Anodized Nanoporous Titania Thin Films for Dental Application: Structure’ Effect on Corrosion Behavior

Nanostructured Titania layers formed on the surface of titanium and titanium alloys by anodic oxidation play an important role in the enhancement of their biocompatibility and osseointegration in the human body. For this purpose, we aimed to study in the current work the structural and electrochemical properties of amorphous and crystallized nanostructured TiO2 thin films elaborated on Ti6Al4V substrate by electrochemical anodization in fluoride ions (F–) containing electrolyte at 10 V during 15 min and heat treated in air at 550 °C for 2 h. The morphology, chemical composition and phase composition of synthesized layers were investigated using field emission scanning electron microscopy (FE-SEM) and X-ray diffraction (XRD). The corrosion resistance improvement of both as-anodized and annealed titania layers was evaluated in 0.9 wt. % NaCl solution with pH = 6.4 at room temperature by means of open circuit potential (Eoc),potentiodynamic polarization (PDYN) and electrochemical impedance spectroscopy (EIS)

Effect of Annealing on the Properties of Nanocrystalline CdS Thin Films Prepared by CBD Method

The CdS thin films were deposited on glass substrate by chemical bath deposition (CBD). The effect of annealing temperature on the morphological, structural, optical and electrical properties of the crystalline CdS films were investigated for different annealing temperature (as deposited, 300, 400 and 500 °C).The annealing time is 1 h. The materials have been prepared using simple aqueous solutions containing cadmium sulfate, as source of cadmium, and thiourea as source of sulfur and ammonium hydroxide as the complexing agent. The temperature of the bath was maintained at low temperature of 80 °C. The surface morphological properties studied by SEM and AFM respectively. The structural properties of CdS thin film was studied by X-ray diffraction. The optical parameter such as transmittance and energy band gap of the films with thermal annealing temperature was investigated by UV-Visible spectrophotometer. The variation of band gap values of CdS thin film samples were found to be in the range of 2.37 to 2.5 eV. Electrical resistivity measurements were carried out in four-probe Van Der Pauw geometry at room temperature by the Hall measurement. SEM image confirmed that film of smooth surface morphology

Properties Study of ZnS Thin Films Prepared by Spray Pyrolysis Method

Zinc sulfide (ZnS) is important II-VI semiconductors material for the development of various modern technologies and photovoltaic applications. ZnS thin film was prepared by using chemical spray pyrolysis technique. The starting solution is a mixture of 0.1 M zinc chloride as source of Zn and 0.05 M thiourea as source of S. The glass substrate temperature was varied in the range of 300 °C-400 °C to investigate the influence of substrate temperature on the structure, chemical composition, morphological and optical properties of ZnS films. The DRX analyses indicated that ZnS films have polycrystalline cubic structure with (111) preferential orientation and grain size varied from 25 to 60 nm, increasing with substrate temperature. The optical properties of these films have been studied in the wavelength range 300-2500 nm using UV-VIS spectro-photometer. The ZnS films has a band gap of 3.89 eV-3.96 eV

Properties Study of ZnS Thin Films Prepared by Spray Pyrolysis Method

Zinc sulfide (ZnS) is important II-VI semiconductors material for the development of various modern technologies and photovoltaic applications. ZnS thin film was prepared by using chemical spray pyrolysis technique. The starting solution is a mixture of 0.1 M zinc chloride as source of Zn and 0.05 M thiourea as source of S. The glass substrate temperature was varied in the range of 300 °C-400 °C to investigate the influence of substrate temperature on the structure, chemical composition, morphological and optical properties of ZnS films. The DRX analyses indicated that ZnS films have polycrystalline cubic structure with (111) preferential orientation and grain size varied from 25 to 60 nm, increasing with substrate temperature. The optical properties of these films have been studied in the wavelength range 300-2500 nm using UV-VIS spectro-photometer. The ZnS films has a band gap of 3.89 eV-3.96 eV

Properties of Undoped and (Al, In) Doped ZnO Thin Films Prepared by Ultrasonic Spray Pyrolysis for Solar Cell Applications

Zinc oxide (ZnO) is an n-type semiconductor with a large optical gap (3.4 eV) belonging to the transparent conductive oxides family (TCO). Strongly present as optical window in the chalcopyrite based structures CIGS and CIS. The structural, morphological, optical and electrical properties of ZnO thin films deposited onto glass substrates by ultrasonic spray pyrolysis (USP) technique have been investigated. For comparison and a better understanding of physical properties of undoped and (Al, In) doped ZnO thin films, a number of techniques, including XRD, SEM, optical absorption method (UV) and four-point probe technique were used to characterize the obtained ZnO thin films. Structural analysis shows that all the films were found to be polycrystalline with a wurtzite structure and show a (1 0 1) preferential growth. Besides, we noted that the preferred orientation does not depend on the nature of dopant. The band gaps (Eg) varied from 3.35 to 3.37 eV by Al and In dopants

Influence of Growth Temperature on Structure and Optical Properties of Tin Oxide Films by Spray Pyrolysis Method

Tin oxide films (SnO2) are prepared by the spray pyrolysis technique at different temperatures. The XRD measurement confirm that the thin films grown by this technique have good crystalline tetragonal rutile structures. The observations by scanning electron microscopy indicate that polycrystalline SnO2 film surfaces were formed by pyramidal grains (200 nm 300 nm), The composition on the films was obtained by Auger electron spectroscopy (AES), which is identical to the analysis EDS. Characterization by UV-visible spectrophotometry of thin films showed that the films have an optical transmission above 80 % in the visible and the values of Eg were in the range 3.98-4.02 eV

Покращення електричних властивостей елементів Гретцеля шляхом заміщення шару барвника переходом CdS/ZnO

Сонячні елементи на основі органічного барвника широко використовуються через простоту їх виготовлення. Проста структура складається з кольорового шару TiO2, електроліту та антиелектроду. У дослідженні шари TiO2, CdS та ZnO наносились на електропровідне скло різними методами для заміни органічного барвника. Для підготовки шару TiO2 використовували метод метал-органічного хімічного осадження з газової фази (MOCVD), хімічне осадження у ванні (CBD) для підготовки шару CdS та спрей-піроліз (SP) для приготування шару ZnO. Морфологічні та структурні дослідження показали однорідну морфологію суперпозиції шарів TiO2/CdS/ZnO. XRD та SEM аналіз показав, що відпал шару CdS повинен проводитися в контрольованій атмосфері, щоб уникнути утворення оксиду кадмію та регулювати розмір частинок. Метою роботи є заміщення органічного барвника в елементі Гретцеля переходом CdS(n)/ZnO(n+). Морфологічні та оптичні властивості TiO2/CdS/ZnO на додаток до фотоелектричних характеристик цього структурного переходу були досліджені з різним часом осадження шару CdS. Встановлено, що природа підкладки не впливає на реалізацію переходу. Помічено, що кожен доданий шар призводить до зменшення коефіцієнту пропускання підкладки. Характеристика фотоелектричних властивостей елементів на основі переходу CdS/ZnO показує більш високий вихід в порівнянні зі звичайними елементами на основі органічного барвника. Також рекомендовано проводити відпал в контрольованій атмосфері, такій як азот, щоб усунути вторинну фазу CdO і зменшити розмір зерен, що може підвищити ефективність сонячних елементів.Solar cells based on organic dye have been widely used for the reason of their simplicity of manufacture. A simple structure is composed of a colored layer of TiO2, an electrolyte and a counter electrode. In this study, the layers of TiO2, CdS and ZnO were deposited on conductive glass by different methods to replace organic dye. Metal organic chemical vapor deposition (MOCVD) method was used to prepare the TiO2 layer, chemical bath deposition (CBD) to prepare the CdS layer, and spray pyrolysis (SP) for the preparation of the ZnO layer. Morphological and structural studies have shown a homogeneous morphology of the superposition of TiO2/CdS/ZnO layers. XRD and SEM characterizations have shown that annealing of the CdS layer must be done under a controlled atmosphere in order to avoid the formation of cadmium oxide and to control the particle size. The aim of this work is the substitution of organic dye in the Grätzel cell by CdS(n)/ZnO(n+) junction. Morphological and optical properties of TiO2/CdS/ZnO in addition to photovoltaic performance of this structure junction were investigated with different deposition times of the CdS layer. It is found that the nature of the substrate has no influence on the realization of the junction. It is noticed that each layer added leads to a decrease in the transmittance of the substrate. Characterization of the photovoltaic properties of cells based on the CdS/ZnO junction shows a higher yield compared to conventional cells based on organic dye. It is also recommended to undertake annealing under a controlled atmosphere such as nitrogen in order to eliminate the CdO secondary phase and decrease the size of the grains which may enhance the efficiency of the solar cells

Розробка оптимізованого поглинаючого шару Cu2ZnSnS4, створеного SILAR методом

У цьому дослідженні тонкі плівки Cu2ZnSnS4 (CZTS) були синтезовані на скляних підкладках за допомогою саморобного методу адсорбції та реакції послідовного іонного шару (SILAR). Хлорид міді (II) (CuCl2), хлорид цинку (II) (ZnCl2), хлорид олова (II) (SnCl2) використовували як катіонні прекурсори, а тіосечовину (CS(NH2)2) – як аніонні. Деіонізована (DI) вода була взята як розчинник для обох прекурсорів. До обох розчинів додавали кілька крапель аміаку, щоб забезпечити адсорбцію на скляній підкладці. Нанесені плівки були відпалені при 200 °C протягом 1 години в атмосфері повітря та досліджені методом рентгенівської дифракції (XRD), скануючої електронної мікроскопії (FESEM), атомно-силової мікроскопії (AFM), спектрофотометрії та діелектричної спектроскопії. Установлено утворення фази кестериту з переважною орієнтацією вздовж площини (112). Морфологічні спостереження за SEM та AFM показали рівномірний і однорідний тонкий шар CZTS. Оптичні властивості, отримані за допомогою аналізу УФ-видимого діапазону, показали, що CZTS має пряму заборонену зону 1,5 еВ у видимому діапазоні, що є близьким до типових значень ідеального поглинаючого шару. Вимірювання діелектричного опору показало, що тонка плівка CZTS представляє адсорбцію на нижніх частотах радіочастотного домену, яка зумовлена атомними коливаннями в кристалічній решітці. Отриманий CZTS має потенціал, щоб служити надійною, економічною та екологічно чистою альтернативою нестабільним, дорогим і токсичним шарам поглинача для фотоелектричних застосувань.In this study, Cu2ZnSnS4 (CZTS) thin films were synthesized on glass substrates by using homemade successive ionic layer adsorption and reaction (SILAR) method. Copper (II) Chloride (CuCl2), Zinc (II) Chloride (ZnCl2), Tin (II) Chloride (SnCl2) were used as a cationic precursors and Thiourea (CS(NH2)2) was used as precursor for anions. De-ionized (DI) water was taken as the solvent for both precursors. Few drops of ammonia were added to both solutions in order to ensure the adsorption on the glass substrate. The deposited films were annealed at 200 °C for 1 h in air atmosphere and characterized by X-rays diffraction (XRD), field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), ultraviolet-visible (UV-Vis) spectrophotometry and dielectric spectroscopy. The structural characterization using XRD revealed the formation of the kesterite phase with preferential orientation along (112) plane. Morphological observations from SEM and AFM exhibited uniform and homogenous CZTS thin layer. Optical properties derived from UV-Vis analysis showed that CZTS has a direct band gap of 1.5 eV in the visible range which is close to typical values of an ideal absorber layer. Dielectric impedance measurements showed that CZTS thin film presents an adsorption in the lower frequencies of RF domain which is due to the atomic vibrations in the crystal lattice. The obtained CZTS has the potential to serve as a reliable, economical, and environment-friendly alternative to unstable, expensive and toxic absorber layers for photovoltaic applications