Effect of -site randomness on the antiferroelectric/relaxor nature of the ground state; Diffuse and inelastic X-ray scattering study of Pb(InNb)O

基底状態における反強誘電性/リラクサ性へのサイトのランダムネスの影響; Pb(InNb)OのX線散漫散乱及び非弾性X線散乱測定

大和田 謙二*; 塚田 慎也*; 福田 竜生  ; 筒井 智嗣*; Baron, A. Q. R.*; 水木 純一郎*; 大和 英弘*; 安田 直彦*; 寺内 暉*

Owada, Kenji*; Tsukada, Shinya*; Fukuda, Tatsuo; Tsutsui, Satoshi*; Baron, A. Q. R.*; Mizuki, Junichiro*; Owa, Hidehiro*; Yasuda, Naohiko*; Terauchi, Hikaru*

The effect of -site randomness on the antiferroelectric/relaxor nature of the ground state was investigated by studying diffuse and inelastic X-ray scattering from ordered and disordered Pb(InNb)O (O- and D-PIN) single crystals. The diffuse scattering measurement of O-PIN (antiferroelectric at ) shows the existence of ferroelectrically interactive local polarization above . Inelastic X-ray scattering shows that the transverse-acoustic (TA) and transverse-optic (TO) modes are dominant at 800 K, while the central peak (CP) and TA modes are coupled and majorly contribute to the critical behavior of the diffuse scattering at . Upon these results, the -site randomness is discussed in terms of suppressing the antiferroelectric instability and enhancing the polarization fluctuation.