Origin of Room Temperature Ferromagnetism in Cr-Doped Lead-Free Ferroelectric Bi0.5Na0.5TiO3 Materials

Thanh, Le Thi Hai; Doan, N. B.; Dũng, Nguyễn Quốc; Cuong, Le Quoc; Bac, Luong Huu; Duc, Nam; Bao, Peng; Dũng, Đặng Đức

doi:10.1007/s11664-016-5248-0

Journal of Elec Materi

2017

DOI: 10.1007/s11664-016-5248-0

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Origin of Room Temperature Ferromagnetism in Cr-Doped Lead-Free Ferroelectric Bi0.5Na0.5TiO3 Materials

Le Thi Hai Thanh

N. B. Doan

Nguyễn Quốc Dũng

et al.

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Cited by 61 publications

(36 citation statements)

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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.…”

supporting

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 .…”

mentioning

confidence: 99%

“…Chatzichristodoulou et al reported that the effective radius of O vacancies (1.31Å) is smaller than that of the O anion ion (1.4Å), resulting in a decrease lattice constants 46 . The flaccidity of the size of O vacancies on the lattice parameters has a more significant influence than that of dopants in perovskite Bi 0.5 Na 0.5 TiO 3 or BaTiO 3 materials 30,47 . Therefore, CaFeO 3-δ materials exists as a well solid solution in the Bi 0.5 Na 0.5 TiO 3 structure and distort the crystal structure of the latter.…”

mentioning

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 .…”

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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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%

mentioning

confidence: 99%

See 3 more Smart Citations

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

Hung

Lam

Nguyen

et al. 2020

Sci Rep

Self Cite

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Fe³⁺‐ and Nb⁵⁺‐Substituted Na_0.5Bi_0.5TiO₃: A Route toward Enhanced Ferroelectric Photovoltaic Response in Al/NBFNT/Ag Solar Cell through Reduced Bandgap and Controlled Oxygen Vacancy

Venkidu,

Raja,

Ruth

et al. 2023

Energy Tech

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Bulk ferroelectrics hold tremendous potential for the rapidly growing field of photovoltaic applications due to the separation of charge carriers caused by polarization, resulting in a high photovoltage. However, the wider bandgap in ferroelectrics limits their photoresponse. Attempts to tune the bandgap degrade ferroelectric polarization, while increased oxygen vacancy (V) in oxide perovskite hinders electron conduction and undermines ferroelectricity. Therefore, controlling V and maintaining polarization in reduced bandgap ferroelectric photovoltaics remains challenging. To address this, aliovalent Fe3+ and Nb5+ are co‐substituted on the B‐site of Na0.5Bi0.5TiO3 ceramics. Various techniques confirm the controlled V concentration, and UV‐absorption data reveal a reduction in bandgap energy from 3.01 to 2.38 eV through metal substitution. Density functional theory calculations identify a localized intermediate gap state within the bandgap, created by Fe–O hybridization, acting as a charge carrier scaffold and further reducing the bandgap energy to 2.47 eV. Remarkably, the Al/NBFNT75/Ag configuration achieves an augmented short‐circuit current density of 18.92 nA cm−2, while the open‐circuit voltage of the Al/NBFNT50/Ag device reaches 4.13 V. The resulting Al/NBFNT75/Ag device exhibits a maximum photovoltaic power density of 0.725 mW m−2 which is 9.5 times greater than Al/Na0.5Bi0.5TiO3/Ag. This approach successfully reduces V and achieves narrow bandgap conditions through suitable aliovalent substitution, leading to enhanced photovoltaic power, photosensing response, photoresponsivity, and specific detectivity.

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

et al. 2018

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Origin of Room Temperature Ferromagnetism in Cr-Doped Lead-Free Ferroelectric Bi0.5Na0.5TiO3 Materials

Cited by 61 publications

References 30 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

Fe³⁺‐ and Nb⁵⁺‐Substituted Na_0.5Bi_0.5TiO₃: A Route toward Enhanced Ferroelectric Photovoltaic Response in Al/NBFNT/Ag Solar Cell through Reduced Bandgap and Controlled Oxygen Vacancy

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

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Origin of Room Temperature Ferromagnetism in Cr-Doped Lead-Free Ferroelectric Bi0.5Na0.5TiO3 Materials

Cited by 61 publications

References 30 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

Fe3+‐ and Nb5+‐Substituted Na0.5Bi0.5TiO3: A Route toward Enhanced Ferroelectric Photovoltaic Response in Al/NBFNT/Ag Solar Cell through Reduced Bandgap and Controlled Oxygen Vacancy

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

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Product

Resources

About

Fe³⁺‐ and Nb⁵⁺‐Substituted Na_0.5Bi_0.5TiO₃: A Route toward Enhanced Ferroelectric Photovoltaic Response in Al/NBFNT/Ag Solar Cell through Reduced Bandgap and Controlled Oxygen Vacancy