Virtual Synthesis of Nanoscale Systems with Pre-Designed Properties: Fundamentals and Applications. Chapter 7. Nickel Oxide Quantum Dots and Polymer Nanowires

TL;DR

This paper uses quantum theory-based computational methods to design and analyze nickel oxide nanosystems, revealing their structural, electronic, and magnetic properties, and demonstrating tunability for various applications.

Contribution

It introduces a virtual synthesis approach for non-stoichiometric Ni-O nanosystems, detailing their structural flexibility, magnetic states, and electronic properties, which can be tailored through synthesis conditions.

Findings

Ni-O quantum dots can have both ferromagnetic and antiferromagnetic states.

Quantum confinement effects cause the optical transition energy to vary significantly.

Structural flexibility enables tuning of electronic and magnetic properties for applications.

Abstract

The virtual (i.e., fundamental many body quantum theory-based, computational) synthesis method is used to establish electronic templates of about 30 non-stoichiometric nanosystems composed of nickel and oxygen atoms and ranging from about 6 {\AA} to 6 nm in linear dimensions. Flexible and stretchable Ni-O bond in such structures accommodates various ratios of Ni to O atoms, and both antiferromagnetic and ferromagnetic spin alignments. Depending on synthesis conditions, smaller Ni-O quantum dots (QDs) composed of up to 14 atoms or so may have both types of spin alignments, while quantum-confined, quasi one dimensional Ni-O nanowires (QWs) appear to be nanopolymers with antiferromagnetic spin alignment. Ni-O bond flexibility and related ease of spin re-arrangement may facilitate physical mechanisms leading to the development or loss of exchange bias when such Ni-O quantum dots and wires (QDWs) interact with surfaces or each other at some thermochemical conditions. These structural and compositional flexibility is reflected by QDWs' molecular electrostatic potential (MEP) and electronic level structure (ELS). In particular, the direct optical transition energy (OTE) of the studied Ni-O systems may vary within an order of magnitude, and their electronic and magnetic properties can be finely tuned to match applications requirements by manipulations with synthesis conditions, the structure and composition of quantum confinement. The developed electronic templates are available upon request.