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Effect of pH on Optic and Structural Characterization of Chemical Deposited AgI Thin Films
(Univ Fed Sao Carlos, Dept Engenharia Materials, 2017) Tezel, Fatma Meydaneri; Kariper, Ishak Afsin
AgI thin films were grown on amorphous commercial glass substrates with chemical bath deposition (CBD) at different pH values (2, 3, 4, 5, 6), 6 hours deposition time and 60 degrees C. The structure of the nanocrystals was characterized by X-ray diffraction (XRD). The ratio of Ag+ and I-ions changed the crystalline structures. The presence of the Ag+ ions produces the.-phase of AgI and excess of iodine concentration produces beta-phase of AgI. The pH: 4 was like a transition pH for these phases. The number of crystallites per unit area has maximum value at pH: 5, as the structure is re-crystallization to hexagonal phase. Also, the thicknesses of produced thin films were decreased with increased pH values. Therefore, transmission, reflection, extinction coefficients and refractive index of the materials were affected by thicknesses, and calculated to be 32, 35, 3, 11, 9 (%) - 27, 25, 61, 45, 49 (%) - 0.036, 0.032, 0.067, 0.107, 0.075 and 3.21, 3.02, 5.16, 8.35, 5.70 in 550 nm at pH: 2-3-4-5-6 values, respectively. The exciton peaks of AgI were observed at between 320 and 420 nm. Surface properties were investigated by using scanning electron microscopy (SEM).
Effect of pH on the structural and optical properties of polycrystalline ZnSe thin films produced by CBD method
(World Scientific Publ Co Pte Ltd, 2019) Tezel, Fatma Meydaneri; Kariper, I. Afsin
In this study, zinc selenide (ZnSe) thin films were produced on glass substrate by using chemical bath deposition (CBD) method at 80 degrees C, from aqueous solutions of zinc sulphate and sodium selenosulphide, which were produced using solid selenium as the E selenium source. The optical and structural properties of ZnSe thin films were investigated at room-temperature. The pH of the chemical bath, in which ZnSe thin films were immersed, were changed between pH:8-11. Optical properties of the films, including extinction coefficient, refractive index, reflectance, absorbance, transmittance, dielectric constants and optical density values were calculated using absorbance and transmittance measurements determined using a Hach Lange 500 spectrophotometer, in 300-1100 nm wavelength range. Optical bandgap values were obtained from transmittance and absorbance spectra ranged between 2.12 and 2.49 eV. According to XRD results, it was found that the films have polycrystalline structure and they exhibited different film thicknesses depending on phase and pH changes.
THE EFFECTS OF pH ON STRUCTURAL AND OPTICAL CHARACTERIZATION OF IRON OXIDE THIN FILMS
(World Scientific Publ Co Pte Ltd, 2017) Tezel, Fatma Meydaneri; Ozdemir, Osman; Kariper, I. Afsin
In this study, the iron oxide thin flims have been produced by chemical bath deposition (CBD) method as a function of pH onto amorphous glass substrates. The surface images of the flims were investigated with scanning electron microscope (SEM). The crystal structures, orientation of crystallization, crystallite sizes, and dislocation density i.e. structural properties of the thin flims were analyzed with X-ray diffraction (XRD). The optical band gap (E-g), optical transmission (T%), reflectivity (R%), absorption coeffcient (alpha), refraction index (n), extinction coeffcient (k) and dielectric constant (epsilon) of the thin flims were investigated depending on pH, deposition time, solution temperature, substrate temperature, thickness of the flims by UV-VIS spectrometer.
Effects of pH on the optical, structural and supercapacitive properties of BiTe thin films produced via CBD
(Indian Acad Sciences, 2021) Tezel, Necmi Serkan; Tezel, Fatma Meydaneri; Kariper, Ishak Afsin
In this study, BiTe thin films are grown on glass substrates by chemical bath deposition method, at different pH levels. Crystallographic structures, crystal dimensions, dislocation densities and crystallization numbers of thin films are characterized by X-ray diffraction, whereas surface morphologies, roughness and film thicknesses are characterized by scanning electronic microscopy and atomic force microscopy. Surface tensions are calculated by Zisman method using different liquids. Capacitance, energy and power densities are calculated for each pH level by using time-dependent current-voltage measurements. Monocrystalline thin films of Bi2Te3 are observed at pH 3 and Bi4Te5 at pH 11, whereas polycrystalline Bi2Te3 and Bi4Te5 structures are formed at pH 7 and 9, respectively. Surface roughness and film thicknesses of polycrystalline thin films are found to be significantly higher than monocrystalline thin films. Capacitance, energy and power density of BiTe thin films produced at pH 3, 7, 9 and 11 are calculated as 503, 562, 569 and 512 F g(-1); 55.19, 61.66, 62.43 and 56.17 Wh kg(-1); and 3311.4, 3699.6, 3745.8 and 3370.2 W kg(-1), respectively. These results show that capacitance, energy and power density of polycrystalline thin films produced at pH 7 and 9, which have high surface load activity, are higher. Electrical resistivity of Bi2Te3 and Bi4Te5 monocrystalline films are lower than those of the polycrystalline BiTe films.
Electromagnetic scattering from a isotropic inhomogeneous impedance cylinder of arbitrary shape
(Natl Inst Optoelectronics, 2016) Tezel, Necmi Serkan; Tezel, Fatma Meydaneri
In this study, the electromagnetic scattering from anisotropic inhomogeneous impedance cylinder of arbitrary shape is presented for both TM and TE plane wave illuminations. In the solution of scattering problem, scattered TE and TM fields are expressed as single layer potentials. Using the boundary condition and jump relations of single layer potential on the boundary, boundary integral equation is obtained and solved via Nystrom method. Obtained results are compared with those obtained by analytical method for inhomogeneous anisotropic impedance cylinder and good agreements are observed.
The impact of pH on the structural, surface, electrical and optical properties of nanostructured PbSe thin films
(Iop Publishing Ltd, 2019) Tezel, Necmi Serkan; Tezel, Fatma Meydaneri; Kariper, I. Afsin
This study involves PbSe deposits fabricated on glass substrates at different pH. Some optical properties of these deposits, including reflectance, extinction coefficient, refractive index, and dielectric constant were calculated by using absorbance values at room temperature with UV spectrophotometer according to wavelength. The surface properties and compositions were examined by SEM and EDX, respectively. Surface tensions were measured by Zisman Method, and obtained to be 39.0, 42.1, 43.1 and 39.1 mNm(-1) for pH: 8, 9, 10 and 11 values, respectively. The optical band gaps (Egap) were calculated as 2.17, 1.82, 1.77 and 2.27 eV for pH: 8, 9, 10 and 11, respectively. PbSe deposits' electrical resistivity was measured via four-point probe technique depending on deposits thicknesses, and they were found to be 65.27, 26.21, 39.87 and 36.03 Omega cm for pH: 8, 9, 10 and 11, respectively.
Influence of aging on mechanical properties, wear and residual stress of a Heusler Al-Cu-Fe alloy
(Carl Hanser Verlag, 2019) Husem, Fazil; Tezel, Fatma Meydaneri; Turan, Muhammet Emre
In this study, the ferromagnetic Heusler alloy Al-Cu-Fe was aged at a temperature of 300 degrees C for 0.5 h, 1 h, 1.5 h, 2 h and 2.5 h, respectively. The mechanical and structural properties, residual stress state and wear performance of the specimens were investigated. The results show that precipitation has a crucial influence on the mechanical properties and wear performance of a Heusler alloy. The hardness and wear resistance of the specimens improve with an increase of precipitation density. These precipitates are associated with Cu-rich and Al-Cu lamellar structures. The density of these precipitates reveal two certain Al2Cu peaks at an aging time of 90 minutes, and 150 minutes for the annealed specimens.
A NEW APPROACH TO PREPARE POLYCRYSTALLINE PbTe-TeO THIN FILM, AND ITS OPTICAL, STRUCTURAL, SURFACE AND ELECTRICAL CHARACTERIZATION
(World Scientific Publ Co Pte Ltd, 2021) Tezel, Fatma Meydaneri; Kariper, I. Afsin
In this study, PbTe thin film was produced on glass substrates, via chemical bath deposition (CBD) method, with 3-h deposition time at 50(circle)C. The produced thin film had polycrystalline structure; TeO2, PbTe, PbTe3 and Te2O5 crystals that were characterized by X-ray diffraction (XRD) had tetragonal, cubic, tetragonal and monoclinic crystal structures, respectively. Reflectivity (R; in %), optical transmission (T; in %), optical bandgap (Eg), absorption, dielectric constant (epsilon), extinction coefficient (k) and refractive index (nr) of polycrystalline PbTe thin film obtained using UV-Vis spectrophotometer were 29.87%, 19.41%, 3.30eV, 0.6, 3.72, 0.05 and 4.08, respectively. Grain sizes of polycrystalline PbTe thin film varied between 8.79nm and 52.55nm. Optical and electrical conductivities of the crystals according to photon energy were calculated using optical parameters, whereas their surface morphology was characterized by scanning electron microscopy (SEM). The thickness of polycrystalline PbTe thin film was measured by atomic force microscopy (AFM), and found to be 900nm.
A new process to synthesize CrSe thin films with nanosize by CBD method
(Iop Publishing Ltd, 2019) Tezel, Fatma Meydaneri; Kariper, I. Afsin
In this study, CrSe thin films were produced by using a new variation of chemical bath deposition (CBD) on glass substrates at different pH values, namely pH: 8, 9, 10 and 11. Some optical properties of these films including T% (transmittance), R% (reflectance), n (refractive index), k (extinction coefficient) and epsilon(1) and epsilon(2) (real and imaginary parts of dielectric constants) for pH: 8, 9, 10 and 11 were found as (82.89, 80.00, 78.54, 79.05%), (3.76, 5.32, 4.08, 5.44), (1.48, 1.59, 1.48, 1.60), (0.055, 0.079, 0.127, 0.116) and (1.33, 1.47, 1.21,1.52) and (0.87, 0.33, 0.12, 0.14) at 550 nm wavelength. Surface morphologies of thin films were examined by SEM. Film thicknesses were measured to be 34, 44, 50 and 104 nm by AFM, and the optical band gap (E-gap) were calculated as 3.14; 3.72; 3.71 and 3.74 eV for pH: 8, 9, 10 and 11, respectively. Optical conductivity variation of CrSe thin films were calculated as a function of frequency for pH: 8, 9, 10 and 11, respectively. The usage areas of these films in optoelectronic applications were discussed.
Optical properties of selenium sulfide thin film produced via chemical dropping method
(Springer, 2018) Kariper, I. Afsin; Ozden, Sadan; Tezel, Fatma Meydaneri
This paper describes the production of selenium sulfide (SeS2) crystalline thin film on commercial glass substrates, via chemical bath deposition. Transmittance, absorption, dielectric constant and refractive index of the produced films were investigated by UV/VIS Spectrum. It was found that changes occurred on the characteristics of the films and they were determined as a function of selenium sulfide concentration, which varied between 2x10(-3) and 5x10(-3)M. The structure of the film was analyzed using FTIR spectrum. The calculated refractive index values fell between 1.5 and 1.6, whereas the transmission ratio of the films was around 80-90%. Moreover, a peak in the reflectance was observed at 320-330nm for all investigated samples. The highest dielectric constant for the films was obtained at the deposition concentration of 0.005M. This study is believed to be useful for thin film production.
Optical, electrical, structural and magnetic properties of BiSe thin films produced by CBD on different substrates for optoelectronics applications
(Iop Publishing Ltd, 2019) Aydin, Fatih; Tezel, Fatma Meydaneri; Kariper, I. Afsin
BiSe thin films have been grown on substrates as PMMA, ITO, glass and Si wafer by using chemical bath deposition (CBD) method. Deposition temperature and time and pH are kept to be constant during the production of the thin films. The thickness of BiSe thin films, which are produced on ITO, glass, PMMA and Si wafer substrate are 513, 468, 1039 and 260 nm, respectively. According to GAXRD results, the films, which are grown on glass and PMMA substrate, have amorphous structure, but, the films, which are grown on ITO and Si wafer substrate, have peaks of Bi2Se3 crystal. Grain sizes, crystallization number per unit area and dislocation density for ITO and Si wafer substrate are calculated as 112.40 nm and 43.04 nm; 2.25 x 10(-5) and 7.91 x 10(-5) (1/nm(2)); 40.11 x 10(-5) (1/nm(2)) and 53.96 x 10(-5) (1/nm(2)), respectively. The contact angles and critical surface tension of distilled water, ethylene glycol, formamide and diiodamethane liquids for thin films grown on glass, ITO, PMMA and Si wafers were obtained by the Zisman method. The % transmittance and % reflectance values of thin films grown on glass, ITO, PMMA are calculated as % T: 79.90, 92.76 and 67.37; % R: 6.18, 2.07 and 10.59, respectively. Eg values of thin films grown on glass, ITO, PMMA are calculated as Eg = 1.92; 2.18; 1.60 eV. The extinction coefficients, refractive indexes and relative dielectric constants of thin films grown on glass, ITO, PMMA are calculated as k = 0.007; 0.002 and 0.012; n = 1.65; 1.34 and 1.96; epsilon(1) = 0.271; 0.083 and 0.528 respectively. Sheet resistance, hall mobility, sheet carrier densities, bulk carrier densities and conductivity types for glass, ITO, PMMA and Si are 6.52 x 10(7), 6.65 x 10(1), 1.09 x 10(8) and 6.45 x 10(2) (Omega/cm(2)); 2.38, 1.21 x 10(-1), 5.34 and 1.52 (cm(2)/V.s); 4.01 x 10(10), 7.71 x 10(17), 1.06 x 10(10) and 6.34 x 10(15) (cm(-2)); 4.58 x 10(14), 1.50 x 10(22), 1.02 x 10(14) and 2.89 x 10(20) (cm(-3)); p, n, p and p, respectively. In addition, I-V characteristics and changes of magnetoresistance values versus magnetic field of the thin films are obtained by Van der Pauw method and HEMS.
PVP ve tuz miktarına bağlı ag-nanotel sentezi ve karakterizasyonu
(Karabük Üniversitesi, 2015) Tezel, Fatma Meydaneri; Eltuğral, Nurettin
En az iki boyutu yaklaşık 1-100 nm aralığında olan nanoteller, boyut sınırlarıyla termal, manyetik, elektriksel, optik özelliklerinden dolayı en çok ilgi duyulan malzemelerdir. Nanotellerin bu kendine has özellikleri temel olarak boyutları ve bileşimleri vasıtasıyla karakterize edilebilir. Boyuta bağlı özelliklerinin çalışmaları için boyut kontrollü nanotel sentezi oldukça önemli bir araştırma konusu olmuştur. Bütün bu nanotellerin arasında, gümüş nanotellerin sentezi, birçok alanda önemli bir malzeme olan bulk gümüşün yüksek elektrik ve ısıl iletkenliği nedeniyle aktif bir araştırma alanı olmaya devam etmektedir. Ayrıca gümüş nanoteller üretimi oldukça zor olan altın nanotüpler gibi diğer nanoyapıları üretmek için de kullanılmaktadır. Organik güneş pilleri, elektronik görüntüler (displays), OLED' ler, sensörler, fotonikler gibi optoelektronik cihazların esnek ve ekonomik olmalarından dolayı sanayi ve endüstriye aktarılabilmesi oldukça önemlidir. Şu ana kadar ki çalışmalarda indium tin oxide (ITO) ve fluorine tin oxide (FTO) tipi malzemeler kullanılmıştır, ancak esnek (flexible) veya yumuşak (soft) özellikli kullanımlarda/aygıtlarda bu malzemeler hem pahalı hem de kırılgandır. Son 10 yıl içerisinde birçok araştırma grubu tarafından metal nanoteller termal, manyetik, optik ve elektriksel özelliklerinden dolayı Ag nanotellerin sentezi için etkin prosesler geliştirilmeye çalışılmıştır. Bununla birlikte bu çalışmaların arasında en sıklıkla Ag nanotellerin polyol metodu ile sentezi aşamasında en etkin parametrenin bulunması üzerine gerçekleştirilmiştir ve istenilen tek tip (en-boy) Ag nanotel üretilememiştir. Bu tez çalışmasında, çözelti bazlı polyol metodu ile Ag-nanotel / nanoparçacık sentezlenmiş, kullanılan tuzların iyonsal değişimi ve çeşidine bağlı olarak oluşan yapıların morfolojisi ile kapsamlı bir parametrik çalışma elde edilmiştir. Oluşan ürünün yapısını etkileyen parametreler; sıcaklık, NaCl miktarı, tuz çeşitleri ve miktarları, manyetik karıştırıcının hızı, AgNO3:PVP molar oranı, silikon yağ banyosu olarak belirlenmiştir. Sonuç olarak bütün deneysel parametrelerin sabit olup, kullanılan tuz çeşidi ve miktarlarının değişimi ile Ag nanotel ve Ag nanopartikül elde edilişi gözlenmiştir. Ayrıca bu yöntemlere göre oluşan Ag nanotellerin en ve boylarının, Ag nanopartiküllerin de boyutlarının ve morfolojilerinin değiştiği gözlenmiştir.
STRUCTURAL AND OPTICAL PROPERTIES OF UNDOPED AND SILVER, LITHIUM AND COBALT-DOPED ZnO THIN FILMS
(World Scientific Publ Co Pte Ltd, 2020) Tezel, Fatma Meydaneri; Kariper, I. Afsin
Undoped and silver, lithium and cobalt-doped ZnO thin films have been successfully deposited on glass by chemical bath deposition (CBD). The reaction temperature was 50 degrees C and the films were annealed at 400 degrees C for 4h in a high temperature furnace. UV/VIS spectrum was used to determine optical transmittance, optical band gap (E-g) and absorbance values of Ag:ZnO, Co:ZnO, Li:ZnO and undoped ZnO thin films. Optical band gap (E-g) and absorbance values of undoped ZnO, Ag: ZnO, Co:ZnO and Li:ZnO thin films were found as 0.0158, 0.0064, 0.2638, 0.0956 and 3.24, 3.13, 3.27, 2.96 eV, respectively. Extinction coefficients and refraction indexes of the films were found to be 0.0096, 0.0038, 0.0068, 0.019 (extinction coefficient) and 1.26, 1.14, 1.66, 2.33 (refraction index), respectively. X-ray patterns of undoped ZnO, Ag:ZnO, Co:ZnO and Li:ZnO thin films were confirmed as amorphous.
Structural and thermo-electrical properties of Sn-Al alloys
(Springer, 2016) Tezel, Fatma Meydaneri; Saatci, Buket; Ari, Mehmet; Acer, Semra Durmus; Altuner, Emine
Thermal conductivities of pure Sn, pure Al and Sn-x wt% Al [x = 0.5, 2.2, 25, 50, 75] binary alloys were measured by radial heat flow method and were found to be 60.60, 208.80, 69.70, 80.30, 112.30, 142.00, 188.50 W/Km, respectively. The values of electrical resistivity were measured by four-point probe method and were found to be 2.90 x 10(-8)-3.90 x 10(-7) Omega cm. The crystal structures, unit cell parameters and orientations of crystallization of the same samples were determined by X-ray diffraction. Smooth surfaces with a clear grain boundary for the samples were shown on the scanning electron microscopy micrographs. The temperature coefficients of electrical and thermal conductivity were also determined.
Structural, surface, optical, and antimicrobial characterization of I2/Polymethyl methacrylate and CuS/I2/polymethyl methacrylate thin films
(Elsevier, 2022) Tezel, Fatma Meydaneri; Kariper, Ishak Afsin; Kaan, Dilek; Bahar, Dilek
In this study, I2/PMMA and CuS/I2/PMMA thin films were produced by Chemical Bath Deposition (CBD) on polymethyl methacrylate (PMMA) substrates, and their physicochemical and antimicrobial properties were analyzed. The film's surface tensions were characterized by KSV instruments, and the surface tensions for plain PMMA, I2/PMMA, and CuS/I2/PMMA thin films were 30.27, 28.77, and 31.86 mN/m, respectively. The I2 and CuS/I2 structures in the XRD patterns are amorphous. After coating CuS, the long rod-like extension structures are formed; spherical shapes form some agglomeration in some regions to SEM images. Chemical analysis was performed with an EDX spectrometer attached to SEM. The thicknesses and surface roughnesses of I2/PMMA and CuS/I2/PMMA thin films were determined to be 50.34 nm, 1126 nm; 62.03 nm and 204.99 nm via AFM, respectively. The optical spectra of the films were recorded in the range of 300-1100 nm with a UV-VIS spec-trophotometer. The antibacterial and antifungal properties of I2 and CuS coating were evaluated against facul-tative gram-negative E. Coli and C. Albicans. The coated films exhibited excellent antimicrobial performance.
Surface and electro-optical properties of amorphous Sb2S3 thin films
(Springer Heidelberg, 2019) Tezel, Necmi Serkan; Tezel, Fatma Meydaneri; Kariper, I. Afsin
Sb2S3 thin films to be used in optoelectronic applications were produced on glass substrates, via chemical bath deposition method (CBD) at different pH values. The optical properties of these films such as T%, R%, n, k, epsilon(1) and epsilon(2) (real and imaginary) were calculated using the absorbance values measured at room temperature with UV spectrophotometer. Critical surface tension was measured by Zisman method, and found as 43.2, 97.4, 150.7 and 123.8 mN/m for pH: 9, 10, 11 and 12. Film thicknesses and surface roughness (R-q) were measured to be 125; 412; 205 and 138nm, and 1.64; 30.31; 49.49 and 19.76nm for pH: 9, 10, 11 and 12, respectively. Optical band gap (E-gap) was calculated as 2.24; 2.11; 2.25 and 2.32eV for pH: 9, 10, 11 and 12, respectively. Average electrical resistivity of the Sb2S3 thin films was calculated to be 35.41; 36.81; 36.76 and 28.72 cm for pH: 9, 10, 11 and 12, respectively. According to the results obtained, usage areas of these films in optoelectronic applications are discussed.
Synthesis of MgO thin films: How heat treatment affects their structural, electro-optical, and surface properties
(Elsevier, 2022) Tezel, Fatma Meydaneri; Veli, Ugur; Kariper, I. . Afsin
In this study, MgO thin films were grown using Chemical Bath Deposition (CBD) and annealed at various tem-peratures (300, 350, 400, and 450 degrees C). Their structural properties were obtained by X-ray diffraction (XRD), and amorphous MgO structures were observed in the XRD pattern. EDX composition analysis showed that the amount of Mg increased with temperature, and so did oxidation. Surface morphologies and surface roughness were analyzed by FESEM and AFM. The amorphous structures were in the form of a sugar cube at 300 degrees C and turned into a homogeneous nanorod-like structure as the temperature increased to 400-450 degrees C. Current-voltage (I-V) measurements were taken with a Keithley 2400 sourcemeter, and electrical resistivity was calculated using film thickness. The increase in surface roughness created a resistance effect in transmission, reducing the charge storage capacity. The transmittance (T), reflectance (R), refractive index (n), and damping coefficient (k) were determined via a UV-vis spectrophotometer. Eg values of MgO thin films tempered at 300, 350, 400, and 450 degrees C were 3.85, 3.98, 3.87, and 4.08 eV, respectively.
Synthesis, surface tension, optical and dielectric properties of bismuth oxide thin film
(De Gruyter Open Ltd, 2017) Tezel, Fatma Meydaneri; Kariper, I. Afsin
Bismuth oxide thin film was deposited by chemical bath deposition (CBD) technique onto a glass substrate. The grain size (D), dislocation density (delta) and number of crystallites per unit area (N), i.e. structural properties of the thin film were determined as 16 nm, 39.06 x 10(-4) line/nm(2), 31.25 x 10(-3) 1/nm(2), respectively. Optical transmittance properties of the thin film were investigated by using a UV-Vis spectrophotometer. The optical band gap (E-g) for direct transitions, optical transmission (T %), reflectivity (R %), absorption, refractive index (n(r)), extinction coefficient (k), dielectric constant (is an element of) of the thin film were found to be 3.77 eV, 25.23 %, 32.25 %, 0.59, 3.62, 0.04 and 2.80, respectively. The thickness of the film was measured by AFM, and was found to be 128 nm. Contact angles of various liquids on the oxide thin film were determined by Zisman method, and surface tension was calculated to be 31.95 mN/m.

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