20 analyzer. Furthermore, samples were characterized by X-Ray diffraction, Scanning Electron Microscopy and relative density. Compacts with two layers, one white and one yellow were uniaxially pressed at 80MPa and sintered at 1530°C-120min. The yellow-powder presented average particles size of 180±66nm, while the white-powder presented particles size of 198±73nm. After sintering, full dense ceramics with tetragonal phase were obtained. The linear shrinkage of the yellow and white-layer was 22.75% and 22.05% respectively. This difference in shrinkage is important in the machining of prostheses in ceramic CAD/CAM systems, because they lead to difficulties in adapting this customized prosthesis in patients.

Magnetic Properties of Sputtered Fe-O and Co-O Thin Films

1995 ◽  
Vol 403 ◽  
Author(s):  
D. V. Dimitrov ◽  
A. S. Murthy ◽  
G. C. Hadjipanayis ◽  
C. P. SWANN
Keyword(s):  
Grain Size ◽  
Low Temperatures ◽  
Room Temperature ◽  
Oxide Films ◽  
X Ray Diffraction ◽  
Dc Magnetron Sputtering ◽  
Large Shift ◽  
X Ray ◽  
Grain Size And Shape ◽  
Spherical Grains

AbstractFe-O and Co-O films were prepared by DC magnetron sputtering in a mixture of Ar and O2 gases. By varying the oxygen to argon ratio, oxide films with stoichiometry FeO, Fe3O4, α-Fe2O3, CoO and Co3O4 were produced. TEM studies showed that the Fe – oxide films were polycrystalline consisting of small almost spherical grains, about 10 nm in size. Co-O films had different microstructure with grain size and shape dependent on the amount of oxygen. X-ray diffraction studies showed that the grains in Fe-O films were randomly oriented in contrast to Co-O films in which a <111> texture was observed. Pure FeO and α-Fe2O3 films were found to be superparamagnetic at room temperature but strongly ferromagnetic at low temperatures in contrast to the antiferromagnetic nature of bulk samples. A very large shift in the hysteresis loop, about 3800 Oe, was observed in field cooled Co-CoO films indicating the presence of a large unidirectional exchange anisotropy.

A Comparative Study of GaN Films Grown on Different Faces of Sapphire by ECR-Assisted MBE

1992 ◽  
Vol 242 ◽  
Author(s):  
T. D. Moustakas ◽  
R. J. Molnar ◽  
T. Lei ◽  
G. Menon ◽  
C. R. Eddy
Keyword(s):  
Surface Morphology ◽  
Low Temperatures ◽  
Smooth Surface ◽  
Growth Process ◽  
X Ray Diffraction ◽  
Epitaxial Relationship ◽  
X Ray ◽  
Sapphire Substrates ◽  
Growth Method ◽  
Step Growth

ABSTRACTGaN films were grown on c-plane (0001), a-plane (1120) and r-plane (1102) sapphire substrates by the ECR-assisted MBE method. The films were grown using a two-step growth process, in which a GaN buffer is grown first at relatively low temperatures and the rest of the film is grown at higher temperatures. RHEED studies indicate that this growth method promotes lateral growth and leads to films with smooth surface morphology. The epitaxial relationship to the substrate, the crystalline quality and the surface morphology were investigated by RHEED, X-ray diffraction and SEM studies.

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