The sign of the electric field gradient in FeGe and FeSn systems

The isostructural compounds FeGe and FeSn having the hexagonal (B35) phase have been studied by Mössbauer spectroscopy in an external magnetic field of 2.2T in the paramagnetic state. The sign of the principal component V_zz of the electric field gradient tensor is found to be negative for both of them and the value of the asymmetry parameter is 0.33 for FeGe and 0.91 for FeSn. It was not possible to determine the sign of V_zz for the cubic FeGe. This compound has been shown to possess a stable magnetic moment at the iron site even above its bulk transition temperature.     

Mössbauer studies of FexNbS2 (x = 0.25, 0.33 and 0.5)

Mössbauer studies of Fe_xNbS₂ (x = 0.25, 0.33 and 0.5) have been carried out for temperatures from 4.2K to about 715K. The iron exists in high spin divalent state for all the compositions. The temperature dependence of quadrupole splitting and center shift shows a reversible phase transition at about 600K and a possible disordering of Fe vacancies beyond this temperature for Fe_0.25NbS₂ and a reversible phase transition at 490K for Fe_0.5NbS₂. The hyperfine magnetic fields have been evaluated from the magnetically ordered spectra. The observed temperature dependent line intensities of the quadrupole doublet are attributable to the temperature dependence of the difference in the meansquare amplitude of vibrations parallel and perpendicular to the EFG axis.     

Regiospecific Chlorination of Xylenes Using K-10 Montmorrillonite Clay

Regiospecific chlorination of xylenes has been developed by employing NCS as a reagent and K-10 montmorrillonite clay as a solid support.     

CuCN-Mediated O-Alkylation of N,N,-Dimethylformamide with Alkyl Halides

This article reports the CuCN-mediated O-alkylation of formamide with 2-bromomethylindole. In addition, the formyloxylation products have been successfully exploited in the synthesis of novel indol-2-ylmethyl ether derivatives.     

Statistical evaluation of forming limit diagram for annealed Al 1350 alloy sheets using first order reliability method

This paper investigates the formability and forming limit curve of aluminium alloy sheet of grade Al 1350 with respect to annealing temperature and strain conditions through statistical approach. The uncertainty of forming limit curve (FLC) due to anisotropy parameter and strain hardening exponent have also been taken into consideration. The plastic instability criteria and its relevant equations given by Hill have been used to construct the theoretical FLC which is compared with experimental FLC. The stochastic modeling has been made on the statistical evaluation of the FLC with a high confidence level. First Order Reliability Method (FORM) and Monte-Carlo simulation (MCS) methods have been used to compare the probability of the data points determining FLC by considering normal distribution of material properties.     

Effect of aluminum on the hyperfine field and crystallization behaviour of NANOPERM alloy

The effect of Al on the hyperfine fields and crystallization of NANOPERM alloy has been studied by introducing 2% Al for Fe in Fe₈₈Zr₇B₄Cu₁. Al is found to enhance the nucleation rate in these alloys. Mössbauer spectroscopic technique has been used to trace the effect of Al on the hyperfine interactions in the amorphous and nanocrystalline state of these alloys. The hyperfine field clearly shows the presence of Al both in the amorphous and the nanocrystalline phase. Magnetic measurements using VSM and also XRD, TEM and DSC studies have been used to support the conclusions derived using Mössbauer spectroscopy.