Hyperfine interactions, charge compensation mechanisms, and the distribution of tin dopant cations in rare-earth orthochromites RCrO_3 (R = Sm, Eu, Gd, Ho)

摘要

The reduction in the squared cosine of angle θ of the Cr-O-Cr bond in the Sm-Ho series in samples containing Sn~(4+) ions in the Cr~(3+) position in the crystallite bulk is accompanied by a linear increase in hyperfine field H T→0 K at 119Sn nuclei. Upon annealing in H_2, tin attains oxidation state +2 occupying the Cr~(3+) and R~(3+) positions on the surfaces of particles. M?ssbauer measurements in situ at 100 K do not reveal the spin polarization of Sn~(2+), but this polarization does manifest itself for part of the daughter Sn~(4+) ions formed when samples come into contact with air.