scholarly journals Optical Properties and Radiation Stability of Magnesium Silicate

2021 ◽  
pp. 132-137
Author(s):  
V. V. Harutyunyan ◽  
A. O. Badalyan
Keyword(s):  
Heat Treatment ◽  
Optical Properties ◽  
Hydrothermal Synthesis ◽  
Low Temperature ◽  
Magnesium Silicate ◽  
Radiation Stability ◽  
Water Soluble ◽  
Soluble Salts ◽  
Nanosized Powder ◽  
X Ray

A microwave (MW) method of hydrothermal synthesis of magnesium silicate is developed. At low temperature (240 0C), nuclei of crystalline phase of магний silicate are obtained. Some optical characteristics of the synthesized product are determined. Based on, X-ray and thermographic studies are revealed that the synthesis of magnesium silicate from water-soluble salts of initial components in microwave ovens promotes the formation of magnesium at lower temperatures. MW synthesis of magnesium silicate ensures obtaining of nanosized powder after heat treatment at 850 0C.

scholarly journals Hydrothermal Synthesis of Rare-Earth Modified Titania: Influence on Phase Composition, Optical Properties, and Photocatalytic Activity

Materials ◽  
2019 ◽  
Vol 12 (5) ◽  
pp. 713 ◽  
Author(s):  
Nejc Rozman ◽  
David Tobaldi ◽  
Uroš Cvelbar ◽  
Harinarayanan Puliyalil ◽  
João Labrincha ◽  
...  
Keyword(s):  
Optical Properties ◽  
Photocatalytic Activity ◽  
Rare Earth ◽  
Hydrothermal Synthesis ◽  
Rare Earth Elements ◽  
Rare Earths ◽  
Light Absorption ◽  
Pure Tio2 ◽  
X Ray ◽  
Hydroxyl Oxygen

In order to expand the use of titania indoor as well as to increase its overall performance, narrowing the band gap is one of the possibilities to achieve this. Modifying with rare earths (REs) has been relatively unexplored, especially the modification of rutile with rare earth cations. The aim of this study was to find the influence of the modification of TiO2 with rare earths on its structural, optical, morphological, and photocatalytic properties. Titania was synthesized using TiOSO4 as the source of titanium via hydrothermal synthesis procedure at low temperature (200 °C) and modified with selected rare earth elements, namely, Ce, La, and Gd. Structural properties of samples were determined by X-ray powder diffraction (XRD), and the phase ratio was calculated using the Rietveld method. Optical properties were analyzed by ultraviolet and visible light (UV-Vis) spectroscopy. Field emission scanning electron microscope (FE-SEM) was used to determine the morphological properties of samples and to estimate the size of primary crystals. X-ray photoelectron spectroscopy (XPS) was used to determine the chemical bonding properties of samples. Photocatalytic activity of the prepared photocatalysts as well as the titania available on the market (P25) was measured in three different setups, assessing volatile organic compound (VOC) degradation, NOx abatement, and water purification. It was found out that modification with rare earth elements slows down the transformation of anatase and brookite to rutile. Whereas the unmodified sample was composed of only rutile, La- and Gd-modified samples contained anatase and rutile, and Ce-modified samples consisted of anatase, brookite, and rutile. Modification with rare earth metals has turned out to be detrimental to photocatalytic activity. In all cases, pure TiO2 outperformed the modified samples. Cerium-modified TiO2 was the least active sample, despite having a light absorption tail up to 585 nm wavelength. La- and Gd-modified samples did not show a significant shift in light absorption when compared to the pure TiO2 sample. The reason for the lower activity of modified samples was attributed to a greater Ti3+/Ti4+ ratio and a large amount of hydroxyl oxygen found in pure TiO2. All the modified samples had a smaller Ti3+/Ti4+ ratio and less hydroxyl oxygen.

Hydrothermal Synthesis and Structure of Neptunium(V) Oxide

2006 ◽  
Vol 985 ◽  
Author(s):  
Tori Z. Forbes ◽  
Peter C. Burns ◽  
L. Soderholm ◽  
S. Skanthakumar
Keyword(s):  
Hydrothermal Synthesis ◽  
Low Temperature ◽  
Single Crystals ◽  
Hydrothermal Reaction ◽  
Three Dimensional ◽  
Direct Methods ◽  
Monoclinic Space Group ◽  
X Ray ◽  
Unique Data ◽  
Ccd Detector

AbstractSingle crystals of Np2O5 have been synthesized by low-temperature hydrothermal reaction of a Np5+ stock solution with natural calcite crystals. The structure of Np2O5 was solved by direct methods and refined on the basis of F2 for all unique data collected on a Bruker X-ray diffractometer equipped with an APEX II CCD detector. Np2O5 is monoclinic, space group P2/c, with a = 8.168(2) Å, b = 6.584(1) Å, c = 9.3130(2) Å, β = 116.01(1)˚, V = 449.8(2) Å3, and Z = 1. The structure contains chains of edge-sharing neptunyl pentagonal bipyramids linked into sheets through cation-cation interactions with distorted neptunyl square bipyramids. Additional cation-cation interactions connect the sheets into a three-dimensional framework. The formation of Np2O5 on the surface of calcite crystals has important implications for the precipitation of isolated neptunyl phases in natural aqueous systems.

Hydrothermal Synthesis of Diluted Magnetic Zn1-xMnxO Semiconductor

2013 ◽  
Vol 313-314 ◽  
pp. 184-187
Author(s):  
Wen Li Zheng ◽  
Wei Yang
Keyword(s):  
Hydrothermal Synthesis ◽  
Low Temperature ◽  
Curie Temperature ◽  
Fill Factor ◽  
Diluted Magnetic Semiconductor ◽  
Magnetic Semiconductor ◽  
Height Ratio ◽  
Atom Concentration ◽  
X Ray ◽  
Diluted Magnetic

Diluted magnetic semiconductor Zn1-xMnxO crystals were synthesized at 430°C for 24h by hydrothermal method. 3mol·L-1KOH was used as the mineralizer, and the fill factor is 35%. The obtained crystals show a ZnO wurtzite structure, with positive polar faces{0001}, negative polar faces{000 },pfaces{ 011} and–pfaces { 01 } exposed. The height of the crystal is 5-30 m and radius-height ratio is2:1. Mn atom concentration of 2. 6% (x=0.026) was determined using X-ray energy dispersive spectroscopy ( EDS). The crystals show low-temperature ferromagnetism with Curie temperature of 50K.

scholarly journals Growth of GaN films on (0 0 1) and (1 1 1) GaAs surfaces by a modified MBE method

1996 ◽  
Vol 1 ◽  
Author(s):  
T. S. Cheng ◽  
C. T. Foxon ◽  
N. J Jeffs ◽  
O. H. Hughes ◽  
B. G. Ren ◽  
...  
Keyword(s):  
Optical Properties ◽  
Low Temperature ◽  
Gaas Substrate ◽  
Plasma Source ◽  
Columnar Structure ◽  
Structural And Optical Properties ◽  
Active Nitrogen ◽  
X Ray ◽  
Zinc Blende ◽  
Gaas Substrates

Films of GaN have been grown using a modified MBE method in which the active nitrogen is supplied from an RF activated plasma source. Wurtzite films grown on (0 0 1) oriented GaAs substrates show highly defective, ordered polycrystalline growth with a columnar structure; the (0 0 0 1) planes of the layers being parallel to the (0 0 1) planes of the GaAs substrate. Films grown using a coincident As flux, however, have a single crystal zinc-blende growth mode. They have better structural and optical properties. To improve the properties of the wurtzite films we have studied the growth of such films on (1 1 1)A and (1 1 1)B oriented GaAs substrates. The improved structural properties of such films, assessed using x-ray and TEM methods, correlate with better low temperature PL performance.

Synthesis and Fluorescence Properties of Water-Soluble L-Cysteine-Modified ZnSe:Ag Quantum Dots

2014 ◽  
Vol 1033-1034 ◽  
pp. 1172-1175
Author(s):  
Li Ping Lin ◽  
Feng Hua Huang ◽  
Pei Feng Chen
Keyword(s):  
Crystal Structure ◽  
Quantum Dots ◽  
Optical Properties ◽  
Absorption Spectrum ◽  
Photoluminescence Spectrum ◽  
Water Soluble ◽  
Precipitation Method ◽  
X Ray ◽  
Surface Modifier ◽  
Co Precipitation

The water-soluble ZnSe:Ag quantum dots were synthesized in aqueous medium by chemical co-precipitation method with L-cysteine as surface modifier. The crystal structure and optical properties of the obtained ZnSe:Ag quantum dots have been characterized by X-ray power diffraction, infrared spectrum, UV-Vis absorption spectrum and photoluminescence spectrum. Results indicate that ZnSe:Ag quantum dots belong to the cubic blende structure and have good fluorescent characteristics. The L-cysteine modified on the surface of ZnSe:Ag quantum dots renders the quantum dots water-soluble, biocompatible.

scholarly journals Facile Low Temperature Hydrothermal Synthesis of BaTiO3 Nanoparticles Studied by In Situ X-ray Diffraction

Crystals ◽  
2018 ◽  
Vol 8 (6) ◽  
pp. 253 ◽  
Author(s):  
Ola Grendal ◽  
Anders Blichfeld ◽  
Susanne Skjærvø ◽  
Wouter van Beek ◽  
Sverre Selbach ◽  
...  
Keyword(s):  
Hydrothermal Synthesis ◽  
Low Temperature ◽  
X Ray Diffraction ◽  
X Ray ◽  
Batio3 Nanoparticles

scholarly journals Enhanced Photocatalytic Activity of TiO2/SnO2 Binary Nanocomposites

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Tetiana A. Dontsova ◽  
Anastasiya S. Kutuzova ◽  
Kateryna O. Bila ◽  
Svitlana O. Kyrii ◽  
Iryna V. Kosogina ◽  
...  
Keyword(s):  
Photocatalytic Activity ◽  
Hydrothermal Synthesis ◽  
Low Temperature ◽  
Hydrothermal Method ◽  
Oxide Content ◽  
Porous Structures ◽  
Anionic Dyes ◽  
Commercial Sample ◽  
X Ray ◽  
Adsorption Desorption

The paper presents the results of characterization and study of adsorption-photocatalytic properties of commercial and synthesized-by-hydrothermal method TiO2 and TiO2-SnO2 nanocomposites. Hydrothermal synthesis of TiO2-based nanocomposites was performed in two ways: single-stage and two-stage methods. Characterization was carried out by XRD, X-ray fluorescence method, XPS, EPR, PL, and low-temperature adsorption-desorption of nitrogen, which showed that TiO2-SnO2 nanostructured composites were obtained with tin(IV) oxide content of 10 wt.% and had acidic surface and different porous structures. Besides, modification of a commercial sample with tin(IV) oxide led to a slight decrease in the specific surface area, while modification of a synthesized-by-hydrothermal method TiO2 sample led to an increase. It was found that sorption properties of the obtained nanocomposites and pure TiO2 are better towards anionic dyes. Photocatalytic activity, on the contrary, is higher towards cationic dyes, which is consistent with additional studies on the destruction of these dyes. It was established that in terms of photocatalytic activity, TiO2-SnO2 nanocomposites are more promising than solid solutions, and modification of TiO2 with tin(IV) oxide, in general, leads to improvement of its photocatalytic activity.

Hydrothermal Synthesis of SrSO4:Eu2+ Microcrystals with Different Morphologies and its Luminescence Properties

2014 ◽  
Vol 633-634 ◽  
pp. 341-344 ◽  
Author(s):  
Jia Yue Sun ◽  
Qiu Mei Di ◽  
Liu Han ◽  
Qi Guang Xu ◽  
Chen Liang Ma
Keyword(s):  
Electron Microscopy ◽  
Aqueous Solution ◽  
Scanning Electron Microscopy ◽  
Optical Properties ◽  
Hydrothermal Synthesis ◽  
Emission Spectroscopy ◽  
Electron Trapping ◽  
X Ray Diffraction ◽  
X Ray ◽  
Scanning Electron

Electron trapping materials SrSO4:Eu2+were prepared by hydrothermal method from fatty alcohol polyoxyethylene (3) ether (AEO-3) aqueous solution at 200 °C for 20 h. The phase structure, microstructure and optical properties were characterized with X-ray diffraction (XRD), scanning electron microscopy (SEM) and excitation-emission spectroscopy (PL-PLE), respectively.

scholarly journals Controlling the Emission Properties of Quantum Rods via Multiscale 3D Ordered Organization

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Thomas Bizien ◽  
Marie Postic ◽  
Pascale Even-Hernandez ◽  
Pascal Panizza ◽  
Cristelle Mériadec ◽  
...  
Keyword(s):  
Optical Properties ◽  
Self Assembly ◽  
Optical Response ◽  
Optically Active ◽  
Water Soluble ◽  
X Ray ◽  
Quantum Rods ◽  
X Ray Scattering ◽  
Optical Electron ◽  
Assembly Behavior

A specific organization of optically active nanoscale objects can greatly affect the optical response of a system. Here, we report the controlled modification of the fluorescent emission by the assembly of water-soluble quantum rods (QRs). Our study combines optical, electron microcopy, and X-ray scattering characterizations to reveal a correlation between the self-assembly behavior of QRs into ordered 3D-arrays and the optical properties (luminescence) of formed assemblies, where the observed optical response is highly dependent on the QR aspect ratio. Specifically, shorter, 18 nm long QRs (QR18), exhibiting a well-defined smectic packing, demonstrate an enhancement of the emission intensity accompanied by a red shift and a lifetime reduction. In contrast, 40 nm long QRs (QR40), forming a columnar phase, does not show these optical properties.

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