Taking　the　advantage　of　the　low　transition　barrier　between　P4bm　and　P4mm　distortions,　tetragonal　structured　0.875Bi(0.5)Na(0.5)TiO(3)-0.125BaTiO(3)　was　designed　to　construct　an　electrocaloric　ceramics　with　large　electrocaloric　strength　by　adding　the　third　compound　Bi(Mg0.5Ti0.5)O-3　(BMT).　The　experiments　show　that,　through　adding　2.5　mol.%　BMT,　a　large　Delta　T　of　0.80　K　was　directly　observed　under　4　kV/mm;　especially,　a　high　Delta　T/Delta　E　of　0.020-0.023　K　cm/kV　was　achieved,　approximate　to　BaTiO3-based　and　some　lead-based　relaxors.　The　high　electrocaloric　effect　is　attributed　to　that　the　2.5　mol.%　BMT　added　sample　bridges　the　nonergodic　ferroelectric　and　ergodic　relaxor　states,　and　exhibits　a　microstructure　coexisting　P4bm　and　P4mm　symmetries.　Our　design　provides　a　new　route　in　probing　lead-free　BNT-based　electrocaloric　materials　apart　from　the　MPB.　(C)　2021　Elsevier　B.V.　All　rights　reserved.