Enhancement in superconducting transition temperature (Tc) and upper critical field (Hc2) in new Yb-doped Ce1−xYbxO0.9F0.1FeAs superconductors

► The effect of chemical pressure on new oxypnictides Ce1−xYbx(O/F)FeAs is studied. ► Both the lattice parameters were found to decrease with increase in Yb-content. ► Yb doping on CeO0.9F0.1FeAs resulted in enhancement of Tc up to ∼49 K (x = 0.5). ► All Yb doped compositions (x = 0.3, 0.4 and 0.5) have higher Tc than Ce(O/F)FeAs. ► High upper critical field Hc2(0) = 142 T was estimated for x = 0.3 composition.