Elements Of X Ray Diffraction

Multiferroic bismuth ferrite-based materials for multifunctional applications: Ceramic bulks, thin films and nanostructures

Structural, FTIR and photoluminescence studies of Cu doped ZnO nanopowders by co-precipitation method

The influence of defects on the photoactivity of ZnO has been revealed. The defects can be formed via ball-milling treatment, and part of the defects can be repaired via annealing treatment. The photocatalytic activity of the ZnO sharply decreased as the ball-milling speed and milling time increased. After the annealing treatment, the photocatalytic activity recovered partly but could not return to the activity of the pristine ZnO. The bulk defects such as oxygen vacancies (VO), zinc vacancies (VZn) and a lot of nonradiative defects were formed after the milling treatment. The annealing treatment can only repair part of the bulk defects and nonradiative defects. Thus, only part of the photoactivity was recovered. The species trapping experiments showed that the introduction of the bulk defects did not change the photocatalytic mechanism. The main oxidative species for the pristine ZnO, the milled ZnO, and the annealed ZnO are photogenerated holes and hydroxyl radicals.

Influence of Defects on the Photocatalytic Activity of ZnO

Sol–gel route of synthesis of nanoparticles of MgFe2O4 and XRD, FTIR and VSM study

Structural, spectroscopic and magnetic study of nanocrystalline Ni-Zn ferrites

In this work, we have focused on the influence of Gd3+ substitution on the structural, magnetic and electrical properties of cobalt ferrite synthesized using a sol–gel auto-combustion method. The powder X-ray diffraction analysis reveals that the Gd-substituted cobalt ferrites crystallize in a single phase spinel structure for lower concentrations of Gd3+, while a trace of GdFeO3 appears as a minor phase for higher concentrations. Raman and Fourier transform infrared spectra confirm the formation of the spinel structure. Furthermore, Raman analysis shows that the inversion degree of cobalt ferrite decreases with Gd3+ doping. The field emission scanning electron microscopy images show that the substitution of small amounts of Gd3+ causes a considerable reduction of the grain size. Studies on the magnetic properties reveal that the coercivity of Gd-substituted cobalt ferrites enhances from 1265 Oe to 1635 Oe, the saturation magnetization decreases monotonically from 80 emu g−1 to 53.8 emu g−1 and the magnetocrystalline anisotropy constant increases from 5.8 × 105 erg cm−3 to 2.23 × 106 erg cm−3 at 300 K. The electrical properties show that the Gd3+ doped samples exhibit high dielectric constant (616 at 100 Hz) and ac conductivity (4.83 × 10−5 S cm−1 at 100 Hz) values at room temperature. The activation energy is found to decrease from 0.408 to 0.347 eV with the rise in Gd3+ content. The impedance study brings out the effect of the bulk grain and the grain boundary on the electrical resistance and capacitance of cobalt ferrite. Gd substitution and the nano-size of cobalt ferrite enhance the electrical and magnetic properties which could enable a higher memory storage capability.

G. Chandrasekaran

Papers

Sol–gel route of synthesis of nanoparticles of MgFe2O4 and XRD, FTIR and VSM study

Structural, spectroscopic and magnetic study of nanocrystalline Ni-Zn ferrites

Impact of Gd3+ substitution on the structural, magnetic and electrical properties of cobalt ferrite nanoparticles

FTIR study of Ni, Cu and Zn substituted nano-particles of MgFe2O4

Structural, magnetic and electrical properties of nanocrystalline zinc ferrite