Synthesis and characterisation of materials with potential multiferroic behaviour

The ceramic method was used to produce Aurivillius phase materials, B i ₃NbTiO₉ and Bi₄Ti₃O₁₂. Unit cell structures have been determined to be of A2₁am and Fmmm symmetry, respectively. In addition, the fractional co-ordinates of the constituent atoms has been calculated by Rietveld refinement. A range of materials of general formula Bi₅Fe_1+xTi₃-x)\O\(₁₅ was produced with a value of x ranging from 0 to 2.5, which is higher than reported. Attempts to produce Bi₅Fe₄O₁₅, with all the Ti⁴+ sites occupied by iron atoms proved unsuccessful. The space group of Bi₅FeTi₃O₁₅ was determined to be A2₁am, however, the other 4-layer bismuth phases proved difficult to characterise without more data. Increasing the number of pseudo-perovskite layers from 2 to 3 to 4 (Bi₃NbTiO₉ to Bi₄Ti₃O₁₂ to Bi₅FeTi₃O₁₅) had a notable effect in increasing the unit cell size along the z-axis, going from c=25.192(1)Å to c=32.785(1)Å to c = 41.179(1). The magnetic properties of Bi₅FeTi₃O₁₅, Bi₅Fe₂Ti₂O₁₅ and Bi₅Fe₃TiO₁₅ have been recorded, as part of an attempt to find multiferroic materials. The information collected would suggest that Bi₅FeTi₃O₁₅ and Bi₅Fe₃TiO₁₅ display some anti-ferromagnetic behaviour, whereas Bi₅Fe₂Ti₂O₁₅ appears to be a paramagnet. Failure to produce Bi₅MnTi₃O₁₅ , by other researchers methods, raises doubts about manganese substitution into the bismuth-layer structure.

Name dc:type.qualificationname

m_rs

Level dc:type.qualificationlevel

m_rs

Grantor dc:publisher.institution

University of Birmingham

Year dc:date.issued

2010

Author dc:creator

• D'Souza, Rhys

• QD Chemistry