B-site disorder driven Griffiths-like phase and electrochemical behavior in Y₂NiCrO₆ double perovskite

Abstract

In this investigation, nanoparticles of B-site disordered Y2NiCrO6 (YNCO) double perovskite were synthesized by the facile sol-gel method to evaluate their magnetic and electrochemical properties. Their crystallgraphic structure is monoclinic and the average size of the particles is 79±16 nm. XPS analysis indicated a mixed oxidation states of B-site transition metals Ni2+/Ni3+ and Cr2+/Cr3+. The mixed valence states of Ni and Cr, along with the mixed magnetic phases of YNCO, constitute a signature of the B-site disorder. This antisite disorder contributed to the observation of a Griffiths-like phase arising from ferromagnetic short-range interactions above the magnetic transition up to the Griffiths temperature, TG=137 K. The synthesized YNCO double perovskite demonstrated a promising behavior as an electrode material for electrochemical supercapacitors. In a three-electrode system, it displayed a specific capacitance of 270 F g-1 at a current density of 0.5 A g-1. In a symmetric two-electrode system, YNCO exhibited a specific capacitance of 180 F g-1 at 0.5 A g-1, alongside an energy density of 6.25 Wh kg-1 at 250 W kg-1 power density. In both cases, we employed a mild 0.5 M neutral aqueous Na2SO4 solution as the electrolyte, in contrast to the typically employed corrosive and concentrated alkaline aqueous solution. The fascinating magnetic and charge storage properties of the B-site disordered YNCO double perovskite indicate its potential for use in spintronic devices and as efficient electrodes in symmetric hybrid supercapacitors.

Anomalous magnetic and electrical properties of disordered double perovskite alloy LaCaMnFeO6

“…and λ = 0.57 (1). Notably, the value of λ is comparable with those previously reported for other double perovskites [35,37], proving the presence of the GP in the LCFMO sample. According to previous works on DPs [26,[36][37][38], the observed GP in the studied sample can be ascribed to the quenched disorder resulting from the inhomogeneous distribution of Mn and Fe ions giving rise to the complex completion of magnetic interactions.…”

“…These FM regions begin interacting with each other, resulting in a sharp increase in the magnetization below a specific temperature T * (≈185 K at H = 20 Oe), which can be defined as the position of the maximum in the dχ −1 /dT derivative curve (see the inset in figure 4(b)) [34]. Additionally, μ eff decreases as increasing the magnetic field (figure 6), which can be explained due to an increase in the polarization of spins in the PM matrix overshadowing the contribution from the FM clusters [35][36][37].…”

“…Furthermore, the high-temperature FM clusters in the studied sample exhibit features of a Griffiths phase (GP): a downward divergence from the Curie-Weiss line that gradually softens as the magnetic field increases (figure 4(b)). To clarify the GP nature of these FM clusters, the inverse susceptibility data has been analyzed by using the following equation describing the GP singularity [35][36][37]:…”