scholarly journals Modulation of Lithium Disilicate Translucency through Heat Treatment

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2094
Author(s):  
Seok-Ki Jung ◽  
Dae Woon Kim ◽  
Jeongyol Lee ◽  
Selvaponpriya Ramasamy ◽  
Hyun Sik Kim ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Particle Size ◽  
Light Scattering ◽  
Flexural Strength ◽  
Control Method ◽  
Light Transmission ◽  
Lithium Disilicate ◽  
Lower Heat ◽  
Average Size ◽  
Ball Test

The aim of this study was to present a control method for modulating the translucency of lithium disilicate ceramics through thermal refinement. Identical lithium disilicate blocks were thermally refined using four different heat treatment schedules, and the microstructure, translucency, and flexural strength of the ceramics were investigated in detail by SEM, spectroscopy, and a piston-on-three-ball test. The results showed that ceramics treated under higher heat had larger grains, with an average size between 240 and 1080 nm. In addition, a higher transmittance of all wavelengths was observed in ceramics treated under lower heat, and the transmittance in the 550 nm wavelength ranged from 27 to 34%. The results suggest that the translucency of ceramics can be modified through thermal refinement under two conditions: (1) the particle size of the ceramic is small enough to achieve minimal grain-boundary light scattering, and (2) the percentage of particles allowing visible light transmission is altered by the heat treatment.

scholarly journals An Advanced Sensor for Particles in Gases Using Dynamic Light Scattering in Air as Solvent

Sensors ◽  
2021 ◽  
Vol 21 (15) ◽  
pp. 5115
Author(s):  
Dan Chicea ◽  
Cristian Leca ◽  
Sorin Olaru ◽  
Liana Maria Chicea
Keyword(s):  
Particle Size ◽  
Light Scattering ◽  
Light Intensity ◽  
Dynamic Light Scattering ◽  
Scattered Light ◽  
Experimental Setup ◽  
Scattering Experiment ◽  
Processing Procedure ◽  
Average Size ◽  
Data Processing Procedure

Dynamic Light Scattering is a technique currently used to assess the particle size and size distribution by processing the scattered light intensity. Typically, the particles to be investigated are suspended in a liquid solvent. An analysis of the particular conditions required to perform a light scattering experiment on particles in air is presented in detail, together with a simple experimental setup and the data processing procedure. The results reveal that such an experiment is possible and using the setup and the procedure, both simplified to extreme, enables the design of an advanced sensor for particles and fumes that can output the average size of the particles in air.

Angle-dependent effects in Dynamic Light Scattering measurements of polydisperse particles

2021 ◽  
Author(s):  
Lin Jin ◽  
Curtis W Jarand ◽  
Mark L Brader ◽  
Wayne F Reed
Keyword(s):  
Particle Size ◽  
Light Scattering ◽  
Dynamic Light Scattering ◽  
Laser Wavelength ◽  
Recent Emergence ◽  
Large Particles ◽  
Average Diffusion ◽  
Biological Polymers ◽  
Average Size ◽  
The Relationship

Abstract Dynamic light scattering (DLS) is widely used for analyzing biological polymers and colloids. Its application to nanoparticles in medicine is becoming increasingly important with the recent emergence of prominent lipid nanoparticle-(LNP)based products, such as the SARS-CoV-2 vaccines from Pfizer, Inc.-BioNTech (BNT162b2) and Moderna, Inc. (mRNA-1273). DLS plays an important role in the characterization and quality control of nanoparticle-based therapeutics and vaccines. However, most DLS instruments have a single detection angle ,and the amplitude of the scattering vector, q, varies among them according to the relationship q=(n/sin(/2) where 0 is the laser wavelength. Results for identical, polydisperse samples among instruments of varying q yield different hydrodynamic diameters, because, as particles become larger they scatter less light at higher angles, so that higher-q instruments will under-sample large particles in polydisperse populations, and report higher z-average diffusion coefficients, and hence smaller effective hydrodynamic diameters than lower-q instruments. As particle size reaches the Mie regime the scattering envelope manifests angular maxima and minima, and the monotonic decrease of average size versus q is lost. This work examines results for different q-value instruments, using mixtures of monodisperse latex sphere standards, for which experimental measurements agree well with computations, and also polydisperse solutions of LNP, for which results follow expected trends. Mie effects on broad unimodal populations are also considered. There is no way to predict results between two instruments with different q for samples of unknown particle size distributions.

The Heat Treatment of Nanocrystalline Cu2O to Enhance the Catalytic Effect at the Surface Layer

2006 ◽  
Vol 118 ◽  
pp. 635-638 ◽  
Author(s):  
Young Rang Uhm ◽  
Byung Sun Han ◽  
Min Ku Lee ◽  
Chang Kyu Rhee
Keyword(s):  
Heat Treatment ◽  
Particle Size ◽  
Surface Layer ◽  
Catalytic Effect ◽  
Adsorption Ability ◽  
Air Exposure ◽  
Gas Condensation ◽  
Heat Treated ◽  
Temperature Ranges ◽  
Average Size

Cu oxide nano powders were synthesized by the levitational gas condensation (LGC) method, and heated at temperature ranges from 150 to 450 C. The nano powders consist of mainly Cu2O with an average size of 35 nm. The analysis of the IR-spectra of the nanopowders demonstrates that the surface of the sample under an air exposure is coated by hydroxylhydride (-OH, H2O) and hydroxycarbonated [Cu2(OH)2CO3]. The change of the particle size by heat treatment below 450 °C is relatively small. The variation of the adsorption ability is mainly defined under heating at least up to 300 °C, by the surface state of the particles. The catalytic effect was increased at heat treated samples.

scholarly journals Phase Transitions in the α–γ–β Spodumene Thermodynamic System and Impact of γ-Spodumene on the Efficiency of Lithium Extraction by Acid Leaching

Minerals ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 519
Author(s):  
Colin Dessemond ◽  
Gervais Soucy ◽  
Jean-Philippe Harvey ◽  
Philippe Ouzilleau
Keyword(s):  
Heat Treatment ◽  
Particle Size ◽  
Extraction Efficiency ◽  
Mechanical Energy ◽  
Acid Leaching ◽  
Thermodynamic System ◽  
Coarse Fraction ◽  
X Ray ◽  
Heat Treated ◽  
Lower Heat

Heat-treatment of spodumene concentrate at 1323 K (1050 °C) for 30 min in a rotary kiln yielded a successful decrepitation. Particle size decreased from 2 cm to less than 425 µm for 80% of the initial mass. X-ray analysis of both fractions did not reveal the presence of α-spodumene or γ-spodumene. The coarse fraction was ground to less than 425 µm with minimal mechanical energy and mixed with the finer fraction to perform lithium extraction. The lithium extraction efficiency reached 98 wt% without the need for flotation. Some aspects of the thermodynamic behavior of the spodumene system were assessed. Results show that metastable γ-spodumene may hinder the formation of β-spodumene at lower heat treatment temperatures. Some heat-treated samples presented non-negligible γ-spodumene content and lithium extraction efficiency decreases as the γ content increases. Finally, the assumed irreversibility of the transformations was studied by analyzing heat-treated samples following long controlled-storage periods. The results show that concentrate composition is not static over the studied time. This suggests that the β formation is not as irreversible as claimed. It is recommended to avoid long periods between heat-treatment and extraction to avoid the slow conversion of β-spodumene to other allotropes, which are less susceptible to lithium extraction.

scholarly journals Synthesis by Microwaves of Bimetallic Nano-Rhodium-Palladium

2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
M. Ugalde ◽  
E. Chavira ◽  
M. T. Ochoa-Lara ◽  
I. A. Figueroa ◽  
C. Quintanar ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Particle Size ◽  
Sol Gel ◽  
Inert Atmosphere ◽  
Microwave Oven ◽  
Microwave Assisted ◽  
Gel Technique ◽  
Pd Clusters ◽  
Average Size ◽  
By Products

An improved acrylamide sol-gel technique using a microwave oven in order to synthesize bimetallic Rh-Pd particles is reported and discussed. The synthesis of Pd and Rh nanoparticles was carried out separately. The polymerization to form the gel of both Rh and Pd was carried out at 80°C under constant agitations. The method chosen to prepare the Rh and Pd xerogels involved the decomposition of both gels. The process begins by steadily increasing the temperature of the gel inside a microwave oven (from 80°C to 170°C). In order to eliminate the by-products generated during the sol-gel reaction, a heat treatment at a temperature of 1000°C for 2 h in inert atmosphere was carried out. After the heat treatment, the particle size increased from 50 nm to 200 nm, producing the bimetallic Rh-Pd clusters. It can be concluded that the reported microwave-assisted, sol-gel method was able to obtain nano-bimetallic Rh-Pd particles with an average size of 75 nm.

Features Of Particle Size Measurements In The Nanosilica Hydrosol By The Optical Methods

2016 ◽  
Vol 11 (4) ◽  
pp. 68-77
Author(s):  
Konstantin Zobov ◽  
Vyacheslav Syzrantsev ◽  
Sergey Bardakhanov
Keyword(s):  
Particle Size ◽  
Light Scattering ◽  
Dynamic Light Scattering ◽  
Rayleigh Scattering ◽  
Light Transmission ◽  
Light Attenuation ◽  
Optical Methods ◽  
Medium Size ◽  
Small Scale ◽  
Transmission Electron Microscopy Analysis

The current level of study and application of nanoparticles raises the question of their classification. One of the main parameters in this case is the particle size. However, its measurement on such a small scale is a valuable problem as usual models are not correct. The article presents the results of measurements of the light attenuation in the hydrosols (dispersions of nanoparticles in water). The Rayleigh scattering theory was applied to the experimental data for obtaining the average size of nanoparticles with various specific surfaces. The obtained values were compared with the results of the transmission electron microscopy analysis and with the results of dynamic light scattering measurements. All of measurements variants presented the specified value of medium size. It could be caused by the mechanics characteristics, structure and other properties of nanoparticles related to the surface properties and their production process. The Rayleigh theory gave the undervalued particle size, and dynamic light scattering gave overvalued one in a comparison with the microscopy data. It is shown that the light transmission attenuation strongly depends from the particle size, only for particles bigger than 15 nm. For smaller particles the association was not found. There are two different particle size ranges for dynamic light scattering measurement of different produced particle.

Preparation of Fe/SiO2 films by sputtering and their magnetic properties.

1995 ◽  
Vol 400 ◽  
Author(s):  
Tomoko Akai ◽  
Mitsuharu Tabuchi ◽  
Ryoji Funahashi ◽  
Hiroshi Yamanaka
Keyword(s):  
Thin Films ◽  
Heat Treatment ◽  
Particle Size ◽  
Magnetic Properties ◽  
Treatment Time ◽  
Average Particle Size ◽  
Heat Treating ◽  
Average Particle ◽  
Sio2 Films ◽  
Average Size

AbstractSiO2 thin films containing fine Fe particles were prepared by a co-sputtering method. α-Fe particles were then formed by heat-treating the film at 650°C to 700°C. The average size of the particles was controlled by changing heat-treatment time and temperature. The magnetic properties of these samples were investigated and discussed in terms of the size of the particles. It was found that the coercivity of the sample containing α-Fe particles (average particle size = 24nm) is as large as 36 Oe which is much higher than that of the bulk Fe.

Effect on Strength and Hardness of Clay Ceramic Substrate after Treatment Using Koalin Based Geopolymer Glaze

2013 ◽  
Vol 594-595 ◽  
pp. 575-580 ◽  
Author(s):  
Abdullah Mohd Mustafa Al Bakri ◽  
J. Liyana ◽  
Md Tahir Muhammad Faheem ◽  
Hussin Kamarudin ◽  
A.R. Razak ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Particle Size ◽  
High Temperature ◽  
Flexural Strength ◽  
Ceramic Industry ◽  
Processing Route ◽  
Alkali Concentration ◽  
Calcined Kaolin ◽  
Hardness Values ◽  
Size Powder

Geopolymerization is an alternative for ceramic industry by using clay based material such as kaolin or calcined kaolin geopolymer. Geopolymer paste is initially produced by alkaline activation of calcined kaolin with NaOH and Na2SiO3solution), dried at 80oC for 4 hours, pulverized and sieved to fixed particle size powder. The parameters involved in this processing route (alkali concentration, kaolin or calcined kaolin to activator ratio, alkali activator ratio and heating conditions) are investigated. Geopolymeric powder is added with water to produce slurry to be coated on the surface of clay ceramic. It undergoes heat treatment at high temperature to produce glaze on the surface. Flexural strength and hardness analysis are studied. Result evidences the processing show of incresing strength value between 8-10% after treatment with geopolymer glaze and also the Vickers hardness values of geopolymers improved.

Sign in / Sign up

Export Citation Format

Share Document