Browsing by Author "Rhode, M"

Now showing 1 - 1 of 1
  • Thumbnail Image
    Item
    Defect perovskites in the SrO-ZrO2-Nb2O5 system
    (Australian Institute of Physics, 2006-02-07) Schmid, S; Elcombe, MM; Rhode, M
    Compounds that can reversibly intercalate lithium have the potential to be used as cathodes in rechargeable lithium ion batteries. Two characteristics, the availability of interstitial or defect sites for the incorporation of lithium and the presence of reducible cations are found in some defect perovskites. The aim of this study is to synthesise a number of defect perovskites, which might be useful as host materials for Li intercalation, and investigate their structures using X-ray and neutron powder diffraction. The SrxNbO3, 0.7 ≤ x ≤ 1, solid solution having niobium in both oxidation states +IV and +V whenever x < 1, has been reported to adopt the ideal cubic perovskite structure across the whole solid solution field. Despite intensive searching when data were collected on good quality single crystals no additional reflections were detected [1]. This indicates random ordering between strontium and vacancies on the perovskite A sites. Given the vacancies in the structure (particularly at the low strontium end of the solid solution) and the accompanying presence of niobium +V, which can be easily reduced by lithium metal, this solid solution appeared to be an interesting candidate to investigate Liintercalation properties. Given that niobium +IV is not stable at high temperatures in air but rather gets oxidised, previous syntheses of the solid solution were conducted in high vacuum. Substitution of all niobium +IV by zirconium +IV allows syntheses to be carried out in air. Since previous studies have shown that niobium and zirconium are able to occupy positions in a structure at random [2-4], it was expected that a similar solid solution might be formed. Therefore an investigation was undertaken in the SrO-ZrO2-Nb2O5 system to see whether an analogous solid solution is indeed formed, what the extent of the solid solution range is and whether this material has the potential to intercalate Li ions reversibly.