scholarly journals A Comparative Study on Luminescence Properties of Y2O3: Pr3+ Nanocrystals Prepared by Different Synthesis Methods

Nanomaterials ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 1574
Author(s):  
Andrea Diego-Rucabado ◽  
Marina T. Candela ◽  
Fernando Aguado ◽  
Jesús González ◽  
Fernando Rodríguez ◽  
...  
Keyword(s):  
Optical Properties ◽  
Comparative Study ◽  
Figure Of Merit ◽  
Luminescence Decay ◽  
Synthesis Methods ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Reaction Conditions ◽  
Wet Chemistry ◽  
Transmission Electron

Pr3+-doped Y2O3 nanocrystals (NCs) have been obtained via five wet-chemistry synthesis methods which were optimized in order to achieve superior optical properties. To this end, a systematic study on the influence of different reaction parameters was performed for each procedure. Specifically, precursor concentration, reaction temperature, calcination temperature, and time, among others, were analyzed. The synthesized Y2O3: Pr3+ NCs were characterized by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), powder X-ray diffraction (PXRD), transmission electron microscopy (TEM), and reflectance and Raman spectroscopy. In addition, the optical properties of such NCs were investigated by excitation, emission, and luminescence decay measurements. Concretely, emission from the 1D2 level was detected in all samples, while emission from 3PJ was absent. Finally, the effect of the synthesis methods and the reaction conditions on the luminescence decay has been discussed, and a comparative study of the different methods using the fluorescence lifetime of so-obtained Y2O3: Pr3+ NCs as a figure of merit has been carried out.

Surfactant involved in Copper Sulfide Nanocrystallites Synthesis

2009 ◽  
Vol 59 (12) ◽  
Author(s):  
Claudia Maria Simonescu ◽  
Valentin Serban Teodorescu ◽  
Camelia Capatina
Keyword(s):  
Copper Sulfide ◽  
X Ray Diffraction ◽  
Reaction Parameters ◽  
Reaction Conditions ◽  
X Ray ◽  
Selected Area Electron Diffraction ◽  
Transmission Electron ◽  
Shape Of Nanoparticles ◽  
Tem Transmission Electron Microscopy ◽  
Shape And Size

This paper presents the obtaining of copper sulfide CuS (covelite) from Cu(CH3COO)2.H2O and thioacetamide (TAA) system. The reaction was conducted in presence or absence of sodium-bis(2-ethylhexyl) sulfosuccinate (Na-AOT). The effects of various reaction parameters on the size and on the shape of nanoparticles have been examined. CuS obtained was characterized by X ray diffraction, IR spectroscopy, TEM � transmission electron microscopy and SAED selected area electron diffraction. The influence of surfactant to the shape and size of CuS (covellite) nanocrystals was established. The size of the nanocrystals varied from 10-60 nm depending on the reaction conditions such as quantity of surfactant.

scholarly journals Temperature Dependence of Stress and Optical Properties in AlN Films Grown by MOCVD

Nanomaterials ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 698
Author(s):  
Wenwang Wei ◽  
Yi Peng ◽  
Jiabin Wang ◽  
Muhammad Farooq Saleem ◽  
Wen Wang ◽  
...  
Keyword(s):  
Optical Properties ◽  
Compressive Stress ◽  
Sapphire Substrate ◽  
Light Transmission ◽  
Chemical Vapor ◽  
Biaxial Stress ◽  
X Ray Diffraction ◽  
Patterned Sapphire Substrate ◽  
Transmission Electron ◽  
Nano Patterning

AlN epilayers were grown on a 2-inch [0001] conventional flat sapphire substrate (CSS) and a nano-patterned sapphire substrate (NPSS) by metalorganic chemical vapor deposition. In this work, the effect of the substrate template and temperature on stress and optical properties of AlN films has been studied by using Raman spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM), UV-visible spectrophotometer and spectroscopic ellipsometry (SE). The AlN on NPSS exhibits lower compressive stress and strain values. The biaxial stress decreases from 1.59 to 0.60 GPa for AlN on CSS and from 0.90 to 0.38 GPa for AlN on NPSS sample in the temperature range 80–300 K, which shows compressive stress. According to the TEM data, the stress varies from tensile on the interface to compressive on the surface. It can be deduced that the nano-holes provide more channels for stress relaxation. Nano-patterning leads to a lower degree of disorder and stress/strain relaxes by the formation of the nano-hole structure between the interface of AlN epilayers and the substrate. The low crystal disorder and defects in the AlN on NPSS is confirmed by the small Urbach energy values. The variation in bandgap (Eg) and optical constants (n, k) with temperature are discussed in detail. Nano-patterning leads to poor light transmission due to light scattering, coupling, and trapping in nano-holes.

scholarly journals Effects of Sintering Temperature on Densification, Microstructure and Mechanical Properties of Al-Based Alloy by High-Velocity Compaction

Metals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 218
Author(s):  
Xianjie Yuan ◽  
Xuanhui Qu ◽  
Haiqing Yin ◽  
Zaiqiang Feng ◽  
Mingqi Tang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
High Velocity ◽  
Sintered Density ◽  
Sintering Temperature ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Transmission Electron ◽  
High Velocity Compaction ◽  
Sintered Temperature

This present work investigates the effects of sintering temperature on densification, mechanical properties and microstructure of Al-based alloy pressed by high-velocity compaction. The green samples were heated under the flow of high pure (99.99 wt%) N2. The heating rate was 4 °C/min before 315 °C. For reducing the residual stress, the samples were isothermally held for one h. Then, the specimens were respectively heated at the rate of 10 °C/min to the temperature between 540 °C and 700 °C, held for one h, and then furnace-cooled to the room temperature. Results indicate that when the sintered temperature was 640 °C, both the sintered density and mechanical properties was optimum. Differential Scanning Calorimetry, X-ray diffraction of sintered samples, Scanning Electron Microscopy, Energy Dispersive Spectroscopy, and Transmission Electron Microscope were used to analyse the microstructure and phases.

Solvothermal synthesis and characterization of well-dispersed cerium-doped Y2SiO5 phosphor particles

2021 ◽  
Vol 112 (10) ◽  
pp. 812-816
Author(s):  
Xianxue Li
Keyword(s):  
Solvothermal Method ◽  
Luminescence Decay ◽  
X Ray Diffraction ◽  
X Ray ◽  
Fluorescence Spectrophotometry ◽  
Decay Properties ◽  
Transmission Electron ◽  
Water As Solvent ◽  
Pure Phase

Abstract Well-dispersed cerium-doped Y2SiO5 (Ce:YSO) phosphor particles with spherical morphology and good luminescence intensity have been achieved by a solvothermal method with ethanol and water as solvent media. X-ray diffraction, Fourier transform infrared spectroscopy, fluorescence spectrophotometry and transmission electron microscopy were employed to characterize the as-synthesized Ce:YSO precursor and powders. The results showed that pure-phase Ce:YSO powders with a mean particle size of about 162 nm were accurately available at 310°C and above. The fluorescence ability and persistent luminescence decay properties of the Ce:YSO powders were also studied, and the excellent fluorescence properties could be attributed to the homogeneous Ce:YSO particles obtained through the solvothermal method.

scholarly journals Preparation, characterization and scale-up of sesamol loaded solid lipid nanoparticles

2012 ◽  
Vol 2 (1) ◽  
pp. 8 ◽  
Author(s):  
Vandita Kakkar ◽  
Indu Pal Kaur
Keyword(s):  
Solid Lipid Nanoparticles ◽  
Scale Up ◽  
Spherical Shape ◽  
Entrapment Efficiency ◽  
Lipid Nanoparticles ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Solid Lipid ◽  
Transmission Electron ◽  
The Brain

Sesamol loaded solid lipid nanoparticles (SSLNs) were prepared with the aim of minimizing its distribution to tissues and achieving its targeting to the brain. Three scale-up batches (100x1 L) of S-SLNs were prepared using a microemulsification technique and all parameters were statistically compared with the small batch (1x;10 mL). S-SLNs with a particle size of less than 106 nm with a spherical shape (transmission electron microscopy) were successfully prepared with a total drug content and entrapment efficiency of 94.26±2.71% and 72.57±5.20%, respectively. Differential scanning calorimetry and infrared spectroscopy confirmed the formation of lipidic nanoparticles while powder X-ray diffraction revealed their amorphous profile. S-SLNs were found to be stable for three months at 5±3°C in accordance with International Conference on Harmonisation guidelines. The SLN preparation process was successfully scaled-up to a 100x batch on a laboratory scale. The procedure was easy to perform and allowed reproducible SLN dispersions to be obtained.

scholarly journals Nanostructured germanium deposited on heated substrates with enhanced photoelectric properties

2016 ◽  
Vol 7 ◽  
pp. 1492-1500 ◽  
Author(s):  
Ionel Stavarache ◽  
Valentin Adrian Maraloiu ◽  
Petronela Prepelita ◽  
Gheorghe Iordache
Keyword(s):  
Optical Properties ◽  
Response Time ◽  
Spectral Width ◽  
Fast Response ◽  
Superior Performance ◽  
X Ray Diffraction ◽  
Electrical Measurements ◽  
Preparation Conditions ◽  
Photoelectric Properties ◽  
Transmission Electron

Obtaining high-quality materials, based on nanocrystals, at low temperatures is one of the current challenges for opening new paths in improving and developing functional devices in nanoscale electronics and optoelectronics. Here we report a detailed investigation of the optimization of parameters for the in situ synthesis of thin films with high Ge content (50 %) into SiO2. Crystalline Ge nanoparticles were directly formed during co-deposition of SiO2 and Ge on substrates at 300, 400 and 500 °C. Using this approach, effects related to Ge–Ge spacing are emphasized through a significant improvement of the spatial distribution of the Ge nanoparticles and by avoiding multi-step fabrication processes or Ge loss. The influence of the preparation conditions on structural, electrical and optical properties of the fabricated nanostructures was studied by X-ray diffraction, transmission electron microscopy, electrical measurements in dark or under illumination and response time investigations. Finally, we demonstrate the feasibility of the procedure by the means of an Al/n-Si/Ge:SiO2/ITO photodetector test structure. The structures, investigated at room temperature, show superior performance, high photoresponse gain, high responsivity (about 7 AW−1), fast response time (0.5 µs at 4 kHz) and great optoelectronic conversion efficiency of 900% in a wide operation bandwidth, from 450 to 1300 nm. The obtained photoresponse gain and the spectral width are attributed mainly to the high Ge content packed into a SiO2 matrix showing the direct connection between synthesis and optical properties of the tested nanostructures. Our deposition approach put in evidence the great potential of Ge nanoparticles embedded in a SiO2 matrix for hybrid integration, as they may be employed in structures and devices individually or with other materials, hence the possibility of fabricating various heterojunctions on Si, glass or flexible substrates for future development of Si-based integrated optoelectronics.

scholarly journals Role of Surfactants in the Properties of Poly(Ethylene Terephthalate)/Purified Clay Nanocomposites

Materials ◽  
2018 ◽  
Vol 11 (8) ◽  
pp. 1397 ◽  
Author(s):  
Elaine dos Santos ◽  
Marcus Fook ◽  
Oscar Malta ◽  
Suédina de Lima Silva ◽  
Itamara Leite
Keyword(s):  
Clay Nanocomposites ◽  
Phosphonium Salts ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Transmission Electron ◽  
Poly Ethylene Terephthalate ◽  
Poly Ethylene ◽  
Alkyl Ammonium ◽  
Pet Crystallization

Purified clay was modified with different amounts of alkyl ammonium and phosphonium salts and used as filler in the preparation of PET nanocomposites via melt intercalation. The effect of this type of filler on morphology and thermal and mechanical properties of PET nanocomposites was investigated by X-ray diffraction (XRD), differential scanning calorimetry (DSC), thermogravimetric analyses (TG), tensile properties, and transmission electron microscopy (TEM). The results showed that the mixture of alkyl ammonium and phosphonium salts favored the production of PET nanocomposites with intercalated and partially exfoliated morphologies with slight improvement in thermal stability. In addition, the incorporation of these organoclays tended to inhibit PET crystallization behavior, which is profitable in the production of transparent bottles.

scholarly journals The Evaluation of Meloxicam Nanocrystals by Oral Administration with Different Particle Sizes

Molecules ◽  
2022 ◽  
Vol 27 (2) ◽  
pp. 421
Author(s):  
Yao Yu ◽  
Yang Tian ◽  
Hui Zhang ◽  
Qingxian Jia ◽  
Xuejun Chen ◽  
...  
Keyword(s):  
Particle Size ◽  
Water Solubility ◽  
Cell Model ◽  
Particle Sizes ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Laser Scattering ◽  
Transport Studies ◽  
Transmission Electron ◽  
Transmission And Absorption

Meloxicam (MLX) is a non-steroidal anti-inflammatory drug used to treat rheumatoid arthritis and osteoarthritis. However, its poor water solubility limits the dissolution process and influences absorption. In order to solve this problem and improve its bioavailability, we prepared it in nanocrystals with three different particle sizes to improve solubility and compare the differences between various particle sizes. The nanocrystal particle sizes were studied through dynamic light scattering (DLS) and laser scattering (LS). Transmission electron microscopy (TEM) was used to characterize the morphology of nanocrystals. The sizes of meloxicam-nanocrystals-A (MLX-NCs-A), meloxicam-nanocrystals-B (MLX-NCs-B), and meloxicam-nanocrystals-C (MLX-NCs-C) were 3.262 ± 0.016 μm, 460.2 ± 9.5 nm, and 204.9 ± 2.8 nm, respectively. Molecular simulation was used to explore the distribution and interaction energy of MLX molecules and stabilizer molecules in water. The results of differential scanning calorimetry (DSC) and powder X-ray diffraction (PXRD) proved that the crystalline state did not change in the preparation process. Transport studies of the Caco-2 cell model indicated that the cumulative degree of transport would increase as the particle size decreased. Additionally, plasma concentration–time curves showed that the AUC0–∞ of MLX-NCs-C were 3.58- and 2.92-fold greater than those of MLX-NCs-A and MLX-NCs-B, respectively. These results indicate that preparing MLX in nanocrystals can effectively improve the bioavailability, and the particle size of nanocrystals is an important factor in transmission and absorption.

Evolution of Crystalline Phase and Morphology of the Products Formed during the Hydrothermal Synthesis of Y2O3 Powders

2011 ◽  
Vol 189-193 ◽  
pp. 1275-1279
Author(s):  
Ying Wang ◽  
Gao Yang Zhao ◽  
Li Yuan
Keyword(s):  
Electron Microscopy ◽  
Hydrothermal Treatment ◽  
Crystalline Phase ◽  
Hydrothermal Reaction ◽  
Yttrium Nitrate ◽  
Temperature Reaction ◽  
X Ray Diffraction ◽  
Reaction Conditions ◽  
X Ray ◽  
Transmission Electron

The crystalline phase and morphology of the products formed during the synthesis of yttrium oxide via the hydrothermal treatment yttrium nitrate were characterized by X-ray diffraction, transmission electron microscopy and scanning electron microscopy. Products with high OH/NO3ratios are formed with the increasing of hydrothermal treatment. The crystalline phases are evolved from Y2(OH)5.14(NO3)0.86•H2O toY4O(OH)9(NO3) and finally Y(OH)3. The hydrothermal reaction conditions play an important role in the synthesis of the microstructures. Results show the particle size and final morphology of samples could be controlled by reaction temperature, reaction time, and OH-concentration. Sheets, hexagonal and needle-like Y2O3powders are obtained with the hydrothermal treatment of yittrium nitrate at 180 oC to 200oC for 2-8 hours at pH 9-13.

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