Ag-doped NiO thin films were fabricated by dip coating and subsequently annealed at 373, 473, 573, and 673 K to elucidate the influence of annealing temperature on their structural, morphological, optical, and NO2-sensing characteristics. X-ray diffraction confirmed the formation of polycrystalline Ag/NiO films, with progressively improved crystallinity and larger crystallite size at elevated annealing temperatures. Atomic force microscopy revealed a homogeneous surface morphology with grain growth, with the average grain diameter increasing from 26.40 to 34.2 nm. Optical analysis showed high visible-region transmittance (65–70%) and a gradual reduction in the optical band gap from 2.75 to 2.07 eV with increasing annealing temperature. Gas-sensing performance was evaluated at 6 ppm NO₂ at room temperature and at 323, 373, and 423 K. The response was strongly dependent on both annealing and operating temperatures, with optimum performance achieved for the film annealed at 573 K and operated at 373 K, exhibiting a maximum sensitivity of 57%, a response time of 10.2 s, and a recovery time of 10 s. The enhanced sensing behavior is attributed to the combined effects of improved crystallinity, favorable surface morphology, and the p-type semiconducting nature of NiO, in which adsorption of oxidizing NO2 increases hole concentration and decreases electrical resistance. These findings demonstrate that Ag-doped NiO thin films are promising materials for NO₂ sensing applications. Since the present study mainly focuses on elucidating the effect of annealing temperature on the structural, optical, and sensing behavior of the films, further work will be directed toward evaluating the detection limit, long-term stability, and selectivity under practical operating conditions.
Powders for (TiO 2 ) 1−x(MoO 3 ) x composites have been prepared with the use of a dry mix of TiO2 and MoO3 oxides with a variety of compositions (x = 0, 0.2, 0.4, 0.6, 0.8, and 1), then sintering at 1473 K. The materials have been ground and formed into pellets so that they could be used as targets for the pulsed laser deposition (PLD) process, which produced thin flms with a thickness of ≈150 nm on a glass substrate. When MoO3 is added to TiO2 , the crystal size has been observed to decrease from 33.3 to 25.8 nm, yet it after that continued to expand as MoO3 was added. The molybdenum ions were confrmed by XRD patterns, indicating that the substitution regarding Mo+6 ions for Ti +4 ions in TiO2 matrix is what is re
... Show MoreThis work concerned on nanocrystalline NiAl2O4 and ZnAl2O4 having spinel structure prepared by Sol–gel technique. The structural and characterization properties for the obtained samples were examined using different measurements such as X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), finally, Field emission scanning electron microscope (FESEM).The Spinel-type for two prepared compound (NiAl2O4) and (ZnAl2O4) at different calcination temperature examined by XRD. Williamson-Hall Methods used to estimate crystallite size, Average distribution crystallite size of two compound were, 34.2 nm for NiAl2O4 and32.6 for ZnAl2O4, the increase in crystallite size affecting by increasing in calcination temperature for both comp
... Show MoreAlloys of InxSe1-x were prepared by quenching technique with
different In content (x=10, 20, 30, and 40). Thin films of these alloys
were prepared using thermal evaporation technique under vacuum of
10-5 mbar on glass, at room temperature R.T with different
thicknesses (t=300, 500 and 700 nm). The X–ray diffraction
measurement for bulk InxSe1-x showed that all alloys have
polycrystalline structures and the peaks for x=10 identical with Se,
while for x=20, 30 and 40 were identical with the Se and InSe
standard peaks. The diffraction patterns of InxSe1-x thin film show
that with low In content (x=10, and 20) samples have semi
crystalline structure, The increase of indium content to x=30
decreases degree o
In this study NiO - CoO bimetallic catalysts are prepared with two Ni/Co ratios (70:30 and 80: 20) using the precipitation method of nitrate salts. The effects of Ni /Co ratio and preparation methods on the catalyst are analyzed by using different characterization techniques, i.e. atomic absorption (AA) , XRD, surface area and pore volume measurements according to the BET method . The results indicate that the best catalyst is the one containing the percentage of Ni :Co ( 70 : 30 ). Experiments indicate that the optimal conditions to prepare catalyst are stirring for three hours at a temperature of 60oC of the preparation , pH= (8-9) , calcination temperature at 400oC for two hours
... Show MorePurepolyaniline and doped with hydrochloric acid was prepared in different molarities at room temperature. The a.c electrical properties were stadied.AC conductivityσac (ω), is found to vary as ωS in the frequency range (100Hz-10MH), S< 1and decreases indicating a dominate hopping process. Thedielectric constant ε1and dielectric loss ε2 have been determined for bulk polyaniline. ε1 decrease with the increase frequency. Electrical conductivity measurements increase with the increases both of the amount of HCl and the dose of radiation. The dielectric investigations show decrease with dose radiation.
Ternary semiconductors AB5C8 (A = Cu/Ag, B = In and C = S, Se or Te) have been investigated. The CuIn5S8 and AgIn5S8 have been synthesize in cubic spinel structure with space group (Fd3m), whereas CuIn5Se8, AgIn5Se8, CuIn5Te8 and AgIn5Te8 have tetragonal structures with space group P-42m. The relaxed crystal geometry, electrical properties such as electronic band structure and optoelectronic properties are predicted by using full potential method in this work. For the determination of relaxed crystal geometry, the gradient approximation (PBE-GGA) is used. All the studied compounds are semiconductors based on their band structures in agreement with the experimental results, and their bulk moduli are in the range 35 to 69 GPa. Wide absorption
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