Observation of large dielectric permittivity and dielectric relaxation phenomenon in Mn-doped lanthanum gallate

Mohan, Hari; Saxena, Shailendra K.; Late, Ravikiran; Mishra, Vikash; Rajput, Parasmani; Sagdeo, Archna; Kumar, Rajesh; Sagdeo, Pankaj R.

doi:10.1039/c5ra28074e

Cited by 28 publications

(22 citation statements)

References 85 publications

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“…3,6 It is noticeable that this value of ε′ is estimated to be highest among lanthanide gallates ranging from La to Gd (LnGaO 3 ; Ln = La to Gd) as reported by Senyshyn et al 5 through rigorous computational analysis. Frequencyindependent and temperature-independent (up to ∼400 K) dielectric response (ε′ and tan δ) of LGO along with such low losses 3,4,6 makes it a good choice as a dielectric material. Moreover, LGO exhibits room-temperature (RT) orthorhombic crystal symmetry with pnma space group, and it undergoes various structural phase transformations under different temperature and pressure conditions.…”

Section: ■ Introductionmentioning

confidence: 82%

“…1,2 Further LGO exhibits a moderate dielectric constant (ε′ ≈ 25) 3−6 at room temperature with very low dielectric losses (tan δ < 0.01), 3,4,6 which remains almost unchanged up to 400 K when measured for different frequencies. 3,6 It is noticeable that this value of ε′ is estimated to be highest among lanthanide gallates ranging from La to Gd (LnGaO 3 ; Ln = La to Gd) as reported by Senyshyn et al 5 through rigorous computational analysis. Frequencyindependent and temperature-independent (up to ∼400 K) dielectric response (ε′ and tan δ) of LGO along with such low losses 3,4,6 makes it a good choice as a dielectric material.…”

Section: ■ Introductionmentioning

confidence: 99%

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Room-Temperature Magneto-dielectric Effect in LaGa_0.7Fe_0.3O_3+γ; Origin and Impact of Excess Oxygen

et al. 2017

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We report an observation of room-temperature magneto-dielectric (RTMD) effect in LaGaFeO compound. The contribution of intrinsic/resistive sources in the presently observed RTMD effect was analyzed by measuring direct-current (dc) magnetoresistance (MR) in four-probe geometry and frequency-dependent MR via impedance spectroscopy (MRIS). Present MRIS analysis reveals that at frequencies corresponding to grain contribution (≥1 × 10 Hz for present sample), the observed MD phenomenon is MR-free/intrinsic, whereas at lower probing frequencies (<1 × 10 Hz), the observed MD coupling appears to be MR-dominated possibly due to oxygen excess, that is, due to coexistence of Fe and Fe. The magnetostriction is anticipated as a mechanism responsible for MR-free/intrinsic MD coupling, whereas the MR-dominated part is attributed to hopping charge transport along with Maxwell-Wagner and space charge polarization. The multivalence of Fe ions in LaGaFeO was validated through iodometric titration and Fe K-edge X-ray absorption near-edge structure measurements. The excess of oxygen, that is, coexistence of Fe and Fe, was understood in terms of stability of Fe by means of "bond-valence-sum" analysis and density functional theory-based first-principles calculations. The cation vacancies at La/Ga site (or at La and Ga both) were proposed as the possible origin of excess oxygen in presently studied compound. Present investigation suggests that, to justify the intrinsic/resistive origin of MD phenomenon, frequency-dependent MR measurements are more useful than measuring only dc MR or comparing the trends of magnetic-field-dependent change in dielectric constant and tan δ. Presently studied Fe-doped LaGaO can be a candidate for RTMD applications.

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Section: ■ Introductionmentioning

confidence: 82%

Section: ■ Introductionmentioning

confidence: 99%

Room-Temperature Magneto-dielectric Effect in LaGa_0.7Fe_0.3O_3+γ; Origin and Impact of Excess Oxygen

et al. 2017

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“…Commercial anatase TiO 2 powder of Alfa Aesar with purity 99.999% has been used for characterization. In order to examine the structural phase purity, X-ray diffraction (XRD) experiment has been carried out on Bruker D8 diffractometer equipped with Cu target having LynxEye detector [6,[19][20][21]. The high-temperature X-ray diffraction measurements were performed to confirm the structural phase transition in the prepared samples.…”

Section: Structural Characterizationsmentioning

confidence: 99%

Investigation of temperature-dependent optical properties of TiO2 using diffuse reflectance spectroscopy

et al. 2019

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Temperature-dependent diffuse reflectance spectroscopy (DRS) measurements have been carried out on the polycrystalline sample TiO 2 . Important values from optical parameters such as band gap (E g ), Urbach energy (E U ), and Urbach focus (E 0 ) have been estimated in the range of 300-450 K. In order to understand the experimental value of band gap (E g ) of TiO 2 , i.e., obtained from DRS, a first-principle calculation has been performed. The dependency of E U and the slope of exponential tails (β 1 , β 2 ) of the density of states has also been studied which determines the distribution of exponential tails near the valence and conduction bands in semiconducting oxides. The behavior of optical band gap and E U has also been investigated with the influence of temperature using Cody model. From the temperature dependence of band gap measurements, the value of thermodynamical parameter such as Debye temperature (θ D ) has also been estimated. Thus it appears that the temperature-dependent optical absorption spectroscopy is very powerful and economical tool to probe the electronic structure near band edge and also to estimate the important thermodynamical parameter.

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“…To the best of our knowledge, JT compounds such as manganites are known to exhibit electron-phonon coupling mechanism through JT polaron hopping mechanism. [11,26] However, the presence of above-mentioned coupling in JT inactive compounds would be very interesting to explore. Therefore, Cr-substituted PrFeO 3 has been prepared by the wet chemical method, [27,28] and the interplay between electron dynamics and lattice has been studied in the same.…”

Section: Introductionmentioning

confidence: 99%

Orbital facilitated charge transfer originated phonon mode in Cr‐substituted PrFeO₃: A brief Raman study

Kumar

Umrao

Sagdeo

2020

J Raman Spectroscopy

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We report the possible origin of orbital facilitated new Raman mode in orthorhombic perovskite PrFe1‐xCrxO3. For this purpose, resonance and power‐dependent Raman spectroscopy measurements have been carried out to understand the origin of local oxygen breathing mode in the mixed Fe–Cr orthorhombic perovskites through the orbital mediated charge transfer mechanism. It has been observed that multi‐phonon scattering is highly sensitive to the presence of mixed Fe–Cr ions and is absent in pure iso‐structural vacuum annealed PrFeO3. The Raman spectroscopy results infer a scaling in the intensity of octahedral breathing Raman mode around 660 cm−1, which is attributed to the lattice rearrangement due to the transfer of an electron from Cr3+(d3) to Fe3+(d5) and results to d2–d6 (Cr4+–O−2–Fe2+) configuration. The interactions of d2–d6 configuration are different from d3–d5 configuration, which leads to the octahedral lattice rearrangement and activates the new Raman mode. The charge transfer phenomenon is supported through first‐principle calculations and valence band spectroscopy.

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Observation of large dielectric permittivity and dielectric relaxation phenomenon in Mn-doped lanthanum gallate

Abstract: Shifting of tan δ-peaks (100 Hz to 1 MHz) towards higher temperature; featuring dielectric relaxation.

Cited by 28 publications

References 85 publications

Room-Temperature Magneto-dielectric Effect in LaGa_0.7Fe_0.3O_3+γ; Origin and Impact of Excess Oxygen

Room-Temperature Magneto-dielectric Effect in LaGa_0.7Fe_0.3O_3+γ; Origin and Impact of Excess Oxygen

Investigation of temperature-dependent optical properties of TiO2 using diffuse reflectance spectroscopy

Orbital facilitated charge transfer originated phonon mode in Cr‐substituted PrFeO₃: A brief Raman study

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Observation of large dielectric permittivity and dielectric relaxation phenomenon in Mn-doped lanthanum gallate

Abstract: Shifting of tan δ-peaks (100 Hz to 1 MHz) towards higher temperature; featuring dielectric relaxation.

Cited by 28 publications

References 85 publications

Room-Temperature Magneto-dielectric Effect in LaGa0.7Fe0.3O3+γ; Origin and Impact of Excess Oxygen

Room-Temperature Magneto-dielectric Effect in LaGa0.7Fe0.3O3+γ; Origin and Impact of Excess Oxygen

Investigation of temperature-dependent optical properties of TiO2 using diffuse reflectance spectroscopy

Orbital facilitated charge transfer originated phonon mode in Cr‐substituted PrFeO3: A brief Raman study

Contact Info

Product

Resources

About

Room-Temperature Magneto-dielectric Effect in LaGa_0.7Fe_0.3O_3+γ; Origin and Impact of Excess Oxygen

Room-Temperature Magneto-dielectric Effect in LaGa_0.7Fe_0.3O_3+γ; Origin and Impact of Excess Oxygen

Orbital facilitated charge transfer originated phonon mode in Cr‐substituted PrFeO₃: A brief Raman study