The role of extended defects in the formation of the spectrum of electronic states in high-purity p-CdTe polycrystals with stoichiometric composition

ABSTRACTComplexes of vacancy at indium site with one to four hydrogen atoms and isolated hydrogen or hydrogen dimer and other infrared absorption lines, tentatively be assigned to hydrogen related defects were investigated by FTIR. Hydrogen can passivate imperfections, thereby eliminating detrimental electronic states from the energy bandgap.Incorporated hydrogen can introduce extended defects and generate electrically-active defects. Hydrogen also can acts as an actuator for creating of antistructure defects. Isolated hydrogen related defects(e.g. H12+) may play an important role in the conversion of the annealed wafers from semiconducting to the semi-insulating behavior. H2+ may be a deep donor, whose energy level is very near the iron deep acceptor level in the energy gap.

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Fine structure and properties of defects in naturally occurring silicates and oxides

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100175430 ◽

1990 ◽

Vol 48 (4) ◽

pp. 460-461

Author(s):

David R. Veblen

Keyword(s):

Chemical Reactions ◽

High Resolution Electron Microscopy ◽

Extended Defects ◽

Single Chain ◽

Naturally Occurring ◽

Resolution Electron ◽

Fine Structures ◽

Image Simulations ◽

Similar Crystal Structure

Extended defects and interfaces control many processes in rock-forming minerals, from chemical reactions to rock deformation. In many cases, it is not the average structure of a defect or interface that is most important, but rather the structure of defect terminations or offsets in an interface. One of the major thrusts of high-resolution electron microscopy in the earth sciences has been to identify the role of defect fine structures in reactions and to determine the structures of such features. This paper will review studies using HREM and image simulations to determine the structures of defects in silicate and oxide minerals and present several examples of the role of defects in mineral chemical reactions. In some cases, the geological occurrence can be used to constrain the diffusional properties of defects.The simplest reactions in minerals involve exsolution (precipitation) of one mineral from another with a similar crystal structure, and pyroxenes (single-chain silicates) provide a good example. Although conventional TEM studies have led to a basic understanding of this sort of phase separation in pyroxenes via spinodal decomposition or nucleation and growth, HREM has provided a much more detailed appreciation of the processes involved.

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The role of the excited electronic states in the C++H2O reaction

The Journal of Chemical Physics ◽

10.1063/1.2903465 ◽

2008 ◽

Vol 128 (14) ◽

pp. 144310 ◽

Cited By ~ 3

Author(s):

Jesús R. Flores ◽

Adán B. González

Keyword(s):

Electronic States ◽

Excited Electronic States

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Роль состояний переноса заряда "лиганд-металл" в процессах возбуждения люминесценции индолкарбоксилатов европия

Оптика и спектроскопия ◽

10.21883/os.2022.01.51899.26-21 ◽

2022 ◽

Vol 130 (1) ◽

pp. 121

Author(s):

В.И. Царюк ◽

К.П. Журавлев

Keyword(s):

Excitation Energy Transfer ◽

Electronic States ◽

Decisive Role ◽

Low Energy ◽

Excitation Spectra ◽

Metal Charge ◽

Ternary Compounds ◽

Aromatic Carboxylates ◽

Metal Charge Transfer

The luminescence excitation energy transfer in europium and terbium indole-3-carboxylates, indole-3-acetates and indole-3-propionates as well as ternary indolecarboxylates containing 1,10-phenanthroline and 2,2'-bipyridine molecules have been studied. The luminescence excitation spectra, the lifetimes of the 5D0 (Eu3+) and 5D4 (Tb3+) states, and the luminescence intensity are analyzed. The decisive role of ligand-metal charge transfer (LMCT) states in the quenching of the luminescence of europium aromatic carboxylates containing a π-excessive pyrrole or indole fragment is demonstrated. Most europium compounds are characterized by quenching due to the depopulation of the 5D0 state of the Eu3+ ion through the low-energy LMCT state. But in some ternary compounds, the LMCT state being of higher energy participates in the nonradiative depopulation of the excited electronic states of the ligand.

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Детерминизм локального атомного упорядочения в монослоях золота в формировании их электронной структуры

Физика твердого тела ◽

10.21883/ftt.2022.03.52089.238 ◽

2022 ◽

Vol 64 (3) ◽

pp. 303

Author(s):

В.Л. Карбовский ◽

А.А. Романский ◽

Л.И. Карбовская ◽

В.В. Стонис

Keyword(s):

Coordination Sphere ◽

Electronic States ◽

Mutual Arrangement ◽

Quantum Mechanical ◽

Quantum Mechanical Calculations ◽

The Third ◽

Long Range Interactions ◽

Valence Bands ◽

D Orbitals

The total and partial densities of electronic states of gold monolayer structures of different symmetry are calculated by the quantum mechanical calculations methods in the DFT approximation. It is shown that the first coordination sphere is determinant in the formation of the fine structure and the extent of the valence bands of the monolayer gold structures under study. The peaks splitting of the TDOS curve, which leads to its finer structure, is influenced not only by the lengths of interatomic bonds but also by the mutual arrangement of atoms. The influence of long-range interactions on the electronic structure of gold monolayers has been established. For example, for the (110) plane, a change in the atomic ordering in the third coordination sphere as a result of the introduction of a vacancy leads to noticeable changes in the TDOS curve, which indicates either a significant role of the atoms of the third coordination sphere or a significant redistribution of the interaction of d-orbitals of different symmetries of close neighbours. A correlation between the packing density, as well as the number of neighbours in the first coordination sphere, and the width of the energy band of gold monolayers has been established.

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Molecular-scale investigation of the oxidation behavior of chromia-forming alloys in high-temperature CO2

npj Materials Degradation ◽

10.1038/s41529-021-00194-1 ◽

2021 ◽

Vol 5 (1) ◽

Author(s):

Richard P. Oleksak ◽

Rafik Addou ◽

Bharat Gwalani ◽

John P. Baltrus ◽

Tao Liu ◽

...

Keyword(s):

High Temperature ◽

Power Systems ◽

High Purity ◽

Photoelectron Spectroscopy ◽

Ambient Pressure ◽

Critical Role ◽

Atomic Scale ◽

Atomic Diffusion ◽

Carbon Transport

AbstractCurrent and future power systems require chromia-forming alloys compatible with high-temperature CO2. Important questions concerning the mechanisms of oxidation and carburization remain unanswered. Herein we shed light onto these processes by studying the very initial stages of oxidation of Fe22Cr and Fe22Ni22Cr model alloys. Ambient-pressure X-ray photoelectron spectroscopy enabled in situ analysis of the oxidizing surface under 1 mbar of flowing CO2 at temperatures up to 530 °C, while postexposure analyses revealed the structure and composition of the oxidized surface at the near-atomic scale. We found that gas purity played a critical role in the kinetics of the reaction, where high purity CO2 promoted the deposition of carbon and the selective oxidation of Cr. In contrast, no carbon deposition occurred in low purity CO2 and Fe oxidation ensued, thus highlighting the critical role of impurities in defining the early oxidation pathway of the alloy. The Cr-rich oxide formed on Fe22Cr in high purity CO2 was both thicker and more permeable to carbon compared to that formed on Fe22Ni22Cr, where carbon transport appeared to occur by atomic diffusion through the oxide. Alternatively, the Fe-rich oxide formed in low purity CO2 suggested carbon transport by molecular CO2.

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Role of deformation twins in static recrystallization kinetics of high-purity alpha titanium

Metals and Materials International ◽

10.1007/s12540-016-6369-y ◽

2016 ◽

Vol 22 (6) ◽

pp. 1041-1048 ◽

Cited By ~ 7

Author(s):

Jong Woo Won ◽

Taekyung Lee ◽

Seong-Gu Hong ◽

Yongmoon Lee ◽

Jeong Hun Lee ◽

...

Keyword(s):

High Purity ◽

Static Recrystallization ◽

Recrystallization Kinetics ◽

Deformation Twins ◽

Alpha Titanium ◽

Kinetics Of

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Electronic states created inp‐Si subjected to plasma etching: The role of inherent impurities, point defects, and hydrogen

Applied Physics Letters ◽

10.1063/1.108532 ◽

1993 ◽

Vol 62 (9) ◽

pp. 958-960 ◽

Cited By ~ 17

Author(s):

O. O. Awadelkarim ◽

T. Gu ◽

P. I. Mikulan ◽

R. A. Ditizio ◽

S. J. Fonash ◽

...

Keyword(s):

Point Defects ◽

Plasma Etching ◽

Electronic States

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Photoinduced Absorption Spectroscopy of Poly-3-Alkylthiophenes

MRS Proceedings ◽

10.1557/proc-247-669 ◽

1992 ◽

Vol 247 ◽

Author(s):

C. Botta ◽

S. Luzzati ◽

A. Bolognesi ◽

R. Tubino ◽

A. Borghesi

Keyword(s):

Absorption Spectroscopy ◽

Near Infrared ◽

Laser Intensity ◽

Electronic States ◽

Chain Mechanism ◽

Photoinduced Absorption ◽

Polymer Aggregates ◽

Cast Films ◽

Solution Cast

ABSTRACTWe report a study of the near infrared photoinduced absorption of a series of poly -3-decylthiophene with different supermolecular organization as solution cast films, good solvent and aggregated bad solvent solutions.Photoinduced subgap electronic states are detected both in the solid and in solutions independently from the presence of polymer aggregates. The study of the photoinduced activity Δ/T on the laser intensity I indicate a I0.6 dependence for the films and a I0.95 dependence for the solutions. This is the evidence that the photoinduced states are generated in the solid via an inter-chain mechanism while in the solution via an intra-chain mechanism.A possible role of the solvent into the photoexcitation pathway is discussed.

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Deformation Mechanisms and Solid-Solution Strengthening in Ordered Alloys

MRS Proceedings ◽

10.1557/proc-213-499 ◽

1990 ◽

Vol 213 ◽

Cited By ~ 3

Author(s):

Dennis M. Dimiduk ◽

Satish Rao

Keyword(s):

Solid Solution ◽

Flow Behavior ◽

Stoichiometric Composition ◽

Dislocation Core ◽

Deformation Mechanisms ◽

Solid Solution Hardening ◽

Solid Solution Strengthening ◽

Ordered Alloys ◽

Solute Hardening

ABSTRACTFundamental to understanding the results of alloy design studies, is the need for understanding the intrinsic role of solutes in a particular compound. For many compounds such an understanding must be built from a systematic exploration of the role of deviations from the stoichiometric composition as well as the role of ternary solute additions on the variation of flow behavior. Within most intermetallic systems the problem is complicated since the fundamental mechanisms of flow are not well established and, in those systems where these mechanisms are known, thermal activation can lead to dislocation-core transformations and changes in the operative slip systems with temperature. In general, flow may be governed by more than one dislocation process at a given temperature and deformation twinning may be a major contributing deformation mechanism. The problem of isolating the mechanisms of solid-solution hardening may, therefore, require treatment as a problem of combined strengthening mechanisms operating in parallel. This paper reviews the key aspects of deformation mechanisms and solute strengthening in intermetallic alloys. Classical elastic theories of solute hardening serve as an origin, from which, the progress made to date in isolating the mechanisms of solute hardening in ordered alloys is discussed.

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