Adhesion and electronic structures of Cu/Zn2SnO4 interfaces: A first-principles study

Abstract

Detailed insights into metal/ternary ceramic interfaces at the atomic and electronic scales are highly desirable for the development of a fundamental understanding of interfacial interactions. As a typical ternary ceramic, Zn2SnO4 exhibits excellent compatibility with metals; however, the unclear adhesive mechanism significantly limits the rational design and optimization of Zn2SnO4/metal composites with stable interfaces for specific applications. In this paper, we investigate Cu/Zn2SnO4 adhesive and interfacial characteristics via first-principles calculations. The universal binding energy and relaxation methods are applied sequentially to determine the adhesion strengths of various Cu/Zn2SnO4 interfacial structures. The work of separation (Wsep) indicates that O-rich Cu(111)/Zn2SnO4(111) (denoted as interface I) provides the preferred orientation relationship and atomic structure. We compare the interfacial adhesion strengths and stabilities of Cu/Zn2SnO4 interface I and other Cu/binary ceramics using their relaxed Wsep values. We find that the multication ceramic Zn2SnO4 exhibits a strong affinity for the Cu metal. Analysis of Cu–O bond lengths and coordination structures reveals that strong adhesion between Cu and Zn2SnO4 depends heavily on tetrahedral coordination structures constructed of short strong Cu–O bonds. The electronic structures within the Cu/Zn2SnO4 interface are further analyzed to elucidate relevant atomic interactions and bonding characteristics. Charge transfer and redistribution generate Cu–O bonds with a polar-covalent character, which contribute to enhanced interfacial adhesion strength and maintain interfacial stability. Our work discloses the atomic and electronic structures of Cu/Zn2SnO4 and extends the rational and effective designs of metal/ternary ceramic materials for various applications.