13 results on '"Tizazu Abza"'
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2. Synthesis, growth and characterization of magnesium chloride doped L-alanine cadmium chloride single crystal: For nonlinear optical application
- Author
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Dessale Alemu, Idris Shafi, and Tizazu Abza
- Subjects
solution method ,doping ,crystal growth ,harmonic generation ,nonlinear optics ,Veterinary medicine ,SF600-1100 ,Science - Abstract
The aim of this research was to synthesize and characterize pure and magnesium chloride(MgCl2) doped L–alanine cadmium chloride (LACC) single crystals. Pure and MgCl2doped LACC single crystals were synthesized by solution method with slow evaporation solution growth technique at room temperature. The single crystal X-ray diffraction studies of pure, 1 and 2 mol% MgCl2doped LACC single crystals revealed monocliniccrystal structure with C2 space group. The optical properties of pure and MgCl2dopedLACC single crystals investigated by UV–VIS/NIR spectrometer confirmed that the crystals were transparent in the wavelength range of 230-1100nm. The optical band gap energy of pure and doped LACC single crystals were found to have the same value of 5.4eV. The energy-dispersive X-ray analysis indicated the incorporation of magnesium and chlorine atoms in an LACC single crystal. The second harmonic generation efficiency of 1 and 2 mol% MgCl2doped LACC crystals were analyzed by Kurtz-Perry powder technique and found to be 1.75 and 2 times greater than that of the standard potassium dihydrogen phosphate crystal,respectively
- Published
- 2022
- Full Text
- View/download PDF
3. The Study of Structural, Optical, and Dielectric Properties of Magnesium Chloride-Doped Triglycine Sulphate Ferroelectric Single Crystals
- Author
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Dessale Alemu, Shita Firehun, Tizazu Abza, and M. Esthaku Peter
- Subjects
Materials of engineering and construction. Mechanics of materials ,TA401-492 - Abstract
Triglycine sulphate (TGS) and 1 and 2 mol% of magnesium chloride-doped TGS single crystals have been grown by using the slow evaporation solution method at room temperature. Pure and magnesium chloride-doped triglycine sulphate single crystals in a dimension of 12 × 12 × 5 cm3 have been grown at room temperature. The grown samples have been investigated by various characterization techniques such as single crystal X-ray diffraction, UV-VIS/NIR spectroscopy, dielectric studies, and energy dispersive X-ray analysis (EDAX). The single crystal X-ray diffraction studies revealed that both 1 and 2 mol% of MgCl2-doped TGS single crystals have been crystallized in monoclinic crystal structure with space group P21/m. The UV-VI/NIR spectra analysis confirmed that both pure and 1 and 2 mol% of MgCl2-doped TGS single crystals have wide optical transparency in the wavelength range of 236–1100 nm. The bandgap energy of both samples has been found to be 5.25 eV. The dielectric properties of the grown samples were recorded by measuring the dielectric constant as a function of temperature from 45 to 55°C with various frequencies (100 Hz – 1 MHz). The dielectric studies revealed that the dielectric constants of 1 and 2 mol% of MgCl2-doped TGS single crystals were increased with decreasing frequency and that the transition temperature was found to be 51°C. The EDAX spectrum confirmed the incorporation of MgCl2 into TGS single crystals.
- Published
- 2022
- Full Text
- View/download PDF
4. Synthesis and Characterization of Iron Doped Titanium Dioxide (Fe: TiO2) Nanoprecipitate at Different pH Values for Applications of Self-Cleaning Materials
- Author
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Tizazu Abza, Abel Saka, Jule Leta Tesfaye, Lamessa Gudata, N. Nagaprasad, and Ramaswamy Krishnaraj
- Subjects
Materials of engineering and construction. Mechanics of materials ,TA401-492 - Abstract
Fe:TiO2 nano particles were deposited through sol-gel techniques, and the influence of pH values on structural, morphological, optical, and photoluminescence spectral behaviors was studied. Iron doped titanium dioxide nanopowders were analyzed using XRD, SEM, UV–ViS, and PL. Nano crystallized samples of titanium dioxide (72 nm, 77 nm, 78 nm, and 83 nm) were gained from X-Ray diffraction data and showed that there was the creation of unalloyed anatase and ructile segment with tetragonal configuration. The average crystal size was 77.5 nm. pH values provide the alteration of segments from anatase to ructile. The crystal size of prepared iron doped titanium dioxide nanoparticles was greater than before as pH value rises from 2 to 6 while FWHM and scrap sizes declined. Homogeneously disseminated cylindrical forms of iron doped titanium dioxide nanoparticles were perceived from scanning electron microscope graphics and rises in size with growing pH values from 2 to 6 in an acidic medium. Extremely translucent nanopowders are witnessed in the observable region by visible and redshifts near advanced wavelengths with rising pH values because of an increase in the size of particles from XRD data and SEM micrographs. The band gap of energy produced by nano concentrates was reduced with growing pH values that resemble the redshift of optical absorption superiority. The structural behaviors of deposited nanoparticles were also analyzed by Raman spectra and disclosed the existence of tetragonal anatase and ructile segments. EDS results confirmed that the dopant of pH values of the solutions might affect the size distributions of the Fe: TiO2 nanoparticles. The general decrement intensity was witnessed from photoluminescence outcomes.
- Published
- 2022
- Full Text
- View/download PDF
5. Characterization of Cobalt Sulfide Thin Films Synthesized from Acidic Chemical Baths
- Author
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Tizazu Abza, Dereje Gelanu Dadi, Fekadu Gashaw Hone, Tesfaye Chebelew Meharu, Gebremeskel Tekle, Eyobe Belew Abebe, and Kalid Seid Ahmed
- Subjects
Materials of engineering and construction. Mechanics of materials ,TA401-492 - Abstract
Cobalt sulfide thin films were synthesized from acidic chemical baths by varying the deposition time. The powder X-ray diffraction studies indicated that there are hexagonal CoS, face-centered cubic Co3S4, and cubic Co9S8 phases of cobalt sulfide. The crystallite size of the hexagonal CoS phase decreased from 52.8 nm to 22.5 nm and that of the cubic Co9S8 phase increased from 11 nm to 60 nm as the deposition time increased from 2 hrs to 3.5 hrs. The scanning electron microscopic images revealed crack and pinhole free thin films with uniform and smooth background and few large polygonal grains on the surface. The band gap of the cobalt sulfide thin films decreased from 1.75 eV to 1.3 eV as the deposition time increased from 2 hrs to 3.5 hrs. The photoluminescence (PL) spectra of the films confirmed the emission of ultraviolet, violet, and blue lights. The intense PL emission of violet light at 384 nm had red shifted with increasing deposition time that could be resulted from the increase in the average crystallite size. The FTIR spectra of the films indicated the presence of OH, C-O-H, C-O, double sulfide, and Co-S groups. As the deposition time increased, the electrical resistivity of the cobalt sulfide thin films decreased due to the increase in both the crystallite size and the films’ thickness.
- Published
- 2020
- Full Text
- View/download PDF
6. Microstructural and Optical Characterization of Heterostructures of ZnS/CdS and CdS/ZnS Synthesized by Chemical Bath Deposition Method
- Author
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Temesgen Geremew and Tizazu Abza
- Subjects
Materials of engineering and construction. Mechanics of materials ,TA401-492 - Abstract
ZnS/glass and CdS/glass single layers and ZnS/CdS and CdS/ZnS heterojunction thin films were deposited by the chemical bath deposition method using zinc acetate and cadmium acetate as the metal ion sources and thioacetamide as a nonmetallic ion source in acidic medium. Na2EDTA was used as a complexing agent to control the free cation concentration. The single layer and heterojunction thin films were characterized with X-ray diffraction (XRD), a scanning electron microscope (SEM), energy dispersive X-ray (EDX), and a UV-VIS spectrometer. The XRD patterns of the CdS/glass thin film deposited on the soda lime glass substrate crystalized in the cubic structure with a single peak along the (111) plane. The ZnS/CdS heterojunction and ZnS/glass single layer thin films were crystalized in the hexagonal ZnS structure. The CdS/ZnS heterojunction thin film is nearly amorphous. The optical analysis results confirmed single band gap values of 2.75 eV and 2.5 eV for ZnS/CdS and CdS/ZnS heterojunction thin films, respectively. The CdS/glass and CdS/ZnS thin films have more imaginary dielectric components than the real part. The optical conductivity of the single layer and heterojunction films is in the order of 1015 1/s. The optical study also confirmed refractive index values between 2 and 2.7 for ZnS/glass, ZnS/CdS, and CdS/ZnS thin films for incident photon energies between 1.2 eV and 3.8 eV. The surface morphology studies revealed compacted spherical grains covering the substrate surfaces with few cracks on ZnS/glass, ZnS/CdS, and CdS/glass and voids on CdS/ZnS thin films. The EDX result confirmed nearly 1 : 1 metallic to nonmetallic ion ratio in the single-layered thin films and the dominance of Zn ion over Cd ion in both ZnS/CdS and CdS/ZnS heterojunction thin films.
- Published
- 2020
- Full Text
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7. Synthesis and characterization of aluminum dope zinc sulfide (Al:ZnS) thin films by chemical bath deposition techniques
- Author
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Asnake Girma, Tizazu Abza, and Gemechis Megersa Jigi
- Subjects
chemistry.chemical_compound ,Materials science ,chemistry ,Chemical engineering ,Aluminium ,chemistry.chemical_element ,Thin film ,Zinc sulfide ,Characterization (materials science) ,Chemical bath deposition - Abstract
A well adherent thin films of Aluminum doped zinc sulphide (Al:ZnS) has been deposited on silica glass substrates using acidic chemical bath deposition (CBD) containing zinc acetate, Aluminum Chloride, and thioacetamide. EDTA was used as complexing agent to control the free ion concentration of the thin films. Aluminum concentrations were doped by 2%, 4%, and 6% while keeping other deposition parameters constant as deposited Al:ZnS thin films. The samples were characterized by BrukerD8 diffractometer with cuKα (λ=1.5406A˚) radiation working at 40 mA and 40 kV, JOEL-2300 Analysis Station Scanning electron microscope (SEM), and Perkin Elmer Lambda 950 UV-vis/NIR spectrophotometer. The structural characterization of the samples show that no intense peaks were observed indicating the amorphous nature of the films. The surface morphology studies of as deposited Al:ZnS thin films shown the films were uniform, dense, and composed of spherical shaped grains. EDAX shows the elemental composition of Zn, S, and Al. The ratios of Zn/S in Stoichiometric even though the concentration of Aluminum is increased. Optical absorbance of the films decreased with increase Aluminum concentration. The large band gap makes them good materials for application as a window layer for solar cells.
- Published
- 2021
8. Synthesis and characterization of lanthanum chloride doped L-alanine maleate single crystals
- Author
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M. Esthaku Peter, Tizazu Abza, and Dessale Alemu Fentaw
- Subjects
010302 applied physics ,Materials science ,Band gap ,Doping ,Analytical chemistry ,chemistry.chemical_element ,02 engineering and technology ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,Evaporation (deposition) ,Inorganic Chemistry ,Crystal ,chemistry ,0103 physical sciences ,Materials Chemistry ,Lanthanum ,Thermal stability ,Orthorhombic crystal system ,0210 nano-technology ,Single crystal - Abstract
Doping of non-linear optical materials by different elements and compounds is the common method to tune the various properties of these materials. In this work we report single crystals of undoped and lanthanum chloride (LaCl3) doped L-Alanine Maleate (LAM) grown by slow evaporation solution growth method at room temperature. From the single crystal X-ray diffraction analysis it was observed that both undoped, 1 and 2 mol% LaCl3-doped LAM samples were crystallized in the orthorhombic crystal system with P212121 space group. The optical properties of the LAM single crystals investigated by UV–VIS/NIR spectrometer revealed that the crystals were transparent in the wavelength range of 300–1100 nm. The band gap of the undoped and LaCl3 doped LAM single crystals were found to be 4.13 eV. Energy dispersive X-ray analysis confirmed the incorporation of LaCl3 in LAM single crystals. Simultaneous TG/DT analysis revealed the thermal stability of the samples below 145 °C. The second harmonic generation efficiency of the samples was analyzed by Kurtz-Perry powder technique and compared with the standard KDP crystal.
- Published
- 2019
9. Characterization of Cobalt Sulfide Thin Films Synthesized from Acidic Chemical Baths
- Author
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Fekadu Gashaw Hone, Kalid Seid Ahmed, Gebremeskel Tekle, Tizazu Abza, Tesfaye Chebelew Meharu, Eyobe Belew Abebe, and Dereje Gelanu Dadi
- Subjects
chemistry.chemical_classification ,Photoluminescence ,Materials science ,Sulfide ,Article Subject ,Scanning electron microscope ,Band gap ,General Engineering ,Analytical chemistry ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Cobalt sulfide ,0104 chemical sciences ,chemistry.chemical_compound ,chemistry ,TA401-492 ,Deposition (phase transition) ,General Materials Science ,Crystallite ,Thin film ,0210 nano-technology ,Materials of engineering and construction. Mechanics of materials - Abstract
Cobalt sulfide thin films were synthesized from acidic chemical baths by varying the deposition time. The powder X-ray diffraction studies indicated that there are hexagonal CoS, face-centered cubic Co3S4, and cubic Co9S8 phases of cobalt sulfide. The crystallite size of the hexagonal CoS phase decreased from 52.8 nm to 22.5 nm and that of the cubic Co9S8 phase increased from 11 nm to 60 nm as the deposition time increased from 2 hrs to 3.5 hrs. The scanning electron microscopic images revealed crack and pinhole free thin films with uniform and smooth background and few large polygonal grains on the surface. The band gap of the cobalt sulfide thin films decreased from 1.75 eV to 1.3 eV as the deposition time increased from 2 hrs to 3.5 hrs. The photoluminescence (PL) spectra of the films confirmed the emission of ultraviolet, violet, and blue lights. The intense PL emission of violet light at 384 nm had red shifted with increasing deposition time that could be resulted from the increase in the average crystallite size. The FTIR spectra of the films indicated the presence of OH, C-O-H, C-O, double sulfide, and Co-S groups. As the deposition time increased, the electrical resistivity of the cobalt sulfide thin films decreased due to the increase in both the crystallite size and the films’ thickness.
- Published
- 2020
- Full Text
- View/download PDF
10. Microstructural and Optical Characterization of Heterostructures of ZnS/CdS and CdS/ZnS Synthesized by Chemical Bath Deposition Method
- Author
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Tizazu Abza and Temesgen Geremew
- Subjects
010302 applied physics ,Soda-lime glass ,Materials science ,Article Subject ,Scanning electron microscope ,General Engineering ,Analytical chemistry ,Heterojunction ,02 engineering and technology ,Substrate (electronics) ,021001 nanoscience & nanotechnology ,01 natural sciences ,Amorphous solid ,chemistry.chemical_compound ,chemistry ,0103 physical sciences ,TA401-492 ,General Materials Science ,Thin film ,0210 nano-technology ,Materials of engineering and construction. Mechanics of materials ,Chemical bath deposition ,Cadmium acetate - Abstract
ZnS/glass and CdS/glass single layers and ZnS/CdS and CdS/ZnS heterojunction thin films were deposited by the chemical bath deposition method using zinc acetate and cadmium acetate as the metal ion sources and thioacetamide as a nonmetallic ion source in acidic medium. Na2EDTA was used as a complexing agent to control the free cation concentration. The single layer and heterojunction thin films were characterized with X-ray diffraction (XRD), a scanning electron microscope (SEM), energy dispersive X-ray (EDX), and a UV-VIS spectrometer. The XRD patterns of the CdS/glass thin film deposited on the soda lime glass substrate crystalized in the cubic structure with a single peak along the (111) plane. The ZnS/CdS heterojunction and ZnS/glass single layer thin films were crystalized in the hexagonal ZnS structure. The CdS/ZnS heterojunction thin film is nearly amorphous. The optical analysis results confirmed single band gap values of 2.75 eV and 2.5 eV for ZnS/CdS and CdS/ZnS heterojunction thin films, respectively. The CdS/glass and CdS/ZnS thin films have more imaginary dielectric components than the real part. The optical conductivity of the single layer and heterojunction films is in the order of 10 15 1/s. The optical study also confirmed refractive index values between 2 and 2.7 for ZnS/glass, ZnS/CdS, and CdS/ZnS thin films for incident photon energies between 1.2 eV and 3.8 eV. The surface morphology studies revealed compacted spherical grains covering the substrate surfaces with few cracks on ZnS/glass, ZnS/CdS, and CdS/glass and voids on CdS/ZnS thin films. The EDX result confirmed nearly 1 : 1 metallic to nonmetallic ion ratio in the single-layered thin films and the dominance of Zn ion over Cd ion in both ZnS/CdS and CdS/ZnS heterojunction thin films.
- Published
- 2020
11. Preparation of cadmium zinc sulfide (Cd1−xZnxS) thin films from acidic chemical baths
- Author
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F. Boakye, Fekadu Gashaw Hone, R.K. Nkum, Francis Kofi Ampong, and Tizazu Abza
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Materials science ,genetic structures ,Band gap ,Analytical chemistry ,chemistry.chemical_element ,02 engineering and technology ,Zinc ,01 natural sciences ,chemistry.chemical_compound ,Lattice constant ,0103 physical sciences ,Materials Chemistry ,Thin film ,010302 applied physics ,Cadmium ,Metals and Alloys ,Surfaces and Interfaces ,021001 nanoscience & nanotechnology ,Zinc sulfide ,eye diseases ,Cadmium sulfide ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,chemistry ,sense organs ,0210 nano-technology ,Chemical bath deposition - Abstract
Ternary cadmium zinc sulfide (Cd1−xZnxS) thin films were deposited by chemical bath deposition method for the entire range of 0 ≤ x ≤ 1 from acidic chemical bath using tartaric acid and hydrazine as a complexing agents. The X-ray diffraction (XRD) studies revealed that the deposited thin films had hexagonal crystal structure in the range of 0 ≤ x ≤ 0.6 and pure cubic phase at x = 1, whereas, the thin films deposited in the range of 0.72 ≤ x ≤ 0.9 had a mixed cubic and hexagonal structures. Furthermore, the XRD results showed that the crystalline size and lattice constants were decreased linearly with the gradual incorporations of zinc ion in the Cd1−xZnxS thin films. The optical spectroscopy investigation established that the band gap of the deposited ternary thin films found in the range of 3.84 eV to 3.94 eV. The scanning electron microscope studies illustrated that the surface morphologies of the prepared thin films were formed from spherical grains. The presence of cadmium, sulfur and Zinc elements in the synthesized thin films were confirmed by the energy dispersive x-ray analyses. The unusual large band gap obtained for pure cadmium sulfide and ternary Cd1−xZnxS thin films deposited under the present deposition condition together with the preferred orientation along the (002) plane make these thin films useful as a buffer layer in thin film solar cells.
- Published
- 2018
12. A New Route for the Synthesis of CdS Thin Films from Acidic Chemical Baths
- Author
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R.K. Nkum, F. Boakye, Fekadu Gashaw Hone, Tizazu Abza, Isaac Nkrumah, and Francis Kofi Ampong
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Materials science ,Chemical engineering ,Mechanics of Materials ,Surfaces and Interfaces ,Thin film ,Surfaces, Coatings and Films - Published
- 2017
13. The effect of deposition time on the structural, morphological and optical band gap of lead selenide thin films synthesized by chemical bath deposition method
- Author
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Tizazu Abza, Fekadu Gashaw Hone, Isaac Nkrumah, Mark Paal, R.K. Nkum, F. Boakye, and Francis Kofi Ampong
- Subjects
Materials science ,Band gap ,Scanning electron microscope ,Mechanical Engineering ,Analytical chemistry ,Mineralogy ,Combustion chemical vapor deposition ,Condensed Matter Physics ,Nanocrystalline material ,chemistry.chemical_compound ,chemistry ,Mechanics of Materials ,General Materials Science ,Crystallite ,Thin film ,Lead selenide ,Chemical bath deposition - Abstract
Nanocrystalline lead selenide thin films have been deposited on silica glass substrates by chemical bath deposition method at a bath temperature of 90 °C and a pH of about 12. Three samples were prepared by employing different deposition times. The deposited thin films, which were uniform, well adherent and gray in color, were characterized by powder X-ray diffraction, scanning electron microscopy, energy dispersive X-ray analysis and optical absorption spectroscopy. The results showed that the deposition time had a strong influence on the morphology, preferred orientation of the crystallites as well as other structural parameters such as microstrain and dislocation density. The optical band gap also varied with increasing deposition time from 1.25 eV to 1.11 eV. The elemental compositions of the films were confirmed by energy dispersive X-ray spectroscopy.
- Published
- 2015
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