CdO Phase Research Articles

The role of substrate materials on stabilization of CdO, 2CdO·CdSO4 and 2CdS·2CdO·CdSO4 from CdS powder film annealed in air

The relative stability of CdS and CdO with respect of substrates has been widely studied up to 500 °C, the upper temperature in many applications. The physical-chemical properties of the deposited films are often revealed to be influenced by deposition substrates. In this paper, using XRD, SEM and EDX methods, we have studied the oxidation/desulphurization of CdS to CdO and the intermediate stabilized materials therein (i.e. 2CdO·CdSO4 and 2CdS·2CdO·CdSO4), by using CdS films deposited on different substrates (i.e. nickel, Si-polycrystalline, glaze porcelain and α-Al2O3) which were annealed in air up to 800 °C. At the annealing temperatures used in this study, different phases were found to be stabilized on different substrates. The relative stability of CdO and 2CdO·CdSO4 phases is greater on α-Al2O3 than on glazed porcelain substrate. A mixed phase of CdO and 2CdO·CdSO4 was obtained at the annealing temperature of 800 °C if films are deposited on Ni and polycrystalline silica. The amount of the oxidized CdS (i.e. CdO and 2CdO·CdSO4) obtained by mixing CdS and Al2O3 powders at different Al2O3/CdS ratios and annealed up to 800 °C, were also investigated. Decreasing the Al2O3/CdS ratio, the interactions between Al2O3 and CdS particles are reduced, consequently the CdO stabilization is strongly retarded in favour of 2CdO·CdSO4, while reverse results was proven for high values of Al2O3/CdS ratio. The results show the role of the interface area between Al2O3 and Cd-materials for stabilization of CdO. A low interface area was also obtained by filling an α-Al2O3 crucible with CdS powder. After annealing, the CdO stabilization was strongly reduced, in line with the low Al2O3/CdS ratio sample. Spreading the CdS powder on the α-Al2O3 substrate, instead of drop coating deposition method, showed a remarkable CdO stabilization in line with the results obtained with drop coating method. To account for the role of the interface area a model is proposed (Stabilization model), based on surface energy, as responsible to phase stabilization to explain the nucleation – stabilization of the CdO and 2CdS·2CdO·CdSO4. The morphologies of the CdO and 2CdS·2CdO·CdSO4 resemble hexagonal-prism shapes and compact chips, respectively, while 2CdO·CdSO4 phases has a sponge-like appearance.

Synthesis, characterization, DNA binding/cleavage, and anticancer and antimicrobial activities: Nano‐sized Co(II) and Cd(II) complexes and their use as a precursor for CoO and CdO nanoparticles

In the search of effective bioactive compounds, Co(II) (C1) and Cd(II) (C2) complexes of the type [M(FMAPIMP)(H2O)Cl].nH2O (where M = Co(II); n = 2, Cd(II); n = 3, and FMAPIMP = ligand[2‐((E)‐((2‐(((E)‐furan‐2‐ylmethylene)amino)phenyl)imino)methyl)phenol]) were synthesized and characterized using elemental analysis, UV–Vis., cyclic voltammetry, Fourier‐transform infrared (FT‐IR), nuclear magnetic resonance, and mass spectral studies. The thermal stability of nano‐sized Co(II) and Cd(II) complexes was studied using thermogravimetric analysis (TGA). Cobalt and cadmium oxides were synthesized using cobalt and cadmium nanoparticle (NP) structure Schiff base complexes as the raw material after calcination for 5 h at 600 °C. According to the results, Co(II) and Cd(II) complexes with mole ratio 1:1 of metal: H‐FMAPIMP which octahedral are the most probable geometry for it. On the contrary, synthesized C1 and C2 NPs were used as suitable precursors for the preparation of CoO and CdO NPs. The obtained NPs were characterized using FT‐IR, UV–Vis., TGA, powder X‐ray diffraction (PXRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and atomic force microscopy techniques. PXRD analysis revealed that the obtained oxides were crystalline and corresponded to CoO and CdO phases. Crystal size, shape, and morphology were determined using SEM and TEM. H‐FMAPIMP and its two complexes (C1 and C2) were tested against human ovarian cancer cell line (PA‐1). The synthesized Co(II) and Cd(II) complexes exhibited enhanced activity against the tested bacterial (Staphylococcus aureus and Escherichia Coli) and fungal strains (Candida albicans and Aspergillus fumigatus) as compared to H‐FMAPIMP. The results of the DNA‐cleavage activity indicated that the ligand and its two complexes can cleave calf thymus‐DNA at different degrees. Further, antituberculosis activity was performed using microplate alamarBlue assay. Among all these synthesized compounds, C1 exhibited good cleaving ability compared to the newly synthesized C2. Finally, the geometry of H‐FMAPIMP and its Co(II) and Cd(II) complexes was optimized using molecular modeling.

Synthesis of novel heterostructured ZnO-CdO-CuO nanocomposite: Characterization and enhanced sunlight driven photocatalytic activity

In this study, a novel photocatalytic material heterostructured ZnO-CdO-CuO nanocomposite along with pristine ZnO, CdO, and CuO nanoparticles were synthesized by the facile co-precipitation method. The grown nanocomposite was characterized by XRD, FTIR, Raman, SEM, IV, UV–vis and PL techniques. The XRD pattern exhibited the diffraction peaks of ZnO (hexagonal), CdO (cubic) and CuO (monoclinic) with ZnO, CdO, and CuO phases 65%, 16%, and 19%, respectively. The microstructural analysis was carried out using Scherrer plot, W-H and SSP methods. The FTIR and Raman spectra also inveterate the successful formation of ZnO-CdO-CuO. The IV measurements revealed the high electrical response of nanocomposite. The SEM images are shown agglomerated rod-shaped morphology and the elemental analysis also confirmed the higher atomic concentration of Zn. PL spectra shown strong NBE and DLE emissions related to extrinsic defects which could act as the trap centers for charge carriers and enhance photocatalytic activity. The energy bandgap (Eg) was 2.9 eV, specified that the grown nanocomposite could be an excellent photocatalyst. The photocatalytic activity was performed against methylene blue (MB) revealed higher degradation efficiency of 94% as compared to pristine ZnO (60.0%), CdO (41.0%), and CuO (61.0%). The photodegradation of other synthetic dyes i.e. rhodamine-B, methyl orange, and cresol red was also assessed by grown nanocomposite under sunlight, exhibits degradation efficiencies, 87%, 89% and 99% in 100 min illumination, respectively. Furthermore, the species trapping experiment along with the recyclability test was carried out against cresol red dye using the nanocomposite catalyst. A schematic model was also designed to illustrate the photodegradation reaction mechanism.

Structural and optical properties of Fe3+ doped ZnCdO nanostructures for luminescent application

In this investigation, we report the results of the prepared Fe3+ doped ZnCdO nanopowder by simple solution method. Several experimental techniques have been performed on the prepared samples to find out the structural, morphological and luminescence properties. X-ray diffraction has revealed that the prepared ZnCdO nanopowder possesses the hexagonal ZnO and cubic-period of CdO phase. SEM image has revealed that the tiny agglomeration of irregular particles have appeared in the prepared samples and also found that the crystallite size of the powder sample is 28 nm. FTIR peaks have revealed that the positions of the ZnO and CdO are at 836 and 860 cm−1. EPR and optical retention examination findings have been undertaken to know the site symmetry of Fe3+ ion. Photoluminescence studies have showed that the prepared material radiates yellowish green light with the CIE coordinates, x = 0.3301 and y = 0.4042. These results have revealed that the prepared nanopowder can find positional application in the preparation of optoelectronic and photoluminescence devices.

Effects of the r-GO doping on the structural, optical and electrical properties of CdO nanostructured films by ultrasonic spray pyrolysis

Undoped and reduced graphene oxide (r-GO)-doped CdO films were prepared via the ultrasonic spray pyrolysis method with weight ratios of 1, 3 and 5% onto substrates. The successfully prepared films were characterized to understand the influence of r-GO dopant content on the morphological, structural, electrical and optical properties of the films by several diagnostic techniques. XRD measurement confirms that all the films were polycrystalline in the cubic phase of CdO with the preferred orientation (111). The optical band gap of the films decreases with the increase in doping amount. The r-GO@CdO nanostructured films were used as an interfacial layer to fabricate the heterojunction device and to investigate their electrical properties using current–voltage and capacitance–voltage measurements in the dark. The rectification properties of the studied devices increase with the r-GO dopant amount. The obtained results indicate that the r-GO content in the CdO films is responsible for the modification of physical properties of electronic device.

Structural, optical and photocatalytic studies of trimetallic oxides nanostructures prepared via wet chemical approach

Multi metal based photocatalyst (CdO-MgO-Fe2O3) was synthesized via wet chemical approach i.e. co-precipitation method. The single transition metal oxides like CdO, MgO and Fe2O3 were also prepared for comparative studies. Structural elucidation of all prepared powder catalysts (CdO, MgO, Fe2O3 and CdO-MgO-Fe2O3) was conducted by X-ray diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR). XRD showed the presence of the MgO (cubic) – Fe2O3 (rhombohedral)– CdO (cubic) phase with an average crystallite size of MgO (9 nm), Fe2O3 (12 nm), CdO (23 nm). FTIR proved the existence of Mg–O, Fe2-O3 and Cd-O by distinctive vibrational bands at 772 cm−1, 581 cm−1 and 480 cm−1 respectively. UV–vis spectral studies showed that the bandgap for CdO-MgO-Fe2O3 nanocomposite was 1.76 eV which made it an efficient photocatalyst for use both in the UV and visible regions. Two probe I–V measurements confirmed the pure semiconducting behavior and possible formation of heterojunction in the CdO-MgO-Fe2O3 nanocomposite. The photocatalytic performance of the CdO-MgO-Fe2O3 nanocomposite with equal metal ion concentration of Mg, Fe and Cd at different pH values was explored by visible light illumination on methylene blue (MB) dye as a standard organic pollutant. The CdO-MgO-Fe2O3 nanocomposite with metal ion ratio 1:1:1 in an alkaline medium showed the maximum photocatalytic performance. The rate constant (kMB) value for the degradation of MB was ∼ 0.0820 min−1. The photocatalytic activity has been improved due to the effective decrease in the recombination rate of charge carriers. The possible mechanism for improvement of the photocatalytic performance using visible light illumination has also been suggested and discussed.

Effects of laser fluence on the Cd(OH)2/CdO nanostructures produced by pulsed laser ablation method

In this experimental study, Cd (OH)2/CdO nanostructures were produced by pulsed laser ablation method. The beam of a Q-switched Nd:YAG laser with wavelength of 1064 nm at different fluences was employed to irradiate the cadmium target in distilled water. The obtained products at different fluences of laser pulse were characterized by UV–Vis-NIR spectroscopy, X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. Results show that both morphology and chemical bonds of produced Cd nanostructures were changed by increasing the laser fluence. The absorption spectra shows that the Cd(OH)2 nanostructures could be transformed into CdO nanostructures with increasing the laser fluence. XRD analysis showed the presence of crystalline γ-Cd(OH)2, Cd(OH)2 and CdO phases, in the monoclinic, hexagonal and cubic structure, respectively. Results revealed that obtained nanostructures are particle in lowest fluence, while wire shaped nanostructures were formed with increasing the laser fluence. An increase of the laser fluence induced the synthesis of higher aspect ratio nanowires with a smaller tendency of adhesion.

Mechanochemical synthesis of zincite doped with cadmium in various amounts

Abstract This work investigates the limit of Cd doping in ZnO derived by means of mechanochemical synthesis using CdCl2, ZnCl2 and Na2CO3 as precursors and NaCl as diluent. The prepared samples were characterized using X-ray diffraction (XRD), Fourier transformed infrared attenuated total reflectance (FTIR ATR) spectroscopy, UV-Vis diffuse reflectance spectroscopy (DRS),N2 adsorption-desorption isotherms, scanning electron microscope (SEM) and energy-dispersive X-ray spectroscopy (EDS), while photocatalytic efficiency has been evaluated for methylene blue degradation process. Zn for Cd replacement limits in the crystal lattice of ZnO derived via mechanochemical synthesis were found to be only 2%. For Cd present in a larger portion, CdO and CdCO3 phases appear. Cd doping limits in ZnO were not affected by the milling interval. However, it was observed that Cd doping impairs the nanocrystallinity of ZnO. The morphology and the electronic structure of ZnO and thus photocatalytic activity was inappreciably affected by the Cd doping.

Electronic energy levels and electrochemical properties of co-electrodeposited CdSe thin films

CdSe semiconductor thin films were grown on indium tin oxide (ITO) coated glass substrates by co-electrochemical deposition method. Deposition potential was kept at − 0.95 V vs. Ag/AgCl reference electrode for ten minutes. Deposition electrolyte includes an aqueous solution of 10 mM CdCl2, 20 mM H2SeO3 as precursors, 200 mM LiCl as complexing agent, and HCl for adjusting of pH. Deposited CdSe thin film was annealed at 500 °C for 30 min in air medium. Precursor and annealed CdSe thin films were characterized using a number of techniques, including SEM, EDX, XRD, UV–vis spectroscopy, and electrochemical impedance spectroscopy. SEM studies show that annealing alters the surface of precursor CdSe film from smooth to granular appearance. According to EDX analyses, the ratio of Cd/Se is close to 1.07 and 1.04 for the precursor and annealed CdSe thin film, respectively. XRD analysis shows that each film has polycrystalline structure. Precursor film has only cubic structure of CdSe, while annealed film has hexagonal structure of CdSe and cubic crystal phase of CdO. Optical energy band gap of the as-deposited CdSe film increases from 1.64 to 1.71 eV after annealing due to the mixture of the two phases. Refractive index against wavelength changes between 2.0 and 3.3. Calculations performed by using the data of Mott-Schottky measurements show that precursor CdSe film has 1.72 × 1016 cm−3, while annealed film is of 3.65 × 1017 cm−3 carrier concentration. The prepared films exhibit n-type semiconductor character. The study reports energy level diagrams of the produced semiconductor CdSe thin films by using the Mott-Schottky and Tauc's approximations. The carrier transport properties in the interface between active CdSe thin film and electrolyte are discussed based on an equivalent electronic circuit simulated to the Nyquist data of the CdSe/electrolyte system.

Optimization of CdO nanoparticles by Zr4+ doping for better photocatalytic activity

Chemically controlled co-precipitation method has been adopted for the fabrication of pure and different wt% Zr doped CdO photocatalysts. Conventionally, the crystallite size and crystalline phase of CdO are in the midst of the parameters involved in the control of the photocatalytic activity. Aiming utterly at the size effect that modifies other attributes which are important to assess the photocatalytic activity of nanometric CdO, it was explored to synthesize CdO nanoparticles with controlled size, highly comparable morphology and analogous phase. The crystal structure and the crystallite size were estimated from the X-ray diffraction patterns and were confirmed through transmission electron microscope. The degree of crystallinity varied on Zr doping and the calculated crystallite sizes were in the range of 16–81 nm. The dopant ion Zr4+ have been detected through X-ray photoelectron spectroscopy (XPS) analysis signifying the dopant to substitute for cadmium (Cd2+) in the lattice of CdO. Particle size dependent optical band gaps calculated in the range 2.02–2.57 eV informed the viability of the materials to initiate photocatalytic reaction in the visible light region. Lesser recombination rate of the generated electrons and holes under light irradiation produced low intense photoluminescence peaks that displayed the appropriateness as photocatalysts. Zr4+ doping resulted in the enhancement of photocatalytic activity, evaluated by monitoring the degradation of methylene blue solution. 0.5 wt% Zr doped CdO nanoarticles calcined at 400 °C exhibited the highest photocatalytic activity with better percentage of color abatement (80.95%). The pseudo-first-order reaction rate became faster on Zr doping such that the rate constant is ~ 0.4–0.5 h−1 for Zr doped CdO while that for pure CdO is ~ 0.3 h−1.

Synthesis and Characterization of CdO–SnO2 Nanocomposites Prepared by Hydrothermal Method

In this work, (1−x)CdO–xSnO2 nanocomposites (≤ 0.15) have been synthesized via hydrothermal route. The structural study reveals that CdO nanostructures possess crystalline phase and cubic structure. The CdO–SnO2 nanocomposites possess both cubic and orthorhombic structure with good crystallinity. The crystallite size in the nanocomposites was found to be in the range of 9.6–19.6 nm. Field emission scanning electronic microscopy and high-resolution tunnelling microscopy analysis confirm the presence of both cubic and orthorhombic structures which is also confirmed from X-ray diffraction studies. Fourier transform infrared spectroscopy (FTIR) studies confirm that CdO–SnO2 nanocomposites possess the characteristics band of both CdO and SnO2 nanostructures. The UV–visible absorption studies confirm that the optical absorption band in CdO–SnO2 nanocomposites possesses both blue and red shift as compared to that of CdO nanostructures. Photoluminescence spectroscopy studies reveal the appearance of strong emission peak at 513, 469 and 369 nm corresponding to green, blue and violet emission spectrum, respectively, in CdO–SnO2 nanocomposites. The FTIR studies confirm the presence of hydroxyl and water functional group due to atmospheric water vapours and chemical bonding in CdO and CdO–SnO2 nanocomposites. Raman spectroscopy confirms the presence of Raman bands of both CdO and SnO2 phases in the CdO–SnO2 nanocomposites.

A comparison investigation of optical, structural and luminescence properties of CdOxTe1−x and CdTexSe1−x nanoparticles prepared by a simple one pot method

We present L-cysteine capped CdOXTe1−X and CdTeXSe1−X nanoparticles (NPs) prepared in one pot. The as-prepared CdOXTe1−X NPs were found to have a hexagonal crystal structure of CdTe with a cubic phase of CdO. There was, however, change in phase to cubic type when 2mM of Se was introduced into the CdTe at 60min of reaction time. The average crystallite sizes obtained from X-ray diffraction analysis for CdOXTe1−X and CdTeXSe1−X NPs were in the range of 10–36nm. The diffraction peaks shifted to higher diffraction angle with longer growth time. Scanning electron microscope images display change in shape and size as reaction progress. Photoluminescence (PL) emission was observed to shift from 510–566nm and 620–653nm for CdOXTe1−X and CdTeXSe1−X NPs respectively followed by variation in the peak intensities. The emission spectra displayed a good symmetry and a narrow full width at half maximum ranging from 41 to 100nm in both cases. The absorbance analysis of the as-prepared NPs displayed well-resolved absorption bands. The optical band gaps of the as-prepared NPs were found to decrease with increase in reaction time. Reaction parameters such as pH, reaction time, reaction temperature and the molar concentration could have major effects on the optical properties of the as-prepared nanoparticles hence their need to control them.

Mechanical and tribological behavior of sol–gel TiO2–CdO films measured at the microscale levels

In this work, we present a mechanical and tribological study at the microscale of sol–gel TiO2–CdO films, which are used in photocatalytic applications. The films were deposited as a good-quality polycrystalline material with majority of CdO or CdTiO3 phases depending on their Ti/Cd concentration ratios. Films with the majority of CdTiO3 phase presented the highest hardness and lowest plastic deformation during the indentation tests. The evolution of wear, friction coefficient, and roughness on the films was quantitatively studied by multiple-passes measurements on a depth-sensing instrumented indentation system. These measurements allowed us to observe the films’ wear mechanisms and correlate them with their microstructure and mechanical properties. To compare the crystal structure, mechanical properties and tribological behavior of these films, we also analyzed sol–gel CdO and TiO2 films deposited under similar conditions.

High-density amorphous phase of CdO

An amorphous CdO model is densified up to a theoretical pressure of 200GPa. A continues phase transformation from a low-density amorphous (LDA) phase to a high-density amorphous (HDA) phase is observed through the simulation. Associated with the phase transformation, the average coordination raises progressively from ~5.5 to ~7.0. The sevenfold coordination is the most abundant motifs in the HDA state. Therefore its short-range order differs principally from that of the known CdO crystals. Upon pressure release, an amorphous state being intermediate between the LDA structure and the HDA phase is recovered with a mean coordination number of 5.9.

Effect of the Support Nanostructure (Nanofibers and Nanotubes) on the Photoelectrochemical Performance of TiO2-CdO@CdS Semiconducting Architectures

Nanofibers and nanotubes of TiO2 were decorated with CdO@CdS type core@shell particles, via a facile route consisting of cadmium electrodeposition on previously formed TiO2 nanostructures, its thermal oxidation to obtain CdO and later surface sulfidation by ion-exchange in Na2S aqueous solution. The diffraction patterns (XRD) of the resulting hetero-nanostructures confirm the formation of the cubic CdO and CdS phases, whereas their Photoelectron spectra (XPS) indicate the sole presence of CdS on the surface. Interestingly, tested as photoanodes in a home-made photoelectrochemical (PEC) cell, they exhibit better performances, toward water oxidation and hydrogen generation than pristine TiO2 nanostructures. These improvements are attributed to a higher visible light absorbance and a convenient band alignment between TiO2-CdO and CdO-CdS. Moreover, although TiO2 nanofibers present a higher surface area to be coupled with CdO@CdS, TiO2 nanotubes coupled with CdO@CdS achieved the maximum photoresponse at −0.25 V vs SCE, under 1 sun illumination. It indicates that this nanostructure, because of its ability for directional electron transport, is the most suitable matrix to build efficient TiO2-CdO@CdS photoanodes for PEC use.

Exploring novel phases of Cd–O system at ambient pressure

First-principles evolutionary searches are used to explore stable Cd–O compounds at ambient pressure. Besides the well-known rock-salt CdO, a new cubic thermodynamically stable phase CdO2 with space group Pa3 and two metastable compounds: zinc-blende and wurtzite phases of CdO have been discovered at ambient pressure. Among these, CdO2 was successfully synthesized with perfect structural agreement to our theoretical predictions. The global stability of the well known rock-salt phase of CdO, our calculations of elastic constants and phonon dispersion curves demonstrate that the Pa3, zinc-blende and wurtzite structures are mechanically and dynamically stable. Finally, the state-of-the-art LDA-1/2 methods reveal that at ambient conditions, zinc-blende and wurtzite phases are semiconducting with a direct band gap (Γ–Γ) of 0.89 eV and 0.97 eV respectively; whereas the semiconducting cubic-Pa3 structure shows direct band gap (Γ–Γ) of ∼2.93 eV and an indirect band gap of ∼2.58 eV agreeing well with the experimental value of ∼2.4 eV.

Synthesis and characterization of Mn2+ doped CdOZn3(PO4)2 nanocomposites

Undoped and Mn2+ doped CdOZn3(PO4)2 nanocomposites are fruitfully synthesized by chemical precipitation process at room temperature. The morphology, structure and spectroscopic properties of the prepared samples are characterized by X-ray diffraction (XRD), optical absorption, Scanning electron microscope (SEM) with EDS, Fourier transform infrared (FT-IR) spectroscopy, Photolumiscence (PL) and Electron Paramagnetic Resonance (EPR). XRD data confirms the cubic phase of CdO and monoclinic phase of Zn3(PO4)2. Strain and dislocation density are also calculated from XRD studies. Optical absorption spectrum of Mn2+ doped CdOZn3(PO4)2 nanocomposite shows different spin-forbidden DMSO-d6 bands which are the characteristics of octahedral site symmetry related to Mn2+. The crystal field parameter Dq and inter electronic repulsion parameters (B and C) are deliberate using optical absorption data. Surface morphology of sample is firm by Using Scanning electron microscopy (SEM) and the distribution of Zn, Cd, phosphate and oxygen species in the prepared sample is identified by EDS. PL studies recognize the white light emission. The ‘g’ value of the nanocomposite material synthesized is lesser than (negative shift) the free electron value (2.0023), which gives ionic nature to the bonding and confirms the presence of Mn2+ in distorted octahedral site symmetry.

Transparent conducting ZnO-CdO mixed oxide thin films grown by the sol-gel method

Mixed oxides of zinc and cadmium with different proportions were deposited on ordinary glass substrates using the sol-gel spin coating method under optimized deposition conditions using zinc acetate dihydrate and cadmium acetate dihydrate as precursors. X-ray diffraction patterns confirmed the polycrystalline nature of the films. A combination of cubic CdO and hexagonal wurtzite ZnO phases was observed. The oxidation states of Zn, Cd and O in the deposited films were determined by X-ray photoelectron spectroscopic studies. Surface morphology was studied by scanning electron microscopy and atomic force microscopy. The compositional analysis of the thin films was studied by secondary ion mass spectroscopy. The transmittance of the thin films was measured in the range 300–800nm and the optical bandgap was calculated using Tauc’s plot method. The bandgap decreased from 3.15eV to 2.15eV with increasing CdO content. The light emission properties of the ZnO:CdO thin films were studied by photoluminescence spectra recorded at room temperature. The current-voltage characteristics were also assessed and showed ohmic behaviour. The resistance decreased with increasing CdO content.

Production of ZnO and CdO-ZnO thin Films by Extraction–Pyrolytic Method

Abstract The extraction-pyrolytic method has been applied to produce the ZnO and CdO-ZnO thin films on glass and quartz glass substrates. According to X-ray diffraction measurements, the ZnO and CdO phases have been produced with an average size of crystallites about 8–42 nm in the films. The thickness of the layers measured by a profilometer has been up to 150 nm. The surface morphology measurements show that the surface of the films may be rough and non-continuous. The SEM results confirm the dependence between the preparation procedure and the quality of the thin film.

Growth of Hydrothermally Derived CdS-Based Nanostructures with Various Crystal Features and Photoactivated Properties.

CdS crystallites with rod- and flower-like architectures were synthesized using a facile hydrothermal growth method. The hexagonal crystal structure of CdS dominated the growth mechanisms of the rod- and flower-like crystallites under specific growth conditions, as indicated by structural analyses. The flower-like CdS crystallites had a higher crystal defect density and lower optical band gap value compared with the rod-like CdS crystallites. The substantial differences in microstructures and optical properties between the rod- and flower-like CdS crystallites revealed that the flower-like CdS crystallites exhibited superior photoactivity, and this performance could be further enhanced through appropriate thermal annealing in ambient air. A postannealing procedure conducted in ambient air oxidized the surfaces of the flower-like CdS crystallites and formed a CdO phase. The formation of heterointerfaces between the CdS and CdO phases mainly contributed to the improved photoactivity of the synthesized flower-like CdS crystallites.