Behavior of Implanted α-Al2O3 in an Oxidizing Annealing Environment

1983 ◽  
Vol 27 ◽  
Author(s):  
G. C. Farlow ◽  
C. W. White ◽  
C. J. Mchargue ◽  
B. R. Appleton
Keyword(s):  
Transition Metal ◽  
Single Crystals ◽  
Bulk Diffusion ◽  
Transition Metal Ions ◽  
Divalent Ions ◽  
Oxygen Sublattice ◽  
Group Iii ◽  
Random Direction ◽  
Α Al2o3 ◽  
Flowing Oxygen

ABSTRACTThe transition metal ions Fe, Mn, Ni, Ti, and Cr as well as the group III-A ion Ga were implanted in a random direction close to the c-axis of α-Al2O3 single crystals. These were subsequently annealed in flowing oxygen at temperatures between 600 and 1500°C. The impurity and damage distributions were determined by He backscattering and channeling techniques. The normally trivalent ions, Fe, Ga, and Cr show strong tendency to become incorporated into substitutional sites, whereas the normally divalent ions, Cu and Mn show no such tendency, even at high temperatures. Most of the impurities tend to move toward the surface with only Fe, Ga, and Cr showing tendency towards bulk diffusion. In all cases the Al sublattice recovers at lower temperatures than the oxygen sublattice.

Electron-Nuclear Hyperfine Interactions of 53Cr 3+ in Mg2SiO4 (Forsterite)

1980 ◽  
Vol 35 (12) ◽  
pp. 1296-1303 ◽  
Author(s):  
H. Rager
Keyword(s):  
Transition Metal ◽  
Hyperfine Interaction ◽  
Metal Ions ◽  
Room Temperature ◽  
Hyperfine Interactions ◽  
Small Variation ◽  
Transition Metal Ions ◽  
Oxygen Sublattice ◽  
Oxygen Coordination ◽  
Nuclear Spin System

Abstract The magnetic hyperfine interaction between the electron and nuclear spin system of 53Cr3+ was studied at the Mg sites, M1 and M2, in Mg2SiO4. The study was undertaken at room temperature and 9.52 GHz. The hyperfine structure data exhibit a covalent Cr-O bonding of approximately 10% indicating a mainly but not purely ionic bonding. Including the corresponding results obtained for 57Fe 3+ [1] and 55Mn2+ [2] in Mg2SiO4, this is interpreted such that the bonding of transition metal ions is mainly dominated by the oxygen sublattice in Mg2SiO4 and less by the properties of the transition metal ions themselves. The small variation of the hyperfine splitting parameters found for 53Cr3+ at M1 and M2, and also for 57Fe3+ at these positions indicates that the hyperfine interaction varies also with varying average metal oxygen distances as well as with changes in the oxygen coordination size.

Growth and characterization of divalent transition metal ions doped zinc hydrogen phosphate single crystals

2018 ◽  
Author(s):  
Delma D’Souza ◽  
N. Jagannatha ◽  
K. P. Nagaraja ◽  
P. S. Rohith ◽  
K. V. Pradeepkumar
Keyword(s):  
Transition Metal ◽  
Metal Ions ◽  
Single Crystals ◽  
Transition Metal Ions ◽  
Hydrogen Phosphate

scholarly journals Dielectric, Thermal and FTIR Studies of Cobalt Doped Magnesium Hydrogen Maleate Hexahydrate Single Crystals

2011 ◽  
Vol 8 (1) ◽  
pp. 91-96
Author(s):  
B. Rajagopal ◽  
M. V. Ramana ◽  
A. V. Sarma
Keyword(s):  
Activation Energy ◽  
Dielectric Constant ◽  
Dielectric Properties ◽  
Melting Point ◽  
Transition Metal ◽  
Single Crystals ◽  
Loss Tangent ◽  
Transition Metal Ions ◽  
Ftir Studies ◽  
First Time

Present work reports the dielectric, thermal and FTIR studies of Co2+: MHMH single crystal for the first time. The influence of addition of transition metal ions on the dielectric properties, like dielectric constant, loss tangent,a.c. conductivity and activation energy of these crystals was discussed. FTIR studies confirm the presence of carboxylate ions. The melting point of the sample and final product after decomposition are studied using TG/DTA.

scholarly journals Optical Observation of Striations in Y2Ti2O7 Single Crystals

Crystals ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 233 ◽  
Author(s):  
Changyou Liu ◽  
Antoni Dabkowski ◽  
Wanqi Jie ◽  
Bruce D. Gaulin ◽  
Hanna A. Dabkowska
Keyword(s):  
Thermal Conductivity ◽  
Transition Metal ◽  
Single Crystals ◽  
Polarized Light ◽  
Transition Metal Ions ◽  
Molten Zone ◽  
Floating Zone ◽  
Growth Interface ◽  
Host Materials ◽  
High Degree

RE2Ti2O7 (RE = Y, Yb, Ho, Er) pyrochlores are very interesting as potential candidates for host materials for applications in transition-metal ions lasers. Y2Ti2O7 crystals were grown by the optical floating zone (OFZ) method. The shape of the growth interface is of paramount importance for the growth of single crystals. As striation and the growth interface have the same shape, we observed the striations in as-grown crystals under polarized light. The degree of overheating of the molten zone influences the shape of the growth interface. An increase of power supplied to the molten zone combined with a decrease of both, thermal conductivity and the amount of heat dissipated by the seed-rod, causes an increase in the degree of overheating of the floating zone. Under a high degree of overheating, the interface of the crystal grown is less convex, with smaller curvature. With the speed of rotation of these crystals decreasing from 30 to 7 rpm, the curvature of striations decreases and the shape of the growth interface changes from convex to less convex, and finally to concave.

A Simple and Convenient EPR Standard for Determination of g-Factors and Spin Concentrations

1979 ◽  
Vol 34 (7) ◽  
pp. 906-908 ◽  
Author(s):  
B. Schmitz ◽  
M. Jakubith ◽  
G. Lehmann
Keyword(s):  
Transition Metal ◽  
Metal Ions ◽  
Single Crystals ◽  
Transition Metal Ions ◽  
Small Space ◽  
Spin Concentration ◽  
Space Requirement ◽  
Signal Intensities ◽  
G Factors

The commercially available cement Picein 80 has been tested and successfully used for the determination of g- factors and spin concentrations at X- and Q-band frequencies. The main advantages compared to other standards are a very small space requirement and the fact that the concentra­tion of the standard can be easily adjusted to the signal intensities of the sample. This standard exhibits a single line at a g-factor of 2.0041 with a halfwidth of .47 mT and a spin concentration of 2.1015 spins/mg Picein. An additional weaker resonance occurs at g = 2.0177, and at Q-band a partly overlapping multiplet with 5.8 mT separation is observable, but the intensities of both signals are low com­pared to that of the main signal. This standard is applicable over the whole range of useful spin concentrations, and the linewidth makes it particularly useful for measurements on transition metal ions in diluted single crystals.

HREM Study of electron-induced surface radiation damage in ReO3

1991 ◽  
Vol 49 ◽  
pp. 636-637
Author(s):  
R. Ai ◽  
H.-J. Fan ◽  
L. D. Marks
Keyword(s):  
Transition Metal ◽  
Metal Ions ◽  
Metal Oxides ◽  
Electron Irradiation ◽  
Transition Metal Oxides ◽  
Carbon Film ◽  
Transition Metal Ions ◽  
Surface Radiation ◽  
Valence Transition ◽  
Electron Microscopes

It has been known for a long time that electron irradiation induces damage in maximal valence transition metal oxides such as TiO2, V2O5, and WO3, of which transition metal ions have an empty d-shell. This type of damage is excited by electronic transition and can be explained by the Knoteck-Feibelman mechanism (K-F mechanism). Although the K-F mechanism predicts that no damage should occur in transition metal oxides of which the transition metal ions have a partially filled d-shell, namely submaximal valence transition metal oxides, our recent study on ReO3 shows that submaximal valence transition metal oxides undergo damage during electron irradiation.ReO3 has a nearly cubic structure and contains a single unit in its cell: a = 3.73 Å, and α = 89°34'. TEM specimens were prepared by depositing dry powders onto a holey carbon film supported on a copper grid. Specimens were examined in Hitachi H-9000 and UHV H-9000 electron microscopes both operated at 300 keV accelerating voltage. The electron beam flux was maintained at about 10 A/cm2 during the observation.

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