Mössbauer spectroscopic studies of Fe-substituted YIG

Compositional dependence of hyperfine parameters, determined through Mössbauer spectral analysis has been studied for Y_3−xFe_5+xO₁₂ (x = 0.0, 0.1, 0.3 and 0.5) garnet system at 300 K. The Mössbauer spectra have been fitted with three sextets in the ferrimagnetic state corresponding to Fe³⁺ ions at tetrahedral (d), octahedral (a) and dodecahedral (c) sites of the crystal structure. It is observed that isormershift, quadrupole shift and hyperfine field of d-site show no significant variation with Fe³⁺ concentration. The change in hyperfine fields of a- and c-sites with composition (x) has been explained on the basis of strength of exchange integrals, change in isomershift can be understood due to s-electron charge distribution and asymmetric displacement of oxygen ions surrounding the a- and c-sites seems to be responsible for observable quadrupole shift. The magneton number values obtained from magnetization and Mossbauer data are in agreement to those calculated using Neel's three sublattice model of ferrimagnetism.     

Enhanced visible-light photoresponse of DVT-grown Ni-doped SnSe crystal

Semiconductors with the group of IV-VI are key components of future photonics technology due to their unique properties. In the present study, we investigated the influence of nickel inclusion on the structural and electrical responsiveness of SnSe-layered crystals produced through direct vapour transport. The elemental composition, stoichiometry of grown crystals and the orthorhombic structure were investigated by EDAX and XRD analysis. The phase and high crystallinity of produced compounds are revealed by scanning electron microscopy and the SAED pattern of transmission electron microscopy. Nickel-doped SnSe photodetector exhibited a photocurrent of 53.83 nA, which is six times higher compared to the pristine SnSe. Moreover, the pristine and nickel-doped SnSe demonstrated excellent photoresponse behaviour under visible light. Additionally, important photodetection characteristics such as photoresponsivity (R), spectral detectivity (D), rise time and decay time are assessed. Our findings contribute to a better understanding of SnSe and Ni-doped SnSe-based photodetection capabilities which open up the future gateway for SnSe-based optoelectronic devices.