Phase analysis studies of titanium-chromium oxides derived from rutile by crystallographic shear

Abstract

An electron microscopic phase analysis of rutile plus 0–25 mole% CrO 1.5, at 1573°K, is reported. A “rutile” matrix, containing mottled contrast, short crystallographic shear ( CS) planes and an unusually high density of dislocations, coexists with lamellae of (253) r CS planes (approx MX 1.97) for 0–8 mole% CrO 1.5. For 8–25 mole% at least 50 different structures were characterized. Within experimental error there is an essentially continuous variation of CS plane orientation and spacing with composition. The CS planes cooperatively reorient from (253) r to (121) r , pivoting about the [1 11] r zone axis. The CS plane spacing simultaneously decreases from 2.4 to 1.3 nm. Lattice images show that both the spacing and orientation of the CS planes are very uniform within each crystal flake, confirming our earlier suggestion of continuous ordered solid solution. The results are compared to previous studies of chromia-doped rutile and other reduced rutile systems.