Use this URL to cite or link to this record in EThOS: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.532733
Title: Structural and magnetic characterisation of some mixed metal oxides and oxyhalides
Author: Stephens, Deborah Ann
Awarding Body: University of Birmingham
Current Institution: University of Birmingham
Date of Award: 2011
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Abstract:
This thesis investigates the structural and physical effects of changing the ratio of Mn:Ga in the anion deficient perovskite, YSr\(_3\)Mn\(_{4-x}\)GaxO\(_{10.5}\). YSr\(_3\)Mn\(_{4-x}\)GaxO\(_{10.5}\) crystallises in the tetragonal space group I4/mmm, with lattice parameters a~7.64 Å and c~15.66 Å. Magnetic characterisation indicates that the material is antiferromagnetic overall, with ferromagnetic ordering in the [001] direction of the unit cell. Earlier work on the structural analogue, Y\(_{1.07}\)Sr\(_{2.93}\)Mn\(_{2.67}\)Ga\(_{1.33}\)O\(_{10.5}\), identified a magnetic peak in the neutron diffraction pattern that could not be fitted following refinement of NPD data. This work concluded that the extra peak was due to a small MnO impurity. The effects of oxidation and fluorination on the structural and physical properties of YSr\(_3\)Mn\(_{4-x}\)Ga\(_x\)O\(_{10.5}\) with various Mn:Ga ratios are investigated. The physical and structural effects of substituting Mn\(^{3+}\) or Co\(^{3+}\) for Fe\(^{3+}\) in the perovskite related material, Pb\(_4\)Fe\(_3\)O\(_8\)Cl, have been investigated using XRPD, NPD and magnetic susceptibility measurements. An earlier characterisation of Pb\(_8\)WO\(_{10}\)Cl\(_2\) suggested a deficit on all atom sites within the unit cell. This work suggests a different structure with an intact cation and main oxygen sub-lattice. The site of an additional oxygen was established linked to tungsten. Pb\(_8\)WO\(_{10}\)Cl\(_2\) crystallises in space group I4/mmm, with a = 3.9846(2) and c = 22.690(2) Å.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.532733  DOI: Not available
Keywords: TP Chemical technology ; QD Chemistry
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