No abstract

No abstract

Combinatorial substrate epitaxy (CSE) is used to investigate polymorph competition between metastable scrutinyite (α-PbO2) structured (s-) and stable rutile structured (r-) SnO2 during local epitaxial growth­ across orientation space on­ polycrystalline columbite (c‑) CoNb2O6 substrates. Growth occurs in a grain-over-grain fashion, where individual grains of c-CoNb2O6 support the growth of individual grains of SnO2. Both metastable s-SnO2 and stable r-SnO2 crystals are observed, each growing on specific ranges of substrate orientations and each having a single specific orientation relationship (OR) with substrate grains on which it grew. s-SnO2 adopts the unit-cell over unit-cell OR that can be expressed as the alignment of primary eutactic planes: (100) s* [001] s* ∥(100) c* [001] c* (where the * indicates the use of Pcnb setting). s-SnO2 grains grow on a slight majority of orientations and specifically on orientations inclined from the (010) pole of c*-CoNb2O6. r-SnO2 adopts an OR that can be expressed as the alignment of a secondary set of eutactic planes: (101) r [010] r ∥(010) c* [001] c* . r-SnO2 grows only on orientations close to the (010) pole of c*-CoNb2O6. The collected set of observations is discussed and rationalized with respect to the combination of misfit strain energies and cation packing interfacial energy penalties. We conclude that CSE should allow for the rational and computationally guided development of new materials adopting scrutinyite, rutile, and related structures.

No abstract