MICROSTRUCTURE OF CONDUCTIVE LAXSR1-XCOO3 GROWN ON MGO(001)

LaxSr1-xCoO3 (LSCO) (0 < x < 0.5) has attracted much attention recently because of its applications as electrodes for fuel cells and for ferroelectric memories. In this paper, the microstructure of LSCO grown on MgO(001) by metal-organic chemical vapour deposition has been analysed by transmission electron microscopy. The LSCO film is dominated by an ordered anisotropic perovskite-type structure, denoted as new La0.5Sr0.5CoO3 (n-LSCO). This structure is the result of lattice substitution between La and Sr. The atomic model of the structure is determined for the first time. The LSCO him is composed of domains exhibiting a [001], [010] and/or [100] directional anisotropic n-LSCO structure. Numerous stacking faults with displacement vector of 1/4[011] have been observed. The stacking faults are confined in the (100) and (010)planes and are produced by the [100] and [010] steps respectively on the MgO(001) substrate. The (010) and (100) interplanar distances in LSCO are constrained owing to lattice mismatch between LSCO and MgO and the presence of (010) and (100) planar stacking faults.