Single crystals of Sr3Cr2O8, Sr3Cr1,9V0.1O8 and Sr3Cr1.9Fe0.1O8 were grown using the floating zone technique, and their magnetization behaviors were systematically investigated under pulsed field up to 54 T at various temperatures ranging from 2 K to 20 K. Temperature-induced transition from singlet ground state to triplet state and magnetic-field-induced Bose Einstein condensation were observed, of which the critical temperature and the critical field are correlative to ion-dopants. The analysis of the ground state and low-field magnetization behaviors indicates that the ion-dopants lead to an enhancement of the intradimer exchange J(0), which changes the transition temperatures, and increases the critical fields Hi. The magnetic Fe ion dopant makes the transition from singlet to triplet states more sensitive to the applied magnetic field, in clearly contrast to the situation of the nonmagnetic V5+ dopant. (C) 2015 Elsevier B.V. All rights reserved.