Crystal structure of Bi0.9Sm0.1Fe1−xMnxO3 multiferroics

Abstract

Bi(0.9)Sm(0.1)Fe(1-x)Mn(x)O(3), with x=0.00, 0.15, 0.30 have been synthesised by solid-state reaction. The structures of the materials, characterised via Rietveld analysis of high resolution powder neutron diffraction data, reveal a structural transition from R3c to orthorhombic Imma symmetry is complete for the x=0.30 sample. The antiferromagnetic ordering temperature, magnitude of the ordered magnetic moment at the B-site, and the dielectric constant all decrease as a function of increasing Mn content.

Structural and magnetic properties of isovalently substituted multiferroic BiFeO3: Insights from Raman spectroscopy

“…As soon as Mn is introduced at the B site, the spectral features become fewer, broaden, and decrease in intensity. The decrease in the observed number of peaks is consistent with the R3c to I mma transition, 21 which should be accompanied by a decrease in the number of allowed Raman active modes from 13 in R3c to between five and seven in I mma, depending on the surface orientation. 3 and BiFeO 3 in the spectral range 150-1700 cm −1 .…”

“…For the Bi 0.9 Sm 0.1 Fe 1−x Mn x O 3 series x = 0.0, 0.15, and 0.30, and the Bi 1−x Tb x FeO 3 samples x = 0.05, 0.10, 0.15, and 0.20 used in the present magnetization investigations, the samples were those of the original neutron diffraction studies and these were prepared via conventional solid state synthesis route as detailed elsewhere. 15,21 Raman spectra collected on equivalent samples prepared by the different synthesis routes showed good agreement, however, the solution route samples showed greater phase purity and larger particle size and were therefore preferred for the detailed Raman studies.…”

“…The observation of biphasic substitution regions is often seen in similar perovskite series 19,21 and reflects a small energy difference between the two structures that might drive a separation into dopant rich and dopant deficient regions. For this reason, the clearly biphasic samples are excluded from the detailed Raman analysis that follows below.…”

“…15,21 For Bi 1−x Tb x FeO 3 , the transition is complete at x = 0.2, with a gradual nature at intermediate substitution levels being a sign of micron-scale substitution inhomogeneities.…”

“…7 Recent high resolution neutron diffraction data on the Bi 0.9 Sm 0.1 Fe 1−x Mn x O 3 series show a transition towards the centrosymmetric orthorhombic I mma symmetry (tilt system a 0 b − b − ) starting at x = 0.15 and complete for x = 0.3. 21 However, Khomchenko et al have shown a more complicated transition from a R3c structure to an incommensurate structure via P nam of the PbZrO 3 type. 22 Motivated by the discrepancies in reported structural data as well as a general lack of detailed Raman studies, we present here Raman, powder x-ray diffraction (PXRD), and magnetization data on Bi 1−x La x FeO 3 (Lax) (0 x 1), Bi 1−x Tb x FeO 3 (Tbx) (0 x 0.2), and Bi 0.9 Sm 0.1 Fe 1−x Mn x O 3 (Sm10Mnx) (0 x 0.3).…”