Mössbauer spectrum of Baotite

Abstract

Baotite Ba₄{(Ti, Nb, Fe)₈[Si₄O₁₂O₁₆}Cl is a four-membered ring silicate. Two sets of quadrupole doublets were obtained from the Mössbauer spectrum. The A doublet is caused by Fe³⁺ in the Ti−O octahedra (I.S.=0.389 mm/s, Q.S.=0.636 mm/s, Γ=0.602 mm/s, A/GSA=0.569), whereas the B doublet reflects Fe²⁺ in the octahedra (I.S.=1.029 mm/s, Q.S.=2.632 mm/s.). Fe³⁺/Fe²⁺=1.32. The spectrum indicates that: (1) both Fe³⁺ and Fe²⁺ are present in Baotite; (2) Fe³⁺ and Fe²⁺ exist as isomorphs in the Ti−O octahedra.