Magnetic and Electric Properties of Phase Separated Glass Ceramics in CoO–TiO2–SiO2 System Prepared by Melt Quenching Process

2008 ◽  
Vol 1118 ◽  
Author(s):  
Hiroki Nakamura ◽  
Tetsuo Kishi ◽  
Yuji Muro ◽  
Ryuji Tamura ◽  
Kazuyasu Tokiwa ◽  
...  
Keyword(s):  
High Performance ◽  
Room Temperature ◽  
Glassy Phase ◽  
Glass Ceramics ◽  
The Other ◽  
Melt Quenching ◽  
Nano Structure ◽  
Quenching Process ◽  
Magnetic And Electric Properties ◽  
Co Doped

ABSTRACTThe developments of high performance magnetic materials are required in various applications such as high sensitive magnetic sensing and hyperthermia in cancer treatment. Recently, Co-doped TiO2 has been received considerable attention as a candidate for such materials because of their ferromagnetic properties at room temperature. On the other hand, the phase-separated glasses and the derived glass-ceramics having unique micro-nano structure are utilized for various applications. In this study, the phase separated glass-ceramics in CoO-TiO2-SiO2 system with Al2O3 addition were prepared by melt-quenching process. The as-quenched samples consisted of the TiO2-rich phase and the SiO2-rich one which were formed by a nucleation-growth mechanism of phase separation. From the results of XRD measurements, the samples were found to have a TiO2 crystalline phase and a SiO2-rich glassy phase. The samples showed the magnetic property, which were regarded as a mixture of ferromagnetic and paramagnetic phases. The samples also showed the electric conductivity at room temperature. However, the conductivity of the sample decreased with increase of the Co content, and the temperature dependence of the conductivity of the ferromagnetic samples was different from the other ones. As a result, the Co ions in the phase-separated glass-ceramics in TiO2-SiO2 system were found to affect on both the magnetic and the electric conductive characteristics.

On the Chemistry of Tetrabenzyl Thiuram Disulfide and Tetramethyl Thiuram Disulfide with Bis (Triethoxysilylpropyl) Tetrasulfide in Silica Compounds

2003 ◽  
Vol 76 (4) ◽  
pp. 876-891 ◽  
Author(s):  
R. N. Datta ◽  
A. G. Talma ◽  
S. Datta ◽  
P. G. J. Nieuwenhuis ◽  
W. J. Nijenhuis ◽  
...  
Keyword(s):  
High Performance ◽  
Room Temperature ◽  
Succinic Anhydride ◽  
Dynamic Properties ◽  
The Other ◽  
Resonance Spectroscopy ◽  
Reaction Products ◽  
Negative Effect ◽  
Higher Temperature ◽  
Analytical Tools

Abstract The use of thiurams such as Tetramethyl thiuram disulfide (TMTD) or Tetrabenzyl thiuram disulfide (TBzTD) has been explored to achieve higher cure efficiency. The studies suggest that a clear difference exists between the effect of TMTD versus TBzTD. TMTD reacts with Bis (triethoxysilylpropyl) tetrasulfide (TESPT) and this reaction can take place even at room temperature. On the other hand, the reaction of TBzTD with TESPT is slow and takes place only at higher temperature. High Performance Liquid Chromatography (HPLC) with mass (MS) detection, Nuclear Magnetic Resonance Spectroscopy (NMR) and other analytical tools have been used to understand the differences between the reaction of TMTD and TESPT versus TBzTD and TESPT. The reaction products originating from these reactions are also identified. These studies indicate that unlike TMTD, TBzTD improves the cure efficiency allowing faster cure without significant effect on processing characteristics as well as dynamic properties. The loading of TESPT is reduced in a typical Green tire compound and the negative effect on viscosity is repaired by addition of anhydrides, such as succinic anhydride, maleic anhydride, etc.

Immobilization of a simulated HLW in phosphate based glasses/glass-ceramics by melt-quenching process

2020 ◽  
Vol 545 ◽  
pp. 120246
Author(s):  
Fu Wang ◽  
Yuanlin Wang ◽  
Qilong Liao ◽  
Jianxing Zhang ◽  
Wenjing Zhao ◽  
...  
Keyword(s):  
Glass Ceramics ◽  
Melt Quenching ◽  
Quenching Process

scholarly journals Ammonia Room Temperature Gas Sensor Using Different TiO2 Nano-structure

2021 ◽  
Author(s):  
Mostafa Shooshtari ◽  
Alireza Salehi
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Room Temperature ◽  
Operating Temperature ◽  
Anatase Phase ◽  
Fold Increase ◽  
The Other ◽  
Nano Structure ◽  
Two Samples ◽  
Quartz Glasses

Abstract In this study, TiO2 Nano-structure were synthesized by three different processes including nanowires, nanoparticles and thin- films. The morphology and crystal structure of the three different TiO2 structures deposited on quartz glasses were characterized by XRD, SEM and FTIR. It has been found that nanowires and nanoparticles showed only the anatase phase while the thin-film exhibited both anatase and rutile phases. The three TiO2 Nano-structures were then used to fabricate gas sensors for ammonia (NH3) detection at different concentrations and various conditions. The samples fabricated with thin-film TiO2 towards 50 ppm NH3 showed a response value of 5% at room temperature, whereas the other two samples exhibited much higher values towards similar condition NH3 at room temperature. Samples with nanowires showed a three-fold increase and samples with nanoparticles exhibit a two-fold increase in response value. We have found that the response of all samples increases with elevating the operating temperature up to 200°C. Increasing the operating temperature improved the nanoparticle sensing conditions more than the other two samples. The samples using nanoparticles showed a 33% increase in response towards 50 ppm NH3 at 200°C compared to the samples with thin films at similar conditions. Further, response and recovery time were investigated and reported in this study.

Degradation of Model Compounds for Cellulose and Lignocellulosic Pulp during Ozonation in Aqueous Solution

Holzforschung ◽  
2000 ◽  
Vol 54 (4) ◽  
pp. 397-406 ◽  
Author(s):  
Carola Olkkonen ◽  
Henrik Tylli ◽  
Ingegerd Forsskåhl ◽  
Agneta Fuhrmann ◽  
Tiina Hausalo ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
High Performance ◽  
Room Temperature ◽  
Model Compound ◽  
The Other ◽  
Model Compounds ◽  
Freeze Dried ◽  
Carbohydrate Complex ◽  
Ozonation Time ◽  
Acidic Compounds

Summary Ozonations of methylpyranosides, as model compounds for cellulose, were performed in unbuffered aqueous solution at room temperature. The degradation of the pyranosides was followed spectrophotometrically and with high-performance liquid chromatography (HPLC) as a function of ozonation time. The substrates studied were the α- and β-anomers of methyl-D-glucopyranoside, methyl-D-mannopyranoside and methyl-D-xylopyranoside. Methyl-α-D-xylopyranoside degraded more slowly than the other compounds, whereas the rate of degradation was fastest for methyl-β-D-mannopyranoside. In general the degradation of the α-anomers was slower than that of the corresponding β-anomers. HPLC and gas chromatography—mass selective (GC-MS) analyses of the ozonated glucopyranoside samples showed that monosaccharides, lactones, furanosides and acidic compounds are formed during ozonation. A lignin-carbohydrate complex (LCC), containing a D-xylose unit connected to an aromatic part through a βglycosidic bond, was used as a model compound for lignocellulosic pulp. The degradation of this compound during ozonation was also investigated. The results from UV analyses showed that the reaction was extremely fast at the beginning and that the degradation of benzene structures in the lignin mimicking part of the LCC was very rapid. The degradation of the carbohydrate part was slower. This suggests that lignin provides some protection for the cellulose in lignin-containing pulps against attack by ozone. IR and NMR analyses of the freeze-dried ozonated LCC samples showed further that C=O structures are produced during ozonation.

Optical and Physical Properties of Cu-Co Doped in Soda Lime Silicate Glasses

2017 ◽  
Vol 728 ◽  
pp. 143-148
Author(s):  
Nattapon Srisittipokakun ◽  
Jakrapong Kaewkhao
Keyword(s):  
Refractive Index ◽  
Optical Properties ◽  
Absorption Spectrum ◽  
Optical Absorption ◽  
Room Temperature ◽  
Wavelength Region ◽  
Soda Lime ◽  
Silicate Glasses ◽  
Melt Quenching ◽  
Co Doped

Co/Cr co-doped in soda lime silicate (SLS) glasses were prepared by using normal melt quenching technique. The current composition was prepared based on the proposed ratio: (64.9-x)SiO2: 10CaO: 25Na2O: 0.1CuO: xCoO where x=0.00, 0.01, 0.02, 0.03, 0.04 and 0.05 mol% were prepared at 1200°C for 3 h, and annealed at 500 °C for 3 h. The physical and optical properties of Co/Cr co-doped in SLS glasses were investigated such as density, molar volume, refractive index and optical absorption were discussed and measured. The optical absorption spectrum of Co/Cr co-doped in SLS glasses measured at room temperature in the wavelength region 200–1100 nm were presented.

Electron microscope studies of the plastic deformation of ternary alloys based on GaAs

1990 ◽  
Vol 48 (4) ◽  
pp. 1120-1120
Author(s):  
R. Haswell ◽  
U. Bangert ◽  
P. Charsley
Keyword(s):  
Plastic Deformation ◽  
Electron Microscope ◽  
Room Temperature ◽  
Stacking Faults ◽  
The Other ◽  
Ternary Alloys ◽  
Dislocation Mobility ◽  
Semiconducting Materials ◽  
Micro Indentation

A knowledge of the behaviour of dislocations in semiconducting materials is essential to the understanding of devices which use them . This work is concerned with dislocations in alloys related to the semiconductor GaAs . Previous work on GaAs has shown that microtwinning occurs on one of the <110> rosette arms after indentation in preference to the other . We have shown that the effect of replacing some of the Ga atoms by Al results in microtwinning in both of the rosette arms.In the work to be reported dislocations in specimens of different compositions of Gax Al(1-x) As and Gax In(1-x) As have been studied by using micro indentation on a (001) face at room temperature . A range of electron microscope techniques have been used to investigate the type of dislocations and stacking faults/microtwins in the rosette arms , which are parallel to the [110] and [10] , as a function of composition for both alloys . Under certain conditions microtwinning occurs in both directions . This will be discussed in terms of the dislocation mobility.

Green synthesis of mixed metallic nanoparticles using room temperature self-assembly

2017 ◽  
Vol 13 (2) ◽  
pp. 4671-4677 ◽  
Author(s):  
A. M. Abdelghany ◽  
A.H. Oraby ◽  
Awatif A Hindi ◽  
Doaa M El-Nagar ◽  
Fathia S Alhakami
Keyword(s):  
Self Assembly ◽  
Metallic Nanoparticles ◽  
Room Temperature ◽  
Bimetallic Nanoparticles ◽  
Reduction Process ◽  
Nano Particles ◽  
Nano Structure ◽  
Small Shift ◽  
Molar Ratios ◽  
Vis Spectroscopy

Bimetallic nanoparticles of silver (Ag) and gold (Au) were synthesized at room temperature using Curcumin. Reduction process of silver and gold ions with different molar ratios leads to production of different nanostructures including alloys and core-shells. Produced nanoparticles were characterized simultaneously with FTIR, UV/vis. spectroscopy, transmission electron microscopy (TEM), and Energy-dispersive X-ray (EDAX). UV/vis. optical absorption spectra of as synthesized nanoparticles reveals presence of surface palsmon resonance (SPR) of both silver at (425 nm) and gold at (540 nm) with small shift and broadness of gold band after mixing with resucing and capping agent in natural extract which suggest presence of bimetallic nano structure (Au/Ag). FTIR and EDAX data approve the presence of bimetallic nano structure combined with curcumin extract. TEM micrographs shows that silver and gold can be synthesized separately in the form of nano particles using curcumin extract. Synthesis of gold nano particles in presence of silver effectively enhance and control formation of bi-metallic structure.

High Performance Optoelectronic Devices Based on Bright Perovskite Nanocrystals Synthesized at Room Temperature

2018 ◽  
Author(s):  
Sotirios Christodoulou ◽  
Francesco Di Stasio ◽  
Santanu Pradhan ◽  
Inigo Ramiro ◽  
Yu Bi ◽  
...  
Keyword(s):  
High Performance ◽  
Room Temperature ◽  
Optoelectronic Devices ◽  
Perovskite Nanocrystals
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