Crystallographic shear of polymorphic TiO2 nanocondensates with enhanced Cr2O3 dissolution via pulsed laser ablation

TiO2 nanoparticles with enhanced solid solution of Cr up to 16 wt% in polymorphs of rutile, anatase, brookite, α-PbO2-type, and occasionally baddeleyite-type were synthesized via pulse laser ablation on ceramic TiO2 target dissolved with Cr2O3 or clamped Cr/Ti plates in air. Analytical electron microscopic observations indicated these nanocondensates have prevalent crystallographic shear (CS) along specific planes to form superstructures. The rutile type typically shows (100) and (010) CS besides the conventional ones rotating about the [111] zone axis as reported for ambient samples. The CS planes are parallel to (001) for anatase, (001) and (1-bar 10) for brookite, whereas (001) and {1 3-bar 1} for the α-PbO2-type TiO2 with varied extent of Cr dissolution. Surface modification, as a result of Cr dissolution and/or internal stress, was observed for all the polymorphs.