21–23 May 2018
Topland | Hotel & Convention Center Phitsanulok
Asia/Bangkok timezone

First principles study of local and electronic structures of yttrium-doped Ba(Zr$_x$Ti$_{1-x}$)O$_3$

22 May 2018, 09:45
15m
Phetchabun Room

Phetchabun Room

Oral Condensed Matter Physics A6: Condensed Matter and Accelerators

Speaker

Mr Wiriya Thammada (Department of Physics, Faculty of Science, Mahidol University)

Description

Here we report the first principles study of yttrium-doped Ba(Zr$_x$Ti$_{1-x}$)O$_3$ (Y-doped BZT) for $x=0.125$, $0.250$, and $0.375$ supercells as a promising rare earth doped lead-free ferroelectric material. The local and electronic structures of Y-doped BZT and pure BZT relaxed supercells are systematically investigated in term of atomic pair distribution functions (PDFs), A and B site cation off-centering, and electronic density of states (DOS) respectively. The PDF spectrums show the increasing of structural disorder as a function of Zr concentration, while the short-range disorder is strongly influenced by the size of cation and their corresponding vacancies. Moreover, the drastic diffusion in PDF spectrums of Y-doped BZT reflects the compositional fluctuation on the local environment of the supercells. For cation off-centering, Ti$^{4+}$ play a major role as the active ferroelectric distortion in BZT. However, the substitution of yttrium ions into BZT matrix enhanced the lattice distortion as observed from the increasing of off-centering magnitude for both A and B site cations. The calculated total and projected DOSs on $d$ states of cations and O-$2p$ states confirm the strong hybridization between Ti $3d$ and O $2p$ states, thus implying the covalent bonding in Ti-O$_6$ octahedral. On the other hand, the little effects of yttrium ions on the electronic structures, especially the highest and lowest valence and conduction bands, were observed.

Primary author

Mr Wiriya Thammada (Department of Physics, Faculty of Science, Mahidol University)

Co-author

Dr Malliga Suewattana (Department of Physics, Faculty of Science, Mahidol University)

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