  Sr substituted perovskites La1.8Sr0.2MMnO6 (M = Ni, Co) were synthesized
using solid state reaction technique to present a systematic study on their
morphological, structural and magnetic properties. The average grain size of
the as-prepared La1.8Sr0.2NiMnO6 samples are in the range of 0.2-0.7 {\mu}m and
those for La1.8Sr0.2CoMnO6 manganites are 0.1-2.8 {\mu}m, which is
significantly less than that of unsubstituted La2NiMnO6 (LNMO) and La2CoMnO6
(LCMO) manganites. The XPS analysis enlightened about phase purity, binding
energy and oxygen vacancy of La1.8Sr0.2MMnO6 manganites. The Sr substituted
LNMO has revealed a sharp ferromagnetic to paramagnetic phase transition at 160
K which is about 120 K less than that of parent LNMO. The Sr substituted LCMO
exhibited such a transition at 220 K which is 8 K less than that of parent
LCMO. The temperature dependent magnetization measurements suggest that the
effect of Sr on the transition temperature in LNMO is more significant than
that of LCMO.
