Colossal dielectric behavior and dielectric anomalies in Sr2TiCrO6 ceramics

Sun, Jiaxin; Ahmed, Rashida; Wang, G. J.; Wang, S. T.; Wang, J.; Xie, Yong; Hong, Bo; Wang, C. C.

doi:10.1007/s10853-018-03298-3

Cited by 10 publications

(3 citation statements)

References 44 publications

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“…[ 21 ] So, the XPS analysis for oxygen must show, in addition to, peak for lattice oxygen (LO) and peaks for oxygen vacancy (VO), a peak for chemically adsorbed water (CO). [ 22 ] The XPS spectrum of O1s is fitted with Gaussian–Lorentz curve fitting, and three peaks at 528.8, 530.9, and 531.8 eV were fitted ( Figure 6 ). The CO peak reduces, as the Al concentration increases, until it almost vanishes at x = 1 sample.…”

Section: Resultsmentioning

confidence: 99%

Effect of Humidity Adsorption on Mixed Valence Dielectric Material LaFe_1−xAl_xO₃

Ahmed

Rehman

et al. 2020

Physica Status Solidi (b)

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In mixed‐valence colossal dielectric materials, the room temperature Maxwell–Wagner response is commonly assigned, in the past literature, to the electrode effect, grain boundary effect, or internal barrier layer capacitor effect. Another underlying phenomenon is brushed aside, and that is of adsorbance of the hydroxyl ions onto the defect centers on the surface of dielectric material. The properties of dielectric materials, especially those having oxygen vacancies, are sensitive to the atmospheric moisture and easily degrade in the humid environment. To study this effect, a series of LaFe1 − xAlxO3 samples (x = 0, 0.1, 0.2, …, 0.8, and 1) are prepared by the sol–gel method, and the effect of humidity sensitivity on their dielectric properties is seen. The samples with greater Fe concentration show distinct humidity‐sensitive properties with both metal electrodes (Pt and Ag) with a very miniscule difference in their measurement values. The effect of hydroxyl ions is further confirmed by the dielectric measurements after the thermal quenching of the samples that verify the adsorbance of water molecules on the surface of dielectric material.

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Section: Resultsmentioning

confidence: 99%

Effect of Humidity Adsorption on Mixed Valence Dielectric Material LaFe_1−xAl_xO₃

Ahmed

Rehman

et al. 2020

Physica Status Solidi (b)

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“…Preliminary studies on poly-crystalline Sr 2 CrTiO 6 reveal the compound as insulating with a ferroelectric hysteresis loop though the origins are not clear [24]. Similarly, Sun et al [25] observe a colossal dielectric behaviour in polycrystalline Sr 2 CrTiO 6 . However, the magnetic behaviour of Sr 2 CrTiO 6 has not been explored experimentally or theoretically.…”

Section: Introductionmentioning

confidence: 97%

Structural, electronic and magnetic properties of weakly correlated metal Sr₂CrTiO₆: a first principles study

Dhawan

Padmanabhan

Nautiyal

2021

J. Phys.: Condens. Matter

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Structural, electronic and magnetic behaviour of a less-explored material Sr2CrTiO6 has been investigated using ab initio calculations with generalized gradient approximation (GGA) and GGA + U methods, where U is the Hubbard parameter. For each of the three possible Cr/Ti cationic arrangements in the unit cell, considered in this work, the non-magnetic band structure shows distinct traits with significant flat-band regions leading to large t 2g density of states around the Fermi energy. The Cr4+ ion in Sr2CrTiO6, which is a d 2 system, shows a reverse splitting of the t 2g orbitals. The calculated hopping matrix contains non-zero off-diagonal elements between the d xz and d yz orbitals, while the d xy orbitals remain largely unmixed. A minimal tight binding model successfully reproduces the six t 2g bands around the Fermi energy. The Fermi surface shows a two-dimensional nesting feature for the layered arrangement of Cr and Ti atoms. Fixed spin moment studies suggest that the magnetism in this compound cannot be explained by Stoner’s criterion of an itinerant band ferromagnet. In the absence of Hubbard U term, the ground state is a half-metallic ferromagnet. Calculations for the anti-ferromagnetic spin arrangement show re-arrangement of orbital character resulting in (a) narrow d xz /d yz bands and sharp peaks in the density of states at the Fermi energy and (b) highly dispersive d xy bands with a broader density of states around the Fermi energy. The metallicity persists even with increasing U for both the spin arrangements, thus suggesting that Sr2CrTiO6 belongs to the class of weakly correlated metals, while the shifting of O 2p states towards the Fermi energy with U indicates a negative charge-transfer character in Sr2CrTiO6.

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“…However, these descriptions cannot simultaneously account for high loss factors, low breakdown voltages, low resistance over grain boundaries, nor how colossal permittivity scales with system size . Colossal permittivity ranges by orders of magnitude in different materials, but also in samples of the same stoichiometry . This means there is an intrinsic effect in these materials which is responsible for IBLC.…”

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The Fundamental Mechanism Behind Colossal Permittivity in Oxides

Taylor

Davies

et al. 2019

Advanced Materials

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Colossal permittivity materials exhibit extreme polarization in an applied electric field, providing applications in electronics and energy transmission. Understanding the atomic‐scale mechanism behind colossal permittivity remains a challenging task and is key to optimizing materials with this property. The fundamental mechanism of colossal permittivity is reported and, using CaCu3Ti4O12 as an example, it is attributed to the formation of an unusual metallic interface between the grain and grain boundary materials (CaCu3Ti4O12 and CuxO (x = 1, 2), respectively), not created by oxygen vacancies as is normally the case in oxide materials. This metallic layer around the grain forms confined shells of charge that pool on one side when under an applied field, which results in colossal permittivity. A route towards enhancing colossal permittivity is explained by means of manipulating the interface properties, as well as altering sample geometries. A methodology to artificially engineer colossal permittivity metamaterials is also shown.

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Colossal dielectric behavior and dielectric anomalies in Sr2TiCrO6 ceramics

Cited by 10 publications

References 44 publications

Effect of Humidity Adsorption on Mixed Valence Dielectric Material LaFe_1−xAl_xO₃

Effect of Humidity Adsorption on Mixed Valence Dielectric Material LaFe_1−xAl_xO₃

Structural, electronic and magnetic properties of weakly correlated metal Sr₂CrTiO₆: a first principles study

The Fundamental Mechanism Behind Colossal Permittivity in Oxides

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Colossal dielectric behavior and dielectric anomalies in Sr2TiCrO6 ceramics

Cited by 10 publications

References 44 publications

Effect of Humidity Adsorption on Mixed Valence Dielectric Material LaFe1−xAlxO3

Effect of Humidity Adsorption on Mixed Valence Dielectric Material LaFe1−xAlxO3

Structural, electronic and magnetic properties of weakly correlated metal Sr2CrTiO6: a first principles study

The Fundamental Mechanism Behind Colossal Permittivity in Oxides

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Product

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Effect of Humidity Adsorption on Mixed Valence Dielectric Material LaFe_1−xAl_xO₃

Effect of Humidity Adsorption on Mixed Valence Dielectric Material LaFe_1−xAl_xO₃

Structural, electronic and magnetic properties of weakly correlated metal Sr₂CrTiO₆: a first principles study