Hysteretic magnetoelectric behavior of CoFe2O4–BaTiO3 composites prepared by reductive sintering and reoxidation

Mapping Intimacies ◽

10.31219/osf.io/xv67d ◽

2019 ◽

Author(s):

Roberto Köferstein

Keyword(s):

Impedance Spectroscopy ◽

Low Temperature ◽

Secondary Phases ◽

Field Sweep ◽

Photometric Analysis ◽

Magnetoelectric Composites ◽

Synthesis Route

Magnetoelectric composites (CoFe2O4)x–(BaTiO3)1-x with x = 0.1, 0.2, 0.3, 0.4 and 0.5 were prepared bya polyol mediated synthesis route. The densification step was performed in a reducing forming gasatmosphere at 1250 1C. Under these conditions Co2+ and Fe3+ are reduced to the corresponding metalsand thus a reaction of these elements with the BaTiO3 matrix is prevented. Reoxidation in air to CoFe2O4at a rather low temperature of 800 1C leads to samples free of secondary phases. While the course of thesynthesis was monitored by TGA, XRD and photometric analysis, the final composites were characterizedvia SEM, EDX, impedance spectroscopy and magnetic and magnetoelectric (ME) measurements. Allsamples show pronounced ME hystereses and aME maxima dependent on the Hdc field sweep direction.The sample with x = 0.4 exhibits the highest maximum aME of 420 mV Oe-1 cm-1.

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ChemInform Abstract: A Low-Temperature Synthesis Route for CaAlSiN3Doped with Eu2+.

ChemInform ◽

10.1002/chin.201327019 ◽

2013 ◽

Vol 44 (27) ◽

pp. no-no

Author(s):

Mariusz Kubus ◽

H.-Juergen Meyer

Keyword(s):

Low Temperature ◽

Low Temperature Synthesis ◽

Temperature Synthesis ◽

Synthesis Route

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Study on Low Temperature Conduction Mechanism of Al Doped ZnO/SiO2/ P-Si Heterojunction

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.904.363 ◽

2021 ◽

Vol 904 ◽

pp. 363-368

Author(s):

Xiao Yan Zhou ◽

Bang Sheng Yin

Keyword(s):

Activation Energy ◽

Impedance Spectroscopy ◽

Low Temperature ◽

Grain Boundaries ◽

Ac Conductivity ◽

Spray Pyrolysis Method ◽

Temperature Conductivity ◽

Calculated Activation Energy ◽

Doped Zno ◽

Temperature Conduction

The 3 at% Al doped ZnO thin films were deposited on p-Si substrate with a native SiO2 layer by spray pyrolysis method. Low temperature conduction behaviors were studied by analysis of impedance spectroscopy and low temperature ac conductivity. The results of impedance spectroscopy showed that the grain boundaries contributed to the resistivity of Al doped ZnO/SiO2/p-Si heterojunction. The calculated activation energy was 0.073 eV for grain boundaries. The equivalent circuit to demonstrate the electrical properties of Al doped ZnO/SiO2/p-Si heterojunction was a series connection of two parallel combination circuits of a resistor and a universal capacitor. Low temperature ac conductivity measurements indicated that the conductivity increased with temperature. Low temperature conductivity mechanism was electron conductivity, and the activation energy was 0.086 eV.

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Low temperature fluid alteration of oceanic layer 2 basalts, DSDP Leg 37

Canadian Journal of Earth Sciences ◽

10.1139/e77-086 ◽

1977 ◽

Vol 14 (4) ◽

pp. 911-926 ◽

Cited By ~ 54

Author(s):

A. J. Andrews

Keyword(s):

Low Temperature ◽

Chemical Nature ◽

Sea Water ◽

Significant Rise ◽

Secondary Phases ◽

Acoustic Basement ◽

Layer 2 ◽

Fluid Alteration ◽

Fluid Interaction ◽

Mineralogical Evidence

Penetration of cold seawater into layer 2 of the oceanic crust occurs to at least 600 m, the maximum depth drilled below the sediment-acoustic basement boundary during Leg 37 of the DSDP. The main alteration phases are Mg-saponite, Fe-K rich celadonite, phillipsite, calcite, and hematite. The only exception to this occurs in the form of intensely hydrothermally altered gabbro breccias from an intrusive complex at site 334. There is no mineralogical evidence to suggest an increase in metamorphic grade with depth; however, a variation in mineralogy and alteration intensity, occurs as a function of structure, permeability, and the chemical nature of rock-fluid interaction. On this basis three types of alteration are defined as follows: (A) fracture focussed, oxidative; (B) palagonitic; and (C) non-oxidative, pervasive.Electron microprobe analyses reveal that alteration of fresh glass to palagonite involves the addition of H2O, an increase in total Fe, K2O, TiO2, and possibly SiO2, and the loss of CaO, MgO, Na2O, and MnO.Detailed examination of the mineralogy and chemistry of oxidative alteration suggests that during low temperature sea water–basalt interaction, basalt experiences a net gain in CaO, total Fe and K2O, while SiO2 and MgO appear to have been locally remobilized. These trends are generally consistent with the distribution of secondary phases. The distributions of Mn, Cu, Ni, Zn, Co, and Sr do not appear to have been significantly affected during this process.It is apparent that seawater must have experienced significant Eh lowering during this interaction; however, the occurrence of hematite–magnetite and absence of sulphide in this particular environment requires that seawater was either highly depleted in total sulfur or experienced a significant rise in pH.

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Znx-1CuxMn2O4 Spinels; Synthesis, Structural Characterization and Electrical Evaluation

Journal of the Mexican Chemical Society ◽

10.29356/jmcs.v54i1.958 ◽

2019 ◽

Vol 54 (1) ◽

Author(s):

Francisco Méndez-Martínez ◽

Federico González ◽

Enrique Lima ◽

Pedro Bosch ◽

Heriberto Pfeiffer

Keyword(s):

Impedance Spectroscopy ◽

Structural Characterization ◽

Morphological Changes ◽

Secondary Phases ◽

Varistor Ceramic ◽

X Ray Diffraction ◽

X Ray ◽

Copper Addition ◽

Partial Inverse ◽

Scanning Electron

This work presents the structural characterization and electrical evaluation of Znx-1CuxMn2O4 spinels, which are materials presented as secondary phases into the varistor ceramic systems. Samples were analyzed by X-ray diffraction, solid-state nuclear magnetic resonance, infrared spectroscopy, scanning electron microscopy and impedance spectroscopy. Although, the addition of copper to the ZnMn2O4 spinel did not produce morphological changes, the structure and electrical behaviors changed considerably. Structurally, copper addition induced the formation of partial inverse spinels, and its addition increases significantly the electrical conductivity. Therefore, the formation of Znx-1CuxMn2O4 spinels, as secondary phases into the varistor materials, may compromise significantly the varistor efficiency. Ceramic, Impedance Spectroscopy, spinel, Varistor, XRD.

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Monoclinic Li2TiO3 Nano-particles via sol-gel method: Structure and impedance spectroscopy

Mediterranean Journal of Chemistry ◽

10.13171/10.13171/mjc8319051109fza ◽

2019 ◽

Vol 8 (3) ◽

pp. 209

Author(s):

Fatima Zahra Krimech ◽

Salaheddine Sayouri ◽

Taj-Edine Lamcharfi ◽

Fatima Zahra Ahjyaje

Keyword(s):

Impedance Spectroscopy ◽

Sol Gel ◽

Low Frequency ◽

Transport Processes ◽

Nano Particles ◽

Secondary Phases ◽

Conventional Solid State Reaction ◽

Gel Method ◽

Sol Gel Method ◽

Heat Treated

Pure phase Li2TiO3 nano-particles were synthesized by the sol-gel method and the structural properties were examined with X-ray diffraction (XRD) technique. The latter showed that these materials, heat treated at relatively low temperature 900°C during 4h compared to the conventional solid-state reaction which calcination temperature is about 900–1100°C for 10 h; crystallize in the monoclinic phase without the presence of secondary phases. The microstructure of the LT ceramic (sintered at 1100°C) were determined by SEM and a good crystalline nature was observed with an average of granular size 2 μm. Moreover, the impedance spectroscopy showed at a higher temperature of 500°C the low-frequency arc due either to the grain boundary or sample-electrode charge transport processes.

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