Sol-gel processing of varistor powders

1992 ◽  
Vol 7 (3) ◽  
pp. 546-548 ◽  
Author(s):  
Gert Hohenberger ◽  
Gerhard Tomandl
Keyword(s):  
Grain Boundaries ◽  
Mixed Oxide ◽  
Sol Gel ◽  
Homogeneous Distribution ◽  
Electrical Behavior ◽  
Gel Method ◽  
Sol Gel Method ◽  
Zno Varistor ◽  
Gel Processing ◽  
Source Materials

A new sol-gel method for the preparation of ZnO varistor powders, using inexpensive source materials such as acetates and nitrates, is described. It yields powders with a more homogeneous distribution of dopants compared to the commercially used mixed oxide technique. Varistor ceramics made from sol-gel powders can be sintered at lower temperatures and show improved electrical behavior. This is a consequence of formation of more varistor-active grain boundaries within the ceramics.

Bisphenol A Imprinted SiO2‐ZrO2 Mixed Oxide Materials Prepared by Acetic Anhydride Sol‐Gel Method

2007 ◽  
Vol 37 (10) ◽  
pp. 771-777 ◽  
Author(s):  
Masahiro Fujiwara ◽  
Ikou Yamamura ◽  
Motoyasu Nishiyama ◽  
Kumi Shiokawa ◽  
Souichi Ohtsuki ◽  
...  
Keyword(s):  
Acetic Anhydride ◽  
Bisphenol A ◽  
Mixed Oxide ◽  
Sol Gel ◽  
Oxide Materials ◽  
Gel Method ◽  
Sol Gel Method

Magnetoresistance of Nanostructured Sr2FeMoO6/CeO2 Composites

2012 ◽  
Vol 507 ◽  
pp. 44-47
Author(s):  
Xiang Hu Li ◽  
Dan Li ◽  
Dong Wu Xiao
Keyword(s):  
Grain Boundaries ◽  
Sol Gel ◽  
Gel Method ◽  
Sol Gel Method

(Sr2FeMoO6)1-x/(CeO2)xcomposites with nanosized crystallite were prepared by Sr2FeMoO6obtained from the sol-gel method and nanosized CeO2powders. The magnetoresistance of composites increase with the CeO2increasing. And the MR ratio at 10 K is 1.23%, and 2.48% for the x = 0.05 and 0.2 samples with H = 1 kOe, which are 1.25 times and 2.53 times as large as that for pure Sr2FeMoO6, respectively. The enhanced magnetoresistance was attributed to the spin-dependent tunneling at the interface of grain boundaries.

Elucidating the nature and role of copper species in catalytic carbonylation of methanol to methyl acetate over copper/titania–silica mixed oxides

2017 ◽  
Vol 7 (16) ◽  
pp. 3511-3523 ◽  
Author(s):  
Xianjie Meng ◽  
Heqin Guo ◽  
Qiang Wang ◽  
Yong Xiao ◽  
Congbiao Chen ◽  
...  
Keyword(s):  
Mixed Oxide ◽  
Methyl Acetate ◽  
Mixed Oxides ◽  
Sol Gel ◽  
Copper Species ◽  
Gel Method ◽  
Sol Gel Method ◽  
Catalytic Carbonylation

In this study, a series of copper/titania–silica mixed oxide (Cu/TS) catalysts with different copper contents were prepared by a sol–gel method.

scholarly journals Shielding of metals from the corrosion induced by water and humidity by using scratch resistant and hydrophobic silica coatings

2018 ◽  
Vol 39 (1) ◽  
pp. 23-30
Author(s):  
M. R. Shedam ◽  
S. S. Patil ◽  
Rakesh M. Shedam ◽  
Shridhar N. Mathad
Keyword(s):  
Corrosion Resistance ◽  
Metal Surfaces ◽  
Sol Gel ◽  
Deposition Technique ◽  
Gel Method ◽  
Sol Gel Method ◽  
Practical Applications ◽  
Silica Coatings ◽  
Hydrophobic Silica ◽  
Gel Processing

Abstract The objective of the present paper is to demonstrate the effect of sol-gel derived scratch resistant coatings on different metal surfaces for anticorrosive applications. However, practical applications are limited by problems intrinsic to sol-gel processing or specific of coating/metal systems. Coatings aimed to improve oxidation and wet corrosion resistance have been studied the most. The results published in the literature show that sol-gel coatings may offer good protection against oxidation. More difficult is to achieve a protection against wet corrosion. An important aspect of the application of the sol-gel method for coating metallic objects is also the deposition technique.

scholarly journals Synthesis and characterization of nanoscaled Ba(Ti1-x-ySnxGey)O3 powders and corresponding ceramics

2019 ◽  
Author(s):  
Roberto Köferstein
Keyword(s):  
Phase Transition ◽  
Mixed Oxide ◽  
Sol Gel ◽  
Correlation Spectroscopy ◽  
Germanium Content ◽  
Gel Method ◽  
Sol Gel Method ◽  
Phase Transition Temperatures ◽  
Germanium Concentration

Nanoscaled Ba(Ti1−x−ySnxGey)O3 (BTSG − x − y, x = 0–0.1, y = 0–0.05) powders were synthesized by a sol–gel method (SG) and, as a reference, coarse powders by a mixed-oxide method (MO). The particle sizes were determined by XRD, BET, photon correlation spectroscopy (PCS) and scanning electron microscopy (SEM). The sol–gel method supplied globular particles with narrow fractions in the range between 53 nm and 125 nm. However, from the mixed-oxide method irregularly grown particles were generated with diameters between 300 nm and 700 nm. The SG powders showed a higher sintering activity and, additionally, Sn4+ ions were incorporated at lower temperatures into the BaTiO3 structure. The addition of at least 2 mol% BaGeO3 (BG) resulted in ceramics of densities as high as 96% even at 1050 °C. Furthermore, the cubic ⇆ tetragonal phase transition temperatures were measured by dilatometry, differential thermal analysis (DTA) and dielectric measurements. The temperature and sharpness of the transition are dependent on tin and germanium content. Increasing tin and germanium concentration causes the phase transition temperature to decrease and more diffuse transition.

Cerium–zirconium mixed oxide synthesized by sol-gel method and its effect on the oxygen vacancy and specific surface area

2021 ◽  
pp. 122752
Author(s):  
Pablo Teles Aragão Campos ◽  
Claudinei Fabiano Oliveira ◽  
João Pedro Vieira Lima ◽  
Daniele Renata de Queiroz Silva ◽  
Sílvia Cláudia Loureiro Dias ◽  
...  
Keyword(s):  
Oxygen Vacancy ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Mixed Oxide ◽  
Sol Gel ◽  
Gel Method ◽  
Sol Gel Method

Characterization of Al2O3-ZrO2 mixed oxide catalytic supports prepared by the sol-gel method

1998 ◽  
Vol 20 (4-6) ◽  
pp. 293-306 ◽  
Author(s):  
Tatiana Klimova ◽  
Maria Luisa Rojas ◽  
Perla Castillo ◽  
Rogelio Cuevas ◽  
Jorge Ramírez
Keyword(s):  
Mixed Oxide ◽  
Sol Gel ◽  
Gel Method ◽  
Sol Gel Method ◽  
Catalytic Supports

Study of Viscosity and Stability of SiO2 Sol Prepared by Sol-Gel Method

2013 ◽  
Vol 834-836 ◽  
pp. 454-457
Author(s):  
Kun Peng ◽  
Ming Yue Yuanyin ◽  
Jia Jun Zhu ◽  
De Yi Li ◽  
Ling Ping Zhou
Keyword(s):  
Activation Energy ◽  
Sol Gel ◽  
Silica Sol ◽  
Gel Time ◽  
Gel Method ◽  
Sol Gel Method ◽  
Sol Gel Process ◽  
Gel Processing

Silica sol was prepared using TEOS as the precursor and HCl as the catalyst by sol-gel process. The effects of the ratio of the reactants and temperature on the viscosity of SiO2 sol during the sol-gel processing were investigated and the reaction activated energy was calculated. With the increase of the EtoH/TEOS ration, the viscosity reduced, a higher viscosity can be obtained at the H2O/TEOS ratio of about 8. The viscosity increased and the gel time decreased with the increase of temperature, the activation energy of the formation of gel was about 73.8kJ/mol.

Control of mixed oxide textural and acidic properties by the sol-gel method

1997 ◽  
Vol 35 (3) ◽  
pp. 269-292 ◽  
Author(s):  
James B. Miller ◽  
Edmond I. Ko
Keyword(s):  
Mixed Oxide ◽  
Sol Gel ◽  
Acidic Properties ◽  
Gel Method ◽  
Sol Gel Method
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