Acid-Base and Luminescent Properties of Gd2O2S: Tb Luminescent Phosphors Synthesized in a Reducing Atmosphere

2020 ◽  
Vol 854 ◽  
pp. 57-63
Author(s):  
Anna V. Rodionova ◽  
Victor I. Kuular ◽  
Tamara S. Minakova ◽  
Parviz Sh. Ustabaev ◽  
Vadim V. Bakhmetyev
Keyword(s):  
Particle Size ◽  
Luminescence Intensity ◽  
Ph Value ◽  
Flaw Detection ◽  
Photoluminescence Intensity ◽  
Acid Base ◽  
X Ray ◽  
Synthesis Conditions ◽  
Reducing Atmosphere ◽  
Charge Mixture

Gd2O2S:Tb phosphors with different terbium content are prepared in a reducing atmosphere at various synthesis conditions. The effect of an activator and Na4P2O7 flux concentrations upon photo-and X-ray induced luminescence of the synthesized samples as well as on their acid-base properties and morphology is studied. The addition of Na4P2O7 flux into the charge mixture leads to a significant increase of the phosphor particle size. A positive correlation is found between the particle size and pH value of the phosphor aqueous slurry. The photoluminescence intensity is found to mostly depend on the activator concentration, while X-ray luminescence intensity primarily depends on the particle size and crystal structure perfectness of the phosphor matrix. Charge mixture compositions and synthesis conditions providing Gd2O2S:Tb phosphors with the highest photo-and X-ray luminescence intensity are determined. A Gd2O2S:Tb phosphor with X-ray luminescence intensity exceeding the values for the commercial phosphor KEP-45 of a similar composition is developed. The obtained phosphors can be used for the manufacture of intensifying screens applied in industrial X-ray flaw detection.

Characteristics of wood-silica composites influenced by the pH value of silica sols

Holzforschung ◽  
2018 ◽  
Vol 72 (4) ◽  
pp. 311-319 ◽  
Author(s):  
Jun Jiang ◽  
Jinzhen Cao ◽  
Wang Wang
Keyword(s):  
Particle Size ◽  
Zeta Potential ◽  
Dimensional Stability ◽  
Colloidal Particle ◽  
Ph Value ◽  
Surface Hardness ◽  
X Ray ◽  
Ph Values ◽  
First Case ◽  
Silica Sols

AbstractSouthern pine (Pinusspp.) sapwood samples were impregnated with silica sols with known zeta potential and particle size distribution at various pH values (3, 5, 7, 9, 11 and 13) to produce wood-silica composites (WSiCs). The morphological and chemical properties of the composites were evaluated by scanning electron microscopy-energy dispersive X-ray (SEM-EDXA) and Fourier transform infrared (FTIR) spectroscopy. The overall performance of the composites was characterized by X-ray diffraction (XRD) and thermogravimetric (TG) analysis, and dynamic wettability tests, and their dimensional stability and surface hardness were also investigated as well. The pH value of the sols had a remarkable effect on the distribution of zeta potential and colloidal particle size, and on their penetration and distribution in the wood. The composites produced at pH 5 and pH 11 show relatively better impregnability and overall properties. In the first case the compatibility with the wood pH (ca. 5) is relevant, and at these pH values are the sol’s particle sizes low. Sols with pH around 13 resulted in inferior properties, such as increased water absorption, high thermal degradation and poor dimensional stability. This could be ascribed to wood degradation under high alkaline conditions. The results were discussed in view of the colloidal particle redistribution and the interaction between silica sol and wood.

Copper (II) Oxide Powder Prepared by Low Temperature Hydrothermal Method

2020 ◽  
Vol 861 ◽  
pp. 270-276
Author(s):  
Pusit Pookmanee ◽  
Maneerat Mueangjai ◽  
Sukon Phanichphant ◽  
Chanchana Thanachayanont
Keyword(s):  
Particle Size ◽  
Low Temperature ◽  
Hydrothermal Method ◽  
Ph Value ◽  
Average Particle Size ◽  
Fine Powder ◽  
Chemical Compositions ◽  
Average Particle ◽  
Mixed Solution ◽  
X Ray

In this research, CuO powder was prepared by low temperature hydrothermal method. Copper (II) nitrate trihydrate (Cu (NO3)2.3H2O) and sodium hydroxide (NaOH) were used as the starting precursors. The final pH value of the mixed solution was adjusted to 9 by 4M NaOH and treated at 100 oC and 200 oC for 4 and 6 h. The black fine powder was obtained after dried at 80 oC for 4 h. The phase was characterized by X-ray diffraction (XRD). A single phase of monoclinic structure of CuO powder prepared by low temperature hydrothermal method at 200 oC for 4 and 6 h was obtained without calcination step. The morphology and particle size were investigated by scanning electron microscopy (SEM). The morphology was flower-like in shape and the average particle size in range of 0.3×0.7 μm. The element composition was indicated by energy dispersive X-ray spectrometry (EDX). The chemical compositions showed the characteristic X-ray energy of copper (Kα = 0.95 keV) and oxygen (Kα = 0.53 keV). The functional group was indentified by fourier transform spectrophotometry (FTIR). The wavenumber at 433-531 cm-1 was corresponded to vibration of Cu-O stretching.

scholarly journals Simple Methods to Synthesize YVO4 Nanocrystals or Microcrystals without Any Templates or Surfactants

2020 ◽  
Vol 2020 ◽  
pp. 1-7
Author(s):  
Baogeng Xie ◽  
Min Chen ◽  
Junyue Lin ◽  
Xiaobing Liu ◽  
Shujun Peng ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Hydrothermal Treatment ◽  
Powder Diffraction ◽  
Ph Value ◽  
Photoluminescence Intensity ◽  
X Ray ◽  
Ph Values ◽  
Transmission Electron

YVO4 crystals with different sizes and shapes were produced through hydrothermal treatment and sonication method without any surfactants or templates. X-ray powder diffraction (XRD), transmission electron microscopy (TEM), and photoluminescence (PL) were used to characterize the obtained products. YVO4 nanocrystals with spindle-like shape had been produced through the two different treating methods. YVO4 crystals, which are bipyramid-capped and micrometer-sized, had been obtained through a simple hydrothermal treatment. Uniform microsized cuboids had been produced through hydrothermal treatment with the final pH value = 2.5. The effects of different final pH values on the shape and crystallinity of products were studied. To determine photoluminescence performances, Eu3+(5%)-doped YVO4 nanocrystals had been synthesized through different methods in various environments and it had been confirmed that crystallinity would affect photoluminescence intensity.

Flame Synthesis of Y2O3:Eu Nanophosphors Using Ethanol as Precursor Solvents

2005 ◽  
Vol 20 (11) ◽  
pp. 2960-2968 ◽  
Author(s):  
Xiao Qin ◽  
Yiguang Ju ◽  
Stefan Bernhard ◽  
Nan Yao
Keyword(s):  
Particle Size ◽  
Monoclinic Phase ◽  
Water Solution ◽  
Flame Temperature ◽  
Ethanol Solution ◽  
Concentration Quenching ◽  
Flame Synthesis ◽  
Photoluminescence Intensity ◽  
X Ray Diffraction ◽  
X Ray

Y2O3:Eu nanophosphors were prepared by flame synthesis using ethanol or water as precursor solutions. The effects of precursor solvents and flame temperature on particle size, morphology, and photoluminescence intensity were investigated. The results showed that flame synthesis using ethanol solution could produce nanoparticles with better homogeneity, smoother surface structure, and stronger photoluminescence intensity than using water. It was found that the concentration quenching limit of the as-prepared nanophosphors from both ethanol and water solution was 18 mol% Eu, which is higher than the reported limit at similar particle size. The x-ray diffraction (XRD) spectra showed that the ethanol precursor solvent produced monoclinic phase Y2O3:Eu nanoparticles at a lower flame temperature than previously reported. It was also shown that the particle size could be controlled by varying the precursor concentration and flame temperature.

The effect of Tin additionon on Structural and magnetic properties of the stannoferrite Li0.5+0.5XFe2.5-1.5XSnXO4

2016 ◽  
Vol 12 (3) ◽  
pp. 4307-4321 ◽  
Author(s):  
Ahmed Hassan Ibrahim ◽  
Yehia Abbas
Keyword(s):  
Particle Size ◽  
Fine Particles ◽  
Magnetic Moments ◽  
Lithium Ferrite ◽  
Tem Analysis ◽  
Weiss Temperature ◽  
X Ray ◽  
Two Phases ◽  
Nanocrystalline Ferrite ◽  
20 Nm

The physical properties of ferrites are verysensitive to microstructure, which in turn critically dependson the manufacturing process.Nanocrystalline Lithium Stannoferrite system Li0.5+0.5XFe2.5-1.5XSnXO4,X= (0, 0.2, 0.4, 0.6, 0.8 and 1.0) fine particles were successfully prepared by double sintering ceramic technique at pre-sintering temperature of 500oC for 3 h andthepre-sintered material was crushed and sintered finally in air at 1000oC.The structural and microstructural evolutions of the nanophase have been studied using X-ray powder diffraction (XRD) and the Rietveld method.The refinement results showed that the nanocrystalline ferrite has a two phases of ordered and disordered phases for polymorphous lithium Stannoferrite.The particle size of as obtained samples were found to be ~20 nm through TEM that increases up to ~ 85 nmand isdependent on the annealing temperature. TEM micrograph reveals that the grains of sample are spherical in shape. (TEM) analysis confirmed the X-ray results.The particle size of stannic substituted lithium ferrite fine particle obtained from the XRD using Scherrer equation.Magneticmeasurements obtained from lake shore’s vibrating sample magnetometer (VSM), saturation magnetization ofordered LiFe5O8 was found to be (57.829 emu/g) which was lower than disordered LiFe5O8(62.848 emu/g).Theinterplay between superexchange interactions of Fe3+ ions at A and B sublattices gives rise to ferrimagnetic ordering of magnetic moments,with a high Curie-Weiss temperature (TCW ~ 900 K).

Storage Problems of Poplar Chips from Short Rotation Plantations with Special Emphasis on Fungal Development

2012 ◽  
Vol 8 (1) ◽  
pp. 123-132 ◽  
Author(s):  
Zsuzsanna Horváth ◽  
Béla Marosvölgyi ◽  
Christine Idler ◽  
Ralf Pecenka ◽  
Hannes Lenz
Keyword(s):  
Particle Size ◽  
Health Risk ◽  
Dry Matter ◽  
Ph Value ◽  
Wood Chips ◽  
Raw Material ◽  
Special Focus ◽  
Fungal Development ◽  
Short Rotation ◽  
Fungal Particles

Abstract - There are several problems in storing wood chips freshly harvested from short rotation plantations, which result in quality losses as well as in dry matter and energy losses. The factors influencing the degradation of raw material are examined in this paper with special focus on fungal development. An excessive growth of fungi is connected to dry matter losses and also to an increased health risk during raw material handling. The following factors were measured during 6 months storage of poplar wood chips depending on particle size: box temperature, moisture content, pH-value, appearance of fungi in the storage and the concentration of fungal particles in the air. The results show a close connection between particle size, temperature and attack of fungi. During the storage mesophilic and termophilic species of the genera Alternaria, Aspergillus, Cladosporium, Mucor and Penicillium appeared. The concentration of fungal particles is the highest for fine chips and decreases in bigger particles. There was a special focus on the investigation of the properties of coarse chips (G 50), which represent a good compromise between handling, storage losses and health risk due to fungal development.

Exploring the characteristics of the nickel oxide nanoparticles via Sol - gel method

2020 ◽  
Vol 3 (3) ◽  
Author(s):  
Jothi M ◽  
Sowmiya K
Keyword(s):  
Nickel Oxide ◽  
Ph Value ◽  
Lattice Structure ◽  
Sol Gel ◽  
Systematic Change ◽  
Average Crystalline Size ◽  
Nio Nanoparticles ◽  
Nickel Oxide Nanoparticles ◽  
X Ray ◽  
Vis Spectroscopy

Nickel Oxide (NiO) is an important transition metal oxide with cubic lattice structure. NiO is thermally stable that is suitable for tremendous applications in the field of optic, ceramic,glass, electro-chromic coatings, plastics, textiles, nanowires, nanofibers, electronics,energy technology, bio-medicine, magnetism and so on. In this present study, NiO nanoparticles were successfully synthesized by sol-gel technique. Nano-sols were prepared by dissolving Nickel-Chloride [NiCl2.6H2O] in NaOH solvent and were converted into nano structured gel on precipitation. A systematic change in preparation parameters like calcination temperature, time, pH value has been noticed in order to predict the influence on crystallite size. Then the prepared samples were characterized by the X-ray Diffraction Spectroscopic (XRD), UV-VIS Spectroscopy, Fourier Transform Infra-Red Spectroscopy (FTIR), Energy Dispersive X-ray Spectroscopy (EDX), Scanning Electron Microscopy (SEM) and Particle Size Analyzer (PSA). From XRD, the average crystalline-size has been calculated by Debye-Scherrer Equation and it was found to be 12.17 nm and the band gap energy of Nickel oxide (NiO) from UV studies reveals around 3.85 eV. Further, EDX and FTIR studies, confirm the presences of NiO nanoparticles. The SEM study exhibits the spherical like morphology of Nickel oxide (NiO). Further from PSA, the mean value of NiO nanoparticles has been determined.

Processing of granite quarry solid waste into industrial high silica materials using leaching process with HCl concentration variation

2020 ◽  
Vol 11 (2) ◽  
pp. 43-50
Author(s):  
Yusup Hendronursito ◽  
Muhammad Amin ◽  
Slamet Sumardi ◽  
Roniyus Marjunus ◽  
Frista Clarasati ◽  
...  
Keyword(s):  
Particle Size ◽  
Rotational Speed ◽  
Inductively Coupled Plasma ◽  
Chemical Elements ◽  
Silica Content ◽  
X Ray ◽  
Concentration Variation ◽  
Leaching Process ◽  
Hcl Concentration ◽  
Granite Powder

This study was aimed to increase granite's silica content using the leaching process with HCl concentration variation. The granite used in this study came from Lematang, South Lampung. This study aims to determine the effect of variations in HCl concentration, particle size, and rotational speed on the crystalline phase and chemical elements formed in the silica product produced from granite. The HCl concentration variations were 6.0 M, 7.2 M, 8.4 M, and 9.6 M, the variation in particle size used was 270 and 400 mesh. Variations in rotational speed during leaching were 500 and 750 rpm. Granite powder was calcined at 1000 ºC for 2 hours. Characterization was performed using X-Ray Fluorescence (XRF), X-Ray Diffraction (XRD), and Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP- OES). The results showed that the silica content increased with increasing HCl concentration, the finer the particle size, and the higher the rotational speed. XRF analysis showed that the silica with the highest purity was leached with 9.6 HCl with a particle size of 400 mesh and a rotational speed of of 750 rpm, which was 73.49%. Based on the results above, by leaching using HCl, the Si content can increase from before. The XRD diffractogram showed that the granite powder formed the Quartz phase.

Preparation and properties of green rust type substances

1987 ◽  
Vol 52 (1) ◽  
pp. 93-102 ◽  
Author(s):  
Jaroslav Vinš ◽  
Jan Šubrt ◽  
Vladimír Zapletal ◽  
František Hanousek
Keyword(s):  
Chemical Composition ◽  
Electron Diffraction ◽  
Green Rust ◽  
X Ray ◽  
Synthesis Conditions ◽  
Diffraction Patterns

A method has been worked out for the reproducible preparation of Green Rust substances involving SO42-, Cl-, Br-, and I- anions. The chemical composition of the substances prepared has been followed in dependence on the synthesis conditions. The powder X-ray and electron diffraction patterns and infrared and Moessbauer spectra have been measured and discussed.

scholarly journals Modification of Wood with Monoethanolamino-borate by The Data of X-Ray Photoelectron Spectroscopy

2018 ◽  
Vol 196 ◽  
pp. 04005
Author(s):  
Irina Stepina ◽  
Irina Kotlyarova
Keyword(s):  
Particle Size ◽  
Photoelectron Spectroscopy ◽  
Model Compound ◽  
Hydrolytic Stability ◽  
Photoelectron Spectra ◽  
Wood Cellulose ◽  
Rapid Loss ◽  
X Ray ◽  
Wood Protection ◽  
Cellulose Materials

The difficulty of wood protection from biocorrosion and fire is due to the fact that modifiers in use are washed out from the surface of the substrate under the influence of environmental factors. This results in a rapid loss of the protective effect and other practically important wood characteristics caused by the modification. To solve this problem is the aim of our work. Here, monoethanolaminoborate is used as a modifier, where electron-donating nitrogen atom provides a coordination number equal to four to a boron atom, which determines the hydrolytic stability of the compounds formed. Alpha-cellulose ground mechanically to a particle size of 1 mm at most was used as a model compound for the modification. X-ray photoelectron spectra were recorded on the XSAM-800 spectrometer (Kratos, UK). Prolonged extraction of the modified samples preceded the registration of the photoelectron spectra to exclude the fixation of the modifier molecules unreacted with cellulose. As a result of the experiment, boron and nitrogen atoms were found in the modified substrate, which indicated the hydrolytic stability of the bonds formed between the modifier molecules and the substrate. Therefore monoethanolaminoborate can be considered as a non-extractable modifier for wood-cellulose materials.

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