The behaviour of LaMnO3 and LaMnO3+δ at high pressure

LaMnO3 is the parent compound of a family of doped manganates that exhibit a range of electronic phases and unusual properties with potential applications in new electronic devices. LaMnO3 crystallises in the orthorhombically distorted perovskite structure (Pbmn), in which every Mn3+ ion with high-spin configuration is surrounded by an octahedron of six oxygen ligands. Under ambient conditions, the Jahn-Teller (JT) instability of the singly occupied eg orbitals gives rise to cooperative distortions of the MnO6 octahedral units, resulting in orbital ordering and the insulating behaviour of LaMnO3. It is teh aim of this proposal to investigate as to how pressure alters the MnO6 octyahrdra distortion in LaMnO3 and the related material LaMNO3+δ in which no Jahn Teller instabilities are observed.