scholarly journals Nanoparticles (NPs) of WO3-x Compounds by Polyol Route with Enhanced Photochromic Properties

Nanomaterials ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 1555 ◽  
Author(s):  
Bourdin ◽  
Gaudon ◽  
Weill ◽  
Duttine ◽  
Gayot ◽  
...  
Keyword(s):  
Vacancy Concentration ◽  
Annealing Treatment ◽  
Polyol Synthesis ◽  
Crystallographic Structure ◽  
Oxygen Vacancy Concentration ◽  
Photochromic Properties ◽  
Photochromic Behavior ◽  
Monoclinic System ◽  
Electronic Band ◽  
Post Annealing

Tungsten trioxide (WO3) is well-known as one of the most promising chromogenic compounds. It has a drastic change of coloration induced from different external stimuli and so its applications are developed as gas sensors, electrochromic panels or photochromic sensors. This paper focuses on the photochromic properties of nanoWO3, with tunable composition (with tunable oxygen sub-stoichiometry). Three reference samples with yellow, blue and black colors were prepared from polyol synthesis followed by post annealing under air, none post-annealing treatment, or a post-annealing under argon atmosphere. These three samples differ in terms of crystallographic structure (cubic system versus monoclinic system), oxygen vacancy concentration, electronic band diagram with occurrence of free or trapped electrons and their photochromic behavior. Constituting one main finding, it is shown that the photochromic behavior is highly dependent on the compound’s composition/color. Rapid and important change of coloration under UV (ultraviolet) irradiation was evidenced especially on the blue compound, i.e., the photochromic coloring efficiency of this compound in terms of contrast between bleached and colored phase, as the kinetic aspect is high. The photochromism is reversible in a few hours. This hence opens a new window for the use of tungsten oxide as smart photochromic compounds.

scholarly journals Photoluminescence of Zinc Oxide Nanowires: The Effect of Surface Band Bending

2012 ◽  
Vol 2012 ◽  
pp. 1-6 ◽  
Author(s):  
Dake Wang ◽  
Nicholas Reynolds
Keyword(s):  
Zinc Oxide ◽  
Vacancy Concentration ◽  
Annealing Treatment ◽  
Oxygen Vacancy Concentration ◽  
Zinc Oxide Nanowires ◽  
Surface Band ◽  
Band Bending ◽  
Oxide Nanowires ◽  
Visible Luminescence ◽  
Thermal Annealing Treatment

The photoluminescence of zinc oxide nanowires was investigated via the thermal annealing treatment in oxygen-rich and oxygen-poor conditions. Dramatic changes in the relative intensity of the ultraviolet and the green visible luminescence were observed following different annealing treatments. The changes in photoluminescence bear little correlation to the changes in the oxygen-to-zinc ratios that were revealed using Raman scattering and other characterization techniques. The chemisorption of oxygen and the subsequent surface band bending, instead of the oxygen vacancy concentration, are shown to be the mechanism that determines the observed changes in photoluminescence.

Room temperature fabrication and post-annealing treatment of amorphous Ga2O3 photodetectors for deep-ultraviolet light detection

2022 ◽  
Author(s):  
Tan Zhang ◽  
Denggao Guan ◽  
Ningtao Liu ◽  
Jianguo Zhang ◽  
Jinfu Zhang ◽  
...  
Keyword(s):  
Response Time ◽  
Room Temperature ◽  
Vacancy Concentration ◽  
Annealing Treatment ◽  
Cost Effective ◽  
Metal Structure ◽  
Synthetic Methods ◽  
Oxygen Vacancy Concentration ◽  
Metal Semiconductor Metal ◽  
Deep Ultraviolet

Abstract This work fabricates deep-ultraviolet (DUV) photodetectors (PDs) with a metal-semiconductor-metal structure based on radio-frequency sputtered amorphous Ga2O3 films at room temperature. The Ga2O3-based PD exhibits a low dark current of 1.41×10-11 A, good responsivity of 1.77 A/W and a fast-rise response time of 114 ms. A series of annealing treatments with different atmospheres have been found effective to reduce the oxygen vacancy concentration, exhibiting a trade-off effect between the responsivity and response time. These results demonstrate a cost-effective room-temperature approach for fabricating amorphous Ga2O3-based PDs and develop possible post-synthetic methods for tuning the PD performance.

scholarly journals Combined iDPC and EELS analyses for quantifying oxygen vacancy concentration in LSMO

2021 ◽  
Vol 27 (S1) ◽  
pp. 1196-1197
Author(s):  
Aubrey Penn ◽  
Sanaz Koohfar ◽  
Divine Kumah ◽  
James LeBeau
Keyword(s):  
Oxygen Vacancy ◽  
Vacancy Concentration ◽  
Oxygen Vacancy Concentration

scholarly journals Effects on Microstructure and Ionic Conductivity of the Co-Doping with Strontium and Samarium of Ceria with Constant Oxygen Vacancy Concentration

Solids ◽  
2021 ◽  
Vol 2 (4) ◽  
pp. 341-370
Author(s):  
Toby Sherwood ◽  
Richard T. Baker
Keyword(s):  
Oxygen Vacancy ◽  
Grain Boundary ◽  
Vacancy Concentration ◽  
Synthesis Method ◽  
Ionic Conductivities ◽  
Solubility Limit ◽  
Material Structure ◽  
Oxygen Vacancy Concentration ◽  
Co Doping ◽  
Phase Pure

Partially substituted cerias are attractive materials for use as electrolytes in intermediate-temperature solid oxide fuel cells (SOFCs). Ceria doped with Sm or Gd has been found to have high ionic conductivities. However, there is interest in whether doping with multiple elements could lead to materials with higher ionic conductivities. The present study looks at the effects of co-doping Sr and Sm in ceria. A compositional series, Ce0.8+xSm0.2−2xSrxO2−δ (with x = 0–0.08), designed to have a constant oxygen vacancy concentration, was successfully prepared using the citrate–nitrate complexation method. A solubility limit of ~5 cation% Sr was found to impact material structure and conductivity. For phase-pure materials, with increasing Sr content, sinterability increased slightly and intrinsic conductivity decreased roughly linearly. The grain boundaries of phase-pure materials showed only a very small blocking effect, linked to the high-purity synthesis method employed, while at high %Sr, they became more blocking due to the presence of a SrCeO3 impurity. Grain capacitances were found to be 50–60 pF and grain boundary capacitances, 5–50 nF. The variation in the bulk capacitance with Sr content was small, and the variation in grain boundary capacitance could be explained by the variation in grain size. Slight deviations at high %Sr were attributed to the SrCeO3 impurity. In summary, in the absence of deleterious effects due to poor microstructure or impurities, such as Si, there is no improvement in conductivity on co-doping with Sr and Sm.

scholarly journals Post-Annealing Effect on Optical and Electronic Properties of Thermally Evaporated MoOX Thin Films as Hole-Selective Contacts for p-Si Solar Cells

2021 ◽  
Author(s):  
Yuanwei Jiang ◽  
Shuangying Cao ◽  
Linfeng Lu ◽  
Guanlin Du ◽  
Yinyue Lin ◽  
...  
Keyword(s):  
Solar Cells ◽  
Work Function ◽  
Electronic Properties ◽  
Crystalline Silicon ◽  
Annealing Treatment ◽  
Crystalline Silicon Solar Cells ◽  
Post Annealing ◽  
Si Solar Cells ◽  
Optical And Electronic Properties ◽  
Large Work

Abstract Owing to its large work function, MoOX has been widely used for hole-selective contact in both thin film and crystalline silicon solar cells. In this work, thermally evaporated MoOX films are employed on the rear sides of p-type crystalline silicon (p-Si) solar cells, where the optical and electronic properties of the MoOX films as well as the corresponding device performances are investigated as a function of post-annealing treatment. The MoOX film annealed at 100oC shows the highest work function and proves the best hole selectivity based on the results of energy band simulation and contact resistivity measurements. The full rear p-Si/MoOX/Ag contacted solar cells demonstrate the best performance with an efficiency of 19.19%, which is the result of the combined influence of MoOX’s hole selectivity and passivation ability.

Magnetic State of Ba-Doped Manganites Depending on the Oxygen Vacancy Concentration

2002 ◽  
Vol 233 (2) ◽  
pp. 321-330 ◽  
Author(s):  
S.V. Trukhanov ◽  
N.V. Kasper ◽  
I.O. Troyanchuk ◽  
H. Szymczak ◽  
K. B�rner
Keyword(s):  
Oxygen Vacancy ◽  
Magnetic State ◽  
Vacancy Concentration ◽  
Oxygen Vacancy Concentration ◽  
Doped Manganites

MECHANISM STUDY ON OXYGEN VACANCY INDUCED RESISTANCE SWITCHING IN Au/LaMnO3/SrNb0.01Ti0.99O3

2013 ◽  
Vol 27 (11) ◽  
pp. 1350074 ◽  
Author(s):  
YU-LING JIN ◽  
ZHONG-TANG XU ◽  
KUI-JUAN JIN ◽  
CHEN GE ◽  
HUI-BIN LU ◽  
...  
Keyword(s):  
Oxygen Vacancy ◽  
Oxygen Vacancies ◽  
Vacancy Concentration ◽  
Resistance Switching ◽  
Switching Behavior ◽  
Oxygen Vacancy Concentration ◽  
Mechanism Study ◽  
Switching Performance ◽  
Switching Characteristics

Mechanism of resistance switching in heterostructure Au / LaMnO 3/ SrNb 0.01 Ti 0.99 O 3 was investigated. In Au / LaMnO 3/ SrNb 0.01 Ti 0.99 O 3 devices the LaMnO 3 films were fabricated under various oxygen pressures. The content of the oxygen vacancies has a significant impact on the resistance switching performance. We propose that the resistance switching characteristics of Au / LaMnO 3/ SrNb 0.01 Ti 0.99 O 3 arise from the modulation of the Au / LaMnO 3 Schottky barrier due to the change of the oxygen vacancy concentration at Au / LaMnO 3 interface under the external electric field. The effect of the oxygen vacancy concentration on the resistance switching is explained based on the self-consistent calculation. Both the experimental and numerical results confirm the important role of the oxygen vacancies in the resistance switching behavior.

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