Effect of synthesis method on structure, band gap and surface morphology of delafossite oxides, CuAlO2 and CuFeO2

Author(s):  
Aadil Abass Shah ◽  
Ameer Azam
2018 ◽  
Vol 14 (3) ◽  
pp. 397-402 ◽  
Author(s):  
Faiz Hafeez Azhar ◽  
Zawati Harun ◽  
Muhamad Zaini Yunos ◽  
Azlinorazia Ahmad ◽  
Siti Hajar Mohd Akhair ◽  
...  

The significant effect of concentration (TBut/HCl) ratio in synthesizing titania nanoflowers (TNF) towards powder morphologies, crystallographic phases, surface area and band gap were investigated. Various synthesized titania nanostructure were prepared via facile hydrothermal method using titanium butoxide (TBut) and hydrochloric acid (HCl) as a mixing composition. The morphologies of synthesizing titania powder was analyzed by using FE-SEM to observe the shape and geometry of the synthesized powder. XRD was used to determine the crystallographic phases of synthesized powder at 2θ angles of 25° to 75°. Each samples were then investigated under BET analyzer to observe the particles surface morphology and UV-Vis analyzer to determine the band gap. The results demonstrated that the concentration of TBut/HCl ratio gave a very significant effect in transforming the mixing solution into geometrical shape of microspheres, nanoflowers and nanorods of titania as increasing the ratio. At TN0.5, the synthesized powder was clearly showed a circle geometrical shape of particles. The shape was suddenly change into round nanoflowers form consist of tiny nanorods at TN1. At TN1.5, the powder morphologies shows the nanoflowers started to form in irregular pattern. As the TBut/HCl ratio increased, the nanoflowers form disappeared and nanorods begin to clumps. In addition, all synthesized powder was in rutile phases guided by XRD peaks and band gap value reported from previous works. The particles surface area was also different for each samples since the geometrical shape of powder was change by increasing the concentration (TBut/HCl) ratio. Thus, concentration ratio of the mixing composition plays a major role in transforming the overall morphologies and structures of hydrothermally titania synthesized particles.


2019 ◽  
Vol 6 (3) ◽  
pp. 190100 ◽  
Author(s):  
Sanhita Mandal ◽  
Neha Jain ◽  
Mukesh Kumar Pandey ◽  
S. S. Sreejakumari ◽  
Prashant Shukla ◽  
...  

Graphene and semiconductor nanocomposite garnered much interest in nanoscience and nanotechnology. In this research, TiO 2 , TiO 2 : Sr and TiO 2 : Sr/r-GO (reduced graphene oxide) nanocomposites have been successfully synthesized via a wet chemical synthesis method. The microscopic studies confirmed the formation of graphene sheets which looked like a paper which could easily wrap over the bacterial surface killing them. The optical band gap of these nanocomposites is determined by UV–visible absorption spectra which inferred that optical band gap decreases with Sr 2+ incorporation and r-GO attachment. Furthermore, photoluminescence (PL) study revealed that the intensity of emission is prominent for TiO 2 : Sr/r-GO. The enhancement in PL intensity with r-GO is due to creation of more oxygen vacancies and defects which generally capture the photoinduced carriers inhibiting recombination rate of free carriers promoting the photocatalytic reactions.


2007 ◽  
Vol 4 (2) ◽  
pp. 255-264 ◽  
Author(s):  
Benny Joseph ◽  
C. S. Menon

Thin films of Nickel Phthalocyanine (NiPc) are fabricated at a base pressure of 10-5m.bar using Hind-Hivac thermal evaporation plant. The films are deposited on to glass substrates at various temperatures 318, 363, 408 and 458K. The optical absorption spectra of these thin films are measured. Present studies reveal that the optical band gap energies of NiPc thin films are highly dependent on the substrate temperatures. The structure and surface morphology of the films deposited on glass substrates of temperatures 303, 363 and 458K are studied using X-ray diffractograms and Scanning Electron Micrographs (SEM), show that there is a change in the crystallinity and surface morphology due to change in the substrate temperatures. Full width at half maximum (FWHM) intensity of the diffraction peaks is also found reduced with increasing substrate temperatures. Scanning electron micrographs show that these crystals are fiber like at high substrate temperatures. The optical band gap increases with increase in substrate temperature and is then reduced with fiber-like grains at 408K. The band gap increases again at 458K with full of fiber like grains. Trap energy levels are also observed for these films.


MRS Advances ◽  
2016 ◽  
Vol 1 (47) ◽  
pp. 3207-3213 ◽  
Author(s):  
John P. Murphy ◽  
Jessica M. Andriolo ◽  
Brandon M. Ross ◽  
Gary F. Wyss ◽  
Nicole E. Zander ◽  
...  

ABSTRACTA new organometallic halide perovskite (OHP) synthesis method, whereby a polymer melt is used to thermodynamically drive the reaction that forms OHP crystallites, is demonstrated. The synthesis method allows for the facile encapsulation of moisture-sensitive OHP without the loss of simplicity during fabrication, which makes OHP materials so attractive for the photovoltaic industry. Degradation of OHP crystallites embedded in a polystyrene matrix was studied using UV-Vis absorbance over a period of several days. The OHP crystallites degrade as a result of the reversible nature of the reaction that forms the crystallites. After the reversion to precursors (PbI2 and CH3NH3I) the CH3NH3I irreversibly degrades [2] allowing the degradation to be tracked via optical interrogation. Additionally, surface morphology and elemental analysis of fabricated samples was carried out using SEM/EDS techniques.


2012 ◽  
Vol 29 (12) ◽  
pp. 126802 ◽  
Author(s):  
Muhamad Saipul Fakir ◽  
Zubair Ahmad ◽  
Khaulah Sulaiman

RSC Advances ◽  
2016 ◽  
Vol 6 (14) ◽  
pp. 11903-11910 ◽  
Author(s):  
Mohammad Reza Golobostanfard ◽  
Hossein Abdizadeh

Graded band gap chalcopyrite solar cells are fabricated based on an all solution processable synthesis method with the aid of electrophoretic deposition and a superstrate structure.


2018 ◽  
Vol 14 (2) ◽  
pp. 5624-5637
Author(s):  
A.A. Attia ◽  
M.M. Saadeldin ◽  
K. Sawaby

Para-quaterphenyl thin films were deposited onto glass and quartz substrates by thermal evaporation method. p-quaterphenyl thin films wereexposed to gamma radiation of Cobat-60 radioactive source at room temperature with a dose of 50 kGy to study the effect of ?-irradiation onthe structure and the surface morphology as well as the optical properties of the prepared films. The crystalline structure and the surface morphology of the as-deposited and ?-irradiated films were examined using the X-ray diffraction and the field emission scanning electron microscope. The optical constants (n & k) of the as-deposited and ?-irradiated films were obtained using the transmittance and reflectance measurements, in the wavelength range starting from 250 up to 2500 nm. The analysis of the absorption coefficient data revealed an allowed direct transition with optical band gap of 2.2 eV for the as-deposited films, which decreased to 2.06 eV after exposing film to gamma irradiation. It was observed that the Urbach energy values change inversely with the values of the optical band gap. The dispersion of the refractive index was interpreted using the single oscillator model. The nonlinear absorption coefficient spectra for the as-deposited and ?-irradiated p-quaterphenyl thin films were obtained using the linear refractive index.


ALCHEMY ◽  
2015 ◽  
Vol 4 (1) ◽  
Author(s):  
Khusnan Mustofa ◽  
Nur Aini ◽  
Susi Nurul Khalifah

<p>TiO<sub>2</sub> Anatase activities should be increased from the UV to the visible light photocatalytic activity of TiO<sub>2</sub> to increase anatas. One efforts to optimize TiO<sub>2</sub> anatase activity is doping by using dopant vanadium(V). Synthesis method which is used in this research is a solid reaction method. The steps being taken in this methods include grinding and heating at high temperatures. Dopant concentrations of vanadium(V) which are used in the research was 0.3%, 0.5% and 0.7%. and the characterization used is X-ray diffraction and UV-Vis Diffuse Reflectance Spectroscopy. The result shows that there are a changing of particle size, band gap energy, and absorption of TiO<sub>2</sub> anatas wavelength because of dopan vanadium(V) addition. While TiO<sub>2</sub>’s structure does not change. The crystal sizes of each TiO<sub>2</sub> without doping, V-TiO<sub>2</sub> 0,3%, 0,5% and 0,7% are 53.21 nm, 47.67 nm, 79.65 nm dan 68.99 nm.  Band gap energy of each TiO<sub>2</sub> without doping, V-TiO<sub>2</sub> 0,3%, 0,5% dan 0,7% are 3.309 eV, 3.279 eV, 3.270 eV and 3.259 eV. While wavelength absorption of each TiO<sub>2</sub> without doping, V-TiO<sub>2</sub> 0,3%, 0,5% and 0,7% are 374.9 nm, 378.4 nm, 379.5 nm and 380.8 nm.<em> </em></p><p class="BodyAbstract"> </p><strong><em>Keywords</em>:</strong> <em>Synthesis, titanium dioxide, vanadium(V), solid state method</em>


Crystals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 968
Author(s):  
Reina Galeazzi Isasmendi ◽  
Isidro Juvenal Gonzalez Panzo ◽  
Crisóforo Morales-Ruiz ◽  
Román Romano Trujillo ◽  
Enrique Rosendo ◽  
...  

Copper oxide (CuO) films were deposited onto glass substrates by the microwave assisted chemical bath deposition method, and varying the pH of the solution. The pH range was varied from 11.0 to 13.5, and the effects on the film properties were studied. An analytical study of the precursor solution was proposed to describe and understand the chemical reaction mechanisms that take place in the chemical bath at certain pH to produce the CuO film. A series of experiments were performed by varying the parameters of the analytical model from which the CuO films were obtained. The crystalline structure of the CuO films was studied using X-ray diffraction, while the surface morphology, chemical composition, and optical band-gap energy were analyzed by scanning electron microscopy, X-ray photoelectron spectroscopy, and UV–Vis spectrophotometry, respectively. The CuO films obtained exhibited a monoclinic crystalline phase, nanostructured surface morphology, stoichiometric Cu/O ratio of 50/50 at%, and band-gap energy value of 1.2 eV.


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