New Series of Nickel-Based Pnictide Oxide Superconductors (Ni2Pn2)(Sr4Sc2O6) (Pn = P, As)

TL;DR

This paper reports the discovery of new nickel-based pnictide oxide superconductors with layered structures, exhibiting superconductivity at low temperatures and expanding the family of layered superconducting materials.

Contribution

The study introduces a new series of nickel-based pnictide oxide superconductors with unique layered structures and demonstrates their superconducting properties.

Findings

Superconductivity observed at 3.3 K and 2.7 K for P and As compounds.

Layered structure with alternating Ni2Pn2 and Sr4Sc2O6 layers.

Confirmed bulk superconductivity through diamagnetism measurements.

Abstract

We have discovered new nickel-based pnictide oxide superconductors, (Ni2Pn2)(Sr4Sc2O6) (Pn = P, As). These compounds have a tetragonal unit cell with a space group of P4/nmm and they consist of alternate stacking of anti-fluorite Ni2Pn2 layers and K2NiF4-type Sr4Sc2O6 blocking layers. Lattice parameters were a = 4.044 A and c = 15.23 A for (Ni2P2)(Sr4Sc2O6) and a = 4.078 A and c = 15.41 A for (Ni2As2)(Sr4Sc2O6), indicating their thicker blocking layers than that of LaNiPO (c ~ 8.1 A). Both (Ni2P2)(Sr4Sc2O6) and (Ni2As2)(Sr4Sc2O6) exhibited superconductivity with zero resistivity at 3.3 K and 2.7 K, respectively. The perfect diamagnetism observed in both compounds guaranteed their bulk superconductivity.