Probing of nanoscaled nonstoichiometric 1:1 ordering in Pb(Mg1/3Nb2/3)O3-based relaxor ferroelectrics by Raman spectroscopy

The nanoscaled nonstoichiometric 1:1 ordering in various Pb(Mg1/3Nb2/3)O3-based relaxor ferroelectric ceramics [Pb1−xREx{(Mg1−yDy)(1+x)/3Nb(2−x)/3}O3, where RE=La3+, Pr3+, 4+, Nd3+, Sm3+, D=Ni2+, Zn2+, Cd2+, x=0–0.2, and y=0–0.2], is investigated by X-ray diffractometry, transmission electron microscopy (TEM), and Raman spectroscopy. Raman spectroscopy discerns the nonstoichiometric 1:1 ordering in the nanoscaled region smaller than 20 nm, which could be investigated only by the selected area electron diffraction patterns of TEM. It is demonstrated that Raman spectroscopy can be a useful tool for probing of the nanoscaled nonstoichiometric 1:1 ordering in the Pb(B′II1/3B″V2/3)O3-type relaxor ferroelectric ceramics.