SnO
2 and SnO
2/Zn, at the Zn percentages of 10 and 30, films were prepared at the substrate temperature of 350±5 °C by ultrasonic spray pyrolysis (USP) technique, and the effect of Zn incorporation ...on the some physical properties of SnO
2 films was investigated. To possess information about the electrical properties of all films, their electrical resistivities, conduction mechanisms, activation and trap energies were investigated. The film structures were studied by X-ray diffraction. Surface morphologies and elemental analyses of the films were studied scanning electron microscopy and energy dispersive X-ray spectroscopy, respectively. It can be inferred from all investigations that some physical properties of SnO
2 films remarkable changed with Zn concentration.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Sn
1−
x
Mn
x
O
2 (
x=0.01–0.05) thin films were synthesized on quartz substrate using an inexpensive ultrasonic spray pyrolysis technique. The influence of doping concentration and substrate ...temperature on structural and magnetic properties of Sn
1−
x
Mn
x
O
2 thin films was systematically investigated. X-ray diffraction (XRD) studies of these films reflect that the Mn
3+ ions have substituted Sn
4+ ions without changing the tetragonal rutile structure of pure SnO
2. A linear increase in
c-axis lattice constant has been observed with corresponding increase in Mn concentration. No impurity phase was detected in XRD patterns even after doping 5
at% of Mn. A systematic change in magnetic behavior from ferromagnetic to paramagnetic was observed with increase in substrate temperature from 500 to 700
°C for Sn
1−
x
Mn
x
O
2 (
x=0.01) films. Magnetic studies reveal room-temperature ferromagnetism (RTFM) with 3.61×10
−4
emu saturation magnetization and 92
Oe coercivity in case of Sn
1−
x
Mn
x
O
2 (
x=0.01) films deposited at 500
°C. However, paramagnetic behavior was observed for the films deposited at a higher substrate temperature of 700
°C. The presence of room-temperature ferromagnetism in these films was observed to have an intrinsic origin and could be obtained by controlling the substrate temperature and Mn doping concentration.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Ultrasonic spray pyrolysis method for the synthesis of carbon nanotubes (CNTs) has been investigated with zeolite supporting material. Single wall carbon nanotubes (SWCNTs) were obtained at 850
°C in ...nitrogen environment. Such deposition system makes it possible to grow CNTs without reducing agent at atmospheric pressure in a simple setup. Iron and cobalt acetate were used as catalyst and ethanol as carbon source for the synthesis of CNTs. Results show that nature of zeolite and cobalt concentration play important roles for SWCNTs production. Interestingly, we notice that in catalyst particles of sharp shape, nucleation of a nanotubes cap occurs dominantly in the forward direction.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
CdS and CdS:In films (at the In percentages of 25, 35 and 45) were deposited onto glass substrates at the substrate temperature of 300±5°C by ultrasonic spray pyrolysis technique and the effect of In ...concentration on some physical properties of the films were presented. The deposited films were characterized for their electrical, structural, morphological and elemental properties using current–voltage measurements, X-ray diffraction patterns, scanning electron microscopy micrographs and energy dispersive X-ray spectroscopy analyses, respectively. It was determined from the results of these investigations that the electrical, structural, morphological and elemental properties of CdS films considerably changed with In doping and CdS:In films are more desirable than CdS for window layer applications in photovoltaic solar cells.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
The heterojunction diodes with n-ZnO/ZnMgO/p-GaN structure have been deposited on the commercially available p-GaN/sapphire substrates by a simple process of ultrasonic spray pyrolysis. To ...demonstrate the effect of ZnMgO layer as electron blocking layer, the carrier transport mechanisms of both n-ZnO/p-GaN and n-ZnO/ZnMgO/p-GaN heterojunctions were systemically investigated by temperature-dependent current–voltage measurements. The results revealed that the multistep tunneling is the dominant carrier transport mechanism in n-ZnO/ZnMgO/p-GaN heterojunctions under forward current, accurately controlled ZnMgO layer thickness can effectively block electron injection from ZnO to GaN and promote hole injection from GaN to ZnO. Therefore, the design and application of ZnO based heterostructure devices will benefit significantly from these achievements.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Single-walled carbon nanotubes (SWCNTs) were synthesized using ethanol and bimetallic catalyst of cobalt and molybdenum acetates by ultrasonic spray pyrolysis method on silicon substrates at 850 °C. ...This process made it possible to grow carbon nanotubes without use of vacuum pump and hydrogen reducing agent in nitrogen environment under simple set-up. Similar result so far has not been reported earlier in this method. Synthesis of CNTs are found to be highly affected in catalyst concentration. As-grown carbon nanotubes were characterized by Raman spectra, scanning electronic microscope (SEM) and transmission electronic microscope (TEM). This technique suggests for the low cost rout of SWCNTs synthesis. The diameter of as-grown CNTs was within 0.8 nm to 1.2 nm.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
In
2O
3 thin films were deposited on glass substrates at different temperatures (380–500
°C). The optical films properties were determined from transmission and reflection spectra in the 260–2600
nm ...spectral range. The transmission coefficient in the visible and infrared regions, exceed 85% and is weakly affected by deposition temperature. The band gap for direct transitions is 3.57–3.68
eV. The dispersion of the real refractive index (
n) and extinction coefficient (
k) have been obtained from transmission and reflection spectra by means of the Forouhi and Bloomer model.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
499.
RAPID SYNTHESIS OF MULLITE POWDERS Goren, R; Ozgur, C
Journal of Ceramic Processing Research,
2012, Volume:
13, Issue:
3
Journal Article
Peer reviewed
High purity mullite powders were synthesised by ultrasonic spray pyrolysis and the microstructure of bulk materials prepared using this powder was evaluated. TEOS and aluminium nitrate nanohydrate ...were used to prepare an aqueous solution and this solution was turned into aerosol droplets using an ultrasonic nebuliser. The aerosol droplets were carried to the vertical tube furnace, the temperature of which was set beforehand using a gas with a flow rate of 1.5 L/min. Spherically shaped mullite powders were synthesised at 1075 C. Bulk materials were obtained by sintering the pressed mullite powders at different temperatures (1500, 1550, 1600 and 1650 C) with a soaking time of 5 hours. SEM showed that the particle shape changed with the sintering temperature of the bulk ceramics. For low temperature sintering, the particles remained spherical whereas they tend to form a rod-like structure with increasing sintering temperature.
We demonstrate the growth of ZnO and ZnMgO nanorods on Si substrates through a two-step process without a catalyst by using a simple ultrasonic spray pyrolysis method. First, a ZnO thin film was ...deposited on a Si substrate to make a seed layer; then, ZnO and ZnMgO nanorods were deposited on that seed layer. ZnO and ZnMgO nanorods with a p-n junction were obtained by using nitrogen doping for p-type nanorods, and gallium doping for n-type nanorods. A distinct electroluminescence was observed at room temperature from the ZnO and the ZnMgO nanorod structures under forward bias conditions.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
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