Limits on quantitative information from high-resolution electron microscopy of YBa2Cu3O7 superconductors

A series of image simulations is presented in which the sensitivity of high-resolution transmission electron microscopy (HREM) to both the degree of order and the oxygen stoichiometry in YBa2Cu3O7 superconductors is examined, taking into account the uncertain nature of many of the variables in these calculations. A strong dependence of the simulated images on defocus and on the Debye-Waller factor is found. As both of these are to some degree unknown, it is concluded that, although HREM can detect order, it cannot be used with confidence to quantify either the degree of ordering in the material or the oxygen stoichiometry.