A straightforward approach for high-end anti-counterfeiting applications based on NIR laser-driven lanthanide doped luminescent glasses

2021 ◽  
Author(s):  
Naji Vahedigharehchopogh ◽  
Orhan Kıbrıslı ◽  
Erdinc Erol ◽  
Miray Çelikbilek Ersundu ◽  
Ali Erçin Ersundu
Keyword(s):  
Nano Particles ◽  
Luminescent Materials ◽  
Perovskite Nanocrystals ◽  
Straightforward Approach ◽  
Nir Laser

Increment of forgery in documents and authentic products have aroused the search for new high-end anti-counterfeiting strategies. Various chameleon-like luminescent materials such as up-conversion nano particles or perovskite nanocrystals have...

Ultra-Stable CsPbBr3 Nanocrystals with Lead-Carboxylate/SiO2 Encapsulation for LED Application

2021 ◽  
Author(s):  
Yixuan Liu ◽  
Lulu Zhang ◽  
Xuemi Long ◽  
Panpan Jiang ◽  
Chong Geng ◽  
...  
Keyword(s):  
Luminescent Materials ◽  
Led Lighting ◽  
Perovskite Nanocrystals ◽  
Stability Issue ◽  
Surface Nature

Perovskite nanocrystals (PNCs) are promising luminescent materials but suffer servere stability issue due to their ionic surface nature. SiO2 encapsulation is widely adopted for stabilizing PNCs in LED lighting and...

A Novel Preparation Route of YAG:Ce via Polymer Gel Precursor

2007 ◽  
Vol 336-338 ◽  
pp. 2058-2059
Author(s):  
Cheng Zhang ◽  
Qiang Li ◽  
Dan Yu Jiang
Keyword(s):  
Aqueous Solution ◽  
Single Phase ◽  
Heating Temperature ◽  
Nano Particles ◽  
Luminescent Materials ◽  
Polymer Gel ◽  
N2 Atmosphere ◽  
Preparation Route ◽  
The Stability ◽  
Stability Of The Solution

This paper reports a novel route to synthesize nano particles of YAG:Ce3+ luminescent materials via polymer gel precursor. In an aqueous solution containing Y(NO3)3, Ce(NO3)3 and Al(NO3)3, citric acid was added to improve the stability of the solution. Then, acrylamide and N,N`-methylenebis- acrylamide were added. The polymerization of mixture solution was initiated by adding (NH4)2S2O8. By heating the solution at 80oC for 3 h, a transparent gel was obtained. The gel was firstly transformed into active carbon by soaking it at 700oC in ultrahigh pure N2 atmosphere. Carbon in as-received mixture was then removed when the atmosphere was changed from nitrogen to air at the same heating temperature. Well dispersive nano powders of single phase YAG:Ce3+ were thus obtained. XRD, SEM and BET were used to study the characteristics of as-prepared nano YAG:Ce3+ powders.

Electron holography of catalysts

1995 ◽  
Vol 53 ◽  
pp. 416-417
Author(s):  
A. K. Datye ◽  
D. S. Kalakkad ◽  
L. F. Allard ◽  
E. Völkl
Keyword(s):  
Heterogeneous Catalysts ◽  
High Surface ◽  
High Surface Area ◽  
Atomic Scale ◽  
Nano Particles ◽  
Phase Image ◽  
Electron Holography ◽  
Specimen Thickness ◽  
Phase Information ◽  
Particle Structure

The active phase in heterogeneous catalysts consists of nanometer-sized metal or oxide particles dispersed within the tortuous pore structure of a high surface area matrix. Such catalysts are extensively used for controlling emissions from automobile exhausts or in industrial processes such as the refining of crude oil to produce gasoline. The morphology of these nano-particles is of great interest to catalytic chemists since it affects the activity and selectivity for a class of reactions known as structure-sensitive reactions. In this paper, we describe some of the challenges in the study of heterogeneous catalysts, and provide examples of how electron holography can help in extracting details of particle structure and morphology on an atomic scale.Conventional high-resolution TEM imaging methods permit the image intensity to be recorded, but the phase information in the complex image wave is lost. However, it is the phase information which is sensitive at the atomic scale to changes in specimen thickness and composition, and thus analysis of the phase image can yield important information on morphological details at the nanometer level.

Coherent electron nanodiffraction from clean silver nano particles in a UHV STEM

1993 ◽  
Vol 51 ◽  
pp. 1058-1059
Author(s):  
J. Liu ◽  
M. Pan ◽  
G. E. Spinnler
Keyword(s):  
Supported Catalysts ◽  
Imaging Techniques ◽  
Nano Particles ◽  
Metal Particles ◽  
Shape Structure ◽  
Dynamical Simulations ◽  
Small Metal Particles ◽  
Extract Information

Small metal particles have peculiar chemical and physical properties as compared to bulk materials. They are especially important in catalysis since metal particles are common constituents of supported catalysts. The structural characterization of small particles is of primary importance for the understanding of structure-catalytic activity relationships. The shape and size of metal particles larger than approximately 5 nm in diameter can be determined by several imaging techniques. It is difficult, however, to deduce the shape of smaller metal particles. Coherent electron nanodiffraction (CEND) patterns from nano particles contain information about the particle size, shape, structure and defects etc. As part of an on-going program of STEM characterization of supported catalysts we report some preliminary results of CEND study of Ag nano particles, deposited in situ in a UHV STEM instrument, and compare the experimental results with full dynamical simulations in order to extract information about the shape of Ag nano particles.

Ultrafast photo-induced processes in perovskite nanocrystals

2020 ◽  
Author(s):  
Goutam Ghosh ◽  
Amitava Patra ◽  
Arnab Ghosh ◽  
Srijon Ghosh
Keyword(s):  
Perovskite Nanocrystals

Polycaprolactone based membranes for the degradation of diclofenac present in water samples using ZnO nanoparticles as the active agent

MRS Advances ◽  
2020 ◽  
Vol 5 (61) ◽  
pp. 3153-3161
Author(s):  
Marco Antonio Juárez Sánchez ◽  
Miguel Ángel Meléndez Lira ◽  
Celestino Odín Rodríguez Nava
Keyword(s):  
Zno Nanoparticles ◽  
Wastewater Treatment Plants ◽  
Active Agent ◽  
Heterogeneous Photocatalysis ◽  
Nano Particles ◽  
Electrical Characteristics ◽  
Unit Operation ◽  
Fields Of Study ◽  
Drug Contamination ◽  
Positive Results

AbstractDrug contamination in water is one of the current fields of study. Since 1990, the presence of drugs in drinking water has been a concern to scientists and public. In Mexico, these organic compounds are not efficiently removed in wastewater treatment plants; therefore, alternative methodologies have been studied that allow these compounds to have a high percentage of degradation or be completely degraded. One example of these techniques is heterogeneous photocatalysis which has obtained positive results in the degradation of drugs using ZnO nanoparticles. These are commonly selected for their electrical characteristics, even though they disperse in water and an additional unit operation is required to separate them from the liquid medium. To eliminate drugs with nano particles in a single stage, polycaprolactone-based membranes with adhered ZnO nanoparticles, by means of electrospinning, were prepared to degrade drugs such as diclofenac. The technique used has shown to efficiently break down diclofenac in 4 hours according to the capillary electrophoresis readings.

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