Study on Synthesis and Properties of Ba3Y4O9 Phosphors Doped with Up-Converted Rare Earth Ions (RE = Yb3+, Er3+)

2021 ◽  
Vol 16 (3) ◽  
pp. 357-362
Author(s):  
Shiyu Ma ◽  
Bin Liu ◽  
Zongming Liu ◽  
Jinkai Li
Keyword(s):  
Particle Size ◽  
Structural Characteristics ◽  
Ammonium Bicarbonate ◽  
Absorption Capacity ◽  
Rare Earth Ions ◽  
Color Temperature ◽  
Precipitation Method ◽  
Optimal Dosage ◽  
Target Product ◽  
Color Coordinate

Ba3Y(4−4x−4y)Er4xYb4yO9 precursor was synthesized by ammonium bicarbonate co-precipitation method, and its chemical formula is: (NH4)xBa3RE4(OH)y(CO3)z ·nH2O (RE3+ =Y3+, Er3+ and Yb3+). The target product was obtained by calcining at 1400 °C in muffle furnace after 5 h. By means of Thermogravimetric Analysis (TG), X-ray diffraction (XRD), Field Emission Scanning Electron Microscope (FE-SEM), Fourier transform infrared (FT-IR), photoluminescence/photoluminescence excitation (PLE/PL), fluorescence attenuation and color coordinate, the composition, structural characteristics, particle morphology and fluorescence performance of the precursor and target product were studied. The particle size of the precursor was between 50 nm–100 nm, and the particle size of the calcined product was between 1 μm−2 μm. The absorption capacity of the fluorescent material to light is enhanced with the increase of doped ions. The optimal dosage of Yb3+/Er3+ co-doped Ba3Y(4−4x−4y)Er4xYb4yO9 was x = 0.05 and y = 0.20. The color coordinate of Ba3Y3Er0.2Yb0.8O9 phosphor is (0.73, 0.27) and the color temperature is 7383.6 K, showing excellent red light emission.

Effect of Surfactant on the Preparation of Nano-powder for Yb Doping Laser Transparent YAG Ceramic

2013 ◽  
Vol 32 (5) ◽  
pp. 511-515 ◽  
Author(s):  
Xiao Guo Cao ◽  
Jia Wang ◽  
Qi Bai Wu ◽  
Hai Yan Zhang
Keyword(s):  
Particle Size ◽  
Polyethylene Glycol ◽  
Average Particle Size ◽  
Ammonium Bicarbonate ◽  
Spherical Particles ◽  
Precipitation Method ◽  
Average Particle ◽  
X Ray Diffraction ◽  
Nano Powder ◽  
Co Precipitation

AbstractYb:YAG transparent ceramic nano-powder was prepared by chemical co-precipitation method, with ammonium bicarbonate as the precipitant and polyethylene glycol as surfactant. The addition of polyethylene glycol can reduce the agglomeration and particle size of the prepared Yb:YAG powder. The morphology, thermal stability and phase structure of Yb:YAG nano-powder were charactered by scanning electron microscopy (SEM), thermogravimetry and differential thermal analysis (TG-DTA), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy. The results show that well-crystallized nano-powder was obtained by calcining the precursors at 900 °C for 3 h. The average particle size of Yb:YAG powder is about 100–200 nm. When the volume amount of polyethylene glycol is 2.0%, well-dispersed Yb:YAG powder with spherical particles of 100 nm diameter was obtained.

Study on Luminescent Properties of YAG:Ce3+, Gd3+/La3+ Prepared by Co-Precipitation Method

2014 ◽  
Vol 1002 ◽  
pp. 29-34
Author(s):  
Rong Feng Guan ◽  
Ya Jun You ◽  
Juan Song ◽  
Gui Hua Hou
Keyword(s):  
Emission Intensity ◽  
Room Temperature ◽  
Thermal Quenching ◽  
Luminescent Properties ◽  
Ammonium Bicarbonate ◽  
Color Temperature ◽  
Precipitation Method ◽  
Structure Morphology ◽  
Relative Emission Intensity ◽  
Co Precipitation

The YAG:Ce3+, Gd3+/La3+ yellow phosphors were prepared by co-precipitation method with 0.1mol/L ammonium bicarbonate and aqueous ammonia as precipitants, and the crystal structure, morphology, luminescent properties were investigated. The results indicated that the emission peaks of the YAG:Ce3+, Gd3+/La3+ were redshifted from 535nm to 545.5nm /547nm, and the relative emission intensity declined from 330nm to 145/132 with doping content of Gd3+ /La3+ increased from 0 to 0.9mol at room temperature. Compared with Gd-doping phosphors, the redshift of La3+-doping phosphor was larger and the relative emission intensity declined more quickly. Compared with YAG:Ce3+, the thermal quenching characteristics of YAG:Ce,Gd and YAG:Ce,La were noticeably worse when the temperature increased, but the extents of peak wavelength redshifts were almost the same, about is 7-8nm in the experimental temperature range (50-200°C), have little relation with the doping concentration change. Doping concentrations of Gd or La couldn't be too high, and the suitable concentration was less than 0.6mol at the regulating color temperature and color index.

scholarly journals Investigating the Feasibility of Mefenamic Acid Nanosuspension for Pediatric Delivery: Preparation, Characterization, and Role of Excipients

Processes ◽  
2021 ◽  
Vol 9 (4) ◽  
pp. 574
Author(s):  
Nikhat Perween ◽  
Sultan Alshehri ◽  
T. S. Easwari ◽  
Vivek Verma ◽  
Md. Faiyazuddin ◽  
...  
Keyword(s):  
Particle Size ◽  
Mefenamic Acid ◽  
Hydroxypropyl Methylcellulose ◽  
Sodium Dodecyl ◽  
Aqueous Solubility ◽  
Oral Route ◽  
Precipitation Method ◽  
Antisolvent Precipitation

Molecules with poor aqueous solubility are difficult to formulate using conventional approaches and are associated with many formulation delivery issues. To overcome these obstacles, nanosuspension technology can be one of the promising approaches. Hence, in this study, the feasibility of mefenamic acid (MA) oral nanosuspension was investigated for pediatric delivery by studying the role of excipients and optimizing the techniques. Nanosuspensions of MA were prepared by adopting an antisolvent precipitation method, followed by ultrasonication with varying concentrations of polymers, surfactants, and microfluidics. The prepared nanosuspensions were evaluated for particle size, morphology, and rheological measures. Hydroxypropyl methylcellulose (HPMC) with varying concentrations and different stabilizers including Tween® 80 and sodium dodecyl sulfate (SLS) were used to restrain the particle size growth of the developed nanosuspension. The optimized nanosuspension formula was stable for more than 3 weeks and showed a reduced particle size of 510 nm with a polydispersity index of 0.329. It was observed that the type and ratio of polymer stabilizers were responsive on the particle contour and dimension and stability. We have developed a biologically compatible oral nanoformulation for a first-in-class drug beautifully designed for pediatric delivery that will be progressed toward further in vivo enabling studies. Finally, the nanosuspension could be considered a promising carrier for pediatric delivery of MA through the oral route with enhanced biological impact.

scholarly journals Impact of Iron on the Fe–Co–Ni Ternary Nanocomposites Structural and Magnetic Features Obtained via Chemical Precipitation Followed by Reduction Process for Various Magnetically Coupled Devices Applications

Nanomaterials ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 341
Author(s):  
Tien Hiep Nguyen ◽  
Gopalu Karunakaran ◽  
Yu.V. Konyukhov ◽  
Nguyen Van Minh ◽  
D.Yu. Karpenkov ◽  
...  
Keyword(s):  
Particle Size ◽  
Magnetic Properties ◽  
Reduction Process ◽  
Chemical Precipitation ◽  
Precipitation Method ◽  
Magnetic Characteristics ◽  
Reduction Temperature ◽  
Fe Content ◽  
Magnetic Features ◽  
Co Precipitation

This paper presents the synthesis of Fe–Co–Ni nanocomposites by chemical precipitation, followed by a reduction process. It was found that the influence of the chemical composition and reduction temperature greatly alters the phase formation, its structures, particle size distribution, and magnetic properties of Fe–Co–Ni nanocomposites. The initial hydroxides of Fe–Co–Ni combinations were prepared by the co-precipitation method from nitrate precursors and precipitated using alkali. The reduction process was carried out by hydrogen in the temperature range of 300–500 °C under isothermal conditions. The nanocomposites had metallic and intermetallic phases with different lattice parameter values due to the increase in Fe content. In this paper, we showed that the values of the magnetic parameters of nanocomposites can be controlled in the ranges of MS = 7.6–192.5 Am2/kg, Mr = 0.4–39.7 Am2/kg, Mr/Ms = 0.02–0.32, and HcM = 4.72–60.68 kA/m by regulating the composition and reduction temperature of the Fe–Co–Ni composites. Due to the reduction process, drastic variations in the magnetic features result from the intermetallic and metallic face formation. The variation in magnetic characteristics is guided by the reduction degree, particle size growth, and crystallinity enhancement. Moreover, the reduction of the surface spins fraction of the nanocomposites under their growth induced an increase in the saturation magnetization. This is the first report where the influence of Fe content on the Fe–Co–Ni ternary system phase content and magnetic properties was evaluated. The Fe–Co–Ni ternary nanocomposites obtained by co-precipitation, followed by the hydrogen reduction led to the formation of better magnetic materials for various magnetically coupled device applications.

scholarly journals Structure, Luminescence, and Magnetic Properties of Crystalline Manganese Tungstate Doped with Rare Earth Ion

Materials ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3717
Author(s):  
Jae-Young Jung ◽  
Soung-Soo Yi ◽  
Dong-Hyun Hwang ◽  
Chang-Sik Son
Keyword(s):  
Magnetic Field ◽  
Rare Earth ◽  
Sintering Temperature ◽  
Luminescent Properties ◽  
Concentration Quenching ◽  
Rare Earth Ions ◽  
Precipitation Method ◽  
Rare Earth Ion ◽  
Co Precipitation ◽  
Quenching Phenomenon

The precursor prepared by co-precipitation method was sintered at various temperatures to synthesize crystalline manganese tungstate (MnWO4). Sintered MnWO4 showed the best crystallinity at a sintering temperature of 800 °C. Rare earth ion (Dysprosium; Dy3+) was added when preparing the precursor to enhance the magnetic and luminescent properties of crystalline MnWO4 based on these sintering temperature conditions. As the amount of rare earth ions was changed, the magnetic and luminescent characteristics were enhanced; however, after 0.1 mol.%, the luminescent characteristics decreased due to the concentration quenching phenomenon. In addition, a composite was prepared by mixing MnWO4 powder, with enhanced magnetism and luminescence properties due to the addition of dysprosium, with epoxy. To one of the two prepared composites a magnetic field was applied to induce alignment of the MnWO4 particles. Aligned particles showed stronger luminescence than the composite sample prepared with unsorted particles. As a result of this, it was suggested that it can be used as phosphor and a photosensitizer by utilizing the magnetic and luminescent properties of the synthesized MnWO4 powder with the addition of rare earth ions.

scholarly journals Sol-Gel Synthesis of the Double Perovskite Sr2FeMoO6 by Microwave Technique

Materials ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 3876
Author(s):  
Jesús Valdés ◽  
Daniel Reséndiz ◽  
Ángeles Cuán ◽  
Rufino Nava ◽  
Bertha Aguilar ◽  
...  
Keyword(s):  
Particle Size ◽  
Hydrothermal Synthesis ◽  
Microwave Radiation ◽  
Structural Characteristics ◽  
Sol Gel ◽  
Synthesis Method ◽  
Double Perovskite ◽  
Synthesis Methods ◽  
X Ray ◽  
Sol Gel Synthesis

The effect of microwave radiation on the hydrothermal synthesis of the double perovskite Sr2FeMoO6 has been studied based on a comparison of the particle size and structural characteristics of products from both methods. A temperature, pressure, and pH condition screening was performed, and the most representative results of these are herein presented and discussed. Radiation of microwaves in the hydrothermal synthesis method led to a decrease in crystallite size, which is an effect from the reaction temperature. The particle size ranged from 378 to 318 nm when pH was 4.5 and pressure was kept under 40 bars. According to X-ray diffraction (XRD) results coupled with the size-strain plot method, the product obtained by both synthesis methods (with and without microwave radiation) have similar crystal purity. The Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Spectroscopy (EDS) techniques showed that the morphology and the distribution of metal ions are uniform. The Curie temperature obtained by thermogravimetric analysis indicates that, in the presence of microwaves, the value was higher with respect to traditional synthesis from 335 K to 342.5 K. Consequently, microwave radiation enhances the diffusion and nucleation process of ionic precursors during the synthesis, which promotes a uniform heating in the reaction mixture leading to a reduction in the particle size, but keeping good crystallinity of the double perovskite. Precursor phases and the final purity of the Sr2FeMoO6 powder can be controlled via hydrothermal microwave heating on the first stages of the Sol-Gel method.

Mechanical Response of Porous Copper Manufactured by Lost Carbonate Sintering Process

2007 ◽  
Vol 539-543 ◽  
pp. 1863-1867 ◽  
Author(s):  
X.F. Tao ◽  
Li Ping Zhang ◽  
Y.Y. Zhao
Keyword(s):  
Particle Size ◽  
Flexural Strength ◽  
Relative Density ◽  
Mechanical Response ◽  
Compaction Pressure ◽  
Absorption Capacity ◽  
Energy Absorption Capacity ◽  
Three Point Bending ◽  
Porous Copper ◽  
The Impact

This paper investigated the mechanical response of porous copper manufactured by LCS under three-point bending and Charpy impact conditions. The effects of the compaction pressure and K2CO3 particle size used in producing the porous copper samples and the relative density of the samples were studied. The apparent modulus, flexural strength and energy absorption capacity in three-point bending tests increased exponentially with increasing relative density. The impact strength was not markedly sensitive to relative density and had values within 7 – 9 kJ/m2 for the relative densities in the range 0.17 – 0.31. The amount of energy absorbed by a porous copper sample in the impact test was much higher than that absorbed in the three-point bending test, impling that loading strain rate had a significant effect on the deformation mechanisms. Increasing compaction pressure and increasing K2CO3 particle size resulted in significant increases in the flexural strength and the bending energy absorption capacity, both owing to the reduced sintering defects.

scholarly journals Deep machine learning of the spectral power distribution of the LED system with multiple degradation mechanisms

2020 ◽  
Vol 37 ◽  
pp. 172-183
Author(s):  
Cadmus C A Yuan ◽  
JiaJie Fan ◽  
XueJun Fan
Keyword(s):  
Machine Learning ◽  
Thermal Aging ◽  
Empirical Relationship ◽  
Machine Learning Techniques ◽  
Color Temperature ◽  
Design Parameters ◽  
Degradation Mechanisms ◽  
Theoretical Understanding ◽  
Color Coordinate ◽  
Led Luminaire

Abstract The performance and reliability of the light-emitting diode (LED) system significantly depend on the thermal–mechanical loading-enhanced multiple degradation mechanisms and their interactions. The complexity of the LED system restricts the theoretical understanding of the root causes of the luminous fluctuation or the establishment of the direct correlation between the thermal aging loading and the luminous outputs. This paper applies the deep machine learning techniques and develops a gated network with the two-step learning algorithm to build the empirical relationship between the design parameters and the thermal aging loading and the luminous output of LED products. The flexibility of the proposed method will be demonstrated by integrating it with different neural network architectures. The proposed gated network concept has been validated in both multiple LED chip packaging and LED luminaire under thermal aging loading. The validation of the luminous data of multiple LED chip packaging shows that the maximum differences of the correlated color temperature (CCT) and color coordinate are 2.6% and 1.0%, respectively. Moreover, the machine learning results of the LED luminaire exhibit that the differences of lumen depreciation, CCT and color coordinate are 1.6%, 1.9% and 1.1%, after 2160 h of thermal aging.

Effect of the Synthesis Method on the Properties of Ultrafine YAG Powder

2018 ◽  
Vol 281 ◽  
pp. 40-45
Author(s):  
Jie Guang Song ◽  
Lin Chen ◽  
Cai Liang Pang ◽  
Jia Zhang ◽  
Xian Zhong Wang ◽  
...  
Keyword(s):  
Particle Size ◽  
Calcination Temperature ◽  
Hydrothermal Reaction ◽  
Synthesis Method ◽  
Particle Morphology ◽  
Precipitation Method ◽  
Molar Ratio ◽  
Synthesis Process ◽  
Powder Materials ◽  
Co Precipitation

YAG materials has a number of unique properties, the application is very extensive. In this paper, the superfine YAG powder materials were prepared by co-precipitation method and hydrothermal precipitation method. The influence of synthesis process on the morphology of the powder was investigated. The results showed that the precursor powder prepared via the co-precipitation method is mainly from amorphous to crystalline transition with the increasing calcination temperature, the precursor agglomeration is more serious, In the process of increasing the calcination temperature, the dispersibility of the roasted powder is greatly improved, which is favorable for the growth of the crystal grains, so that the particle size of the powder is gradually increased, the YAG precursor prepared by the co-precipitation method is transformed into YAG crystals, the phase transition occurs mainly between 900 and 1100°C. When the molar ratio of salt to alkali is Y3+: OH-=1: 8 via the hydrothermal reaction, the YAG particles with homogeneous morphology can be obtained. When the molar ratio of salt and alkali is increased continuously, the morphology of YAG particles is not obviously changed. The co-precipitation method is easy to control the particle size, the hydrothermal method is easy to control the particle morphology.

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