Hakan Çolak

Synthesis,Crystal Structural and Electrical Conductivity Properties of Fe-Doped Zinc Oxide Powders at High Temperatures

The synthesis, crystal structure and electrical conductivity properties of Fe-doped ZnO powders (in the range of 0.25{15 mol%) were reported in this paper. I-phase samples, which were indexed as single phase with a hexagonal (wurtzite) structure in the Fe-doped ZnO binary system, were determined by X-ray difiraction (XRD). The solubility limit of Fe in the ZnO lattice is 3 mol% at 950 ‐ C. The above mixed phase was observed. And the impurity phase was determined as the cubic-ZnFe2O4 phase when compared with standard XRD data using the PDF program. This study focused on single I-phase ZnO samples which were synthesized at 950 ‐ C because the limit of the solubility range is the widest at this temperature. The lattice parameters a and c of the I-phase decreased with Fe-doping concentration. The morphology of the I-phase samples was analyzed with a scanning electron microscope. The grain size of the I-phase samples increased with heat treatment and doping concentration. The electrical conductivity of the pure ZnO and single I-phase samples was investigated using the four-probe dc method at 100{950 ‐ C in air atmosphere. The electrical conductivity values of pure ZnO, 0.25 and 3 mol% Fe-doped ZnO samples at 100 ‐ C were 2£10 i6 , 1.7£10 i3 and 6.3£10 i4 S¢cm i1 , and at 950 ‐ C they were 3.4, 8.5 and 4 S¢cm i1 , respectively.

Studies on structural and electrical properties of copper-doped zinc oxide powders prepared by a solid state method at high temperatures

Abstract The synthesis, crystal structure and electrical conductivity properties of Cu-doped ZnO powders (in the range of 0.25 – 15 mole %) is reported. I-phase samples, which were indexed as single phase with a hexagonal (wurtzite) structure in the Cu-doped ZnO binary system, were determined by X-ray diffraction. The limit solubility of Cu in the ZnO lattice at this temperature is 5 mole % at 1000°C. The impurity phase was determined as CuO when compared with standard XRD data using the PDF program. We focused on single I-phase ZnO samples which synthesised at 1000°C because the limit solubility range is widest at this temperature. It was observed that the lattice parameters a increased and c decreased with Cu doping concentration. The morphology of the I-phase samples was analysed with a scanning electron microscope. The electrical conductivity of the pure ZnO and single I-phase samples were studied using the four-probe dc method at temperatures between 100 and 950°C in an air atmosphere. The electrical conductivity values of pure ZnO and 5 mole % Cu-doped ZnO samples at 100°C were 2 × 10−6 and 1.4 × 10−4 ohm−1 cm−1, and at 950°C they were 1.8 and 3.4 ohm−1 cm−1, respectively. In other words, the electrical conductivity slightly increased with Cu doping concentration. Also, it was observed that the activation energy of the I-phase samples was decreased with Cu doping concentration.

Effect of Doping and High-Temperature Annealing on the Structural and Electrical Properties of Zn1–X NiXO(0≤X≤0.15) Powders

This paper reported the synthesis, crystal structure and electrical conductivity properties of Ni-doped ZnO powders (i.e. Zn1–X NiXO binary system, X =0, 0.0025, 0.005, 0.0075 and in the range 0.01≤X≤0.15). I-phase samples, which were indexed as single phase with a hexagonal (wurtzite) structure in the Zn1–X NiXO binary system, were determined by X-ray diffraction (XRD). The widest range of the I-phase was determined as 0≤X≤0.03 at 1200°C; above this range the mixed phase was observed. The impurity phase was determined as NiO when compared with standard XRD data, using the PDF program. We focused on single I-phase ZnO samples which were synthesized at 1200°C because of the widest range of solubility limit at this temperature. It was observed that the lattice parameters a and c of the I-phase decreased with Ni doping concentration. The morphology of the I-phase samples was analyzed with a scanning electron microscope. The electrical conductivity of the pure ZnO and single I-phase samples were studied by using the four-probe dc method at temperatures between 100 and 950°C in air atmosphere. The electrical conductivity values of pure ZnO and 3 mol% Ni-doped ZnO samples at 100°C were 2×10−6 and 4.8×10−6 Ω−1 cm−1, and at 950°C they were 1.8 and 3.6 Ω−1 cm−1, respectively. In other words, electrical conductivity increased with Ni doping concentration.

Green synthesis and antimicrobial activity of ZnO nanostructures Punica granatum shell extract

Abstract The manufacture of nanoparticles (NPs) is a new area of investigation due to potential applications related to the improvement of new technologies; in particular, environmentally safe manufactured nanomaterials have become a growing area within nanoscience. In this research, we synthesized zinc oxide (ZnO)-NPs using an aqueous extract of Punica granatum shell prepared using the green synthesis method. The ZnO-NPs were examined by X-ray diffraction (XRD), field emission-scanning electron microscopy (FE-SEM) and UV-visible spectroscopy. The XRD patterns illustrated a single phase hexagonal (wurtzite) structure. The FE-SEM micrographs revealed the formation of erythrocyte-like structures and the average particle sizes were found to be 30–180 nm. The UV-visible measurements showed that the average optical transparency is over 85% in the visible range. The electrical conductivity values of the nanostructured ZnO-NPs were between 7.07×10−7 and 3.31×10−4 Ω−1 cm−1 in the temperature range 25–650°C. In addition, the ZnO-NPs did not show any antimicrobial affect against a Gram-positive bacterium (Bacillus thuringiensis).

Erratum to: High optoelectronic and antimicrobial performances of green synthesized ZnO nanoparticles using Aesculus hippocastanum

Nanosized materials are of increasing interest due to their optical and electrical properties. In particular, the semiconductor ZnO has a wide band gap of 3.3 eV, which is abundant in nature and is eco-friendly. Green synthesis of nanomaterials is simple, non-toxic and adapted to large-scale production. Here we synthesized ZnO nanoparticles using the fruit shell extract of horse chestnut, Aesculus hippocastanum. ZnO nanoparticles were characterized by X-ray diffraction (XRD) and field emission-scanning electron microscopy. XRD patterns were indexed on the basis of an hexagonal structure, and the pattern indicates high crystalline quality with very well-defined high intensity peaks. The grain sizes ranged between 50 and 100 nm. Ultraviolet–visible data show that ZnO nanoparticles have a high optical transparency of 70–86%. In addition, the bactericidal effect of ZnO nanoparticles was observed against Bacillus thuringiensis.