Effect of Flux Boric Acid (H3BO3) on Yttrium Silicate Y2SiO5:Dy3+ (9 mol%) Nanophosphors Its Characterization and Luminescence Studies

2019 ◽  
Vol 17 (11) ◽  
pp. 898-904
Author(s):  
K. Dhanalakshmi ◽  
A. Jagannatha Reddy

Flux Boric acid (H3BO3) doped on Y2SiO5:Dy3+ phosphors were synthesized by auto ignition based low temperature Solution Combustion Synthesis (SCS) using Oxalic acid dihydrate (ODH) as fuel. Powder X-ray diffraction (PXRD) patterns confirm the nano sized particles corresponding to JCPDS card 36-1476. The crystallite size of the samples estimated from Scherer's formula and Williamson-Hall (W-H) plots was found to be in the range ˜21 nm and 26 nm respectively. Scanning electron Microscope (SEM) micrographs infer addition of flux gives the enhanced grain growth and it attains smooth surface improves the crystallinity and particle morphology of the sample. Fourier transform Infrared (FTIR) data reveals the presence of M–O bonds and Y–O bonds and also the bands at 642 cm–1, 655 cm–1, 668 cm–1, 697 cm–1, 719 cm–1 are ascribed due to the B–O–B linkage in the borate network. Addition of flux on Thermoluminescence (TL) glow curves from 0.5 KGy–4 KGy acts as a sensitizer and the peak appearing at 185 °C is quite stable and can be named as "dosimetric peak" to use in TL phosphor. The kinetic parameters estimated by Chen's peak shape method was found to be second order with activation energy 0.82.

2020 ◽  
Vol 32 (6) ◽  
pp. 1515-1519
Author(s):  
S.G. Prasanna Kumar ◽  
Nagaraju Kottam ◽  
R. Hari Krishna ◽  
M.N. Chandra Prabha ◽  
R. Preetham ◽  
...  

Ca1-xZrO3:xEu3+ (x = 0.05) phosphors have been prepared by using the low temperature solution combustion synthesis. The prepared nano phospors are well characterized by powder X-ray diffraction, scanning electron microscopy, Fourier infrared spectroscopy and transmission electron spectroscopy. PXRD results showed orthorhombic phase and SEM images showed porous agglomerated morphology. Influence of nitridation on structural and photoluminescence properties of the phosphor were investigated for wide range of nitridation time. The photoluminescence (PL) intensity was found to vary with nitridation with small shift in the photoluminescence emission peaks. The probable reasons for the variation of photoluminescence with nitridation are discussed.


2020 ◽  
Vol 32 (3) ◽  
pp. 501-507
Author(s):  
Krushitha Shetty ◽  
B.S. Prathibha ◽  
Dinesh Rangappa ◽  
K.S. Anantharaju ◽  
H.P. Nagaswarupa ◽  
...  

MgFe2O4 nanoferrites were synthesized by sol-gel and solution combustion synthesis (SCS) methods through green and chemical methods. Green and chemical methods for sol-gel were processed with use of lemon extract and citric acid, respectively. A green and chemical method for solution combustion synthesis was followed by using Phyllanthus acidus leaf extract and urea, respectively. The influence of synthesis approach on the behaviour of prepared nanoferrites were studied using powder X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and UV visible spectroscopy, vast variation in particle size, crystallinity, electrochemical and photocatalytic activity of the nanoferrites synthesized by various methods were witnessed. Powder X-ray diffraction (PXRD) result of prepared nanoferrites acquired by green and chemical approaches clarified phase structure as spinel and the crystalline size found to be around 11-24 nm. The spinel surface morphology was witnessed for the synthesized nanoferrites. The tetrahedral and octahedral sites of the prepared nanoferrites were confirmed by FTIR spectra. MgFe2O4 nanoferrites synthesized by green sol-gel approach exposed superior electrochemical activity by possessing very less charge transfer resistance. The results of EIS were correlated with the photocatalytic degradation of Rose Bengal dye. Photocatalytic property of the prepared nanoferrites was examined for photodegradation of Rose Bengal dye under UV-light.


2013 ◽  
Vol 802 ◽  
pp. 84-88
Author(s):  
Sagulthai Kahatta ◽  
Nopsiri Chaiyo ◽  
Chesta Ruttanapun ◽  
Wicharn Techitdheera ◽  
Wisanu Pecharapa ◽  
...  

The microwave-assisted solution combustion synthesis was applied to the initial synthesizing of Ca3Co2O6powder using glycine as a fuel and nitrate as an oxidant. The as-synthesized powders were calcined at 700-1,000ºC for 4h. Product characterization was performed using Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and Scanning electron microscope (SEM). The fuel-to-oxidizer molar ratio was found to affect the combustion reaction and character of the powder obtained. The phase composition of powder after calcination at various temperatures has shown that the formation of Ca3Co2O6occurs directly. The calcined powder possesses a rhombohedral crystal structure with an X-ray diffraction pattern that could be matched with the Ca3Co2O6JCPDS: 89-0629. This method is a simple way of synthesizing fine Ca3Co2O6powder with a low calcination temperature.


2012 ◽  
Vol 485 ◽  
pp. 473-477
Author(s):  
Gui Yang Liu ◽  
Jun Ming Guo ◽  
Li Li Zhang ◽  
Jing Wang ◽  
Bao Sen Wang ◽  
...  

LiAl0.1Mn1.9O4 materials were prepared by a solution combustion synthesis method. In order to improve the purity of the products, the effect of further calcination time was investigated. The phase compositions of the as-prepared products were determined by X-ray diffraction (XRD). The electrochemical performance of the products was tested by using a coin-type half battery versus lithium metal foil as anode material. XRD results suggested that the main phase of the products was LiAl0.1Mn1.9O4, and there was a trace amount Mn2O3 impurity in some of the products. The purity, crystallinity and grain size of the LiAl0.1Mn1.9O4 were increased with increasing further calcination time. Electrochemical experiments demonstrate that the initial discharge capacities of the products with further calcination time of 0, 6, 12 and 24h were 93.7, 105.7, 114.0 and 120.6mAh/g, and about 89.8, 89.5, 89.2 and 88.3% of the initial capacities were retained after 25 cycles, respectively. Further calcination time can enhance the initial capacity, but is not favorable for the cycle ability of the products.


2012 ◽  
Vol 625 ◽  
pp. 251-254 ◽  
Author(s):  
Gui Yang Liu ◽  
Bao Sen Wang ◽  
Ying He ◽  
Jun Ming Guo

In this paper, LiNixMn2−xO4 materials were prepared by solution combustion synthesis method using acetic salts as raw materials and acetic acid as fuel. The phase structures are characterized by X-ray diffraction (XRD). Electrochemical performances of the materials are investigated by galvanostatic charge/discharge methods. XRD results revealed that the main phase of the products with increasing Ni3+ content is LiMn2O4, and there is a trace amount of Mn3O4 found in the product with Ni3+ content of 0.05. Electrochemical experiments showed that the capacity and the cyclability of the LiNixMn2−xO4 materials decrease with increasing Ni3+ content. Ni3+ doping has no significantly improvement for the capacity and the cyclability of the LiMn2O4 spinel.


2012 ◽  
Vol 625 ◽  
pp. 255-258
Author(s):  
Gui Yang Liu ◽  
Bao Sen Wang ◽  
Ying He ◽  
Jun Ming Guo

LiFe0.05Mn1.95O4 materials were prepared by molten-salts combustion synthesis and solution combustion synthesis methods, respectively. The phase structure and compositions of the products were determined by X-ray diffraction (XRD). The main phase of the products prepared by the two methods is LiMn2O4, but at 300-600oC, pure products can not be obtained. At the temperatures of 300 and 400oC, the main impurities are MnO and Mn3O4. The impurities decrease with increasing temperatures, and finally disappear at >500oC. At 500 and 600oC, the main impurity is Mn2O3, but the relative content of Mn2O3 is low.


Materials ◽  
2018 ◽  
Vol 11 (12) ◽  
pp. 2385 ◽  
Author(s):  
Siyong Gu ◽  
Mingli Qin ◽  
Houan Zhang ◽  
Jidong Ma

This work reports the preparation of La2O3 uniformly doped Mo nanopowders with the particle sizes of 40–70 nm by solution combustion synthesis and subsequent hydrogen reduction (SCSHR). To reach this aim, the foam-like MoO2 precursors (20–40 nm in size) with different amounts of La2O3 were first synthesized by a solution combustion synthesis method. Next, these precursors were used to prepare La2O3 doped Mo nanopowders through hydrogen reduction. Thus, the content of La2O3 used for doping can be accurately controlled via the SCSHR route to obtain the desired loading degree. The successful doping of La2O3 into Mo nanopowders with uniform distribution were proved by X-ray photon spectroscopy and transmission electron microscopy. The preservation of the original morphology and size of the MoO2 precursor by the La2O3 doped Mo nanopowders was attributed to the pseudomorphic transport mechanism occurring at 600 °C. As shown by X-ray diffraction, the formation of Mo2C impurity, which usually occurs in the direct H2 reduction process, can be avoided by using the Ar calcination-H2 reduction process, when residual carbon is removed by the carbothermal reaction during Ar calcination at 500 °C.


2008 ◽  
Vol 396-398 ◽  
pp. 591-594 ◽  
Author(s):  
Tiago M. Volkmer ◽  
L.L. Bastos ◽  
V.C. Sousa ◽  
L.A. Santos

The aim of this work is the synthesis of α-tricalcium phosphate by solution combustion synthesis using urea as combustible in the stoichiometric ratio and with excess of combustible. The salts Ca(O3)2.4H2O and (H4)2HPO4 were used as reaction precursors with Ca/P ratio of 1.5. The pH adjustment was made adding nitric acid. A porous foam composed by β-tricalcium phosphate, hydroxyapatite and α or β-dicalcium pyrophosphate were obtained as reaction product. X-ray diffraction was used to identify the phases. The obtainment of α-TCP was possible after a heat treatment where the material was held at 1250°C for 15 hours followed by quenching. Smaller particle size was obtained when four times the stoichiometric ratio of combustible was used in the reaction. α-TCP samples were immersed in SBF in order to verify the biocompatibility.


2020 ◽  
Author(s):  
N. Asefi ◽  
Masood Hasheminiasari ◽  
S. M. Masoudpanah

Abstract Highly pure BiFeO3 (BFO) powders were prepared by solution combustion synthesis method using cetyltrimethylammonium bromide (CTAB) and glycine as fuels at various fuel to oxidant (φ) ratios. Microstructural characteristics, morphology, optical properties, and thermal analysis were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), diffuse reflectance spectroscopy (DRS), and differential thermal/thermogravimetry (DTA/TGA), respectively. The combusted powders prepared at different fuel content contained some impurity phases such as Bi24Fe2O39 and Bi2Fe4O9. During the calcination of BFO powders at 600 °C for 1 hour, nearly pure BFO phase was produced. About 80% of methylene blue dye was photodegraded by combusted powders at φ=2 through 90 minutes of visible light irradiation.


2019 ◽  
Vol 9 (6) ◽  
pp. 1200 ◽  
Author(s):  
Olga Thoda ◽  
Galina Xanthopoulou ◽  
George Vekinis ◽  
Alexander Chroneos

Nanostructured nickel-based catalysts were produced by solution combustion synthesis and it was found that their properties and structure depended on the pretreatment of the precursor solution. X-ray diffraction, N2 adsorption, and an infrared high-speed camera were used to follow the various synthesis steps and to characterize the obtained catalysts, while their catalytic activity was determined in the hydrogenation of maleic acid. It was determined that the amount of water used and the heating of the precursor solution under mild stirring up to 70 °C influenced the nickel nitrate–glycine–water complexes that were formed in the precursor solution in the form of dendrites. These play a key role in the solution combustion synthesis (SCS) reaction mechanism and in particular in the formation of nickel-based catalysts. Understanding the interrelationships between the processing parameters and the ensuing powder properties allowed an efficient optimization of the catalytic performance.


Sign in / Sign up

Export Citation Format

Share Document