Search Results

1 - 10 of 78 items :

  • "nanopowder" x
Clear All
Influence of annealing on structural, morphological and optical properties of CdxZn1−x O nanopowder prepared by Co-precipitation method

Abstract

Structural and optical properties of CdxZn1−x O (x = 0.0, 0.025, 0.050, 0.075, 0.1) nanopowder, synthesized by co-precipitation method have been investigated. The effect of annealing on the structural and morphological properties was studied using X-ray diffraction. The samples with x = 0.0 up to 0.075 exhibit wurtzite hexagonal phase, whereas, the sample with x = 0.1 shows two phases: wurtzite hexagonal ZnO and cubic CdO phase. This behavior is explained on the basis of solubility of CdO in ZnO. Energy Dispersive X-ray analysis (EDX) results revealed the existence of Cd, Zn, and O elements in the nanopowder. Transmission Electron Microscopy (TEM) images confirm that the particle size of the prepared samples is in nano range. The optical band gap values obtained from the absorption spectra show that absorption depends on Cd composition. By doping of ZnO with CdO, a red shift in the absorption edge was observed.

Open access
Defect Luminescence of Yag Nanopowders and Crystals

:Ce single crystals, single crystalline films and nanopowders. Opt. Mater., 31 , 1845-1848. Babin, V., Laguta, V. V., Maaroos, A., Makhov, A, Nikl, M., & Zazubovich, S. (2011). Luminescence of F + - type centers in undoped Lu 3 Al 5 O 12 single crystals. Phys. Status Solidi B, 248 , 239-241. Pankratov, V., Grigorjeva, L., Millers, D., & Chudoba, T. (2007). Luminescence of cerium doped YAG nanopowders. Rad. Meas., 42 , 679-682.

Open access
Fabrication of Si nanopowder and application to hydrogen generation and photoluminescent material

-802. [10] C.-S. Yang, R. A. Bley, S. M. Kauzlarich, H. W. H. Lee and G. R. Delgado, “Synthesis of Alkyl-Terminated Silicon Nanoclusters by a Solution Route”, Y J.Am.Chem.Soc. , 121 (1999) 5191-5195. [11] M. Maeda, K. Imaura, T. Matsumoto and H. Kobayashi, “Fabrication of Si Nanoparticles from Si swarf and application to solar cells”, Appl.Surf.Sci. 312 (2014) 39-42. [12] K. Imamura, K. Kimura, S. Fujie and H. Kobauyashi, “Hydrogen Generation from Water Using Si Nanopowder Fabricated from Si Swarf”, J. Nanoparticle Research , 18 (2016) 116-1-7. [13

Open access
Clean Synthesis of Pyrano[2,3- D]Pyrimidines Using ZnO Nano-Powders

References 1. Ghashang, M.; Kargar, M.; Shafiee, M. R. M.; Mansoor, S. S.; Fazlinia, A.; Esfandiari, H. CuO Nano-structures Prepared in Rosmarinus Officinalis Leaves Extract Medium: Efficient Catalysts for the Aqueous Media Preparation of Dihydropyrano [3, 2-c] chromene Derivatives. Recent Pat. Nanotech. 2015, 9, 204-211. 2. Ghashang, M.; Mansoor, S. S.; Mohammad Shafiee, M. R.; Kargar, M.; Najafi Biregan, M.; Azimi, F.; Taghrir, H. Green chemistry preparation of MgO nanopowders: efficient catalyst for the synthesis of

Open access
PbS nanopowder – synthesis, characterization and antimicrobial activity

Abstract

Lead sulphide (PbS) nanopowder was synthesized by a simple soft chemical route using lead nitrate and thiourea as precursor salts. The as-synthesized nanopowder was characterized by XRD, SEM, EDX, FT-IR, PL, Raman and magnetic measurements. XRD studies reveal the polycrystalline nature of the powder. The powder exhibits face-centered cubic structure with a strong (2 0 0) preferential orientation. The presence of Pb and S in the powder is confirmed by energy dispersive X-ray analysis. The peaks observed at 1112 cm-1 and at 606 cm-1 in the FT-IR spectrum are related to heteropolar diatomic molecules of PbS. The Raman peak shift at 173 cm-1 might have originated from the combination of longitudinal and transverse acoustic phonon modes associated with PbS crystal. The M-H loop confirms the paramagnetic nature of the as-synthesized PbS nanopowder. The nanopowder has significant antimicrobial activity against certain bacteria and fungi strains which make it suitable as antimicrobial agent against pathogenic microorganisms.

Open access
Magnetic studies of 0.7(Fe2O3)/0.3(ZnO) nanocomposites in nanopowder form and dispersed in polymer matrix

ferrimagnetic regions with strong A-B superexchange interaction. This partial inversion is often made accountable for much higher T N observed in ZnFe 2 O 4 nanoparticles. It is still an open question whether that inversion takes place because of the chemical routes usually employed during the nanoparticle synthesis, or is it an intrinsic property of nanometric ZnFe 2 O 4 particles caused by the finite-size effects. The objective of this study is to compare magnetic properties of ZnFe 2 O 4 nanoparticles in two forms: as a concentrated nanopowder and dispersed at very

Open access
Formation of Fe and Ni substituted LiMn2–XMXO4 nanopowders and their crystal and electronic structure and magnetic properties

: LiMn 1.5 Ni 0.5 O 4 and LiMn 1.9 Ni 0.1 O 4 , refinement of the higher terms of shape and strain was unstable, therefore only the K 00 and S 400 parameters were used. An attempt to refine site occupation factors of lithium and manganese vs. the dopant was also unsuccessful as lithium is very weakly seen by XRD and there is only small contrast between Mn and Fe/Ni. Wherever available, statistical uncertainties at 1σ level are reported in parentheses. The microstructural observations of the nanopowders as well as the microcompositional analyses were conducted

Open access
Influence of aluminium concentration in Zn0:9V0:1O nanoparticles on structural and optical properties

Abstract

The (V,Al) co-doped ZnO nano-structured powders (Zn0.9-xV0.1AlxO, where x = 0.02, 0.03 and 0.04) were synthesized via the sol-gel technique and their structural and optical properties were investigated. The effect of Al concentration on the structural and optical properties of the Zn0.9-xV0.1AlxO nanopowders was studied using various techniques. The XRD patterns indicate that the samples have a polycrystalline wurtzite structure. The crystallite size increases with increasing the Al content and lies in the range of 23 to 30 nm. The lattice strain, estimated by the Stokes-Wilson equation, decreases when Al content increases. SEM and TEM micrographs show that Zn0.9-xV0.1AlxO powders are the agglomeration of nanoparticles having spherical and hexagonal shapes with dimensions ranging from 20 to 30 nm. FT-IR spectra show a distinct absorption peak at about 500 cm-1 for ZnO stretching modes and other peaks related to OH and H2O bands. Raman spectra confirm the wurtzite structure of the Zn0.9-xV0.1AlxO nanoparticles. The direct band gaps of the synthesized Zn0.9-xV0.1AlxO nanopowders, estimated from the Brus equation and the crystallite sizes deduced from XRD, are around 3.308 eV. The decomposition process of the dried gel system was investigated by thermal gravimetric analysis (TGA).

Open access
Properties of FeCo Nanopowder Prepared by Chemical Synthesis

Properties of FeCo Nanopowder Prepared by Chemical Synthesis

Chemical synthesis of binary Fe-Co oxalate was used for preparation of Fe-Co nanoparticles. X-ray difftaction spectra recorded during temperature treatment in reduction atmosphere show two main stages of transformation: amorphization of the oxalate mixture and formation of Fe-Co nanoparticles. After X-ray diffraction high temperature treatment the nanoparticles with 50 nm mean crystallite were found. Comparison of magnetic properties during and after different type of temperature treatment shows that coercivity and saturation magnetic polarization are sensitive in dependence on sample condition, length of treatment and temperature. Analysis of Mössbauer spectra reveal several components which were ascribed different phases during temperature treatments.

Open access
Electrical properties comparison of NTC thermistors prepared from nanopowders and in mixed oxide process

Abstract

We have synthesized and studied the effect of cobalt doping on the electrical properties of NTC thermistors with the composition of NiCoxMn2−x O4 (x = 0.0, 0.4, 0.8, 1.2, 1.6). The electrical properties of NTC thermistors prepared from nanopowders by gel auto-combustion and mixed oxides processes have been compared. The measurement results indicate that the fluctuations of B value in the samples made from nanopowders are smaller than that in the samples prepared using mixed oxides method. The electrical properties of these ceramics depend strongly on their grain size. The sintering time and temperature were chosen the same for the samples made from the powders prepared by the two methods. It was found that the samples made from nanopowders have smaller grain sizes.

Open access