Multi-Phasic Ceramic Composites made by Sol-Gel Technique

1984 ◽  
Vol 32 ◽  
Author(s):  
Rustum Roy ◽  
S. Komarneni ◽  
D.M. Roy
Keyword(s):  
Single Phase ◽  
Crystal Size ◽  
Sol Gel ◽  
Ceramic Composites ◽  
Silver Halides ◽  
Metal Atoms ◽  
Metallic Salts ◽  
Second Phases ◽  
Gel Technique ◽  
Work Done

ABSTRACTInstead of aiming to prepare homogeneous gels and xerogels, this paper reports on work done to prepare deliberately diphasic materials. This has been achieved by three different paths: (1) mixing 2 sols; (2) mixing 1 sol with 1 solution; and (3) post formation diffusion of either one or two solutions.By the last named process we have made SiO2, mullite and alumina based composites, with silver halides, BaSO4, CdS, etc., as the dispersed phase. The crystal size can be confined to the initial pores by rapid diffusion giving rise to extremely fine second phases in the submicron range. Subsequent reduction of appropriate metallic salts can be used to give finely dispersed metals (e.g. Cu, Ni) in essentially any xerogel matrix. The open porosity makes these metal atoms very accessible.By the first two processes we have made both single phase and di-phasic gels of the same composition (prototype: mullite) and shown that though they cannot be distinguished by XRD, SEM, and TEM, by DTA and thermal processing, they are radically different. Such di-phasic gels store more metastable energy than any other solids.

Physicochemical characterization of Pt and Ir particles deposited on Ce(1-x)Ru(x)O2 solid-solutions for CO oxidation

MRS Advances ◽  
2019 ◽  
Vol 4 (61-62) ◽  
pp. 3433-3440
Author(s):  
E. Gonzalez-A ◽  
R. Rangel ◽  
J. Lara ◽  
J. J. Alvarado ◽  
P. Bartolo
Keyword(s):  
Solid Solutions ◽  
Crystal Size ◽  
Sol Gel ◽  
Physicochemical Characterization ◽  
Metallic State ◽  
Wet Impregnation ◽  
Iridium Nanoparticles ◽  
Gel Technique ◽  
Near Future

AbstractPt/Ce1-xRuxO2 and Ir/Ce1-xRuxO2 catalysts were prepared through the sol-gel technique, under microwave heating. In a first step, the Ce1-xRuxO2 solid solutions were prepared. Subsequently, an incipient wet impregnation process was carried out to homogeneously achieve the dispersion, either of platinum or iridium nanoparticles. The Pt/Ce1-xRuxO2 and Ir/Ce1-xRuxO2 catalysts were characterized by means of SEM, XRD, XPS, TEM, and specific surface area measurements. Crystal size and shifting into the CeO2 structure were detected after ruthenium doping producing the Ce1-xRuxO2 solid-solutions. Trough XPS technique Pt and Ir nanoparticles were found evenly dispersed in a metallic state. Those features allow us to foresee that, in the near future, these materials could be used efficiently as catalysts for oxidation process.

scholarly journals Application of ZnO Nanoparticles EM Wave Detector Prepared by Sol-Gel and Self-Combustion Techniques

2010 ◽  
Vol 11 ◽  
pp. 25-34 ◽  
Author(s):  
Noorhana Yahya ◽  
Hanita Daud ◽  
Nurulhuda Ali Tajuddin ◽  
Hasnah Mohd Daud ◽  
Afza Shafie ◽  
...  
Keyword(s):  
Zno Nanoparticles ◽  
Single Phase ◽  
Sol Gel ◽  
The Self ◽  
Nano Particles ◽  
Raman Shift ◽  
Major Peak ◽  
Casting Technique ◽  
Gel Technique ◽  
Combustion Technique

Zinc oxide (ZnO) has found many important applications such as optoelectronic devices, sensors and varistors. The challenging part however is synthesizing ZnO nanoparticles and its utilisation as EM detectors. Sol-gel and self-combustion techniques were chosen in this study due to the ability to produce single phase and nano-size samples. The starting mixture consists of 10 grams of zinc (II) nitrate, Zn(NO3)2.6H2O salt which was dissolved in 50 mL of nitric acid, HNO3.The solution was stirred at 250 rpm continuously for 1 day. The mixture was then gradually heated for every 15 minutes until it combusted at 110oC for the self-combustion technique. For the sol-gel technique, the dissolved mixture was heated at 40oC, 50oC, 60oC and 70oC until the gelatine was formed. After the drying process, the as-prepared samples were annealed at 100oC and 200 oC for 1 hour for each technique. Characterizations were performed by using X-Ray Diffraction (XRD), Raman Spectra and Scanning Electron Microscopy (SEM).The XRD analysis showed a major peak of [101] plane at 2Ө for the self-combustion technique and the sol-gel technique. Raman results for the samples prepared via sol-gel and self-combustion techniques had shown the major peak of ZnO that is located at the Raman shifts of 437.67 cm-1. Using the Scherrer equation, single crystal nano particle of ZnO was successfully obtained in the range of 38.49 nm to 50.70 nm for the sample prepared via the sol gel technique. By the self-combustion technique, the average dimension of the as-prepared sample is in the range of 34-49 nm. Further heat treatment resulted in a major change of the Raman shift corresponding to the single phase ZnO nano particles. The best samples were used as electromagnetic (EM) detectors. The EM detectors are polymer based composite which were prepared using a casting technique.

scholarly journals The Physical Properties of Erbium-Doped Yttrium Iron Garnet Films Prepared by Sol-Gel Method

2012 ◽  
Vol 2012 ◽  
pp. 1-5 ◽  
Author(s):  
Ramadan Shaiboub ◽  
Noor Baa'yah Ibrahim ◽  
Mustafa Abdullah ◽  
Ftema Abdulhade
Keyword(s):  
Single Phase ◽  
Sol Gel ◽  
Vibrating Sample Magnetometer ◽  
Yttrium Iron ◽  
X Ray ◽  
Garnet Films ◽  
Erbium Doped ◽  
Gel Technique ◽  
Xrd Patterns ◽  
Iron Garnet

ErxY3-xFe5O12nanoparticle films (x=0.0, 0.6, 1.2, 2.0, and 2.5) have been synthesized by a sol-gel technique. All of the samples were annealed at 1000°C. The nanostructures were characterized by an X-ray diffractometer (XRD), the magnetic properties and the grain size were studied using a vibrating sample magnetometer (VSM), and a field emission scanning electron microscope (FE-SEM), respectively. The XRD patterns of the films show single phase structure. The sizes of the particles are in the range of 78 to 89 nm. The VSM result shows that the saturation magnetization ofErxY3-xFe5O12films decreased with the increment of Er concentration (x).

scholarly journals Electrical, dielectric and photocatalytic properties of Fe-doped ZnO nanomaterials synthesized by sol gel method

2016 ◽  
Vol 10 (3) ◽  
pp. 125-135 ◽  
Author(s):  
Yacine Cherifi ◽  
Ahcène Chaouchi ◽  
Yannick Lorgoilloux ◽  
Mohammed Rguiti ◽  
Abdelaziz Kadri ◽  
...  
Keyword(s):  
Single Phase ◽  
Uv Light ◽  
Sol Gel ◽  
Complex Impedance ◽  
Hexagonal Wurtzite Structure ◽  
Band Gap Energy ◽  
Cbh Model ◽  
Gap Energy ◽  
Gel Technique ◽  
Doped Zno

Fe-doped ZnO nanoparticles were synthesized by sol gel technique. Fine-scale and single phase hexagonal wurtzite structure in all samples were confirmed by SEM and XRD, respectively. The band gap energy depends on the amount of Fe and was found to be in the range of 3.11-2.53 eV. The electric and dielectric properties were investigated using complex impedance spectroscopy. AC conductivity data were correlated with the barrier hopping (CBH) model to evaluate the binding energy (Wm), the minimum hopping distance (Rmin) and the density of states at Fermi level, N(EF). Fe doping in ZnO also improved the photocatalytic activity. Thus, the sample Zn0.95Fe0.05O showed high degradation potential towards methylene blue (MB), i.e. it degrades 90% of BM in 90min under UV light.

scholarly journals Sol-gel synthesis, crystal structure and magnetic properties of nanocrystalline praseodymium orthoferrite

2021 ◽  
Vol 23 (2) ◽  
pp. 196-203
Author(s):  
Xuan Vuong Bui ◽  
Anh Tien Nguyen
Keyword(s):  
Crystal Structure ◽  
Magnetic Properties ◽  
Single Phase ◽  
Crystal Size ◽  
Annealing Temperature ◽  
Sol Gel ◽  
Gel Method ◽  
Lattice Volume ◽  
Sol Gel Synthesis ◽  
Paramagnetic Properties

In this work, nano-sized crystalline praseodymium orthoferrite was successfully synthesized via sol-gel method using water – methanol co-solvent. Single-phase PrFeO3 nanoparticles were formed after annealing the precursors at 650, 750, 850, and 950 °C during 60 min. The crystal size, lattice volume and coercivity (Hc) of nanocrystalline PrFeO3 increase with the annealing temperature. The obtained praseodymium orthoferrite exhibited paramagnetic properties with Hc = 28 – 34 Oe

scholarly journals Improvement of the optical and photocatalytic properties of ZnAl2O4: 1% La3+, x% Pb2+ nanoparticles synthesized by citrate sol-gel route

2021 ◽  
Author(s):  
Hichem Filali ◽  
Nahman Boukheit ◽  
Rafika Bouhroum ◽  
Wassila Chekirou ◽  
Ahcène Karaali
Keyword(s):  
Raman Spectroscopy ◽  
Single Phase ◽  
Sol Gel ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Constant Amount ◽  
Pure Zinc ◽  
Characterization Methods ◽  
X Ray ◽  
Gel Technique

Abstract Samples of pure zinc aluminate (ZnAl2O4) and doped both with lead (Pb2+) at different ratios (0, 0.5, 1, 1.5, 2 and 2.5% mol) and a constant amount of lanthanum (La: 1% mol), were prepared by the citrate sol-gel technique, and then annealed at 900°C for 2h. In order to study the structural, optical and thermal properties; different characterization methods were used, such as: powder X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDX), differential scanning calorimetry (DSC), TGA, Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy. The Analyzes by XRD revealed the presence of the cubic single phase ZnAl2O4 for all samples, with a crystallites size between 19 and 25 nm. These results were confirmed using FTIR, Raman spectroscopy and SEM. Also, photocatalytic study for different samples of ZnAl2O4 shows that they can be used like as photocatalyst and good adsorbents for degradation of Hexamethyl crystallized violet dye in aqueous solution.

scholarly journals The effects of varying the Eu3+ concentration on the structural and optical properties of Mg1.5Al2O4.5:x% Eu3+ (0 ≤ x ≤ 2) nanophosphors prepared by sol–gel method

2018 ◽  
Vol 8 ◽  
pp. 184798041880064 ◽  
Author(s):  
VM Maphiri ◽  
BF Dejene ◽  
TE Motaung ◽  
TT Hlatshwayo ◽  
OM Ndwandwe ◽  
...  
Keyword(s):  
Single Phase ◽  
Crystal Size ◽  
Sol Gel ◽  
X Ray Diffraction ◽  
Gel Method ◽  
X Ray ◽  
Sol Gel Method ◽  
Transmission Electron ◽  
Crystallite Sizes ◽  
The Eu

Mg1.5Al2O4.5: x% Eu3+ (0 ≤ x ≤ 2) nanopowders were successfully synthesized via sol–gel method. The X-ray diffraction (XRD) spectrum revealed that the Mg1.5Al2O4.5: x% Eu3+ matches the single phase of face-centred cubic MgAl2O4. The estimated average crystallite sizes calculated using the XRD spectra were found to be in the order of 4 nm. The estimated crystal size was confirmed by the high-resolution transmission electron microscopy. The energy dispersive X-ray spectroscopy confirmed the presence of all expected elementary composition (Mg, Al, O and Eu). The field emission gun scanning electron microscope showed that varying the Eu3+ concentration influence the morphology of the prepared nanophosphor. The photoluminescence results showed that the host emits the violet colour at around 382 nm, which was attributed to the defects within the band gap ( Eg) of host material. The Eu3+-doped samples showed the emission at around 560, 580, 593, 618, 655 and 704 nm which are, respectively, attributed to the 5D1 → 7F3, 5D0 → 7F0, 5D0 → 7F1, 5D0 → 7F2, 5D0 → 7F3 and 5D0 → 7F4 characteristic transitions in Eu3+. The International Commission on Illumination colour chromaticity showed that the Eu3+ doping influences the emission colour.

Sol-gel synthesis of phosphate ceramic composites II

1998 ◽  
Vol 13 (6) ◽  
pp. 1553-1559 ◽  
Author(s):  
Zhicheng Cao ◽  
Burtrand I. Lee ◽  
William D. Samuels ◽  
Li-Qiong Wang ◽  
Gregory J. Exarhos
Keyword(s):  
Reaction Mechanism ◽  
Solid State ◽  
Solid State Nmr ◽  
Sol Gel ◽  
Ceramic Composites ◽  
Direct Reaction ◽  
Tetraethoxy Silane ◽  
Gel Technique ◽  
Sol Gel Synthesis ◽  
First Time

Phosphate ceramics were synthesized using sol-gel technique of direct reaction of P2O5 with tetraethoxy silane (TEOS) or titanium tetraethoxide (Ti(OEt)4). The reaction mechanism of P2O5 and TEOS was deduced using liquid and solid-state NMR. Hexacoordinated silicon in phosphosilicate gels was observed. A specially structured titanium phosphate-layered Ti(HPO4)2 · 2H2O was synthesized for the first time through the sol-gel method. The gelation process and phase transformations were investigated.

EFFECTS OF La DOPING ON FERROELECTRIC PROPERTIES OF CaBi4Ti4O15 THIN FILMS

2007 ◽  
Vol 14 (02) ◽  
pp. 277-281
Author(s):  
YANXIA DING ◽  
GUANGDA HU ◽  
SUHUA FAN
Keyword(s):  
Thin Films ◽  
Diffraction Analysis ◽  
Single Phase ◽  
Ferroelectric Properties ◽  
Sol Gel ◽  
X Ray Diffraction ◽  
X Ray ◽  
La Doping ◽  
Gel Technique ◽  
A Site

La modified CBTi ( CLBTi ) thin films were prepared on Pt/Ti/SiO 2/ Si (100) substrates by a sol–gel technique. X-ray diffraction analysis showed that single phase of CLBTi thin films were obtained. Their crystallization and hysteresis behavior were strongly dependent on the La contents. An increase of 2Pr as well as a decrease of 2Ec with the increase of La concentration were observed. The leakage properties of CBTi thin films were found to be improved by the La doping. The results were discussed with respect to the effects of La 3+ substitution at perovskite A-site.

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