scholarly journals Impact of annealing temperature to the performance of hematite based humidity sensor

Author(s):  
W.R.W. Ahmad ◽  
M.H. Mamat ◽  
Z. Khusaimi ◽  
A.S. Ismail ◽  
M. Rusop

<span lang="EN-GB">In the present study, hematite (α-Fe<sub>2</sub>O<sub>3</sub>) nanorod structure were grown on fluorine doped tin oxide coated glass substrate via sonicated immersion approach with variation of annealing temperature (350˚C – 600˚C) in one-hour treatment. The impact of varying the temperature of annealing treatment on crystalline phase, structure morphology, optical properties and humidity sensing performance of hematite were examined. X-ray diffraction pattern disclosed a rhombohedral structure with α-phase diffraction peaks. The surface morphology images taken from field emission scanning electron microscopy revealed that the hematite nanorod arrays were grown uniformly in all samples and the average diameters of nanorods were measured in the ranges between 55 and 80 nm. Ultraviolet–visible spectroscopy measurement spectra show that all samples exhibited good optical properties. The hematite humidity sensor sample annealed at 400°C has demonstrated the highest sensitivity response (S=177.78) to humidity range between 40%RH to 90%RH.</span>

2013 ◽  
Vol 770 ◽  
pp. 149-152 ◽  
Author(s):  
T. Plirdpring ◽  
M. Horprathum ◽  
C. Chananonnawathorn ◽  
P. Eiamchai ◽  
A. Harnwunggmoung ◽  
...  

Tantalum oxide (Ta2O5) films at 400 nm thickness were prepared at room temperature by DC reactive magnetron sputtering. The effect of annealing temperature on film crystallinity, microstructure and optical properties were investigated. In order to indentify the crystalline structure and film morphology, X-ray diffraction (XRD) and field-emission scanning electron microscope (FE-SEM) measurements were performance. The optical properties were determined by UV-Vis spectrophotometer and spectroscopic ellipsometry (SE). The result showed that, with the annealing treatment at high temperature (700-900°C), the as-deposited films were crystallized to orthorhombic phase of tantalum pentaoxide (β-Ta2O5). In addition, the transmittance spectrum percentage indicated 87%, which corresponded to the obtained optical characteristic. The refractive index varied at 550 nm from 2.17 to 2.21 with increased of the annealing temperature.


2018 ◽  
Vol 7 (4.36) ◽  
pp. 296 ◽  
Author(s):  
Farah J.Hamood ◽  
Qunoot M.hadi ◽  
Khalid Haneen Abass ◽  
Musaab Khudhur Mohammed

Thermal evaporation method have been used to prepared thin films from tin sulfide (SnS) doping with 20 nm particle size of silver (Ag) at room temperature, under pressure up to 1 × 10-7 mbar with rate of statement 0.5 nm. sec-1. The SnS:Ag thin films deposited on glass substrate at different annealing temperature (as-deposited, 423, 473, 573 and 623 K) for 2 hours. The effect of annealing treatment on the structural and optical properties has been studied. From X- ray diffraction (XRD) examination, predominant peak (111) appears at annealing temperature 623 K, also the others as (101) and (002). Scherer’s formula used to calculate the crystallite size that ranged from 3-7 nm. Using UV-Vis spectrophotometer to recording the transmittance spectra and then calculate the optical properties in the wavelength range 300-900 nm. The absorbance decreased with the increasing of annealing temperature, while the transmittance increased. The optical constants such as refractive index, extinction coefficient, real and imaginary parts of dielectric constant, and absorption coefficient decreased with the increasing of annealing temperature. The energy band gap increased from 2.1 eV for the as- deposited film to 3.3 eV for the film annealed at 623 K.   


2010 ◽  
Vol 428-429 ◽  
pp. 126-131
Author(s):  
Wei Zhong Lu ◽  
Chun Wei ◽  
Qui Shan Gao

Polymethylene bis(p-hydroxybenzoates) were prepared from methyl p-hydroxybenzoate and different diols by melted transesterification reaction. Three liquid crystalline polyesters were synthesized from terephthaloyl dichloride and polymethylene bis(p-hydroxybenzoates). Its structure, morphology and properties were characterized by Ubbelohde viscometer, Fourier transform infrared spectroscopy (FT-IR), Differential scanning calorimetry (DSC), polarized optical microscopy (POM) with a hot stage, and wide-angle X-ray diffraction (WAXD). Results indicated that the intrinsic viscosities were between 0.088 and 0.210 dL/g. Optical microscopy showed that the TLCP has a highly threaded liquid crystalline texture and a high birefringent schlieren texture character of nematic phase and has wider mesophase temperature ranges for all polyesters. DSC analysis were found that the melting point (Tm), isotropic temperature (Ti) of TLCPs decreased and the temperature range of the liquid crystalline phase became wider with increased number of methylene spacers in the polyester. The WAXD results showed that TLCPs owned two strong diffraction peaks at 2θ near 19° and 23°.


2014 ◽  
Vol 624 ◽  
pp. 129-133 ◽  
Author(s):  
Abbas M. Selman ◽  
Zainuriah Hassan

Effects of annealing treatment on growth of rutile TiO2nanorods on structural, morphological and optical properties of TiO2nanorods were investigated. The nanorods were fabricated on p-type (111)-oriented silicon substrates and, all substrates were seeded with a TiO2seed layer synthesized by radio-frequency reactive magnetron sputtering system. Chemical bath deposition (CBD) was carried out to grow rutile TiO2nanorods on Si substrate at different annealing temperatures (350, 550, 750, and 950 °C). Raman spectroscopy, X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) analyses showed the tetragonal rutile structure of the synthesized TiO2nanorods. Optical properties were examined by photoluminescence spectroscopy. The spectra exhibit one strong UV emission peak which can be seen at around 390 nm for all of the samples. In the visible region, TiO2demonstrated two dominant PL emissions centered at around 519 and 705 nm. The experimental results showed that the TiO2nanorods annealed at 550 °C exhibited the optimal structural properties. Moreover, the CBD method enabled the formation of photosensitive, high-quality rutile TiO2nanorods with few defects for future optoelectronic nanodevice applications.


2006 ◽  
Vol 118 ◽  
pp. 53-58
Author(s):  
Elisabeth Meijer ◽  
Nicholas Armstrong ◽  
Wing Yiu Yeung

This study is to investigate the crystallite development in nanostructured aluminium using x-ray line broadening analysis. Nanostructured aluminium was produced by equal channel angular extrusion at room temperature to a total deformation strain of ~17. Samples of the extruded metal were then heat treated at temperatures up to 300oC. High order diffraction peaks were obtained using Mo radiation and the integral breadth was determined. It was found that as the annealing temperature increased, the integral breadth of the peak reflections decreased. By establishing the modified Williamson-Hall plots (integral breadth vs contract factor) after instrumental correction, it was determined that the crystallite size of the metal was maintained ~80 nm at 100oC. As the annealing temperature increased to 200oC, the crystallite size increased to ~118 nm. With increasing annealing temperature, the hardness of the metal decreased from ~60 HV to ~45 HV.


2001 ◽  
Vol 692 ◽  
Author(s):  
K. S. Huh ◽  
D. K. Hwang ◽  
K. H. Bang ◽  
M. K. Hong ◽  
D. H. Lee ◽  
...  

AbstractA series of ZnO thin films with various deposition temperatures were prepared on (100) GaAs substrates by radio-frequency magnetron sputtering using ZnO target. The ZnO films were studied by field emission scanning electron microscope(FESEM), x-ray diffraction(XRD), photoluminescence(PL), cathodoluminescence(CL), and Hall measurements. The structural, optical, and electrical properties of the films were discussed as a function of the deposition temperature. With increasing temperature, the compressive stress in the films was released and their crystalline and optical properties were improved. From the depth profile of As measured by secondary ion mass spectrometry(SIMS), As doping was confirmed, and, in order to activate As dopant atoms, post-annealing treatment was performed. After annealing treatment, electrical and optical properties of the films were changed.


2021 ◽  
Vol 317 ◽  
pp. 53-59
Author(s):  
Muhammad Safwan Sazali ◽  
Muhamad Kamil Yaakob ◽  
Mohamad Hafiz Mamat ◽  
Oskar Hasdinor Hassan ◽  
Muhd Zu Azhan Yahya

In this work, single phase Bismuth Ferrite, BiFeO3 was successfully synthesized by using hydrothermal method assisted with different weight (0.24 g, 0.36 g and 0.48 g) of Chitosan. Potassium hydroxide (KOH) were used as a mineralizer during the synthesis process for the precipitation. The samples were characterized for different properties such as structural and optical properties, and were then compared with previous works. The X-ray diffraction data for all the samples showed that the samples had a single phase belonging to R3c space group with perovskite rhombohedral structure at diffraction angle 32.0° to 32.5° even though the slight presence of secondary phase at diffraction angle 28° was detected. Scanning electron microscope revealed a decrement in particle size as the weight of Chitosan increased indicating effective used of Chitosan in controlling the agglomeration of the particles. All samples BiFeO3 assisted with and without Chitosan showed significant enhancement in energy gap where the obtained results showed a small energy gap values ranging from ~1.22 eV to ~1.88 eV determined from UV-vis absorbance characterization. Therefore, by the addition of Chitosan, the properties of BiFeO3 such as structural and optical have changed as well as preventing from the particle to agglomerate.


2005 ◽  
Vol 20 (9) ◽  
pp. 2516-2522 ◽  
Author(s):  
George Sirinakis ◽  
Rezina Siddique ◽  
Christos Monokroussos ◽  
Michael A. Carpenter ◽  
Alain E. Kaloyeros

Nanocomposite films consisting of gold nanoparticles embedded in an yttria stabilized zirconia (YSZ) matrix were synthesized at room temperature by radio-frequency co-sputtering from YSZ and Au targets at a 5 mTorr working pressure. The films were subsequently annealed for 2 h in 1 atm argon, with the annealing temperature varied from 600 to 1000 °C in steps of 100 °C. The composition, microstructure, and optical properties of the films were characterized as a function of annealing temperature by Rutherford backscattering spectrometry, scanning electron microscopy, Auger electron spectroscopy, x-ray diffraction, and absorption spectroscopy. An optical absorption band due to the surface plasmon resonance (SPR) of the Au nanoparticles was observed around a wavelength of 600 nm. Furthermore, the SPR band full width at half-maximum exhibited an inverse linear dependence on the radius of the Au nanoparticle, with a slope parameter A = 0.18, indicating a weak interaction between the YSZ matrix and the Au nanoparticles. The experimentally observed SPR dependence on nanoparticle size is discussed within the context of the Mie theory and its size-dependent optical constants.


2013 ◽  
Vol 583 ◽  
pp. 47-50 ◽  
Author(s):  
Masanobu Kusunoki ◽  
Taiyo Matsuda ◽  
Naoki Fujita ◽  
Yasuhiro Sakoishi ◽  
Ryou Iguchi ◽  
...  

A technique to control the crystallinity of hydroxyapatite (HA) was investigated for applications such as dentistry, regenerative medicine, cell culture scaffolding, and bio-sensors. An amorphous HA film was first produced by pulsed laser deposition. After deposition, it was separated from a substrate as a free-standing sheet. Annealing was then performed to control the crystallinity of the sheet. It was found that conventional annealing in an electric oven was not suitable for HA sheets, because it led to curling and cracking. Since such problems were assumed to be caused by thermal stress, annealing was next carried out with the HA sheet enclosed in HA powder in the center of a metal capsule. This method allowed annealing to be successfully carried out without causing any curling or cracking. Uniform pieces with dimensions of 10 mm × 10 mm cut from a large HA sheet were annealed at temperatures of 200 to 800 ºC and then examined using X-ray diffraction. It was found that the intensity of the diffraction peaks associated with crystalline HA changed with annealing temperature, and that the strongest peaks were observed for the sample annealed at 500 ºC. These results indicate that the crystallinity of the HA sheet can be controlled using the proposed method.


2005 ◽  
Vol 475-479 ◽  
pp. 3721-3724
Author(s):  
W.L. Wang ◽  
K.J. Liao ◽  
Jian Zhang ◽  
P. Yu ◽  
G.B. Liu

In this paper, the optical properties and structure of CdS films were investigated by SEM, X-ray diffraction, and x-ray photoelectron spectroscopy. The CdS films in this study were deposited on the plane transparent glass by chemical bath deposition technique. The experimental results have shown that the annealing treatment has an important effect on the optical properties and structure of CdS films. This may be ascribed to decreasing surface contaminations and oxide content in the films.


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