Reduction of thermal hysteresis and improvement of magnetocaloric properties in ball milled Mn0.98CoGe

•The thermal hysteresis existed in Mn0.98CoGe compound recedes even disappears for ball milling different time.•For Mn0.98CoGe compound, the increasing of ball milling time leads to the reduction of its crystal sizes.•The magnetic entropy change (ΔSM) decreases and the temperature interval of ΔSM broadens with increasing ball milling time.•The relative cooling powers (RCP) of BM-12 h sample are improved relative to no-milled sample.