Hydrothermal synthesis of LiMnPO4-C(sp2) hybrids, conductive channels, and enhanced dielectric permittivity: a modulated ionic conductor

Sharma, Shubham; Rajeswari, P.; Tiwari, Balgovind; Ram, S.

doi:10.1007/s11581-016-1800-4

Cited by 7 publications

(12 citation statements)

References 38 publications

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“…The frequency σ′ dependence at higher temperatures (Fig. 8b) follows the well-known Jonscher power-law, as prevails in many conductive glasses and polymeric systems [43][44][45] ,…”

Section: Magnetic Propertiessupporting

confidence: 59%

“…In the second region below 1 kHz up to 0.1 Hz (limited according to the frequency window studied), the ε′ value rises progressively at lower frequencies. As usual 43,44 , the temperature progressively promotes the final ε′ values. Two factors govern enhanced ε′ values at low frequencies; (i) space charge polarization and (ii) interfacial polarization due to domain-wall motion, usually found in multicomponent materials [45][46][47] .…”

Section: Magnetic Propertiesmentioning

confidence: 81%

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Structural, Magnetic, and Dielectric properties of Sr4Fe6O13 ferrite prepared of small crystallites

Azab

Mansour

Turky³

2020

Sci Rep

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A stable Sr 4 fe 6 o 13 was prepared as small crystallites by auto-combustion of a sol-gel in air followed by annealing the later at pertinent temperatures. A green sample, as annealed at elevated temperatures, yields a single Sr 4 fe 6 o 13 phase of tailored magnetic properties. the structural, morphological, magnetic and electrical properties were investigated by X-ray diffraction, transmission electron microscopy, vibrating sample magnetometer, and broadband dielectric spectrometer. Hard magnetic Sr 4 fe 6 o 13 properties arise with saturation magnetization M s = 12.4 emu/g, coercivity H c = 3956.7 Oe and squareness 0.512. Studies made at low temperatures reveals M s decreasing on increasing temperature from 17.5 emu/g at 85 K down to 12.4 emu/g at 305 K, while H c rises from 1483 Oe at 85 K to 1944 Oe at 305 K. The ac-conductivity follows the Jonscher relation. The dc-conductivity at high temperatures/ low frequencies exhibits a plateau and it depends linearly on a characteristic frequency according to the Barton-nakajima-namikawa) relation. Perovskites are compounds of a structural formula ABC 3 , where A represents a rare earth, alkaline earth, alkali or large ions such as Pb 2+ , Bi 3+ , B represents a transition metal ion and C represents O, Fl, Cl, I etc 1. A cation may be monovalent like Li, Na, K, divalent like Ca, Ba, Sr or trivalent like La, Nd, Pr, which is cubo-octahedrally coordinated to 12 O 2− ions, while B cation, such as Ti, Ni, Fe, Co, or Mn is octahedrally coordinated to 6 O 2− ions 2. Recently, several investigations performed on a Sr-Fe-O structure reveal its amazing structural and physical features such as cheap price, high magnetic anisotropy, high Curie temperature, a significant magnetization of saturation and remarkable chemical and corrosion resistance 3. The reason certainly presented by oxygen-lacking perovskites and by Ruddlesden-Popper (RP) type structure that possess a desirably negative magnetoresistance (-ve MR) 4-7. A Sr-Fe-O system includes many types of perovskites and perovskite derivatives of widely varied crystalline and magnetic features 8-12. These types of substances are constructed based on a K 2 NiF 4 shape and involve slab segments of SrFeO 3 and SrO, where SrFeO 3 is resulting from a KNiF 3 cubic perovskite of K 2 NiF 4 , and SrO is matching to a NaCl-class KF 8. They characteristically contain paramagnetic Fe 4+ ions. In particular, a stoichiometric compound Sr 4 Fe 6 O 13 has a construction of a perovskite or its derivatives 8. It is observed that a Sr 4 Fe 6 O 13±δ construction is a highly stable single-phase compound and it exhibits significant conductivity of combined-ions and electrons types 13. That is composed of altered sections through a Sr-Fe-O layer (b-axis) and dual slabs of FeO in FeO 5 polygons 14-16. As a result, it owes an anisotropic shape in it conducts through O 2− ions and vacancies across the a-c planes 17. Actually, creation of O 2− empty sites and interstitials develop non-perovskite slabs in a Sr 4 Fe 6 O 13±δ phase keeps them in a broad a...

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“…The frequency σ′ dependence at higher temperatures (Fig. 8b) follows the well-known Jonscher power-law, as prevails in many conductive glasses and polymeric systems [43][44][45] ,…”

Section: Magnetic Propertiessupporting

confidence: 59%

Section: Magnetic Propertiesmentioning

confidence: 81%

Structural, Magnetic, and Dielectric properties of Sr4Fe6O13 ferrite prepared of small crystallites

Azab

Mansour

Turky³

2020

Sci Rep

View full text Add to dashboard Cite

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“…Three distinct elliptical curves comprise the experimental plot in Figure 10a in a "hybrid composite" of recurrent charge carriers. Multiple semicircles were observed recently in C-LiMnPO 4 15 and C-Fe 3 O 4 35 core− shells. The recurring relaxation processes are a key factor of promoting the dielectric properties in a network of small core− shells of multiple surfaces.…”

Section: ωτmentioning

confidence: 57%

“…Dielectric and electrical properties were studied of C-CaIn 2 O 4 pellets over 1 to 1 × 10 6 Hz frequencies at room temperature, using a LCR meter. 15 To make a dense pellet, a powder C-CaIn 2 O 4 was compacted in a 10 mm diameter (l = 2.515 mm thickness) in a mold at a 200 kg/cm 2 pressure and heated in a microwave at 250 °C for 30 min.…”

Section: ■ Experimental Detailsmentioning

confidence: 99%

Biogenic Synthesis of Tunable Core–Shell C-CaIn₂O₄, Interface Bonding, Conductive Network Channels, and Tailored Dielectric Properties

Tiwari

Ram

Banerji

2018

ACS Sustainable Chem. Eng.

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A green aloe-vera gel contains small tissues (as capillaries), which easily upload Ca2+/In3+ species (upon adding in a solution) so as to form a hybrid complex and conduct a local carbothermic reaction (on heating) in the capillaries, forming a nanohybrid C-CaIn2O4, small core–shells of a tunable carbon-shell of a few molecular layers. Thin C-CaIn2O4 plates (15–20 nm thickness) thus were grown preferentially in (200) facets in a tetragonal crystal structure on a mixed gel which was burnt in camphor in air. The shell thickness was thermally etched down, δ = 3 → 0.5 nm, by post-heating at 400–600 °C in air. It finely tailors dielectric properties on account of interfaces, conducting networks, multiple surfaces, and O2– vacancies/twins (induced in a deoxidizing carbon) with effectively enhanced “e––h+” ion pairs useful for supercapacitors and other devices. In a proposed model, the CaIn2O4 bonds over C-sp2 via O2– in polygons in a network of a 2D-interface Ca2+/In3+–O–C (δ ≥ 0.5 nm), which, when heating, exists (≤1% mass) well up to 600 °C in air. A regular monolayer is very critical for feeding a huge dielectric permittivity εr(s) ∼ 6.9 × 106 on a moderate conductivity σdc ≤ 0.8 × 10–4 S·cm–1 at frequency ω → 0. After relaxing rapidly, a fairly steady εr = 7.6 × 103 lasts of yet a usefully large value over ω ≥ 102 Hz. A wide plateau spans in a steady σac ∼ 0.8 × 10–4 S·cm–1 over ω ≤ 103 Hz, before booting it up progressively by nearly two orders on higher ω in a frequency modulated ionic conductor. The “e––h+” pairs in a conductive network govern the conduction process over uneven and dynamic potential wells. A network as disrupts in thicker shells no longer feeds such large εr values.

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“…Qualitatively, the first two bands observed at 528.9 eV and 529.6 eV in strong intensities attribute to O 2− species occupying the two kinds of the oxide polygons of CaO 4 6− and InO 6 9− respectively as per their ratio 1:2 in a spinel CaIn 2 O 4 structure. Thus, a weak satellite band observed at 530.3 eV (or 531.8 eV in the undoped sample) can be assigned to the surface O 2− species present as functionalized groups, like C=O, C-O, or CHO [33][34][35], in a conjoint C-sp 2 surface layer of a stable network on the individual crystallites in a hybrid core-shell structure. It is a hybrid core-shell structure that finely tunes the E b values and intensities in the three distinct overlapping O1s bands in a wide O1s distribution of electrons in the different sites in the lattice in this example.…”

Section: Xps Bands Of Eu 3+ Doped C-cain 2 O 4 Crystallitesmentioning

confidence: 99%

Optical properties of heat-treated hierarchical structure of Eu3+ modified C-CaIn2O4 of small core–shell crystallites

Tiwari

Ram

2020

SN Appl. Sci.

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A natural aloe-vera gel is promptly bridging the Eu 3+ , Ca 2+ and In 3+ species in a bio-complex of a polymer network, so as it yields a sample Eu 3+ :CaIn 2 O 4 of small crystallites bonding over a grafted C-sp 2 surface layer when it is burnt in a selfpropagating combustion in air. The Eu 3+ doped C-CaIn 2 O 4 sample appears in a core-shell structure in part of the carbon forming a conjoint surface layer (shell) thereon of the individual crystallites in a hybrid nanostructure. The results are analyzed in terms of XRD patterns, phonon bands (in IR and Raman spectra), XPS bands, and hierarchical microstructure in the samples prepared with different Eu 3+ dosages in finely tuning the microstructure and optical properties as useful for an efficient phosphor, optical display system, visible lasers, energy-converters, photocatalysts, optical imaging, medical tools, and several others. A partial Eu 3+ → In 3+ doping in a crystal lattice CaIn 2 O 4 clearly reflects in a marked expansion of the lattice, as much as 2.2% found in the Eu 3+ content progressively raised to 2.0 mol% in a tailored hybrid composite structure. An inbuilt C-sp 2 shell structure of the crystallites is characterized in terms of its characteristic phonon bands in a conjoint polymer network, which are accounted well in modified XPS bands in the surface species.* Barkha Tiwari, barkha@matsc.iitkgp.ernet.in | Publisher's Note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

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Hydrothermal synthesis of LiMnPO4-C(sp2) hybrids, conductive channels, and enhanced dielectric permittivity: a modulated ionic conductor

Cited by 7 publications

References 38 publications

Structural, Magnetic, and Dielectric properties of Sr4Fe6O13 ferrite prepared of small crystallites

Structural, Magnetic, and Dielectric properties of Sr4Fe6O13 ferrite prepared of small crystallites

Biogenic Synthesis of Tunable Core–Shell C-CaIn₂O₄, Interface Bonding, Conductive Network Channels, and Tailored Dielectric Properties

Optical properties of heat-treated hierarchical structure of Eu3+ modified C-CaIn2O4 of small core–shell crystallites

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Hydrothermal synthesis of LiMnPO4-C(sp2) hybrids, conductive channels, and enhanced dielectric permittivity: a modulated ionic conductor

Cited by 7 publications

References 38 publications

Structural, Magnetic, and Dielectric properties of Sr4Fe6O13 ferrite prepared of small crystallites

Structural, Magnetic, and Dielectric properties of Sr4Fe6O13 ferrite prepared of small crystallites

Biogenic Synthesis of Tunable Core–Shell C-CaIn2O4, Interface Bonding, Conductive Network Channels, and Tailored Dielectric Properties

Optical properties of heat-treated hierarchical structure of Eu3+ modified C-CaIn2O4 of small core–shell crystallites

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Product

Resources

About

Biogenic Synthesis of Tunable Core–Shell C-CaIn₂O₄, Interface Bonding, Conductive Network Channels, and Tailored Dielectric Properties