Occupational sites and dielectric properties of rare-earth and Mn substituted BaTiO3

Kishi, Hiroshi; Kohzu, Noriyuki; Iguchi, Yoshiaki; Sugino, Junichi; Kato, Makoto; Ohsato, Hitoshi; Okuda, Takashi

doi:10.1016/s0955-2219(01)00083-8

Cited by 83 publications

(40 citation statements)

References 6 publications

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“…21,24,27 The decrease in lattice parameters and unit cell volume observed in BNFM in comparison with pure BFO 24 is due to the fact that the effective ionic radii of Nd þ3 (0.983Å )/ Mn þ4 (0.530Å ) are lower than those of Bi þ3 (1.03Å )/Fe þ3 (0.645Å ) in A and B sites. 28,29 The density of the BNFM ceramics was measured using Archimedes principle and it was found to be 7.32 g/cm 3 . This value is about 92% of the theoretical BFO density, 30 and is close to the value 7.418 g/cm 3 obtained from XRD refinement analysis given in Table I.…”

Section: A Xrd and Rietveld Refinementmentioning

confidence: 99%

Dielectric anomalies due to grain boundary conduction in chemically substituted BiFeO3

Kumari

Ortega

Kumar

et al. 2015

Journal of Applied Physics

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We describe systematic studies on Nd and Mn co-doped BiFeO 3 , i.e., (Bi 0.95 Nd 0.05 ) (Fe 0.97 Mn 0.03 )O 3 (BNFM) polycrystalline electroceramics. Raman spectra and X-ray diffraction patterns revealed the formation of rhombohedral crystal structure at room temperature, and ruled out structural changes in BiFeO 3 (BFO) after low percentage chemical substitution. Strong dielectric dispersion and a sharp anomaly around 620 K observed near the Neel temperature (T N $ 643 K of BFO) support strong magneto-dielectric coupling, verified by the exothermic peak in differential thermal data. Impedance spectroscopy disclosed the appearance of grain boundary contributions in the dielectric data in the region, and their disappearance just near the Neel temperature suggests magnetically active grain boundaries. The resistive grain boundary components of the BNFM are mainly responsible for magneto-dielectric coupling. Capacitive grain boundaries are not observed in the modulus spectra and the dielectric behavior deviates from the ideal Debye-type. The ac conduction studies illustrate short-range order with ionic translations assisted by both large and small polaron hopping. Magnetic studies indicate that the weak antiferromagnetic phase of BNFM ceramics is dominated by a strong paramagnetic response (unsaturated magnetization even at applied magnetic field of 7 T). The bulk BNFM sample shows a good in-plane magnetoelectric coupling (ME) coefficient. V C 2015 AIP Publishing LLC. [http://dx

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Section: A Xrd and Rietveld Refinementmentioning

confidence: 99%

Dielectric anomalies due to grain boundary conduction in chemically substituted BiFeO3

Kumari

Ortega

Kumar

et al. 2015

Journal of Applied Physics

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“…This behavior is clearly different from the previous result for Ho-Mn-substituted BT solid solutions, which shows the decrease of the lattice parameter caused by oxidation of Mn. [7][8][9] To clarify the effect of V on the lattice parameter, the valency of V was examined. Ho-V-substituted samples showed the change of valency of V by re-oxidation, while La-V-substituted samples showed no change.…”

Section: Solubility and Dielectric Properties Of Rare Earth-and V-submentioning

confidence: 99%

Effect of re-oxidation on dielectric properties in Ni-MLCC

et al. 2007

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The effect of re-oxidation treatment on the solubility of dopants and the dielectric properties of rareearths (La, Ho) and V-substituted BaTiO 3 solid solutions, assuming the shell phase of X7R dielectrics, was investigated. Ho-V-substituted samples showed larger increase of the lattice parameter and T c by re-oxidation treatment compared with La-V-substituted samples. Electron spin resonance measurements revealed that the oxidation of V 3+ to V 4+ or V 5+ appeared in the range in which the increase of lattice parameter by re-oxidation treatment was observed. This suggests that the increase of T c is due to the change of preferential occupational site of Ho ion from A-site to Bsite, being accompanied with the oxidation of V 3+ . We also investigated the effect of re-oxidation treatment on the electrical properties and microstructure in Ni-MLCC samples, using rare-earths (La, Ho, Yb) and acceptors (Mn, V) doped BaTiO 3 based X7R dielectrics. The change in temperature characteristic of the dielectric constant by reoxidation treatment was observed for the MLCC samples containing V with smaller content. In the case of Ho-V-and Yb-V-doped samples showed larger increase of the dielectric constant at around 120°C compared with La-V-doped samples. The relationship between the microstructure and electrical properties of the MLCC sample was investigated by impedance measurement at elevated temperature.

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“…Many studies have tried to elucidate the effects of oxygen vacancies on the dielectric relaxation [10,11], the resistance degradation [3,7,[12][13][14][15], and the occupational site of rareearth elements in BaTiO 3 [16][17][18]. On the other hand, few studies have reported the effect of oxygen vacancies on the microstructure and dielectric-temperature behavior in core/shell structured BaTiO 3 .…”

Section: Introductionmentioning

confidence: 99%

Oxidation-induced strain relaxation and related dielectric-temperature behavior in core/shell grained BaTiO3

Jeon

Kang

2015

J Electroceram

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The effect of oxidation on dielectric-temperature behavior of core/shell grained BaTiO 3 was studied in an attempt to reveal the prime governing parameter of dielectrictemperature behavior. BaTiO 3 samples doped with 3 mol% Y 2 O 3 or 3 mol% Dy 2 O 3 with the same effective charges were sintered in a reducing atmosphere (Po 2 <10 −13 ) and oxidized at 1050-1250°C for 10 h in air. In the Y-doped samples, as the oxidation temperature increased, the fraction of the grains with ferroelectric domains in the shell increased from 18 to 54 % and the residual strain decreased. With an increased domain fraction, the dielectric-temperature behavior became poor, and a dielectric peak appeared. On the other hand, all the Dy-doped and air-annealed samples exhibited relatively high fractions of grains with ferroelectric domains in the shell, 32 % at 1050°C and 63 % at 1250°C, indicating a considerable reduction of residual strain in all the samples. The temperature stability of the Dy-doped samples was poor, and there was a dielectric peak, irrespective of the oxidation temperature. This difference in dielectric response between the Ydoped and Dy-doped samples reveals that the prime factor governing the dielectric-temperature stability is the residual strain in the core/shell grains rather than the previously suggested factors of defect concentration, dopant concentration in the shell and the occupational sites of rare-earth dopants.

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Occupational sites and dielectric properties of rare-earth and Mn substituted BaTiO3

Cited by 83 publications

References 6 publications

Dielectric anomalies due to grain boundary conduction in chemically substituted BiFeO3

Dielectric anomalies due to grain boundary conduction in chemically substituted BiFeO3

Effect of re-oxidation on dielectric properties in Ni-MLCC

Oxidation-induced strain relaxation and related dielectric-temperature behavior in core/shell grained BaTiO3

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