Investigative study of Mn2+ concentration on the structure, morphology and photoluminescence of sol-gel ZnAl2O4/ZnO/ SrAl2O4/Sr3Al2O6 mixed phase nanophosphor

2020 ◽  
Vol 578 ◽  
pp. 411746
Author(s):  
M.R. Mhlongo ◽  
L.F. Koao ◽  
R.E. Kroon ◽  
S.V. Motloung
Keyword(s):  
Sol Gel ◽  
Mixed Phase ◽  
Structure Morphology

scholarly journals Effect of Eu3+ Concentration on the BaAl2O4/CaAl4O7: x% Eu3+ (0 ≤ x ≤ 5.5) Mixed-Phase Nanophosphors Synthesized Using Citrate Sol-Gel Method

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Bamba Mahman ◽  
Mpho Enoch Sithole
Keyword(s):  
Electron Microscopy ◽  
Sol Gel ◽  
Mixed Phase ◽  
Nanometer Scale ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Structure Morphology ◽  
Crystallite Sizes ◽  
Gel Technique

A series of undoped mixed-phase BaAl2O4/CaAl4O7 (hereafter called BC) and doped BC: x% Eu3+ (0 < x ≤ 5.5) nanophosphors were successfully prepared by the citrate sol-gel technique. Their structure, morphology, and optical properties were studied in detail by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and photoluminescence (PL) spectroscopy. XRD and SEM showed that all the BC:x% Eu3+ samples consisted of the crystalline structure of the mixed phases of both the BaAl2O4 and CaAl4O7 materials. The structure resembles more that of the BaAl2O4 than the CaAl4O7 phase. The TEM results suggest that the crystallite sizes are in the nanometer scale with rod-like particles. PL results showed multiple emission peaks located at 436, 590, 616, 656, and 703 nm, which were assigned to the intrinsic defects within the BC matrix, 5D0 ⟶ 7F1, 5D0 ⟶ 7F2, 5D0 ⟶ 7F3, and 5D0 ⟶ 7F4 transitions of Eu3+, respectively. The decay curves evidently showed that the nanophosphors have persistent luminescence. The Commission Internationale de l’Eclairage (CIE) analysis revealed that doping has tuned the emission colour from blue to orange-red. The results indicate that the Eu3+-doped samples can potentially be used in the orange/red-emitting phosphors.

Blue Emitting BaAl2O4:Ce3+ Nanophosphors with High Color Purity and Brightness for White LEDs

2019 ◽  
Vol 25 (6) ◽  
pp. 1466-1470 ◽  
Author(s):  
Rituparna Chatterjee ◽  
Subhajit Saha ◽  
Karamjyoti Panigrahi ◽  
Uttam Kumar Ghorai ◽  
Gopes Chandra Das ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Field Emission ◽  
Sol Gel ◽  
Blue Emission ◽  
Diffraction Field ◽  
White Leds ◽  
Display Devices ◽  
Transmission Electron ◽  
Structure Morphology ◽  
The Impact

AbstractIn this work, strongly blue emitting Ce3+-activated BaAl2O4 nanophosphors were successfully synthesized by a sol–gel technique. The crystal structure, morphology, and microstructure of the nanophosphors have been studied by X-ray powder diffraction, field emission scanning electron microscopy, and high-resolution transmission electron microscopy. The photoluminescence spectra show the impact of concentration variation of Ce3+ on the photoluminescence emission of the phosphor. These nanophosphors display intense blue emission peaking at 422 nm generated by the Ce3+ 5d → 4f transition under 350 nm excitation. Our results reveal that this nanophosphor has the capability to take part in the emergent domain of solid-state lighting and field-emission display devices.

scholarly journals Nanostructured LiFe5O8 by a Biogenic Method for Applications from Electronics to Medicine

Nanomaterials ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 193
Author(s):  
Silvia Soreto Teixeira ◽  
Manuel P. F. Graça ◽  
José Lucas ◽  
Manuel Almeida Valente ◽  
Paula I. P. Soares ◽  
...  
Keyword(s):  
Spinel Ferrite ◽  
Sol Gel ◽  
Reaction Medium ◽  
Magnetic Hyperthermia ◽  
Magnetic Characteristics ◽  
Secondary Phases ◽  
Heat Treated ◽  
Structure Morphology ◽  
Sol Gel Process ◽  
Crystallite Sizes

The physical properties of the cubic and ferrimagnetic spinel ferrite LiFe5O8 has made it an attractive material for electronic and medical applications. In this work, LiFe5O8 nanosized crystallites were synthesized by a novel and eco-friendly sol-gel process, by using powder coconut water as a mediated reaction medium. The dried powders were heat-treated (HT) at temperatures between 400 and 1000 °C, and their structure, morphology, electrical and magnetic characteristics, cytotoxicity, and magnetic hyperthermia assays were performed. The heat treatment of the LiFe5O8 powder tunes the crystallite sizes between 50 nm and 200 nm. When increasing the temperature of the HT, secondary phases start to form. The dielectric analysis revealed, at 300 K and 10 kHz, an increase of ε′ (≈10 up to ≈14) with a tanδ almost constant (≈0.3) with the increase of the HT temperature. The cytotoxicity results reveal, for concentrations below 2.5 mg/mL, that all samples have a non-cytotoxicity property. The sample heat-treated at 1000 °C, which revealed hysteresis and magnetic saturation of 73 emu g−1 at 300 K, showed a heating profile adequate for magnetic hyperthermia applications, showing the potential for biomedical applications.

Synthesis, Characterization and Properties of PANI/(La-Nd Doped BaFe12O19) Composites

2017 ◽  
Vol 727 ◽  
pp. 327-334
Author(s):  
Yan Wang ◽  
Jun Wang ◽  
Xiao Fei Zhang ◽  
Ya Qing Liu
Keyword(s):  
Sol Gel ◽  
Network Analyzer ◽  
X Ray Diffraction ◽  
Sem Images ◽  
Structure Morphology ◽  
Xrd Patterns ◽  
Hexagonal Platelet ◽  
Peak Value ◽  
Properties Of Composites

La-Nd co-doped barium hexaferrites, Ba0.7(LamNdn)0.3Fe12O19 (D-BaM), were successfully prepared by sol-gel method. PANI / D-BaM composites were synthesized by in-situ polymerization in solution. The structure, morphology and properties of samples have been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), vibrating sample magnetometer (VSM), four-probe conductivity tester and vector network analyzer. The XRD patterns showed that the crystal structure of all the samples exist as M-type phases. The SEM images revealed that the particles presented a hexagonal platelet-like morphology. The magnetic properties could be improved by substitutions of La and Nd ions. The saturation magnetization (Ms) and coercive force (Hc) increased with the change of La / Nd ratio to the maximum at La / Nd = 3:1. The doped particles have also been embedded in conductive PANI to prepare electromagnetic materials, and the conductivity kept on the order of 10-2. The microwave absorbing properties of composites at 30 MHz-6 GHz improved obviously, the peak value of reflection loss could reach-7.5 dB.

Preparation and Photocatalytic Activity of Mixed Phase Anatase/rutile TiO2 Nanoparticles for Phenol Degradation

2014 ◽  
Vol 70 (2) ◽  
Author(s):  
Mohamad Azuwa Mohamed ◽  
Wan Norharyati Wan Salleh ◽  
Juhana Jaafar ◽  
Norhaniza Yusof
Keyword(s):  
Photocatalytic Activity ◽  
Tio2 Nanoparticles ◽  
High Performance ◽  
Sol Gel ◽  
Phenol Degradation ◽  
Chemical Properties ◽  
Mixed Phase ◽  
Rutile Tio2 ◽  
Physico Chemical ◽  
Degussa P25

The evolution of desirable physico-chemical properties in high performance photocatalyst materials involves steps that must be carefully designed, controlled, and optimized. This study investigated the role of key parameter in the preparation and photocatalytic activity analysis of the mixed phase of anatase/rutile TiO2 nanoparticles, prepared via sol-gel method containing titanium-n-butoxide Ti(OBu)4 as a precursor material, nitric acid as catalyst, and isopropanol as solvent. The prepared TiO2 nanoparticles were characterized by means of XRD, SEM, and BET analyses, and UV-Vis-NIR spectroscopy. The results indicated that the calcination temperature play an important role in the physico-chemical properties and photocatalytic activity of the resulting TiO2 nanoparticles. Different calcination temperatures would result in different composition of anatase and rutile. The photocatalytic activity of the prepared mixed phase of anatase/rutile TiO2 nanoparticles was measured by photodegradation of 50 ppm phenol in an aqueous solution. The commercial anatase from Sigma-Aldrich and Degussa P25 were used for comparison purpose. The mixed phase of anatase/rutile TiO2 nanoparticles (consists of 38.3% anatase and 61.7% rutile) that was prepared at 400°C exhibited the highest photocatalytic activity of 84.88% degradation of phenol. The result was comparable with photocatalytic activity demonstrated by Degussa P25 by 1.54% difference in phenol degradation. The results also suggested that the mixed phase of anatase/rutile TiO2 nanoparticles is a promising candidate for the phenol degradation process. The high performance of photocatalyst materials may be obtained by adopting a judicious combination of anatase/rutile and optimized calcination conditions.

scholarly journals Synthesis, Modification and Characterization of Antimicrobial Textile Surface Containing ZnO Nanoparticles

Polymers ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1210
Author(s):  
L. Martinaga Pintarić ◽  
M. Somogi Škoc ◽  
V. Ljoljić Bilić ◽  
I. Pokrovac ◽  
I. Kosalec ◽  
...  
Keyword(s):  
Ultrasonic Irradiation ◽  
Zno Nanoparticles ◽  
Bacterial Species ◽  
Sol Gel ◽  
E Coli ◽  
Antimicrobial Coating ◽  
Irradiation Power ◽  
Structure Morphology ◽  
Time Kill ◽  
Layer Chromatography

In this research, a textile surface was modified by the sol–gel methodology with a new antimicrobial coating containing nanoparticles active against bacteria resistant to antibiotics. The effect of ultrasonic irradiation power (40 to 90 kHz), the concentration of reagents (nanoparticles, precursor and acids) and time (15 to 72 min) were investigated in relation to the structure, morphology and antimicrobial activity of coatings with zinc oxide nanoparticles. The relationship between the sonocatalytic performance and structure of the resultant modification was established by using various techniques, such as FTIR spectroscopy (FTIR) and scanning electron microscopy with an EDX detector (SEM-EDX), thin-layer chromatography (TLC) and antimicrobial effects were determined on selected model microorganisms. The homogeneity of layers with ZnO nanoparticles on samples was increased by increasing the ultrasonic irradiation power and time. The ultrasonic irradiation unify did not only unify both the structure and the morphology of samples, it also prevented the agglomeration of the nanoparticles. Moreover, under optimal conditions, an antimicrobial coating with ZnO nanoparticles, active against bacterial species S. aureus and E. coli was efficiently prepared. Results of the Time-kill methodology revieled excellent results starting after 6 hours of exposal to antimicrobialy functionalized cellulose polymer.

Fabrication of Porous LSCF-SDC Carbonates Composite Cathode for Solid Oxide Fuel Cell (SOFC) Applications

2011 ◽  
Vol 471-472 ◽  
pp. 179-184 ◽  
Author(s):  
Raharjo Jarot ◽  
Andanastuti Muchtar ◽  
Wan Ramli Wan Daud ◽  
Norhamidi Muhamad ◽  
Edy Herianto Majlan
Keyword(s):  
Thermal Expansion ◽  
Sol Gel ◽  
Composite Cathode ◽  
X Ray Diffraction ◽  
X Ray ◽  
Structure Morphology ◽  
Composite Cathodes ◽  
Gel Technique ◽  
Optimum Porosity ◽  
Cold Pressed

Composite cathodes made of perovskite La0.6Sr0.4Co0.2Fe0.8O3 (LSCF) and SDC carbonates (SDC-(Li/Na)2CO3) were investigated in relation to their structure, morphology, thermal expansion coefficient and porosity. As a first step, the LSCF powder was prepared by sol-gel technique. This was followed by the preparation of the LSCF-SDC carbonates composite cathode by mixing the LSCF with SDC-(Li/Na)2CO3 electrolyte via solid state reaction in various compositions, i.e. 30, 40 and 50 wt.%, namely 70LSCF-30SDC7030, 60LSCF-40SDC7030 and 50LSCF-50SDC7030, respectively. The powder mixtures were then calcined at 680oC. The resultant powder was fine with surface area of about 3.39-7.42 m2/g and particle size of 0.56-0.66µm. The powder consists of two distinct phases, i.e. LSCF and SDC-(Li/Na)2CO3 as confirmed with x-ray diffraction. The microstructures were observed under scanning electron microscopy (SEM). Increasing the amount of the SDC-(Li/Na)2CO3 electrolyte in the composite cathode was found to bring the thermal expansion of the cathode closer to that of the electrolyte. The cathode pellets were later compacted at different pressures (27, 32 and 37 MPa) and sintered at 600oC. The optimum porosity (20.99-24.98%) was achieved for samples with SDC-(Li/Na)2CO3 content of 30-50% sintered at 600oC and cold pressed at 37 MPa.

Associated Aspects on Structure, Morphology and Photoluminescence of MgAl2O4:x% Gd3+ Nanophosphor Prepared via Citrate Sol–Gel Method

2019 ◽  
Vol 48 (6) ◽  
pp. 3947-3957 ◽  
Author(s):  
Setumo Victor Motloung ◽  
Tshwafo Ellias Motaung ◽  
Thulani Thokozani Hlatshwayo ◽  
Lehlohonolo Fortune Koao ◽  
Thembinkosi Donald Malevu ◽  
...  
Keyword(s):  
Sol Gel ◽  
Gel Method ◽  
Sol Gel Method ◽  
Structure Morphology

scholarly journals Yb-Doped BaCeO3 and Its Composite Electrolyte for Intermediate-Temperature Solid Oxide Fuel Cells

Materials ◽  
2019 ◽  
Vol 12 (5) ◽  
pp. 739
Author(s):  
Xueyue Jiang ◽  
Fufang Wu ◽  
Hongtao Wang
Keyword(s):  
Solid Oxide Fuel Cells ◽  
Raw Materials ◽  
Sol Gel ◽  
Solid Oxide ◽  
Oxide Fuel ◽  
Barium Acetate ◽  
Sem Images ◽  
Composite Electrolyte ◽  
Fuel Cell Performance ◽  
Structure Morphology

BaCe0.9Yb0.1O3−α was prepared via the sol-gel method using zirconium nitrate, ytterbium trioxide, cerium nitrate and barium acetate as raw materials. Subsequently, it reacted with the binary NaCl~KCl salt to obtain BaCe0.9Yb0.1O3−α-NaCl~KCl composite electrolyte. The structure, morphology, conductivity and fuel cell performance of the obtained samples were investigated. Scanning electron microscope (SEM) images showed that BaCe0.9Yb0.1O3−α and NaCl~KCl combined with each other to form a homogeneous 3-D reticulated structure. The highest power density and conductivity of BaCe0.9Yb0.1O3−α-NaCl~KCl was 393 mW·cm−2 and 3.0 × 10−1 S·cm−1 at 700 °C, respectively.

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