Interpretation of X-ray Powder Diffraction Patterns . By H. Lipson and H. Steeple. Pp. viii + 335 + 3 plates. (Mac-millan: London; St Martins Press: New York, May 1970.) £4.

X-Ray Diffraction

Synthesis and characterization of zinc oxide thin films for optoelectronic applications

One of the most frequently used methods for characterizing thin films is UV–Vis absorption. The near-edge region can be fitted to a simple expression where the intercept gives the band gap and the fitting exponent identifies the electronic transition as direct or indirect. [See Tauc et al., Physica Status Solidi 15, 627 (1966); naturally, these are usually called “Tauc” plots.] In earlier work, we found that direct band gaps fitted using Tauc's method can be quite accurate, to ∼1% [see Viezbicke et al., Phys. Status Solidi B 252, 1700 (2015)]. Still, slopes of these Tauc plots are less frequently quantified, even though the slopes are directly rooted in key band-structure parameters. In this study, we examine the reproducibility of Tauc plot slopes for ZnO as a model direct-gap material and compare these experimental values with the theoretically derived slope. In contrast to the band gap accuracy, the experimental slope values varied by several orders of magnitude. The histogram of slope values was significantly more compact for Tauc plots exhibiting less Urbach tail contribution. In these cases, the Tauc slopes can provide an order-of-magnitude quantification of other key band characteristics such as carrier effective mass.

Assessing Tauc plot slope quantification: ZnO thin films as a model system

The balance between economic development and environmental damage is also evident in the problem of pollution and waste management. Increased economic activity, mainly in industrial countries, has ...

Green synthesis: Photocatalytic degradation of textile dyes using metal and metal oxide nanoparticles-latest trends and advancements

Currently, nanotechnology is referred to be one of the attractive research sectors in several countries because of its vast potential and commercial impact. Nanotechnology includes the investigation, development, fabrication, and processing of structures and materials on a nanoscale in various fields of science, health care, agriculture, technology, and industries. As such, it has provided a steady restructuring of related technologies. However, the irregularities and uncertainties in dimensions and chemical compositions, makes the viability of such materials questionable. Concerns have been inclined about the transport, destiny, and transformation of nanomaterials discharged into the environment. A critical analysis of the present phase of knowledge concerning the exposure and effects of nanomaterials has been discussed in-depth. In this review, different nanomaterials along with their applications have also been reviewed, that include graphene-based nanomaterials, carbon nanotubes, and their composites, nanoclay composites, nanostructured thin films, metal-organic frameworks, conducting polymers and their composites, MXenes, chalcogenide nanocrystals, and quantum dots. Besides, a few of the groundbreaking applications of nanomaterials for different sectors like human health, processes, photochemical process, energy conversion and energy storage, separation and purification processes, optoelectronics, etc. are discussed in detail with their chemsitry. Moreover, the unique characteristics and applications of nanomaterials, they inherently introduce challenges for their applications and large-scale production. Acknowledgment of the potential benefits and unknown dangers of nanomaterials is critically is critically analyzed and discussed in the manuscript.

Nanomaterials: Applications, waste-handling, environmental toxicities, and future challenges – A review

Effect of gallium doping on the structural, optical and electrical properties of zinc oxide thin films prepared by spray pyrolysis

Hydrothermal synthesis of ZnO nanowires on rf sputtered Ga and Al co-doped ZnO thin films for solar cell application

Thin films of Se79Te10Sb4Bi7, were prepared by Electron beam deposition technique. The structure of the as-prepared and annealed films has been studied by X-ray diffraction and the surface morphology by the scanning electron microscope (SEM). These studies show that there is a gradual change in structure and the formation of some polycrystalline structures in the amorphous phases is observed when the Se79Te10Sb4Bi7 film is annealed in the temperature range of 333–393 K. The optical transmission of these films has been studied as a function of photon wavelength in the range 300–2500 nm. It has been found that the optical band gap E g o p t decreased with increasing annealing temperature in the range 333–393 K. The Urbach energy (Eu), optical conductivity (σopt), imaginary (ei), and real (er) parts of the complex dielectric constant (e) and lattice dielectric constant (eL) were also determined. The changes noticed in optical parameters with increasing annealing temperature were explained on the basis of structural relaxation as well as change in defect states and density of localized states due to amorphous-crystalline transformation.

Effect of annealing on the optical properties of amorphous Se79Te10Sb4Bi7 thin films

ZnO nanowires were grown by hydrothermal synthesis and the effect of annealing on their physical properties was investigated by field-emission scanning electron microscopy, energy dispersive spectroscopy, X-ray diffraction, Raman spectroscopy, spectrophotometry and Hall effect measurements. The nanowires adopted the c-axis [0 0 1] growth orientation of the underlying gallium and aluminium co-doped ZnO seed layer and their vertical alignment improved with annealing temperature up to 250 °C, above which it became random at 350 °C. This was attributed to the improvement in crystallinity up to 250 °C and its deterioration at 350 °C. Energy dispersive spectroscopy confirmed that the Zn:O atomic ratios for all samples were nearly stoichiometric. Average optical transmittances around 50–70% were observed in the visible region. The optimum electrical properties for transparent electrode fabrication were achieved at 250 °C, where the carrier concentration was maximum (5.5 × 1020 cm−3) and electrical resistivity was minimum (1.1 × 10−2 Ω cm).

Effect of annealing on the microstructural, optical and electrical properties of ZnO nanowires by hydrothermal synthesis for transparent electrode fabrication

H. Nyakotyo

Papers

Synthesis and characterization of zinc oxide thin films for optoelectronic applications

Effect of gallium doping on the structural, optical and electrical properties of zinc oxide thin films prepared by spray pyrolysis

Hydrothermal synthesis of ZnO nanowires on rf sputtered Ga and Al co-doped ZnO thin films for solar cell application

Effect of annealing on the optical properties of amorphous Se79Te10Sb4Bi7 thin films

Effect of annealing on the microstructural, optical and electrical properties of ZnO nanowires by hydrothermal synthesis for transparent electrode fabrication