Cation and anion vacancies in cubic molybdenum nitride

1976 ◽

Vol 34 ◽

pp. 614-615 ◽

Cited By ~ 1

Author(s):

L.E. Murr

Keyword(s):

Electron Microscope ◽

Electron Irradiation ◽

Heavy Ion ◽

High Energy ◽

Stoichiometric Ratio ◽

Direct Observations ◽

Transmission Electron ◽

Anion Vacancies ◽

Cation And Anion Vacancies ◽

Lattice Formation

The production of void lattices in metals as a result of displacement damage associated with high energy and heavy ion bombardment is now well documented. More recently, Murr has shown that a void lattice can be developed in natural (colored) fluorites observed in the transmission electron microscope. These were the first observations of a void lattice in an irradiated nonmetal, and the first, direct observations of color-center aggregates. Clinard, et al. have also recently observed a void lattice (described as a high density of aligned "pores") in neutron irradiated Al2O3 and Y2O3. In this latter work, itwas pointed out that in order that a cavity be formed,a near-stoichiometric ratio of cation and anion vacancies must aggregate. It was reasoned that two other alternatives to explain the pores were cation metal colloids and highpressure anion gas bubbles.Evans has proposed that void lattices result from the presence of a pre-existing impurity lattice, and predicted that the formation of a void lattice should restrict swelling in irradiated materials because it represents a state of saturation.

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Determination of the Concentrations of Cation and Anion Vacancies in Solid Potassium Chloride

The Journal of Chemical Physics ◽

10.1063/1.1747460 ◽

1950 ◽

Vol 18 (1) ◽

pp. 72-74 ◽

Cited By ~ 51

Author(s):

Carl Wagner ◽

Paul Hantelmann

Keyword(s):

Potassium Chloride ◽

Anion Vacancies ◽

Cation And Anion Vacancies

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Challenges in Improving Performance of Oxide Thermoelectrics Using Defect Engineering

10.5772/intechopen.96278 ◽

2021 ◽

Author(s):

Jamil Ur Rahman ◽

Gul Rahman ◽

Soonil Lee

Keyword(s):

Thermal Conductivity ◽

Phonon Scattering ◽

Electronic Device ◽

Low Cost ◽

Temperature Stability ◽

Charge Carriers ◽

High Concentration ◽

Anion Vacancies ◽

Cation And Anion Vacancies ◽

Oxide Thermoelectric Materials

Oxide thermoelectric materials are considered promising for high-temperature thermoelectric applications in terms of low cost, temperature stability, reversible reaction, and so on. Oxide materials have been intensively studied to suppress the defects and electronic charge carriers for many electronic device applications, but the studies with a high concentration of defects are limited. It desires to improve thermoelectric performance by enhancing its charge transport and lowering its lattice thermal conductivity. For this purpose, here, we modified the stoichiometry of cation and anion vacancies in two different systems to regulate the carrier concentration and explored their thermoelectric properties. Both cation and anion vacancies act as a donor of charge carriers and act as phonon scattering centers, decoupling the electrical conductivity and thermal conductivity.

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Native Defects in Wurtzite GaN And AlN

MRS Proceedings ◽

10.1557/proc-339-693 ◽

1994 ◽

Vol 339 ◽

Cited By ~ 13

Author(s):

P. Boguslawski ◽

E. Briggs ◽

T. A. White ◽

M. G. Wensell ◽

J. Bernholc

Keyword(s):

Theoretical Study ◽

Shallow Donor ◽

Wave Functions ◽

Quantum Molecular Dynamics ◽

Native Defects ◽

Anion Vacancies ◽

Cation And Anion Vacancies ◽

Wide Gap ◽

Type Character ◽

Formation Energies

AbstractThe results of an extensive theoretical study of native defects in GaN and of vacancies in AlN are presented. We have considered cation and anion vacancies, antisites, and intersti-tials. The computations were carried out using quantum molecular dynamics, in supercells containing 72 atoms. Due to the wide gap of nitrides, the formation energies of defects depend strongly on the position of the Fermi level. The N vacancy in GaN introduces a shallow donor level that may be responsible for the n-type character of as-grown GaN.Other defects introduce deep states in the gap, with strongly localized wave functions.

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Cation and anion vacancies in proton irradiated GaInP

Journal of Applied Physics ◽

10.1063/1.1515123 ◽

2002 ◽

Vol 92 (10) ◽

pp. 5942-5949 ◽

Cited By ~ 6

Author(s):

J. Dekker ◽

J. Oila ◽

K. Saarinen ◽

A. Tukiainen ◽

W. Li ◽

...

Keyword(s):

Anion Vacancies ◽

Cation And Anion Vacancies

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The Effect of (Ba,Sr) and (Mn,Fe,W) Dopants on the Microwave Properties of BaxSr1−xTiO3 Thin Films

MRS Proceedings ◽

10.1557/proc-541-699 ◽

1998 ◽

Vol 541 ◽

Cited By ~ 10

Author(s):

Wontae Chang ◽

James S. Horwitz ◽

Won-Jeong Kim ◽

Jeffrey M. Pond ◽

Steven W. Kirchoefer ◽

...

Keyword(s):

Thin Films ◽

Room Temperature ◽

Bias Field ◽

Film Structure ◽

Single Crystal Substrate ◽

Microwave Frequencies ◽

Anion Vacancies ◽

Crystal Substrate ◽

Cation And Anion Vacancies ◽

Donor Acceptor

AbstractSingle phase BaxSr1−xTiO3 (x=0.5 and 0.6) thin films (∼5000Å thick) have been deposited onto (100) MgO single crystal substrate with (Ba,Sr) compensated and/or (Mn,Fe,W) doped targets using pulsed laser deposition (PLD). The room temperature capacitance (C) and dielectric Q (1/tanδ) have been measured at microwave frequencies of I to 20 GHz as a function of electric field (0-80kV/cm). Microstructural defects associated with cation and anion vacancies have been observed in BaxSr1−xTiO3 films. Compensation of the ablation target with excess Ba and Sr tends to increase the dielectric constant and the dielectric Q. A film deposited with (Ba,Sr) compensated target has been obtained with 25% tuning, where % tuning is defined as {(C(0)-C(E))/C(O))×100, and dielectric Q of ∼ 100 at room temperature (1 — 10 GHz) for DC bias field (E=67 kV/cm). A further increase in the dielectric Q is observed by the addition of donor/acceptor dopants such as Mn, Fe, and W (Q≈100-240). The effects of (Ba, Sr) compensation and (Mn,Fe,W) doping on the film structure and dielectric properties are discussed.

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Polyol-Made Spinel Ferrite Nanoparticles—Local Structure and Operating Conditions: NiFe2O4 as a Case Study

Frontiers in Materials ◽

10.3389/fmats.2021.668994 ◽

2021 ◽

Vol 8 ◽

Author(s):

T. Gaudisson ◽

S. Nowak ◽

Z. Nehme ◽

N. Menguy ◽

N. Yaacoub ◽

...

Keyword(s):

Spinel Phase ◽

Spinel Ferrite ◽

Ferrite Nanoparticles ◽

Operating Conditions ◽

X Ray Diffraction ◽

X Ray ◽

Cation Migration ◽

Anion Vacancies ◽

Nickel Ferrite Nanoparticles ◽

Cation And Anion Vacancies

We report the effect of a polyol-mediated annealing on nickel ferrite nanoparticles. By combining X-ray fluorescence spectroscopy, X-ray diffraction, and 57Fe Mössbauer spectrometry, we showed that whereas the as-prepared nanoparticles (NFO) are stoichiometric, the annealed ones (a-NFO) are not, since Ni0-based crystals precipitate. Nickel depletion from the spinel lattice and reduction in the polyol solvent are accompanied with an important cation migration. Indeed, thanks to Mössbauer hyperfine structure analysis, we evidenced that the cation distribution in NFO departs from the thermodynamically stable inverse spinel structure with a concentration of tetrahedrally coordinated Ni2+ of 20 wt-% (A sites). After annealing, and nickel demixing, originated very probably from the A sites of NFO lattice, the spinel phase accommodates with cation and anion vacancies, leading to the (Fe3+0.84□0.16)A[Ni2+0.80Fe3+1.16□0.04]BO4-0.20 formula, meaning that the applied polyol-mediated treatment is not so trivial.

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Phase-transition–induced p-n junction in single halide perovskite nanowire

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1806515115 ◽

2018 ◽

Vol 115 (36) ◽

pp. 8889-8894 ◽

Cited By ~ 20

Author(s):

Qiao Kong ◽

Woochul Lee ◽

Minliang Lai ◽

Connor G. Bischak ◽

Guoping Gao ◽

...

Keyword(s):

Phase Transition ◽

Building Blocks ◽

Chemical Doping ◽

New Class ◽

Anion Vacancies ◽

Cation And Anion Vacancies ◽

Halide Perovskite ◽

Two Phases ◽

P Type ◽

Formation Energies

Semiconductor p-n junctions are fundamental building blocks for modern optical and electronic devices. The p- and n-type regions are typically created by chemical doping process. Here we show that in the new class of halide perovskite semiconductors, the p-n junctions can be readily induced through a localized thermal-driven phase transition. We demonstrate this p-n junction formation in a single-crystalline halide perovskite CsSnI3 nanowire (NW). This material undergoes a phase transition from a double-chain yellow (Y) phase to an orthorhombic black (B) phase. The formation energies of the cation and anion vacancies in these two phases are significantly different, which leads to n- and p- type electrical characteristics for Y and B phases, respectively. Interface formation between these two phases and directional interface propagation within a single NW are directly observed under cathodoluminescence (CL) microscopy. Current rectification is demonstrated for the p-n junction formed with this localized thermal-driven phase transition.

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