The oscillation of Y2BaCuO5 (2 1 1) particle concentration in form of bands parallel to the growth front was observed in top-seeded melt-grown (TSMG) single-grain YBa2Cu3O7/Y2BaCuO5 bulk superconductors. The formations of these bands have been associated with temperature fluctuations at the growth front, which induce the fluctuation of the growth rate of the YBa2Cu3O7 (123) crystal and consequently also the fluctuation of the amount of trapped 211 particles. We have shown that the oscillation of 21 I-particle concentration does not occur when the growth front is horizontal and the crystal solidifies from below upwards. In the a-growth sector (a-GS) the oscillation was observed only in the nests with very small 211 particles. (C) 2004 Elsevier B.V. All rights reserved.