The electron contact density and electric-field gradient on the Sb nuclear position is calculated in a series of 22 Sb compounds, comprising metallic, covalent as well as ionic Sb(III) and Sb(V) systems. The full-potential linear-muffin-tin-orbitals method is used with the local-density-approximation for exchange and correlation effects. By comparison with experimental ${}^{121}\mathrm{Sb}$ and ${}^{123}\mathrm{Sb}$ nuclear quadrupole resonance data and ${}^{121}\mathrm{Sb}$ M\"ossbauer data, the calibration constants relating measured quadrupole coupling constants and isomer shifts to the electric-field gradient and the electron contact density, respectively, are derived. This leads to an accurate determination of the quadrupole moment of the ${}^{121}\mathrm{Sb}$ nuclear ground state as $Q=\ensuremath{-}66.9{\mathrm{fm}}^{2}.$ The difference between the mean-square radius of the ${}^{121}\mathrm{Sb}$ nucleus in its excited isomeric and ground states is found to be $\ensuremath{\Delta}〈{r}^{2}〉=\ensuremath{-}0.0521{\mathrm{fm}}^{2}.$

Calculations of hyperfine parameters in antimony compounds

Crystal Structures and Magnetic Properties of Ordered Perovskites Ba2LnNbO6 (Ln=Lanthanide Elements)

Magnetic properties of the quaternary oxides Ba2LnTaO6 (Ln = Y or lanthanides) are reported. Their powder x-ray diffraction measurements and Rietveld analysis show that they have an ordered perovskite structure and are monoclinic (Ln = La-Tb) with space group P21/n or cubic (Ln = Y, Dy-Lu) with space group Fmm. Magnetic susceptibilities of Ba2LnTaO6 were measured. All compounds in this work are paramagnetic down to 5 K. Ba2EuTaO6 and Ba2SmTaO6 show Van Vleck paramagnetism; their spin-orbit coupling constants are determined to be 331 cm-1 and 287 cm-1, respectively. 151Eu Mossbauer measurements for Ba2EuTaO6 were carried out at 12, 100, 200 and 300 K. The Eu ion is in the trivalent state, and the symmetry of the Eu site is distorted from the octahedral symmetry. The Debye temperature of Eu3+ was determined to be 335 K from the temperature dependence of the absorption area of intensity curves.

https://iopscience.iop.org/article/10.1088/0953-8984/13/19/302/pdf

Magnetic properties of ordered perovskites Ba2LnTaO6 (Ln = Y, lanthanides)

A comparative study of the crystal and electronic structure and magnetism of divalent europium perovskite oxides EuMO3 (M = Ti, Zr, and Hf) has been performed on the basis of both experimental and ...

Crystal and electronic structure and magnetic properties of divalent europium perovskite oxides EuMO3 (M = Ti, Zr, and Hf): experimental and first-principles approaches.

The occupancy of C2 and S6 sites by Eu3+ ions in nanocrystalline powders and microcrystalline ceramics of Lu2O3 prepared from these powders was studied by M?ssbauer spectroscopy. It was proved that in nanopowders prepared by vigorous combustion syntheses the occupancy of the C2 and S6 sites by Eu3+ is almost random, with only a very limited preference for the former. For ceramic specimens formed at 1750??C within a few hours, it was found that Eu3+ ions strongly prefer to enter the Lu2O3 host at the C2 site. We concluded that thermodynamically the non-centrosymmetric site C2 is preferred to the S6 site by Eu3+. However, if the formation of crystallites is very fast, like in combustion syntheses, the Eu3+ ions are entrapped into the two sites nearly randomly.

https://iopscience.iop.org/article/10.1088/0953-8984/17/17/007/pdf

B.D. Dunlap

Papers

Method for the analysis of pure quadrupole spectra in nuclear gamma-ray resonance