scholarly journals Crystallization behaviour of Li2O·Nb2O5·SiO2 glass containing TiO2

2011 ◽  
Vol 5 (4) ◽  
pp. 223-227 ◽  
Author(s):  
Srdjan Matijasevic ◽  
Vladimir Zivanovic ◽  
Mihajlo Tosic ◽  
Snezana Grujic ◽  
Jovica Stojanovic ◽  
...  
Keyword(s):  
Phase Composition ◽  
Crystallization Behavior ◽  
Glass Ceramics ◽  
Primary Phase ◽  
Surface Crystallization ◽  
Complex Phase ◽  
Crystallite Sizes ◽  
Complex Phase Composition ◽  
Calculated Average

This paper deals with the crystallization of glass 30Li2O?15Nb2O5?50SiO2?5TiO2 (mol%). The crystallization behavior was studied under isothermal and non-isothermal conditions. XRD and SEM methods were employed for determination of phase composition and microstructure of crystallized glass. It was detected that this glass crystallizes by the surface crystallization mechanism. SEM micrographs of the crystallized samples revealed that the crystals grow in the form of dendrites. The glass-ceramics with complex phase composition was obtained. Three crystalline phases were detected where LiNbO3 has grown as primary phase and a secondary ones Li2Si2O5 and SiO2 appeared. The calculated average crystallite sizes are: 27 nm for LiNbO3 , 115 nm for Li2Si2O5 and 45 nm for SiO2 . From the experimental data an activation energy of crystals growth, calculated using the Kissinger relation, is Ea = 275 ?10 KJ / mol.

scholarly journals OXYGEN INFLUENCE ON THE PHASE COMPOSITION AND ELECTRICAL PROPERTIES OF SIPOS FILMS

2020 ◽  
Author(s):  
Vladimir Terekhov ◽  
Konstantin Barkov ◽  
Dmitry Nesterov ◽  
Anatoliy Popov ◽  
Aleksey Barinov ◽  
...  
Keyword(s):  
Phase Composition ◽  
Electrical Properties ◽  
Amorphous Silicon ◽  
Oxygen Content ◽  
Oxidation State ◽  
Breakdown Voltage ◽  
Silicon Nanocrystals ◽  
Electrophysical Properties ◽  
Complex Phase ◽  
Complex Phase Composition

The use of oxygen-doped semi-insulating silicon films of the SIPOS type as passivation coatings for semiconductor devices and IC makes it possible to increase the breakdown voltage of highvoltage devices. The aim of this work is to establish the influence of the oxygen content on the phase composition of SIPOS films and their electrophysical properties. The results of comprehensive studies show that SIPOS films at different values of γ have a complex phase composition of nanocomposites based on amorphous silicon containing silicon nanocrystals and silicon suboxides with a low oxidation state, such as SiO0.47, while SiO2 dioxide is not formed even at large values of γ.

scholarly journals Redox-Promoted Tailoring of the High-Temperature Electrical Performance in Ca3Co4O9 Thermoelectric Materials by Metallic Cobalt Addition

Materials ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1060 ◽  
Author(s):  
Gabriel Constantinescu ◽  
Artur R. Sarabando ◽  
Shahed Rasekh ◽  
Diogo Lopes ◽  
Sergii Sergiienko ◽  
...  
Keyword(s):  
Phase Composition ◽  
High Temperature ◽  
Pechini Method ◽  
Electrical Performance ◽  
Processing Route ◽  
Two Stage ◽  
Complex Phase ◽  
Modified Pechini Method ◽  
Cobalt Addition ◽  
Complex Phase Composition

This paper reports a novel composite-based processing route for improving the electrical performance of Ca3Co4O9 thermoelectric (TE) ceramics. The approach involves the addition of metallic Co, acting as a pore filler on oxidation, and considers two simple sintering schemes. The (1-x)Ca3Co4O9/xCo composites (x = 0%, 3%, 6% and 9% vol.) have been prepared through a modified Pechini method, followed by one- and two-stage sintering, to produce low-density (one-stage, 1ST) and high-density (two-stage, 2ST) ceramic samples. Their high-temperature TE properties, namely the electrical conductivity (σ), Seebeck coefficient (α) and power factor (PF), were investigated between 475 and 975 K, in air flow, and related to their respective phase composition, morphology and microstructure. For the 1ST case, the porous samples (56%–61% of ρth) reached maximum PF values of around 210 and 140 μWm−1·K−2 for the 3% and 6% vol. Co-added samples, respectively, being around two and 1.3 times higher than those of the pure Ca3Co4O9 matrix. Although 2ST sintering resulted in rather dense samples (80% of ρth), the efficiency of the proposed approach, in this case, was limited by the complex phase composition of the corresponding ceramics, impeding the electronic transport and resulting in an electrical performance below that measured for the Ca3Co4O9 matrix (224 μWm−1·K−2 at 975K).

Laboratory Determination of the Solid Phase Composition of Technogenically Salinized Peatlands: Possibilities and Limitations

2020 ◽  
Vol 75 (3) ◽  
pp. 131-137
Author(s):  
Yu. N. Vodyanitskii ◽  
N. A. Avetov ◽  
A. T. Savichev ◽  
S. Ya. Trofimov ◽  
E. A. Shishkonakova
Keyword(s):  
Phase Composition ◽  
Solid Phase ◽  
Laboratory Determination ◽  
Solid Phase Composition

Crystallization Behavior of Nd2O3 Doped Na2O–CaO–SiO2 Laser Glass-ceramics

2015 ◽  
Vol 31 (11) ◽  
pp. 1158-1160 ◽  
Author(s):  
Shuming Wang ◽  
Fenghua Kuang ◽  
Dazhan Zhang ◽  
Xu Zhou ◽  
Minghui Tang
Keyword(s):  
Crystallization Behavior ◽  
Glass Ceramics ◽  
Laser Glass
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