Mössbauer investigation of the single crystal and powder sample of barium nitroprusside Ba[Fe(CN)5NO].3H2O (BNP)

Abstract

Angle-dependent Mossbauer investigation on single crystals of barium nitroprosside (BNP) using a-, b- and c-crystal cuts has been performed. The EFG tensor has been fully determined by the orientation between the main EFG component V ZZ and the b-crystal axis (α=±6(2)°) and by the asymmetry parameter (η=0.04(2)). Mossbauer spectra of powder samples have been recorded at 293 K and at liquid helium temperature in an external magnetic field. In spite of the negligible Goldanskii-Karyagin effect observed in the powder sample a remarkable vibrational anisotropy was found in the crystal. The Lamb–Mossbauer factors along the main crystallographic directions are: f LM (a)=0.36(1); f LM (b)=0.23(1) and f LM (c)=0.50(1). The relative orientation of the main component of the MSD tensor with respect to the b-crystal axis is ω=±36(5)°.