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 Structural, magnetic and electronic properties of Ti-doped BaFeO3-d exhibiting colossal dielectric permittivity
Tác giả hoặc Nhóm tác giả: N.T. Dang, D.P. Kozlenko, N. Tran, B.W. Lee, T.L. Phan, R.P. Madhogaria, V. Kalappattil, D.S. Yang, S.E. Kichanov, E.V. Lukin, B.N. Savenko, P. Czarnecki, T.A. Tran, V.L. Vo, L.T.P. Thao, D.T. Khan, N.Q. Tuan, S.H. Jabarov, M.H. Phan
Nơi đăng: Journal of Alloys and Compounds; Số: 808;Từ->đến trang: 151760;Năm: 2019
Lĩnh vực: Khoa học; Loại: Bài báo khoa học; Thể loại: Quốc tế
TÓM TẮT
We report a systematical investigation of the structural, magnetic, electronic, and dielectric properties of BaFe1-xTixO3-d (x ¼ 0.05, 0.10, 0.15 and 0.20) samples synthesized via the solid-state reaction method. Rietveld refinement using a combination of room-temperature X-ray (XRD) and neutron powder diffraction (NPD) data confirms single phases with a 6H-type structure for all the samples. X-ray absorption spectroscopy (XAS) study reveals a coexistence of Fe3þ and Fe4þ, whose ratio remains almost unchanged with increasing Ti concentration. Magnetization measurements reveal a low-temperature inhomogeneous magnetic state with coexisting ferromagnetic (FM), AFM clusters and a paramagnetic phase. Moreover, magnetization of x ¼ 0.10 shows a pinched hysteresis loop behavior, suggesting the coexistence of hard and soft FM phases in samples with high Ti concentrations. Low-temperature NPD measurements also confirm the absence of any long-range magnetic order in the samples. A colossal dielectric permittivity and two relaxation processes are observed for most of the studied samples. There is a change in electric conduction mechanism from the small polaron hopping to the Mott's variablerange hopping with increasing Ti concentration.
ABSTRACT
We report a systematical investigation of the structural, magnetic, electronic, and dielectric properties of BaFe1-xTixO3-d (x ¼ 0.05, 0.10, 0.15 and 0.20) samples synthesized via the solid-state reaction method. Rietveld refinement using a combination of room-temperature X-ray (XRD) and neutron powder diffraction (NPD) data confirms single phases with a 6H-type structure for all the samples. X-ray absorption spectroscopy (XAS) study reveals a coexistence of Fe3þ and Fe4þ, whose ratio remains almost unchanged with increasing Ti concentration. Magnetization measurements reveal a low-temperature inhomogeneous magnetic state with coexisting ferromagnetic (FM), AFM clusters and a paramagnetic phase. Moreover, magnetization of x ¼ 0.10 shows a pinched hysteresis loop behavior, suggesting the coexistence of hard and soft FM phases in samples with high Ti concentrations. Low-temperature NPD measurements also confirm the absence of any long-range magnetic order in the samples. A colossal dielectric permittivity and two relaxation processes are observed for most of the studied samples. There is a change in electric conduction mechanism from the small polaron hopping to the Mott's variablerange hopping with increasing Ti concentration.
[ 7. toan 2019.pdf ]
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