Charge storage in oxygen deficient phases of TiO$_2$: defect Physics without defects

Autor:	Padilha, A. C. M., Raebiger, H., Rocha, A. R., Dalpian, G. M.
Rok vydání:	2016
Předmět:	Condensed Matter - Materials Science
Druh dokumentu:	Working Paper
Popis:	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 TiO$_2$, known as Magn\'eli phases. These Ti$_n$O$_{2n-1}$ Magn\'eli phases 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 the same electronic quadruple donor transitions akin to interstitial Ti defect levels in TiO$_2$-rutile. Thus, the Magn\'eli phases behave as if they contained a very large pseudo-defect density: $\frac{1}{2}$ per formula unit Ti$_n$O$_{2n-1}$. 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. Comment: 5 pages, two-column, 5 figures
Databáze:	arXiv
Externí odkaz:	http://arxiv.org/abs/1602.02849 Zobrazit plný text záznamu View this record from Arxiv