The Seeding Effects on the Phase Transformation of Sol-Gel Derived PZT Powder

Glass-ceramic powders with a composition of Li2O · Al2O3 · 4SiO2 (LAS) have been synthesized by the sol-gel technique using LiOCH3, Al(OC2H5)3, Si(OC2H5)4, Ti(OC2H5)4, and Zr(OC2H5)4 as starting materials and the phase transformation behavior during calcination has been investigated. Differential thermal analysis (DTA), x-ray diffraction (XRD), and scanning electron microscopy (SEM) were utilized to determine the thermal behavior of the gels. Considering the LAS gels with 6.0 wt. % TiO2 and various wt. % ZrO2 content, and peak position of the β-spodumene phase formation in DTA curves was shifted to a higher temperature when the ZrO2 content was increased. The activation energy of β-spodumene crystallization was 283.8 kcal/mol for LAS gels with 6.0 wt. % TiO2 and 2.0 wt. % ZrO2. Unlike foregoing studies for LAS gels, during calcination of the dried LASTZ gels from 800 °C to 1200 °C neither β-eucryptite nor γ-spodumene was noted to be present. The crystallized phases comprised of β-spodumenes as the major phase and rutile (TiO2) together with zirconia (ZrO2) are precipitated as minor phases.

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Copper-alumina materials made by infiltration in boehmite

Journal of Materials Research ◽

10.1557/jmr.1995.2271 ◽

1995 ◽

Vol 10 (9) ◽

pp. 2271-2276 ◽

Cited By ~ 1

Author(s):

V. Pierre ◽

D. Pierre ◽

A.C. Pierre

Keyword(s):

Thin Films ◽

Heat Treatment ◽

Phase Transformation ◽

Sandwich Structures ◽

Sol Gel ◽

Copper Acetate ◽

New Materials ◽

Heat Treated ◽

Direct Infiltration

New materials were made by infiltration of sol-gel boehmite thin films with copper acetate. The structure and phase transformation of these materials during heat treatment were studied. It was found that infiltration in the boehmite state did not end up in the same material as direct infiltration in the θ-alumina derived from boehmite, even after both types of materials were heat-treated at 900 °C. Infiltration in boehmite makes it possible to synthesize sandwich structures comprised of alternate layers of CuO and of γ-alumina.

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Comparative study of phase transformation of Al2O3 nanoparticles prepared by chemical precipitation and sol-gel auto combustion methods

Materials Today Proceedings ◽

10.1016/j.matpr.2019.05.450 ◽

2020 ◽

Vol 26 ◽

pp. 122-125

Author(s):

Priyanka Nayar ◽

Sayali Waghmare ◽

Priyansh Singh ◽

Mohamed Najar ◽

Suresh Puttewar ◽

...

Keyword(s):

Phase Transformation ◽

Comparative Study ◽

Sol Gel ◽

Chemical Precipitation ◽

Al2o3 Nanoparticles ◽

Auto Combustion

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Study on the Phase Transformation Kinetics of Sol-Gel DrivedTiO2Nanoparticles

Journal of Nanomaterials ◽

10.1155/2010/626978 ◽

2010 ◽

Vol 2010 ◽

pp. 1-5 ◽

Cited By ~ 20

Author(s):

H. Mehranpour ◽

M. Askari ◽

M. Sasani Ghamsari ◽

H. Farzalibeik

Keyword(s):

Activation Energy ◽

Phase Transformation ◽

Sol Gel ◽

Rutile Phase ◽

Transformation Kinetics ◽

X Ray ◽

Prepared Nanoparticles ◽

Phase Transformation Kinetics ◽

Diffusion Controlled ◽

Kinetics Of

Titanium dioxide nanopowders were synthesized by the diffusion controlled sol-gel process (LaMer model) and characterized by DTA-TG, XRD, and SEM. The preparedTiO2nanoparticles have uniform size and morphology, and the phase transformation kinetics of obtained material was studied by interpretation of the X-ray diffraction patterns peaks on the base of Avrami equation. The stating point of anatase-rutile phase transformation temperature in the prepared nanoparticles was found between 100 and200°C. A decreasing trend on the intensity of X-ray peaks of anatase phase was observed up to600°Cwhen the presence of the rutile phase became predominant. Results indicated that the transition kinetics of the diffusion controlled prepared nanoparticles was begun at low temperature, and it can be concluded that the nucleation and growth sites in these particles were more than other. However, it has been found that the nucleation activation energy of rutile phase was 20 kj/mol, and it is the lowest reported activation energy.

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Nanocrystal TiO2 Engulfed SiO2-Barium Hexaferrite for Enhanced Electrons Mobility and Solar Harvesting Potential

Materials Science Forum ◽

10.4028/www.scientific.net/msf.819.226 ◽

2015 ◽

Vol 819 ◽

pp. 226-231

Author(s):

Azrina Abd Aziz ◽

Shaliza Ibrahim ◽

Saravanan Pichiah

Keyword(s):

Phase Transformation ◽

Photocatalytic Activity ◽

Magnetic Separation ◽

Sol Gel ◽

Visible Region ◽

Barium Hexaferrite ◽

Band Gap Energy ◽

Magnetic Core ◽

Magnetic Photocatalyst ◽

Titania Photocatalyst

Barium hexaferrite embedded-silica-titania photocatalyst (TiO2-SiO2-BaFe12O19) was synthesized through sol-gel, liquid catalytic phase transformation and solid reaction routes. The magnetic photocatalyst was aimed to harvest the photoenergy from the sunlight, minimize the electron-holes recombination rate, improve the long lifetime charge-carriers transfer to maximize the photocatalytic activity and enhances the separation and reusability of it. The as-synthesized photocatalyst was characterized and the photocatalytic activity was evaluated for the reduction of 2, 4-dichlorophenol (2, 4-DCP) under direct sunlight. The presence of SiO2 interlayer in TiO2-SiO2-BaFe12O19 prevents the phase transformation of magnetic core. TiO2-SiO2-BaFe12O19 benefits the magnetic separation with appreciable magnitude of coercivity (5035.6 Oe) and saturation magnetization (18.8256E-3 emu/g), respectively. The ferrite ions from the magnetic core which dispersed into TiO2 matrix exhibited an evident shift of the absorption in the visible region. This was again confirmed with the reduced band gap energy of 1.90 eV. Furthermore, TiO2-SiO2-BaFe12O19 destructed 100% of 2, 4-DCP compound within 150 min under very bright sunlight with an average irradiance of 820.8 W/m2 (results not shown). The embedding of BaFe12O19 with a SiO2 layer onto TiO2 nanocrystals contributed for an excellent solar-light utilization and ease magnetic separation of the nanosized photocatalyst.

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