Unveiling Structural Disorders in Honeycomb Layered Oxide: $\rm Na_2Ni_2TeO_6$

TL;DR

This study provides a detailed atomic-level crystallographic analysis of Na₂Ni₂TeO₆, revealing extensive stacking disorders that influence its structural and potentially functional properties, advancing understanding of honeycomb layered oxides.

Contribution

It offers the first comprehensive atomic-resolution characterization of stacking disorders in Na₂Ni₂TeO₆, highlighting their impact on material structure and properties.

Findings

Identification of stacking faults predominantly perpendicular to metal slabs.

Observation of edge dislocations in certain domains.

Altered alkali atom distribution due to stacking faults.

Abstract

Honeycomb layered oxides have garnered tremendous research interest in a wide swath of disciplines owing not only to the myriad physicochemical properties they exhibit, but also their rich crystal structural versatility. Herein, a comprehensive crystallographic study of a sodium-based $\rm Na_2Ni_2TeO_6$ honeycomb layered oxide has been performed using atomic-resolution transmission electron microscopy, elucidating a plethora of atomic arrangement (stacking) disorders in the pristine material. Stacking disorders in the arrangement of honeycomb metal slab layers (stacking faults) occur predominantly perpendicular to the slabs with long-range coherence length and enlisting edge dislocations in some domains. Moreover, the periodic arrangement of the distribution of alkali atoms is altered by the occurrence of stacking faults. The multitude of disorders innate in $\rm Na_2Ni_2TeO_6$ envisage broad implications in the functionalities of related honeycomb layered oxide materials and hold promise in bolstering renewed interest in their material science.