Ba2-xSrxCuO2CO3: A Series of Oxycarbonate Thin Films Grown by Pulsed Laser Deposition on NdGaO3 Substrates

Monophasic thin films of the oxycarbonates Ba2-xSrxCuO2CO3 have been grown by pulsed laser deposition on [110]-oriented NdGaO3 substrates for x = 2, 1.6, 0.9, 0.4, and 0.3. A systematic study of these films by X-ray diffraction and transmission electron microscopy shows that the film orientation varies from a-axis or [110] orientation (copper layers perpendicular to the substrate) to a c-axis or [001] orientation (copper layers parallel to the substrate) as x decreases. Sr2CuO2CO3 (x = 2) is indeed a-axis oriented, whereas for 0.4 < x < 1.6 these films have a [110] orientation, and finally for x = 1.6-1.7 the films exhibit c-axis, [110]- and [110]-oriented domains. The factors which influence the orientation of these films are discussed