Making room-temperature ferromagnetism in lead-free ferroelectric Bi0.5Na0.5TiO3 material

Thanh, Le Thi Hai; Doan, N. B.; Bac, Luong Huu; Thiet, Duong Van; Cho, S.; Bao, Peng; Dũng, Đặng Đức

doi:10.1016/j.matlet.2016.09.105

Cited by 58 publications

(21 citation statements)

References 16 publications

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“…Figure 3(a) presents the optical absorbance spectra of undoped Bi 0.5 Na 0.5 TiO 3 and CaFeO 3-δ -modified Bi 0.5 Na 0.5 TiO 3 materials at various concentrations at room temperature. The pure Bi 0.5 Na 0.5 TiO 3 samples exhibited a single absorbance edge, which is consistent with the recently reported optical properties of Bi 0.5 Na 0.5 TiO 3 materials 29,30,50,51 . The addition of CaFeO 3-δ to Bi 0.5 Na 0.5 TiO 3 caused the absorbance edge to shift to high wavelengths, indicating that the electronic band structures had been modified.…”

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confidence: 91%

“…Ferromagnetism in Fe-doped Bi 0.5 Na 0.5 TiO 3 materials is an intrinsic phenomenon, whereas ferromagnetism in Co-doped Bi 0.5 Na 0.5 TiO 3 materials is due to the presence of magnetic Co clusters 27,28 . Thanh et al reported that Mn-and Cr-doped Bi 0.5 Na 0.5 TiO 3 materials possibly influence room-temperature ferromagnetism 29,30 . On the other hand, the room-temperature ferromagnetic properties in Mn-doped Bi 0.5 Na 0.5 TiO 3 materials result from an interaction of the Mn cation through O vacancies, whereas those in Cr-doped Bi 0.5 Na 0.5 TiO 3 materials were mostly related to self-defects and enhancement via O vacancies 29,30 .…”

mentioning

confidence: 99%

“…Thanh et al reported that Mn-and Cr-doped Bi 0.5 Na 0.5 TiO 3 materials possibly influence room-temperature ferromagnetism 29,30 . On the other hand, the room-temperature ferromagnetic properties in Mn-doped Bi 0.5 Na 0.5 TiO 3 materials result from an interaction of the Mn cation through O vacancies, whereas those in Cr-doped Bi 0.5 Na 0.5 TiO 3 materials were mostly related to self-defects and enhancement via O vacancies 29,30 . Zhang et al predicted that a Na or Ti vacancy, rather than a Bi or O vacancy, could induce magnetism 31 .…”

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confidence: 99%

“…The decrease in the optical band gap in CaFeO 3-δ -modified Bi 0.5 Na 0.5 TiO 3 materials possibly originated from the random distribution of Ca and Fe cations into the host lattice of the Bi 0.5 Na 0.5 TiO 3 materials. The replacement of a Ti cation with a transition metal, such as Mn and Cr, in the Bi 0.5 Na 0.5 TiO 3 materials resulted in a decrease in the optical band gap because the impurities of these transition metal cations formed new local states in the middle of the electronic band structure 29,30 . In addition, the appearance of O vacancies located near the conduction band also affected the optical band gap of the Bi 0.5 Na 0.5 TiO 3 materials 29,30 .…”

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Intrinsic and tunable ferromagnetism in Bi0.5Na0.5TiO3 through CaFeO3-δ modification

Hung

Lam

Nguyen

et al. 2020

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New (1-x)Bi 0.5 na 0.5 tio 3 + xcafeo 3-δ solid solution compounds were fabricated using a sol-gel method. the cafeo 3-δ materials were mixed into host Bi 0.5 na 0.5 tio 3 materials to form a solid solution that exhibited similar crystal symmetry to those of Bi 0.5 na 0.5 tio 3 phases. The random distribution of Ca and fe cations in the Bi 0.5 na 0.5 tio 3 crystals resulted in a distorted structure. The optical band gaps decreased from 3.11 eV for the pure Bi 0.5 na 0.5 tio 3 samples to 2.34 eV for the 9 mol% CaFeO 3-δ -modified Bi 0.5 na 0.5 tio 3 samples. Moreover, the Bi 0.5 na 0.5 tio 3 samples exhibited weak photoluminescence because of the intrinsic defects and suppressed photoluminescence with increasing cafeo 3-δ concentration. Experimental and theoretical studies via density functional theory calculations showed that pure Bi 0.5 na 0.5 tio 3 exhibited intrinsic ferromagnetism, which is associated with the possible presence of Bi, Na, and Ti vacancies and Ti 3+ -defect states. Further studies showed that such an induced magnetism by intrinsic defects can also be enhanced effectively with CaFeO 3-δ addition. This study provides a basis for understanding the role of secondary phase as a solid solution in Bi 0.5 na 0.5 tio 3 to facilitate the development of lead-free ferroelectric materials.The integration of room-temperature ferromagnetic behavior in lead-free ferroelectric materials is a new research trend for the development of green functional materials in smart electronic devices 1,2 . PbTiO 3 -based compounds are one of the most commonly used ferroelectric materials in electronic devices 3 . Therefore, ferroelectric PbTiO 3 -based materials with improved magnetic properties have the potential for the fabrication of next-generation electronic devices.First, the self-organized ferromagnetism of pure ferroelectric PbTiO 3 materials was investigated. The experimental results showed that the weak ferromagnetism in undoped PbTiO 3 nanocrystalline at room temperature resulted from intrinsic defects in events such as O and Ti vacancies 4 . PbTiO 3 thin films also exhibited room-temperature ferromagnetism because of defects in the crystal quality of the film during growth 5 . Shimada et al. predicted that both O and Ti vacancies induce ferromagnetism but through different mechanisms. The ferromagnetism driven by O vacancies originated from the spin-polarized e g state of the nearest Ti atom, whereas that directed by Ti vacancies was attributed to the half-metallic p x state of the nearest O atom 6 . In addition, the ferroelectric property of PbTiO 3 materials at room temperature could be attributed to O vacancies formed on the surfaces, such as vacancies induced ferromagnetism due to local non-stoichiometry and orbital symmetry breaking 7 . Xu et al. conducted first-principle calculations and reported that the O vacancies that formed at the domain wall led to magnetism with a localized spin moment around the vacancies 8 . Second, the conversion of transition metals to ferroelectric PbTiO 3 materials was studied...

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supporting

confidence: 91%

mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Intrinsic and tunable ferromagnetism in Bi0.5Na0.5TiO3 through CaFeO3-δ modification

Hung

Lam

Nguyen

et al. 2020

Sci Rep

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“…The modification optical band gap of NiTiO 3 materials was recently reported for metal (Ag-, Mo-) or non-metal (N-) doped NiTiO 3 materials [20]. Our result was also consistent with recent observation of a reduction in optical band gap in transition metal such as Mn-, Cr-doped lead-free ferroelectric Bi 0.5 Na 0.5 TiO 3 materials, and Fe-and Ni-doped Bi 0.5 K 0.5 TiO 3 materials which resulted from the spin splitting of transition metal under crystal field to make effect optical band gap [21][22][23]. Therefore, we suggested that the reduction of optical band gap energy in NiTiO 3 materials via Co-dopants resulted from the localization new state of Co ions.…”

Section: Methodssupporting

confidence: 92%

EFFECTS OF Co DOPING ON PROPERTIES OF ILMENITE NiTiO3 CERAMICS

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2018

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Pure and Co-doped NiTiO 3 nanocrystalline powders were prepared by the sol-gel method. The effect of Co 2+ doping on structural, optical and magnetic properties of NiTiO 3 was investigated by X-ray diffraction, UV-vis absorption, Raman spectroscopy and vibration samples magnetometer. It was found that all fabricated samples were in single phase with rhombohedral structure. The presence of Co modifies the optical properties of the NiTiO 3 nanocrystalline powders. Co doping in NiTiO 3 resulted in decreasing of optical bandgap from 2.34 to 1.91 eV. The undoped and Co-doped samples showed weak ferromagnetism at room temperature.

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Tunable magnetic properties of Bi0.5Na0.5TiO3 materials via solid solution of NiTiO3

et al. 2018

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Making room-temperature ferromagnetism in lead-free ferroelectric Bi0.5Na0.5TiO3 material

Cited by 58 publications

References 16 publications

Intrinsic and tunable ferromagnetism in Bi0.5Na0.5TiO3 through CaFeO3-δ modification

Intrinsic and tunable ferromagnetism in Bi0.5Na0.5TiO3 through CaFeO3-δ modification

EFFECTS OF Co DOPING ON PROPERTIES OF ILMENITE NiTiO3 CERAMICS

Tunable magnetic properties of Bi0.5Na0.5TiO3 materials via solid solution of NiTiO3

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