Positive temperature coefficient of resistance of tetragonal Ti4+ doped nano SrFeO3−δ

Sendilkumar, A.; Raju, K. C. James; Babu, P. D.; Srinath, S.

doi:10.1016/j.jallcom.2013.01.124

Cited by 11 publications

(7 citation statements)

References 45 publications

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“…The obtained d.c. conductivity values from the Cole-Cole analysis 38 were calculated and are shown in Table 2. The obtained d.c. conductivity values from the Cole-Cole analysis 38 were calculated and are shown in Table 2.…”

Section: Resultsmentioning

confidence: 99%

A new single/few-layered graphene oxide with a high dielectric constant of 10⁶: contribution of defects and functional groups

Suresh

Srinath

et al. 2015

RSC Adv.

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In this study, we introduce a single/few-layered graphene oxide (GO) synthesized with ultrasonication, and demonstrate its high dielectric permittivity in the frequency range of 20 Hz to 2 MHz and temperature range of 30 C to 180 C. A high dielectric constant of GO ($10 6 ) with low loss was observed at 1 kHz and at 30 C, which is even very high compared to conventional dielectric materials such as CaCu 3 Ti 4 O 12 . The conductivity of our GO was calculated and found to be 3.980 Â 10 À5 to 1.943 Â 10 À5 (DC) and 2.0 Â 10 À3 to 1.7 Â 10 À2 (AC). The various conducting mechanisms governing the conductivity (AC and DC) of GO with varying frequency and temperature are assessed using impedance spectroscopy. The mechanistic approach and the role of functional groups, defects, temperature and frequency are elucidated and discussed with regard to the high dielectric constant. The variation of activation energy from 1.15 (1 kHz) to 0.58 (2.0 MHz) is related to the frequency dependent conductivity of the p-p conjugated electrons and their hopping has also been discussed. The present dielectric results are superior to those of GOL (with fewer defects/less sonication time). Moreover, the present findings suggest that the new GO can be used for scaling advances high performance electronic devices and high dielectric-based electronic and energy storage devices.

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Section: Resultsmentioning

confidence: 99%

A new single/few-layered graphene oxide with a high dielectric constant of 10⁶: contribution of defects and functional groups

Suresh

Srinath

et al. 2015

RSC Adv.

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“…), oxygen vacancies are commonly observed in the Fe-doped strontium titanate compound, STO:Fe. In fact, the formation of oxygen vacancies maintains the charge balance [17][18][19]. This structural characteristic can be used to reduce the electrical resistance of the undoped STO and to engineer high-sensitivity oxygen sensors [20].…”

Section: Introductionmentioning

confidence: 99%

Structural characterisation of slightly Fe-doped SrTiO3 grown via a sol–gel hydrothermal synthesis

Fuentes

Muñoz

Barraza

et al. 2015

J Sol-Gel Sci Technol

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A detailed structural study of the incorporation of Fe into SrTiO 3 nanoparticles is reported. Slightly irondoped strontium titanate nanoparticles with 0, 1, 3 and 5 mol% concentration of iron were grown using a sol-gel hydrothermal process and characterised using Raman scattering, X-ray photoelectron and X-ray diffraction spectroscopy. The amorphisation of the nanostructures was observed as the iron content increased, which was confirmed by the TEM images. The XPS results indicated that the oxidation states of the Sr atoms were maintained in 2?. However, a mixture of Fe 3? and Fe 4? atoms was observed as the Fe content increased, resulting in a significant number of oxygen vacancies in the perovskite structure. The analysis of Raman spectra indicated that the intensity, linewidth and frequency shift of the TO 4 phonon can be used as an indicator of the Fe content as well as a local temperature probe for future thermal analysis. Graphical abstract Temperature evolution of the Raman spectra of STO:Fe 1 mol%. The peaks with star correspond to the second-order processes. (b) Temperature dependence of the TO 4 phonon mode. Blue dots denote measured Raman spectra, and the red solid lines are the Lorentzian fits to respective spectra.

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“…8 Magnetization measurements were carried out using PPMS (Quantum Design) up to 90 kOe from 2 K to 300 K. Here after systems with x = 0 is T0, x = 0.1 to 0.3 are named as T1 to T3 for convenience. Results of impedance 17 and neutron diffraction were discussed.…”

Section: Methodsmentioning

confidence: 99%

Exchange bias effect in Ti doped nanocrystalline SrFeO3-δ

Kumar

Srinath

2014

AIP Advances

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Materials of Ti doped nanocrystalline SrFeO3-δ were synthesized through solid state reaction. Detailed magnetization measurements were carried out in zero field cooled (ZFC) and field cooled (FC) conditions. Compounds of SrFe1-xTixO3-δ (x = 0.1 to 0.3) are found to be spin glass and parent compound is a helical antiferromagnet. Non magnetic Ti4+ reduces the strength of exchange interactions and the curvature of hysteresis is changed towards concave nature. Exchange bias is observed below the peak temperature (irreversibility in magnetization (TIrr)) in ZFC-FC of SrFe1-xTixO3-δ (x = 0 to 0.3). The coercivity and exchange bias field values are found to be decreases with increase in temperature. Observed exchange bias effect is attributed to competition between antiferromagnetic superexchange and ferromagnetic double exchange interactions.

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Positive temperature coefficient of resistance of tetragonal Ti4+ doped nano SrFeO3−δ

Cited by 11 publications

References 45 publications

A new single/few-layered graphene oxide with a high dielectric constant of 10⁶: contribution of defects and functional groups

A new single/few-layered graphene oxide with a high dielectric constant of 10⁶: contribution of defects and functional groups

Structural characterisation of slightly Fe-doped SrTiO3 grown via a sol–gel hydrothermal synthesis

Exchange bias effect in Ti doped nanocrystalline SrFeO3-δ

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Positive temperature coefficient of resistance of tetragonal Ti4+ doped nano SrFeO3−δ

Cited by 11 publications

References 45 publications

A new single/few-layered graphene oxide with a high dielectric constant of 106: contribution of defects and functional groups

A new single/few-layered graphene oxide with a high dielectric constant of 106: contribution of defects and functional groups

Structural characterisation of slightly Fe-doped SrTiO3 grown via a sol–gel hydrothermal synthesis

Exchange bias effect in Ti doped nanocrystalline SrFeO3-δ

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Product

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A new single/few-layered graphene oxide with a high dielectric constant of 10⁶: contribution of defects and functional groups

A new single/few-layered graphene oxide with a high dielectric constant of 10⁶: contribution of defects and functional groups