Single crystals of Ca2Co1-xZnxSi2O7 solid solutions with 0 less than or equal to x less than or equal to 1 were synthesized by the floating zone melting technique. A small melting length and a growing speed of 1.0mm/h were suitable for obtaining high quality crystals. Two-dimensional modulation phenomena were observed in the whole range of x. The modulation amplitude was proved to weaken unsteadily with increasing Zn content. Octagonal clustering as the fundamental mechanism of the modulation formation is described as well as variations in the microdomain pattern according to varying degrees of internal stress accommodation. (C) 2004 Elsevier B.V. All rights reserved.