EPR Monitoring of BaTiO3 Formation

Lu, Da-Yong; Ogata, Toru; Unuma, Hidero; Li, X.-B.; Kawai, Takeshi; Sun, Xiu Yun

doi:10.1007/s00723-011-0198-4

Cited by 3 publications

(5 citation statements)

References 30 publications

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“…The corresponding EPR signal at g factor (1.975) is related to Ti 3+ while g‐factor about 2.004 is close to the free electron g‐factor . In the considered materials, the occurrence of oxygen vacancy is a very probable scenario to ensure the local charge neutrality after substitutional doping ions.…”

Section: Resultsmentioning

confidence: 63%

“…And BTNN-5 ceramics exhibits a very slim loop. The piezoelectric properties d 33 and k p also decreases to zero.…”

Section: Resultsmentioning

confidence: 92%

“…The corresponding EPR signal at g factor (1.975) is related to Ti 3+ while g-factor about 2.004 is close to the free electron g-factor. 33,34 In the considered materials, the occurrence of oxygen vacancy is a very probable scenario to ensure the local charge neutrality after substitutional doping ions. In this case, the oxygen vacancy with trapped electron (F-centre) can be relevant and give rise to an EPR signal with the characteristic g-factor.…”

Section: Resultsmentioning

confidence: 99%

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The effect of grain boundary on the visible light absorption of BaTi_1‐x[Ni_1/2Nb_1/2]_xO_3‐δ ferroelectric ceramics

et al. 2019

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(Ni2+, Nb5+) co‐doped BaTiO3 ceramics BaTi1‐x(Ni1/2Nb1/2)xO3‐δ (BTNN‐100x) are prepared by a solid‐state reaction method, and their electrical and light absorption properties are investigated. The results show that BTNN‐100x can generate oxygen vacancies which pin the domain walls. BTNN‐100x bulk ceramics show strong visible light absorption. However, the phenomenon of visible light absorption disappear for BTNN‐100x ceramic powders, and the band gap of doped ceramic powders are nearly unchanged. The experiments demonstrate that stress and density have little effect on the band gap. And the grain boundary shows stronger cathodoluminescence (CL) emission. Actually, oxygen vacancies can be enriched at grain boundaries, and defect [Vo‐NiTi‐Vo] complex structures can be form and give rise to the visible light absorption as demonstrated by First‐principles calculations. Thus, the engineering design of ferroelectric grain boundaries may pave the way for the application of coupled ferroelectric‐photovoltaic processes.

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Section: Resultsmentioning

confidence: 63%

“…And BTNN-5 ceramics exhibits a very slim loop. The piezoelectric properties d 33 and k p also decreases to zero.…”

Section: Resultsmentioning

confidence: 92%

Section: Resultsmentioning

confidence: 99%

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The effect of grain boundary on the visible light absorption of BaTi_1‐x[Ni_1/2Nb_1/2]_xO_3‐δ ferroelectric ceramics

et al. 2019

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“…The signal is assigned to the formed paramagnetic Ti 3? (3d 1 ) species located at the sulfated-acid sites after the diamagnetic and EPR-silent sulfated TiO 2 precursor was calcined [19][20][21][22][23]. The simulation in Fig.…”

Section: Methodsmentioning

confidence: 99%

Probing the Catalytic Center of TiO2/SO4 2− Solid Superacid Catalyst by X-Band In Situ High-Temperature EPR Spectroscopy

et al. 2011

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Paramagnetic centers of the solid superacid catalyst in the sulfated TiO 2 are prone to the electron paramagnetic resonance (EPR) spectroscopy. The induction of the catalytic-active sites in TiO 2 powder presubmerged in H 2 SO 4 solution as a function of the calcinated temperature of 293-873 K is investigated by X-band in situ continuous-wave EPR measurements. Sulfated-acid sites composed of the Ti 3? ion are formed upon calcination. The overall experimental results show that the population of these sites goes uphill with the elevating temperature, reaches a maximum at *623 K and decreases afterward to close zero. During the process, the decomposition of the TiO 2 /SO 4 2-leads to the formation of Ti 3? species and then to the increasing EPR signal amplitude, and the consecutive decomposition of the sulfur at higher temperature ([650 K) to the diminishing signal. The X-ray diffraction indicates that the introduction of SO 4 2-stabilizes the geometric structure in the anatase phase.

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“…In particular, the ESR signal around g ¼ 2.00 is frequently observed in BaTiO 3 ceramics and has been believed to reflect a quite important origin that is closely related to PTCR phenomena 5,6,8,11,12 although different interpretations have been suggested by many researchers for the assignment of the signal. [5][6][7][8][9][10][11][12][13][14] Kutty et al 5 assigned the signal to V Ba by using starting materials with high purity, and Lu et al 14 subsequently supported the assignment. Jida and Miki 6 also used starting materials with high purity and considered that the signal stems from V Ba -V O at the grain boundary based on stoichiometry.…”

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confidence: 99%

Pulse-based electron spin transient nutation measurement of BaTiO3 fine particle: Identification of controversial signal around g = 2.00

Sawai

Yamaguchi

Kitamura

et al. 2018

Applied Physics Letters

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Two dimensional pulse-based electron spin transient nutation (2D-ESTN) spectroscopy is a powerful tool for determining the spin quantum number and has been applied to BaTiO 3 fine powder in order to identify the origin of the continuous wave electron spin resonance (CW-ESR) signal around g ¼ 2.00. The signal is frequently observed in BaTiO 3 ceramics, and the correlation between the signal intensity and positive temperature coefficient of resistivity (PTCR) properties has been reported to date. The CW-ESR spectrum of BaTiO 3 fine particles synthesized by the sol-gel method shows a typical asymmetric signal at g ¼ 2.004. The 2D-ESTN measurements of the sample clearly reveal that the signal belongs to the S ¼ 5/2 high spin state, indicating that the signal is not due to a point defect as suggested by a number of researchers but rather to a transition metal ion. Our elemental analysis, as well as previous studies, indicates that the origin of the g ¼ 2.004 signal is due to the presence of an Fe 3þ impurity. The D value (second-order fine structure parameter) reveals that the origin of the signal is an Fe 3þ center with distant charge compensation. In addition, we show a peculiar temperature dependence of the CW-ESR spectrum, suggesting that the phase transition behavior of a BaTiO 3 fine particle is quite different from that of a bulk single crystal. Our identification does not contradict a vacancy-mediated mechanism for PTCR. However, it is incorrect to use the signal at g ¼ 2.00 as evidence to support the vacancy-mediated mechanism.

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EPR Monitoring of BaTiO3 Formation

Cited by 3 publications

References 30 publications

The effect of grain boundary on the visible light absorption of BaTi_1‐x[Ni_1/2Nb_1/2]_xO_3‐δ ferroelectric ceramics

The effect of grain boundary on the visible light absorption of BaTi_1‐x[Ni_1/2Nb_1/2]_xO_3‐δ ferroelectric ceramics

Probing the Catalytic Center of TiO2/SO4 2− Solid Superacid Catalyst by X-Band In Situ High-Temperature EPR Spectroscopy

Pulse-based electron spin transient nutation measurement of BaTiO3 fine particle: Identification of controversial signal around g = 2.00

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EPR Monitoring of BaTiO3 Formation

Cited by 3 publications

References 30 publications

The effect of grain boundary on the visible light absorption of BaTi1‐x[Ni1/2Nb1/2]xO3‐δ ferroelectric ceramics

The effect of grain boundary on the visible light absorption of BaTi1‐x[Ni1/2Nb1/2]xO3‐δ ferroelectric ceramics

Probing the Catalytic Center of TiO2/SO4 2− Solid Superacid Catalyst by X-Band In Situ High-Temperature EPR Spectroscopy

Pulse-based electron spin transient nutation measurement of BaTiO3 fine particle: Identification of controversial signal around g = 2.00

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The effect of grain boundary on the visible light absorption of BaTi_1‐x[Ni_1/2Nb_1/2]_xO_3‐δ ferroelectric ceramics

The effect of grain boundary on the visible light absorption of BaTi_1‐x[Ni_1/2Nb_1/2]_xO_3‐δ ferroelectric ceramics