Metallic and nonmetallic double perovskites: A case study of A2_2FeReO6_6 (A= Ca, Sr, Ba)

We have investigated the structure and electronic properties of ferrimagnetic double perovskites, A2FeReO6 (A= Ca, Sr, Ba). The A=Ba phase is cubic (Fm3m) and metallic, while the A=Ca phase is monoclinic (P21/n) and nonmetallic. 57Fe Mossbauer spectroscopy shows that iron is present mainly in the high-spin (S=5/2) Fe3+ state in the Ca compound, while it occurs in an intermediate state between high-spin Fe2+ and Fe3+ in the Ba compound. It is argued that a direct Re t2g - Re t2g interaction is the main cause for the metallic character of the Ba compound; the high covalency of Ca-O bonds and the monoclinic distortion (which lifts the degeneracy of t2g states) seem to disrupt the Re-Re interaction in the case of the Ca compound, making it non-metallic for the same electron count.Comment: 1 eps fil

Relative Lamb-Mossbauer factors of tin corrosion products

Variable temperature Sn-119 Mossbauer spectroscopy was used to obtain relative Lamb-Mossbauer factors for three tin corrosion products: hydrated stannic oxide SnO2 center dot xH(2)O, abhurite Sn21O6Cl16(OH)(14), and tin hydroxysulfate Sn3OSO4(OH)(2). Their hyperfine parameters have also been investigated

Simultaneous copper runoff and copper surface analysis in an outdoor area

International audienc

Atmospheric corrosion of nickel in various outdoor environments

International audienc

FT-IR Microscopic Base Imaging System: Applications for Chemical Analysis of Zn and Ni Atmospheric Corrosion

International audienc

FT-IR Microscopic Base Imaging System: Applications for Chemical Analysis of Zn and Ni Atmospheric Corrosion

International audienc