The mobility of W atoms of the (3 2 0) and (2 2 1) regions of the W microcrystal surface with the tip curvature radius similar to 300 nm and the surface diffusion of Dy at average coverage similar to 0.1 ML on these regions were investigated by spectral analysis of field emission current fluctuations in the temperature range 500-800 K. The diffusion appears to be one-dimensional for the W(3 2 0) regions and two-dimensional for the W(2 2 1). The surface-diffusion coefficients were determined by comparison of the experimental results with the theoretical spectral density functions derived by Gesley and Swanson. The surface-diffusion parameters were calculated. The results are discussed from the aspect of substrate structure. (C) 2009 Elsevier B. V. All rights reserved.