Fe centers and charge compensation in ZnWO4 single crystals characterized by ESR and i.r. spectroscopy

1992 ◽  
Vol 53 (7) ◽  
pp. 889-895 ◽  
Author(s):  
A. Watterich ◽  
M. Wöhlecke ◽  
H. Müller ◽  
K. Raksányi ◽  
A. Breitkopf ◽  
...  
Keyword(s):  
Single Crystals ◽  
Charge Compensation

THE METHOD OF ELECTRON PARAMAGNETIC RESONANCE FOR QUANTUM ELECTRONIC MATERIALS INVESTIGATION (YAG, YLuAG, YAP, YLuAP, PbGa2S4)

2012 ◽  
Vol 15 ◽  
pp. 16-21 ◽  
Author(s):  
HIKE ASATRYAN ◽  
PAVEL BARANOV
Keyword(s):  
Single Crystals ◽  
Electronic Materials ◽  
Charge Compensation ◽  
Isomorphic Substitution ◽  
Paramagnetic Resonance ◽  
Laser Crystals ◽  
Field Symmetry ◽  
First Time ◽  
Electron Paramagnetic ◽  
Disordered Compounds

The results of EPR investigations of the laser crystals and scintillators are presented, in particular, Y 3 Al 5 O 12: Dy 3+, Y 3 Al 5 O 12: Er 3+, ( Y 1-x Lu x)3 Al 5 O 12: Er 3+, YAlO 3: Er 3+, Ce 3+, Nd 3+ and Tm 3+, Y (1- x ) Lu x AlO 3 : Ce 3+, PbGa 2 S 4 : Dy 3+, Nd 3+ and Ce 3+. EPR signals of Er 3+, Ce 3+, Nd 3+ and Tm 3+ ions in YAlO 3, as well as of Dy 3+, Nd 3+ and Ce 3+ in lead thiogallate single crystals are detected and analyzed for the first time. The main values of g tensors and hyperfine interaction constants for Er 3+, Tm 3+, Nd 3+ and Dy 3+ odd isotopes are determined. In compositionally disordered compounds YLuAG and YLuAP several new paramagnetic Er 3+ and Ce 3+ centers are observed in comparison with YAG and YAP . These centers appear as a result of the changes in the crystal field symmetry and magnitude due to the isomorphic substitution of Lu 3+ for Y 3+ in the yttrium sublattice. The origin of these new paramagnetic centers is established and their formation probability is calculated depending on the content of the additional lutetium impurity. Possible mechanism of the charge compensation for heterovalent substitution of Pb 2+ by RE 3+ in lead thiogallate single crystals is analyzed.

Growth of Na2W2O7 Single Crystals as Possible Optical Host Material

2014 ◽  
Vol 213 ◽  
pp. 160-164 ◽  
Author(s):  
T.A. Gavrilova ◽  
N.V. Ivannikova ◽  
V.N. Shlegel ◽  
V.D. Grigorieva ◽  
S.F. Solodovnikov ◽  
...  
Keyword(s):  
Solid State ◽  
Low Temperature ◽  
Temperature Gradient ◽  
Single Crystals ◽  
Charge Compensation ◽  
Xrd Analysis ◽  
Czochralski Technique ◽  
High Quality ◽  
Phase Purity ◽  
Ce Content

High-quality Na2W2O7 single crystals have been grown by low temperature gradient Czochralski technique (LTG Cz). The phase purity of grown crystals has been verified by XRD analysis. A set of oxide compositions based on Na2W2O7 and doped with Ce and special additions for charge compensation has been prepared by solid state synthesis. The formation of Na2W2O7-based solid solutions is found at as high Ce content as ~ 5 mol%.

scholarly journals Synthesis and crystal structure of ABW-type SrFe1.40V0.60O4

2020 ◽  
Vol 76 (5) ◽  
pp. 664-667
Author(s):  
Thomas Gstir ◽  
Volker Kahlenberg ◽  
Hannes Krüger ◽  
Simon Penner
Keyword(s):  
Crystal Structure ◽  
Single Crystals ◽  
Three Dimensional ◽  
Charge Compensation ◽  
Membered Ring ◽  
Side Product ◽  
Double Perovskites ◽  
Tetrahedral Framework ◽  
Synthesis And Crystal Structure ◽  
Zeolite Type

Single crystals of SrFe1.40V0.60O4, strontium tetraoxidodi[ferrate(III)/vanadate(III)], have been obtained as a side product in the course of sinter experiments aimed at the synthesis of double perovskites in the system SrO–Fe2O3–V2O5. The crystal structure can be characterized by layers of six-membered rings of TO4-tetrahedra (T: FeIII, VIII) perpendicular to [100]. Stacking of the layers along [100] results in a three-dimensional framework enclosing tunnel-like cavities in which SrII cations are incorporated for charge compensation. The sequence of directedness of up (U) and down (D) pointing vertices of neighboring tetrahedra in a single six-membered ring is UUUDDD. The topology of the tetrahedral framework belongs to the zeolite-type ABW.

The role of OH- Ions in the charge compensation of impurities in ZnWO4 single crystals

1989 ◽  
Vol 135 (6-7) ◽  
pp. 363-367 ◽  
Author(s):  
I. Foldvari ◽  
R. Capelletti ◽  
L.A. Kappers ◽  
O.R. Gilliam ◽  
A. Watterich
Keyword(s):  
Single Crystals ◽  
Charge Compensation

scholarly journals K9Y3[Si12O32]F2

2014 ◽  
Vol 70 (2) ◽  
pp. i11-i11 ◽  
Author(s):  
Volker Kahlenberg ◽  
Tanja Manninger
Keyword(s):  
Crystal Structure ◽  
Single Crystals ◽  
Title Compound ◽  
Single Layer ◽  
Charge Compensation ◽  
Site Symmetry ◽  
Layer Silicates ◽  
Flux Synthesis ◽  
Distorted Octahedra

Single-crystals of the title compound, nonapotassium triyttrium dodecasilicate difluoride, were obtained from flux synthesis experiments in the system SiO2—Y2O3—KF. The crystal structure belongs to the group of single-layer silicates and is based on silicate sheets parallel to (110). A single layer contains secondary (Q2) and tertiary (Q3) silicate tetrahedra in the ratio 1:2 and is build up from six-, eight- and twelve-membered rings. The linkage between neighboring layers is achieved by two crystallographically independent Y3+cations, which are coordinated by six oxygen ligands in form of distorted octahedra. Charge compensation is accomplished by incorporation of additional F−anions and K+cations in the structural channels, forming anion-centred [F2K7] groups. Apart from one K+and one Y3+cation (each with site symmetry -1), the 30 crystallographically independent atoms reside on general positions.

Electron Paramagnetic Resonance of Cu2+ Doped Na2 HAsO4·7H2O Single Crystals

1998 ◽  
Vol 53 (9) ◽  
pp. 779-782
Author(s):  
F. Köksal ◽  
İ. Kartal ◽  
A. Gençten
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Single Crystals ◽  
Ground State ◽  
Room Temperature ◽  
Charge Compensation ◽  
Distorted Octahedron ◽  
Spin Hamiltonian ◽  
Paramagnetic Resonance ◽  
Hamiltonian Parameters ◽  
Electron Paramagnetic

Abstract The electron paramagnetic resonance spectra of Cu2+ doped Na2HAsO4 ·7H2O single crystals were studied at room temperature. The results indicate the substitutional entrance of Cu2+ in two magnetically inequivalent Na+ sites. Charge compensation is supposed to be fulfilled by proton vacancies. The spin Hamiltonian parameters were determined. The ground state for Cu2+ seems to indicate the dominance of the dz² orbital and therefore a compression of the distorted octahedron along its C4v axis.

Electron Paramagnetic Resonance of Cu2+ in KHC03 Single Crystals

1999 ◽  
Vol 54 (3-4) ◽  
pp. 177-179 ◽  
Author(s):  
F. Köksal ◽  
İ. Kartal ◽  
B. Karabulut
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Single Crystals ◽  
Ground State ◽  
Room Temperature ◽  
Hyperfine Coupling ◽  
Charge Compensation ◽  
Paramagnetic Resonance ◽  
Electron Paramagnetic

The electron paramagnetic resonance spectra of Cu2+ doped KHC03 single crystals were studied at room temperature. The results indicate a substitutional entrance of the Cu2+ ions in place of the magnetically inequivalent K+ sites. The charge compensation is supposed to be fulfilled by proton vacancies. The hyperfine lines were well resolved and the 65Cu hyperfine coupling tensors were also found. The ground state of Cu2+ indicates the dominance of the dx2-y2 orbital and, therefore, elongation of the polyhedron, similar to a lengthened octahedron.

The Microstructure of Shock-Synthesized Diamond

1967 ◽  
Vol 25 ◽  
pp. 324-325
Author(s):  
Lucien F. Trueb
Keyword(s):  
Single Crystals ◽  
Preferred Orientation ◽  
High Magnification ◽  
Texture Pattern ◽  
Shock Process ◽  
New Type ◽  
Diffraction Diagram

A new type of synthetic industrial diamond formed by an explosive shock process has been recently developed by the Du Pont Company. This material consists of a mixture of two basically different forms, as shown in Figure 1: relatively flat and compact aggregates of acicular crystallites, and single crystals in the form of irregular polyhedra with straight edges.Figure 2 is a high magnification micrograph typical for the fibrous aggregates; it shows that they are composed of bundles of crystallites 0.05-0.3 μ long and 0.02 μ. wide. The selected area diffraction diagram (insert in Figure 2) consists of a weak polycrystalline ring pattern and a strong texture pattern with arc reflections. The latter results from crystals having preferred orientation, which shows that in a given particle most fibrils have a similar orientation.

A New Defect in Polyethylene Single Crystals

1973 ◽  
Vol 31 ◽  
pp. 70-71
Author(s):  
E. L. Thomas ◽  
S. L. Sass
Keyword(s):  
Single Crystals ◽  
Screw Dislocation ◽  
Small Distance ◽  
Dipole Model ◽  
Dislocation Dipole ◽  
Chain Folding ◽  
Black And White ◽  
Polymer Crystal ◽  
Different Types

In polyethylene single crystals pairs of black and white lines spaced 700-3,000Å apart, parallel to the [100] and [010] directions, have been identified as microsector boundaries. A microsector is formed when the plane of chain folding changes over a small distance within a polymer crystal. In order for the different types of folds to accommodate at the boundary between the 2 fold domains, a staggering along the chain direction and a rotation of the chains in the plane of the boundary occurs. The black-white contrast from a microsector boundary can be explained in terms of these chain rotations. We demonstrate that microsectors can terminate within the crystal and interpret the observed terminal strain contrast in terms of a screw dislocation dipole model.

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