  An attempt was made to tailor the magnetostructural transitions (MSTs) over a
wide temperature range under the principle of isostructural alloying. A series
of wide Curie-temperature windows (CTWs) with a maximal width of 377 K between
69 and 446 K were established in the Mn1-yCoyNiGe1-xSix system. Throughout the
CTWs, the magnetic-field-induced metamagnetic behavior and giant magnetocaloric
effects are obtained. The (Mn,Co)Ni(Ge,Si) system shows great potential as
multifunctional phase-transition materials that work in a wide range covering
liquid-nitrogen and above water-boiling temperatures. Moreover, general
understanding to isostructural alloying and CTWs constructed in
(Mn,Co)Ni(Ge,Si) as well as (Mn,Fe)Ni(Ge,Si) are provided.
