Magnetic and transport properties inCoSr2Y1−xCaxCu

Role of BaO/SrO layers in deciding the electronic structure of Cu0.3Co0.7Ba2−xSrxYCu2O7+δ (CoCu-1212) x=0, 1 and 2

“…Deconvolution of Co (2p) core level spectra shows the presence of Co 3+ and Co 4+ with a satellite peak, at the binding energy of 779.50 eV and 781.20 eV for Co (2p 3/2 ) and 794.81 eV and 796.61 eV for Co (2p 1/2 ), respectively in all compositions. The similar kinds of results have also been reported in literature regarding concentration and binding energy of Co 3+/4+ [24][25][26]. Curve shows the domination of Co 3+ state over Co 4+ state for x = 0 and 1 sample, but for x = 2 both states are almost equal.…”

“…The observed hump in (T) behaviour may be due to these induced holes in Cu/CoO x chains/planes which are taking part in charge transport and causing a dip in resistivity. These holes entered in Cu/CoO x chains, also destruct the effective antiferromagnetic coupling [26]. But here it seems the Cu 0.3 Co 0.7 ratio in chains is responsible for destruction of the effective antiferromagnetic coupling, since all compositions have almost similar magnetic behaviour.…”

“…A hump in resistivity measurement is also observed near 140 K in all composition. The sharpness of hump is increasing with increasing x. Luo et al [26] studied Co-1212 (CoSr 2 Y 1−x Ca x Cu 2 O 7 ) with doping Ca atom at Y-site up to x = 40%. They observed similar kinds of behaviour in x = 20% to 40% composition around 145 K and explained with participation of holes in Cu/CoO x chains/planes, in charge transport.…”

Comparative study of MSr2RECu2O7+δ compounds with M=Al, Nb, Fe, Ru, Ga and Co and RE=Eu, Y

“…For Fe-1212 the paramagnetic to ferromagnetic transition occurs around 80 K in zero field cooled (ZFC) M-T plot. Interestingly, the field cooled (FC) M-T curve is similar to the results reported by Luo et al [27] for x = 0.4 composition where magnetic properties were correlated with increase in hole concentration of CoO x layers or increase in charge state of Co. This behavior reveals that most of Fe is in 3+ state which is also much clear from our Rietveld refinement.…”

A-Site Cation-Ordering Layered Perovskite EuBa0.5Sr0.5Co2–xFexO5+δ as Highly Active and Durable Electrocatalysts for Oxygen Evolution Reaction

“…As can be seen, the Co 2p main lines of EBSCF x shift to the higher binding energy direction. These observations, together with the flatter shapes of the satellite peaks, ,, are indicative of the presence of high-valence Co ions in EBSC and EBSCF x . According to the previous studies by Grimaud et al, the increase in the Co oxidation state represents an increased number of Co 3+ and Co 4+ with the reduction of Co 2+ , leading to the robust OER activity of double perovskites .…”