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.