Sol-Gel Processing of Advanced Dielectric Ceramics for Microwave Applications

1989 ◽  
Vol 155 ◽  
Author(s):  
M. Schnoeller ◽  
W. Wersing
Keyword(s):  
Sol Gel ◽  
Wet Milling ◽  
X Ray Diffraction ◽  
Powder Morphology ◽  
Drying Procedures ◽  
Microwave Components ◽  
Sol Gel Process ◽  
Dielectric Ceramics ◽  
Gel Processing

ABSTRACTHighly dielectric ceramics make it possible to markedly miniaturize passive microwave components. We have successfully synthesized ceramic powders of the most important microwave ceramic systems (ZrTiSn)O2, Ba(TiNiZnTa)O3 and Ba(MgTa)O3 by using the sol-gel process. Nonaqueous solutions of metal organics together with different inorganic metal salts were used as precursors. The gels derived from these solutions are homogeneous and transparent. Different drying procedures were investigated in order to optimize powder morphology. Thermoanalytic methods and high -temperature x-ray diffraction were used to study the decomposition of xerogels and the formation of crystal phases, respectively. The calcination process was found to be complete at temperatures well below 750 °C.For the production of barium-containing powders, wet milling must be avoided because this washes out barium and thus causes undesired phases to appear. A dry milling step of the xerogel solves this problem. The prepared (ZrTiSn)O2 and Ba(TiNiZnTa)O3 already equal or surpass the quality of conventionally prepared ceramics.

scholarly journals Co-Doped LaMnO3 Perovskite Structure Nanoparticles as a Bifunctional Electrocatalysts for Oxygen Reduction/Evolution Reactions

2020 ◽  
Vol 9 (7) ◽  
pp. 1060-1064
Keyword(s):  
Transition Metal Oxides ◽  
Perovskite Structure ◽  
Single Phase ◽  
Sol Gel ◽  
Perovskite Oxide ◽  
X Ray Diffraction ◽  
Powder Morphology ◽  
Bifunctional Electrocatalysts ◽  
Sol Gel Process ◽  
Perovskite Nanoparticles

Current paper, we have examined lanthanum manganese cobalt (LaMn1-xCoxO3 ) perovskite nanoparticles synthesized by utilizing the sol-gel process and following calcinated at 450 °C for 1h and 900 °C for 7h, respectively. The fabricated alloys show single-phase perovskite structure is an order of LaMn1-xCoxO3 (x = 0, 0.2, 0.4, 0.6, 0.8, 1). The synthesized LaMn1-xCoxO3 perovskite oxide nanoparticles have the crystal structure, and powder morphology properties were investigated by X-ray diffraction (XRD), and field emission scanning electron microscopy (FESEM), respectively. The perovskite structure has been shown to be particularly effective for the catalytic reactions of ORR and OER in alkaline medium. The merged valance transition metal oxides are bifunctional electrocatalysts which give rise to potential candidates, the electrochemical functioning of the LaMn1-xCoxO3 catalyst was entirely investigated. All compounds of ORR polarization curves show that the four-electron pathway, which results in KouteckyLevich is compatible with these perovskite structures. Current work, we describe B-site extend adding of Co ratio into perovskite structure is an appropriate strategy to increase ORR and OER electrocatalytic performance for application in metal-air batteries

Luminescence properties of R2MoO6:Eu3+ (R = Gd, Y, La) phosphors prepared by Pechini sol-gel process

2005 ◽  
Vol 20 (10) ◽  
pp. 2676-2681 ◽  
Author(s):  
Maolin Pang ◽  
Xiaoming Liu ◽  
Jun Lin
Keyword(s):  
Grain Size ◽  
Sol Gel ◽  
Luminescent Properties ◽  
Luminescence Properties ◽  
X Ray Diffraction ◽  
Powder Morphology ◽  
X Ray ◽  
Average Grain Size ◽  
Sem Study ◽  
Sol Gel Process

R2MoO6:Eu3+ (R = Gd, Y, La) phosphors were prepared by the Pechini sol-gel process. X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), reflectance spectra, photoluminescence (PL) spectra, and lifetimes were used to characterize the resulting phosphors. The results of XRD indicate that all of the R1.96Eu0.04MoO6 (R = Gd, Y, La) phosphors crystallized completely at 800 °C. Y1.96Eu0.04MoO6 and Gd1.96Eu0.04MoO6 are of isomorphous monoclinic (α) structure, while La1.96Eu0.04MoO6 preferentially adopts the tetragonal (γ) form. FE-SEM study reveals that the samples mainly consist of aggregated particles with an average grain size ranging from 100 to 250 nm. The luminescent properties of R2MoO6:Eu3+ (R = Gd, Y, La) phosphors are largely dependent on their structure, grain size, and powder morphology. The isomorphous Y2MoO6:Eu3+ and Gd2MoO6:Eu3+ phosphors show very similar luminescence properties, which differ greatly from that of the La2MoO6:Eu3+ phosphor.

Properties and microstructure of thin LiNbO3 films prepared by a sol-gel process

1987 ◽  
Vol 2 (5) ◽  
pp. 595-605 ◽  
Author(s):  
D. P. Partlow ◽  
J. Greggi
Keyword(s):  
Sol Gel ◽  
Epitaxial Films ◽  
Silicon Substrates ◽  
X Ray Diffraction ◽  
Film Properties ◽  
Transmission Electron ◽  
Sol Gel Process ◽  
Oriented Polycrystalline ◽  
Diffraction Patterns ◽  
Gel Processing

Thin LiNbO3 films were prepared from polymerized sol-gel precursor solutions having various concentrations and water:alkoxide ratios in an effort to investigate the effects of these and other processing variables on the resultant film properties and microstructure. Films deposted on silicon substrates were mostly amorphous when pyrolyzed at 435°C for 30 min. Randomly oriented polycrystalline films having distinctive microstnietures were produced using longer heating times or higher temperatures. All of the films exhibited low refractive indices due to porosity, which was attributed to the low level of hydrolysis water required to produce stable polymeric precursor solutions. When single-crystal LiNbO4 was used as the substrate, epitaxial growth of the film resulted. This ideal case establishes the feasibility of producing epitaxial films via sol-gel processing. All films were characterized by transmission electron microscopy (TEM) and thin-film x-ray diffraction patterns.

Luminescent Properties of Zn2SiO4:Eu3+,Dy3+ Phosphors via Sol-Gel Process

2012 ◽  
Vol 217-219 ◽  
pp. 733-736
Author(s):  
Xiu Mei Han ◽  
Shu Ai Hao ◽  
Ying Ling Wang ◽  
Gui Fang Sun ◽  
Xi Wei Qi
Keyword(s):  
Thermal Analysis ◽  
Ir Spectra ◽  
Sol Gel ◽  
Luminescent Properties ◽  
Photoluminescence Spectra ◽  
X Ray Diffraction ◽  
X Ray ◽  
Sol Gel Process ◽  
Ft Ir

Zn2SiO4:Eu3+, Dy3+ phosphors have been prepared through the sol-gel process. X-ray diffraction (XRD), thermogravimetric and ddifferential thermal analysis (TG-DTA), FT-IR spectra and photoluminescence spectra were used to characterize the resulting phosphors. The results of XRD indicated that the phosphors crystallized completely at 1000oC. In Zn2SiO4:Eu3+,Dy3+ phosphors, the Eu3+ and Dy3+ show their characteristic red(613nm, 5D0-7F2), blue (481nm, 4F9/2–6H15/2) and yellow (577nm, 4F9/2–6H13/2) emissions.

The Preparation and Photocatalytic Activity of SWNTs Doped ZnO/TiO2 Compound Films

2010 ◽  
Vol 97-101 ◽  
pp. 1611-1615 ◽  
Author(s):  
Qing Wang ◽  
Xin Li Li ◽  
Wei Nie ◽  
Yong Mei Xia ◽  
Jian Feng Dai
Keyword(s):  
Photocatalytic Activity ◽  
Absorption Spectra ◽  
Sol Gel ◽  
Composite Films ◽  
Wavelength Region ◽  
Tio2 Films ◽  
X Ray Diffraction ◽  
Sol Gel Process ◽  
Doped Zno ◽  
Walled Carbon Nanotubes

The ZnO/TiO2 composite films were deposited over glass using spin coating technique by sol-gel process. Single-walled carbon nanotubes (SWNTs) were used to modify the ZnO/TiO2 films successfully in this paper. The structure and composition of the ZnO/TiO2 composite and SWNTs doped ZnO/TiO2 composite were characterized by X-ray diffraction (XRD). The morphology of samples was characterized by scanning electron microscopy (SEM). The photocatalytic activity was investigated by photocatalytic degradation of aqueous methyl orange under ultraviolet (UV) radiation. The UV-vis absorption spectra of the ZnO/TiO2 films and SWNTs doped ZnO/TiO2 films in the wavelength region 200~800 nm were obtained. The results indicate that the SWNTs addition can decrease the grain size of ZnO/TiO2, which can enhance the photocatalytic activity. UV-vis absorption spectra of SWNTs-ZnO/TiO2 showed obvious blue shifts compared with ZnO/TiO2. The optimal amount of doping SWNTs is 1% according to this research. The enhanced mechanism of the SWNTs for the photocatalytic activity in ZnO/TiO2 films was analyzed in this article.

Sol-Gel derived Bi4-xNdxTi3O12 Thin Films and Their Characterization

2002 ◽  
Vol 737 ◽  
Author(s):  
R.E. Melgarejo ◽  
M.S. Tomar ◽  
A. Hidalgo ◽  
R.S. Katiyar
Keyword(s):  
Thin Films ◽  
Spin Coating ◽  
Bismuth Titanate ◽  
Sol Gel ◽  
X Ray Diffraction ◽  
X Ray ◽  
Complete Solid Solution ◽  
Sol Gel Process ◽  
Ferroelectric Memory ◽  
Initial Results

ABSTRACTNd substituted bismuth titanate Bi4-xNdxTi3O12 were synthesized by sol-gel process and thin films were deposited on Pt substrate (Pt/TiO2/SiO2/Si) by spin coating. Thin films, characterized by X-ray diffraction and Raman spectroscopy, shows complete solid solution up to the composition x < 1. Initial results indicate that the ferroelectric polarization increases with increasing Nd content in the film with 2Pr = 50μC/cm2 for x = 0.46, which may have application in non-volatile ferroelectric memory devices.

Fabrication and Characterization of Sol-Gel Derived PZT/WO3 Ceramics

2008 ◽  
Vol 55-57 ◽  
pp. 369-372 ◽  
Author(s):  
T. Sreesattabud ◽  
Anucha Watcharapasorn ◽  
Sukanda Jiansirisomboon
Keyword(s):  
Lead Zirconate Titanate ◽  
Sol Gel ◽  
Rhombohedral Phase ◽  
Lead Zirconate ◽  
X Ray Diffraction ◽  
Calcination Process ◽  
Materials Used ◽  
Phase Characterization ◽  
Gel Processing

Lead zirconate titanate/tungsten oxide (PZT/WO3) ceramics were prepared from the powders synthesized by a modified triol sol-gel processing method. In this study, the starting materials used for synthesis of PZT-sol were zirconium (IV) propoxide, titanium (IV) isopropxide, lead (II) acetate trihydrate and 1,1,1,- tris (hydroxymethyl) ethane. To prepare PZT/xWO3 powders (where x = 0, 0.5, 1 and 3 wt%), nano-sized WO3 was ultrasonically dispersed and mixed with the PZT sol, dried and calcined at 600°C for 4 h. X-ray diffraction results indicated that fully crystallized powders were obtained. Phase characterization suggested that at high WO3 concentration, the reaction between PZT and WO3 occurred during the calcination process. To prepare PZT/xWO3 ceramics, the powders were pressed and sintered at 1100°C for 6 h. Phase characterization by XRD indicated that the content of WO3 significantly affected tetragonal-to-rhombohedral phase transition. Microstructure of thermally etched samples showed that increasing the content of WO3 decreased grain size of the ceramics.

Synthesis and Characterizations of Strontium Substituted Hydroxyapatite Thin Films

2010 ◽  
Vol 93-94 ◽  
pp. 231-234
Author(s):  
B. Hongthong ◽  
Satreerat K. Hodak ◽  
Sukkaneste Tungasmita
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Chemical Composition ◽  
Spin Coating ◽  
Phase Structure ◽  
Sol Gel ◽  
Cross Linking ◽  
X Ray Diffraction ◽  
X Ray ◽  
Sol Gel Process

Strontium substituted hydroxyapatite(SrHAp) were fabricated both in the form of powder as reference and thin film by using inorganic precursor reaction. The sol-gel process has been used for the deposition of SrHAp layer on stainless steal 316L substrate by spin coating technique, after that the films were annealed in air at various temperatures. The chemical composition of SrHAp is represented (SrxCa1-x)5(PO4)3OH, where x is equal to 0, 0.5 and 1.0. Investigations of the phase structure of SrHAp were carried out by using X-ray diffraction technique (XRD). The results showed that strontium is incorporated into hydroxyapatite where its substitution for calcium increases in the lattice parameters, and Sr3(PO4)2 can be detected at 900°C. The SEM micrographs showed that SrHAp films exhibited porous structure before develop to a cross-linking structure.

scholarly journals Preparation and morphology of porous SiO2 ceramics derived from fir flour templates

2010 ◽  
Vol 75 (3) ◽  
pp. 385-394 ◽  
Author(s):  
Li Zhong ◽  
Tiejun Shi ◽  
Liying Guo
Keyword(s):  
Amorphous Material ◽  
Sol Gel ◽  
Size Distributions ◽  
X Ray Diffraction ◽  
Ordered Structures ◽  
Porous Sio2 ◽  
Pore Size Distributions ◽  
Naoh Solution ◽  
Gel Processing ◽  
Highly Porous

The preparation of SiO2 ceramics with controllable porous structure from fir flour templates via sol-gel processing was investigated. The specific size the fir flour, which was treated with 20 % NaOH solution, was infiltrated with a low viscous silica sol and subsequently calcined in air, which resulted in the formation of highly porous SiO2 ceramics. X-Ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and field emission scanning electron microscopy (FESEM) were employed to investigate the microstructure and phase formation during processing as well as of the SiO2 ceramics. N2 adsorption measurements were used to analyze the pore size distributions (PSD) of the final ceramics. The results indicated that the surface topography was changed and the proportion of the amorphous material was increased in NaOH-treated fir flour. The final oxide products retained ordered structures of the pores and showed unique pore sizes and distributions with hierarchy on the nanoscale derived from the fir flour.

Low-Temperature Synthesis of Nano-Crystalline ZnTiO3 Powders by Aqueous Sol-Gel Process

2014 ◽  
Vol 543-547 ◽  
pp. 3741-3744
Author(s):  
Quan Jing Mei ◽  
Cong Ying Li ◽  
Jing Dong Guo ◽  
Gui Wang ◽  
Hai Tao Wu
Keyword(s):  
Sol Gel ◽  
Zinc Nitrate ◽  
X Ray Diffraction ◽  
Low Temperature Synthesis ◽  
Temperature Synthesis ◽  
Calcination Process ◽  
X Ray ◽  
Nano Crystalline ◽  
Transmission Electron ◽  
Sol Gel Process

The ecandrewsite-type ZnTiO3was successfully synthesized by the aqueous sol-gel method using TiO2dioxide and zinc nitrate as starting materials instead of expensive organic solvent and metal alkoxides. The as-prepared nanopowders were characterized by X-ray diffraction (XRD), differential thermal analysis (DTA) and transmission electron microscopy (TEM), respectively. The results showed that the calcination process of gel consisted of a series of oxidation and combustion reactions, accompanied by significantly exothermal effects. Highly reactive nanosized ZnTiO3powders were successfully obtained at 850 °C with particle size ~50 nm. By comparison, the aqueous sol-gel process was the most effective and least expensive technique used for the preparation of ZnTiO3nanopowders.

Sign in / Sign up

Export Citation Format

Share Document