Origin of high thermal stability of amorphous Ge1Cu2Te3 alloy: A significant Cu-bonding reconfiguration modulated by Te lone-pair electrons for crystallization. (15th May 2015)

• Record Type: Journal Article
• Authors: Chen, Nian-Ke; Li, Xian-Bin; Wang, Xue-Peng; Xia, Meng-Jiao; Xie, Sheng-Yi; Wang, Hai-Yu; Song, Zhitang; Zhang, Shengbai; Sun, Hong-Bo
• Is Part Of: Acta materialia. Volume 90(2015)
• Page Start: 88
• Page End: 93
• Publication Date: 2015-05-15
• Subjects: Bonding chemistry/physics -- Thermodynamic stability -- Phase transition -- First-principles calculations; Materials -- Periodicals; Materials science -- Periodicals; Materials -- Mechanical properties -- Periodicals; Metallurgy -- Periodicals; Chemistry, Inorganic -- Periodicals; 620.112
• DOI: 10.1016/j.actamat.2015.02.015
• Languages: English
• ISSNs: 1359-6454

Abstract

Graphical abstract: Abstract: Ge1 Cu2 Te3 is an important candidate for high-temperature phase change memory due to the fine amorphous stability. Yet, the basic bonding chemistry for its high-temperature application is still not completely clear. In this work, a new bonding mechanism for its amorphous and crystalline phases is proposed and demonstrated by first-principles calculations. Compared to the tetrahedral environment distributed evenly in crystalline form, Cu atoms in the amorphous state tend to be accumulated as trigonal clusters. For the crystalline phase, a bonding configuration of nonequivalent sp 3 hybridization with Te lone-pair electrons is proposed without Cu d electron participation. In the amorphous phase, however, a significant bonding reconfiguration of Cu d electrons occurs due to the isolation of the Te lone-pair electrons. Therefore, the notable contrast in the Cu atomic and electronic structures between the crystalline and amorphous phases results in an obvious phase transition barrier for high-temperature storage. The mechanism presented in this study serves as a reference for other transition-metal alloyed phase-change materials.