The role of H2O in the photocatalytic oxidation of toluene in vapour phase on anatase TiO2 catalyst

The hydration of tricalcium silicate (C3S) with three grain sizes of monoclinic (M) and triclinic (T) modifications and on their thermally activated samples were investigated by exposure to water vapour at 80°C for 60 days. The products were investigated by XRD, TG and N2 adsorption. The smaller the particle size the greater was the hydration for both dried and activated samples from (M). In the activated samples a hydrate with 2θ values of 38.4°, 44.6° and 48.6° could be identified. Hydration increased with particle size for the unactivated (T) samples but after activation the intermediate size exhibited enhanced hydration. Thermal treatment at 950°C of (T) samples increased the surface active centers on the expense of those in the bulk. Changes produced in surface texture upon activation and/or hydration are discussed.

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Role of dislocations in nitride laser diodes with different indium content

Scientific Reports ◽

10.1038/s41598-020-79528-z ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Agata Bojarska-Cieślińska ◽

Łucja Marona ◽

Julita Smalc-Koziorowska ◽

Szymon Grzanka ◽

Jan Weyher ◽

...

Keyword(s):

Quantum Wells ◽

Defect Density ◽

Laser Diodes ◽

Diffusion Path ◽

Vapour Phase ◽

Indium Content ◽

Nonradiative Recombination ◽

Light Emitters ◽

Vapour Phase Epitaxy

AbstractIn this work we investigate the role of threading dislocations in nitride light emitters with different indium composition. We compare the properties of laser diodes grown on the low defect density GaN substrate with their counterparts grown on sapphire substrate in the same epitaxial process. All structures were produced by metalorganic vapour phase epitaxy and emit light in the range 383–477 nm. We observe that intensity of electroluminescence is strong in the whole spectral region for devices grown on GaN, but decreases rapidly for the devices on sapphire and emitting at wavelength shorter than 420 nm. We interpret this behaviour in terms of increasing importance of dislocation related nonradiative recombination for low indium content structures. Our studies show that edge dislocations are the main source of nonradiative recombination. We observe that long wavelength emitting structures are characterized by higher average light intensity in cathodoluminescence and better thermal stability. These findings indicate that diffusion path of carriers in these samples is shorter, limiting the amount of carriers reaching nonradiative recombination centers. According to TEM images only mixed dislocations open into the V-pits, usually above the multi quantum wells thus not influencing directly the emission.

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Mg2+ storage and mobility in anatase TiO2: the role of frustrated coordination

Journal of Materials Chemistry A ◽

10.1039/c8ta09939a ◽

2019 ◽

Vol 7 (8) ◽

pp. 3704-3713 ◽

Cited By ~ 4

Author(s):

Kit McColl ◽

Furio Corà

Keyword(s):

Anatase Tio2 ◽

Migration Barriers ◽

Lattice Distortions

Low migration barriers of ∼540 meV allow good Mg mobility under dilute conditions, but cooperative lattice distortions limit mobility at high Mg concentrations.

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