Structural incommensurate modulation rule in hexagonal Ba(Ti1-xMx)O3-δ (M = Mn, Fe) multiferroics

Abstract

The structural incommensurate modulation (SIM) rule in hexagonal Ba(Ti1-xMx)O3-δ (1/18 ≤ x ≤ 1/3, M = Mn, Fe) multiferroic ceramics is investigated using transmission electron microscope (TEM). Our systematic analysis on the modulation characteristics in the electron diffraction patterns, especially along [001] direction, reveals that three types of anti-phase domain boundaries (APBs) dominate the SIMs. According to the derived APB models, the calculated oxygen vacancies at both O1 (face sharing) and O2 (corner sharing) sites qualitatively agree quite well with our previous results. Analysis on the high-resolution TEM images reveals that complex dislocation structures also play important roles in the formation of the SIMs.

Ferromagnetic antiphase domain boundary in Mn-doped hexagonal BaTiO3 multiferroics

“…In spite that the concentration of Ti 3þ ions and Vo in the PA samples cannot be obtained by fitting their susceptibilities using the CW formula, our systematic analysis on the electron diffraction patterns provides us an averaged Vo distribution at O1 and O2 sites from the corresponding APB structures. 18 In the AG BTM11 and AG BTM17, the vacancy contents d ¼ 0.141 and 0.189 are consistent with our calculation based on the CW fitting. In the PA BTM11 and PA BTM17, the vacancy contents are d ¼ 0.097 and 0.103, respectively, which are consistent with our XRD refinements.…”

“…Our systematic TEM studies on Fe and Mn doped h-BaTiO 3 have revealed a structural incommensurate modulation rule, which is ascribed to the antiphase domain boundary (APB) structures. 18 Based on this, we report in this paper the magnetic properties of h-Ba(Ti 1Àx Mn x )O 3Àd (x ¼ 1/9, 1/6) samples. Associated with the thermal treatment effects and dielectric behavior analysis, we present experimental evidences on the origin of high-temperature FM in Mn-doped h-BaTiO 3 .…”

“…Here, two important things worth noting: (i) the density of the APBs in the doped samples is very high, averagely speaking, each antiphase domain contains 2a $ 3a (a is the lattice parameter) h unit cells; (ii) the antiphase boundaries do not strictly locate at certain crystal planes, as imaged by the high-resolution TEM images presented in Ref. 18.…”