A New Iron Pnictide Oxide (Fe2As2)(Ca5(Mg,Ti)4Oy) and a New Phase in Fe-As-Ca-Mg-Ti-O system

TL;DR

This paper reports the discovery of a new iron arsenide oxide with superconducting properties and characterizes its structure and derivatives within the Fe-As-Ca-Mg-Ti-O system.

Contribution

It introduces a novel layered iron arsenide oxide compound and its structural derivative, expanding the understanding of superconducting iron-based materials.

Findings

The new compound exhibits bulk superconductivity.

Structural analysis reveals a layered architecture with perovskite-type sheets.

The compound's lattice constants and interlayer distances are characterized.

Abstract

A new layered iron arsenide oxide (Fe2As2)(Ca5(Mg,Ti)4Oy) and its structural derivative were found in the Fe-As-Ca-Mg-Ti-O system. The crystal structure of (Fe2As2)(Ca5(Mg,Ti)4Oy) is identical to that of (Fe2As2)(Ca5(Sc,Ti)4Oy), which was reported in our previous study. The lattice constants of this compound are a = 3.86(4) A and c = 41.05(2) A. In addition, another phase with a thicker blocking layer was found. The structure of the compound and its derivative was tentatively assigned through STEM observation as (Fe2As2)(Ca8(Mg,Ti)6Oy) with sextuple perovskite-type sheets divided by a rock salt layer. The interlayer Fe-Fe distance of this compound is ~30 A. The compound and its derivative exhibited bulk superconductivity, as found from magnetization and resistivity measurements.