Charge storage in oxygen deficient phases of TiO2: defect Physics without defects

Author(s)

Padilha, A. C. M. ^{[1, 2]} ; Raebiger, H. ^{[1, 2]} ; Rocha, A. R. ^[3] ; Dalpian, G. M. ^[1]

Affiliation

^[1] Univ Fed ABC, Ctr Ciencias Nat & Humanas, Santo Andre, SP - Brazil

^[2] Yokohama Natl Univ, Dept Phys, Yokohama, Kanagawa - Japan

^[3] Univ Estadual Paulista, Inst Fis Teor, Sao Paulo, SP - Brazil

• Document type: Journal article
• Source: SCIENTIFIC REPORTS; v. 6, JUL 1 2016.
• Web of Science Citations: 19

Abstract

Defects in semiconductors can exhibit multiple charge states, which can be used for charge storage applications. Here we consider such charge storage in a series of oxygen deficient phases of TiO2, known as Magneli phases. These Magneli phases (TinO2n-1) present well-defined crystalline structures, i.e., their deviation from stoichiometry is accommodated by changes in space group as opposed to point defects. We show that these phases exhibit intermediate bands with an electronic quadruple donor transitions akin to interstitial Ti defect levels in rutile TiO2. Thus, the Magneli phases behave as if they contained a very large pseudo-defect density: 1/2 per formula unit TinO2n-1. Depending on the Fermi Energy the whole material will become charged. These crystals are natural charge storage materials with a storage capacity that rivals the best known supercapacitors. (AU)

• FAPESP's process: 10/16202-3 - Electronic, magnetic and transport properties of nanostructures
• Grantee: Adalberto Fazzio
• Support type: Research Projects - Thematic Grants
• FAPESP's process: 13/22577-8 - Collaboration of UFABC and Yokohama National University for the theory of nanostructures at interfaces and embedded inside bulk materials
• Grantee: Gustavo Martini Dalpian
• Support type: Research Grants - Visiting Researcher Grant - International
• FAPESP's process: 15/05830-7 - Ab initio simulations of memristive systems: from the raw material to the device
• Grantee: Antonio Cláudio Michejevs Padilha
• Support type: Scholarships abroad - Research Internship - Doctorate
• FAPESP's process: 11/19924-2 - Study and development of advanced novel materials: electronic, magnetic and nanostructured: an interdisciplinary approach
• Grantee: Carlos Rettori
• Support type: Research Projects - Thematic Grants
• FAPESP's process: 11/21719-8 - Ab initio simulations of memristive systems: from the raw material to the device
• Grantee: Antonio Cláudio Michejevs Padilha
• Support type: Scholarships in Brazil - Doctorate