BaTi 2Fe 4O 11 shows the reentrant-spin glass behavior. With increasing x in Ba 1- x Sr x Ti 2- y Sn y Fe 4 O 11 the lattice constant becomes smaller, with T f unchanged and T c increasing, while increasing of y makes the lattice constant larger and the reentrant spin glass changes into spin glass. T f in spin glass decreases with increasing lattice constant. T f of reentrant spin glass has a nature different from that of spin glass. Time dependence of dc magnetization was observed for these samples. The time dependence may be produced by the distribution of superparamagnetic clusters. These samples have characteristics of intensively mixed spin glass and ferrimagnetism.