Electrical and magnetic studies on promising Aurivillius intergrowth compound

Veenachary, Vadla; Puli, Venkata Sreenivas; Babu, S. Narendra; Prasad, G.; Prasad, N. V.

doi:10.1007/s10854-022-09039-2

Cited by 5 publications

(4 citation statements)

References 52 publications

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“…In this scenario, the improved ME response observed for Sm-based intergrowth arises out of structural distortion. The tetragonal strain, orthorhombocity, and orthorhombic distortionsplay a major role in the polarization switching of Aurivillius oxides in view of octahedral distortions [33]. The replacement of Sm, La, Dy at the A-site has resulted in the orthorhombic distortion(b/a), tetragonal strain (c/a), and orthorhombocity (2(a − b)/(a + b)) of (0.9947,0.9974, 0.9943 for 4-layered phase& 0.9993, 0.9993,0.997 for 3-layered phase), (7.6242, 7.606, 7.6484 for 4-layered phase & 5.989, 5.963, 6.001 for 3-layered phase), and (0.0053, 0.0026, 0.0056 for 4-layered phase & 0.0007, 0.0007 0.0033 for 3-layered phase) respectively.…”

Section: Discussionmentioning

confidence: 99%

“…The mode ν 7 (470 cm −1 ) is due to changes that occurred in the bond distance Bi atom within the Bi 2 O 2 layer and its apical O-atom of the perovskite block. Two nearby modes ν 8 and ν 9 observed at 540 cm −1 and 560 cm −1 are due to the physically opposing oxygen atom from TiO 6 octahedral [29,[32][33][34]. The stretching modes of Bi/RE-O stand in A-site shows modes at ν 10 and ν 11 .…”

Section: Ferroelectric Studiesmentioning

confidence: 99%

“…In view of the significant ME coupling of the intergrowths based on the cobalt content, we chose the composition of Bi 3 NdTi 2 Fe 0.7 Co 0.3 O 12-δ -Bi 4 NdTi 3 Fe 0.7 Co 0.3 O 15 as a parent compound. Since rare-earth replacement at the Bismuth site in Aurivillius is known to reduce oxygen vacancies, [5,32,33] different rare earth ions, namely Dy, La, and Sm were doped at the A-site for the improved magnetoelectric coefficient. Detailed phase quantification, magnetization, and ME coupling are presented for different compositions.…”

Section: Introductionmentioning

confidence: 99%

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Magnetic and Magnetoelectric Properties of AurivilliusThree- and Four-Layered Intergrowth Ceramics

et al. 2023

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In this work, we have prepared intergrowth of multiferroic compounds namely Bi4RTi3Fe0.7Co0.3O15-Bi3RTi2Fe0.7Co0.3O12−δ (BRTFCO15-BRTFCO12) (rare earth (R) = Dy, Sm, La) by solid-state reaction method. From the X-ray diffraction Rietveld refinement, the structure of the intergrowths was found to be orthorhombic in which satisfactory fittings establish the existence of three-layered (space group: b 2 c b) and four-layered compounds (space group: A21am). Analysis of magnetic measurements confirmed a larger magnetization for theSm-modified intergrowth compound (BSTFCO15-BSTFCO12) compared to Dy- and La-doped ones. The emergence of higher magnetic properties can be due to distortion in the unit cell when some Bi3+ ions are replaced with the Sm3+, bonding of Fe3+-O-Co3+ as well as a possible mixture of FexCoy-type nanoparticles that are formed generally in the synthesis of intergrowths. The changes in the magnetic state of the Aurivillius intergrowths have been reflected in the magnetoelectric (ME) coupling: higher ME coefficient (~30 mV/Cm-Oe) at lower magnetic fields and is constant up to 3 kOe. The results were corroborated by Raman spectroscopy and variation of temperature with magnetization data. The results revealed that the RE-modified intergrowth route is an effective preparative method for higher-layer Aurivillius multiferroic ceramics.

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Section: Discussionmentioning

confidence: 99%

Section: Ferroelectric Studiesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Magnetic and Magnetoelectric Properties of AurivilliusThree- and Four-Layered Intergrowth Ceramics

et al. 2023

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“…The Aurivillius phase compounds were found to be familiar for their ferroelectric/magnetoelectric behavior, high transition temperatures, and strong anisotropic nature of spontaneous polarization [19]. Rare earth-modified A-site Aurivillius phases were studied to explore the changes in structural and ferroelectric properties [20]. These materials are well-suited for non-volatile memory devices due to their fatigue-free nature.…”

Section: Introductionmentioning

confidence: 99%

Magnetoelectric Properties of Aurivillius-Layered Perovskites

Veenachary,

Ramana,

Narendra Babu

et al. 2024

Crystals

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In the present work, we have synthesized rare-earth ion modified Bi4−xRExTi2Fe0.7Co0.3O12−δ (RE = Dy, Sm, La) multiferroic compounds by the conventional solid-state route. Analysis of X-ray diffraction by Rietveld refinement confirmed the formation of a polycrystalline orthorhombic phase. The morphological features revealed a non-uniform, randomly oriented, plate-like grain structure. The peaks evident in the Raman spectra closely corresponded to those of orthorhombic Aurivillius phases. Dielectric studies and impedance measurements were carried out. Asymmetric complex impedance spectra suggested the relaxation of charge carriers belonging to the non-Debye type and controlled by a thermally activated process. Temperature-dependent AC conductivity data showed a change of slope in the vicinity of the phase transition temperature of both magnetic and electrical coupling natures. Based on the universal law and its exponent nature, one can suppose that the conduction process is governed by a small polaron hopping mechanism but significant distortion of TiO6 octahedral. The doping of the A-sites with rare-earth element ions and changes in the concentrations of Fe and Co ions located on the B-sites manifested themselves in saturated magnetic hysteresis loops, indicating competitive interactions between ferroelectric and canted antiferromagnetic spins. The magnetic order in the samples is attributed to pair-wise interactions between adjacent Fe3+–O–Fe3+, Co2+/3+–O–Co3+/2+, and Co2+/3+–O–Fe3+ ions or Dzyaloshinskii–Moriya interactions among magnetic ions in the adjacent sub-lattices. As a result, enhanced magnetoelectric coefficients of 42.4 mV/cm-Oe, 30.3 mV/cm-Oe, and 21.6 mV/cm-Oe for Bi4−xDyxTi2Fe0.7Co0.3O12−δ (DBTFC), Bi4−xLaxTi2Fe0.7Co0.3O12−δ (LBTFC), and Bi4−xSmxTi2Fe0.7Co0.3O12−δ (SBTFC), respectively, have been obtained at lower magnetic fields (<3 kOe). The strong coupling of the Aurivillius compounds observed in this study is beneficial to future multiferroic applications.

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