Spin-state ordered clusters in the perovskiteNdBaCo2O5.47

${\mathrm{NdBaCo}}_{2}{\mathrm{O}}_{5.47}$ cobaltite has been investigated using neutron and synchrotron powder diffraction. At ${T}_{\mathrm{MI}}\ensuremath{\sim}360\mathrm{K},$ the compound exhibits an associated metal-insulator and spin-state transition commonly observed in these systems. At ${T}_{N}\ensuremath{\sim}275\mathrm{K},$ the $\mathrm{IS}\ensuremath{-}{\mathrm{Co}}^{3+}$ species order in a AFM G-type structure. At ${T}_{\mathrm{SSO}}\ensuremath{\sim}230\mathrm{K},$ the AFM G-type volume fraction is gradually transformed into spin-state ordered clusters having a distinct magnetic structure. These clusters result from a selective $\mathrm{IS}\ensuremath{-}{\mathrm{Co}}^{3+}$ ${(t}_{2g}^{5}{e}_{g}^{1})$ to $\mathrm{LS}\ensuremath{-}{\mathrm{Co}}^{\mathrm{III}}$ ${(t}_{2g}^{6}{e}_{g}^{0})$ crossover and the ordering of the diamagnetic ions over $\ensuremath{\sim}350\mathrm{\AA{}}$ correlation lengths. The same electronic phase segregation is observed in ${\mathrm{TbBaCo}}_{2}{\mathrm{O}}_{5.46}$ and seems to occur only for a narrow range of oxygen stoichiometry.