Growth of Ca₂MnO₄ Ruddlesden-Popper structured thin films using Combinatorial Substrate Epitaxy

الأصل · EN

The local epitaxial growth of pulsed laser deposited Ca₂MnO₄ films on polycrystalline spark plasma sintered Sr₂TiO₄ substrates was investigated to determine phase formation and preferred epitaxial orientation relationships (ORs) for isostructural Ruddlesden-Popper (RP) heteroepitaxy, further developing the high-throughput synthetic approach called Combinatorial Substrate Epitaxy (CSE). Both grazing incidence X-ray diffraction and electron backscatter diffraction (EBSD) patterns of the film and substrate were indexable as single-phase RP-structured compounds. The optimal growth temperature (between 650 ∘C and 800 ∘C) was found to be 750 ∘C using the maximum value of the average image quality (IQ) of the backscattered diffraction patterns. Films grew in a grain-over-grain pattern such that each Ca₂MnO₄ grain had a single OR with the Sr₂TiO₄ grain on which it grew. Three primary ORs described 47 out of 49 grain pairs that covered nearly all of RP orientation space. The first OR, found for 20 of the 49, was the expected RP unit-cell over RP unit-cell OR, expressed as [100][001]film||[100][001]sub. The other two ORs were essentially rotated from the first by 90∘, with one (observed for 17 of 49 pairs) being rotated about the [100] and the other (observed for 10 of 49 pairs) being rotated about the [110] (and not exactly by 90∘). These results indicate that only a small number of ORs are needed to describe isostructural RP heteroepitaxy and further demonstrate the potential of CSE in the design and growth of a wide range of complex functional oxides.