弛豫铁电体Pb(Mg1/3Nb2/3)O3中高于和低于伯恩斯温度时的软模动力学

Soft mode dynamics above and below the Burns temperature in the relaxor Pb(Mg1/3Nb2/3)O3.

作者信息

Gehring P M, Wakimoto S, Ye Z G, Shirane G

机构信息

NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA.

出版信息

Phys Rev Lett. 2001 Dec 31;87(27 Pt 1):277601. doi: 10.1103/PhysRevLett.87.277601. Epub 2001 Dec 11.

DOI:10.1103/PhysRevLett.87.277601

PMID:11800914

Abstract

We report neutron inelastic scattering measurements of the lowest-energy transverse optic (TO) phonon branch in the relaxor Pb(Mg1/3Nb2/3)O3 from 400 to 1100 K. Far above the Burns temperature T(d) approximately 620 K we observe well-defined propagating TO modes at all wave vectors q, and a zone center TO mode that softens in a manner consistent with that of a ferroelectric soft mode. Below T(d) the zone center TO mode is overdamped. This damping extends up to, but not above, the waterfall wave vector q(wf), which is a measure of the average size of the polar nanoregions.

摘要

我们报告了在400至1100 K温度范围内对弛豫铁电体Pb(Mg1/3Nb2/3)O3中最低能量横向光学（TO）声子分支的中子非弹性散射测量结果。在远高于约620 K的伯恩斯温度T(d)时，我们在所有波矢q处观察到定义明确的传播TO模式，以及在波矢为零处的TO模式，其软化方式与铁电软模一致。在T(d)以下，波矢为零处的TO模式出现过阻尼。这种阻尼一直延伸到但不超过瀑布波矢q(wf)，q(wf)是极性纳米区域平均尺寸的一种度量。