Title :
Enthalpies of Formation and Electronic Structures of Various Phases in Lead-Free Piezoelectric (K0.5Bi0.5)TiO3 Evaluated by First-Principles Calculation
Author :
Koyama, T. ; Shigemi, A. ; Wada, T.
Author_Institution :
Ryukoku Univ., Otsu
Abstract :
We calculated enthalpies of formation and evaluate electronic structures of various phases in (K0.5Bi0.5)TiO3 using a plane-wave pseudopotential method within a density functional formalism. In (K0.5Bi0.5)TiO3, the enthalpy of formation for a tetragonal (I4mm) phase was found to be lower than those of a cubic (Fm3 macrm) and a rhombohedral (R3m) phases. The result agreed with the experimental result that the tetragonal phase was stable at low temperatures. In the electronic structure of (K0.5Bi0.5)TiO3, a valence band mainly consisted of O 2p, Ti 3d and Bi 6p orbitals and the conduction band mainly consisted of Ti 3d, Bi 6p and O 2p antibonding orbitals. The features of the bondings between K and O, Bi and O, and Ti and O are discussed.
Keywords :
bismuth compounds; conduction bands; density functional theory; heat of formation; piezoelectric materials; potassium compounds; pseudopotential methods; valence bands; K0.5Bi0.5TiO3; conduction band; density functional formalism; electronic structures; enthalpy of formation; first-principles calculation; lead-free piezoelectric materials; plane-wave pseudopotential method; valence band; Bismuth; Bonding; Chemistry; Environmentally friendly manufacturing techniques; Lead; Linear discriminant analysis; Mesh generation; Orbital calculations; Piezoelectric materials; Temperature;
Conference_Titel :
Applications of Ferroelectrics, 2007. ISAF 2007. Sixteenth IEEE International Symposium on
Conference_Location :
Nara
Print_ISBN :
978-1-4244-1334-8
Electronic_ISBN :
1099-4734
DOI :
10.1109/ISAF.2007.4393231
