The determination of an unknown oxygen atom position in rare-earth zirconate pyrochlores by a 111 systematic-row convergent-beam electron diffractiontechnique

A focused probe systematic-row large angle convergent-beam electron diffrac tion (CBED) technique has been used to determine an unknown oxygen atom fra ctional coordinate in two rare-earth zirconate pyrochlores La2Zr2O7 and Sm2 Zr2O7 to an estimated accuracy of better than 0.005. The bond valence metho d suggests that the CBED-determined x values are chemically plausible. The simplicity of the CBED technique used suggests that it may be a very useful technique for determining positions of light atoms in the presence of stro ngly scattering heavy-metal atoms.