Investigations on electronically conducting oxide systems XX. MgNiMnO4 and properties of MgzNiMn2−zO4 spinels

Feltz, A.; Neidnicht, B.

doi:10.1016/0925-8388(91)90065-4

Cited by 13 publications

(4 citation statements)

References 28 publications

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“…The cation distribution obtained by the Rietveld analysis (Table ) indicated that MnNi 2 O 4 is a normal spinel (MgAl 2 O 4 structural type): Mn and Ni atoms occupy tetrahedral and octahedral sites, respectively. The increase in the Mn content results in the Ni substitution by Mn and formation of inverse spinel, in accordance with literature data Table presents also the crystalline size obtained by the profile fitting.…”

Section: Resultssupporting

confidence: 91%

“…The data were analyzed by the Rietveld structure refinement program, FULLPROF. 10 The structural data for the modeling were taken from previously reported articles for spinel NiMn 2 O 4 11 and NiO. 12 The Thompson−Cox−Hastings pseudo-Voigt function was used for the peak-shape approximation.…”

Section: Methodsmentioning

confidence: 99%

“…The increase in the Mn content results in the Ni substitution by Mn and formation of inverse spinel, in accordance with literature data. 11 Table 3 presents also the crystalline size obtained by the profile fitting. As discussed below, the results agree with those obtained by SEM.…”

Section: Electrode Fabrication and Electrocatalytic Studiesmentioning

confidence: 99%

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Exceptionally Active and Stable Spinel Nickel Manganese Oxide Electrocatalysts for Urea Oxidation Reaction

Sivakumar

Subramanian

Levi

et al. 2016

ACS Appl. Mater. Interfaces

144

105

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Spinel nickel manganese oxides, widely used materials in the lithium ion battery high voltage cathode, were studied in urea oxidation catalysis. NiMn2O4, Ni1.5Mn1.5O4, and MnNi2O4 were synthesized by a simple template-free hydrothermal route followed by a thermal treatment in air at 800 °C. Rietveld analysis performed on nonstoichiometric nickel manganese oxide-Ni1.5Mn1.5O4 revealed the presence of three mixed phases: two spinel phases with different lattice parameters and NiO unlike the other two spinels NiMn2O4 and MnNi2O4. The electroactivity of nickel manganese oxide materials toward the oxidation of urea in alkaline solution is evaluated using cyclic voltammetric measurements. Ni1.5Mn1.5O4 exhibits excellent redox characteristics and lower charge transfer resistances in comparison with other compositions of nickel manganese oxides and nickel oxide prepared under similar conditions.The Ni1.5Mn1.5O4modified electrode oxidizes urea at 0.29 V versus Ag/AgCl with a corresponding current density of 6.9 mA cm(-2). At a low catalyst loading of 50 μg cm(-2), the urea oxidation current density of Ni1.5Mn1.5O4 in alkaline solution is 7 times higher than that of nickel oxide and 4 times higher than that of NiMn2O4 and MnNi2O4, respectively.

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Section: Resultssupporting

confidence: 91%

Section: Methodsmentioning

confidence: 99%

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Exceptionally Active and Stable Spinel Nickel Manganese Oxide Electrocatalysts for Urea Oxidation Reaction

Sivakumar

Subramanian

Levi

et al. 2016

ACS Appl. Mater. Interfaces

144

105

View full text Add to dashboard Cite

show abstract

“…Spinel type manganates are high technology electroceramic materials, which are commonly used in a wide range of thermistor and related applications. [1] Historically, the compound NiMn 2 O 4 has been the basis of NTCR thermistor developments, [2] but nowadays a wide range of dopants are commonly included into the system to increase stability, [3] reduce ageing effects [4] or tune the NTCR thermistor parameters. [5] The key material property relevant for thermistor applications is the resistivity vs temperature (ρ -T ) behaviour.…”

Section: Introductionmentioning

confidence: 99%

Studies of the Temperature and Frequency Dependent Impedance of an Electroceramic Functional Oxide NTC Thermistor

Schmidt

Brinkman

2007

Adv Funct Materials

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The charge transport mechanism and the macroscopic dielectric constant in polycrystalline device materials commonly exhibit several components such as electrode-sample interface, grain boundary and bulk contributions. In order to gain precise understanding of the functionality of polycrystalline electroceramic device materials it is essential to deconvolute these contributions.The paradigm of functional thermistor ceramics based on thick film spinel manganates has been studied by temperature dependent alternating current impedance spectroscopy. Three typical relaxation phenomena were detected, which all showed a separated temperature dependence of resistivity consistent with thermally activated charge transport. The dominating grain boundary and the interface contributions exhibited distinctively different capacitance allowing clear identification. The composite nature of the dielectric properties in polycrystalline functional ceramics was emphasized, and impedance spectroscopy was shown to be a powerful tool to account for and model such behaviour.

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Microstructure and Electrical Properties of Mn-Ni-In Spinels

Metzmacher

Groen

Reaaney

2000

phys. stat. sol. (a)

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Microstructural investigations of negative temperature coefficient (NTC) ceramics in the Mn±Ni±In±O system have been performed using X-ray diffraction (XRD), scanning (SEM) and transmission electron microscopy (TEM). The electrical properties have been characterized by measurements of resistance, activation energy and aging. The replacement of Mn by In in Mn 2.9± ±x Ni x In 0.1 O 4 (x 0:50À0:66) leads to higher resistivities and thermal constants, both decreasing with increasing Ni content, and minimum aging of 0.1% for x 0:58. Microstructural changes deduced from the a/c ratio and caused by aging are observable for Mn 2.32 Ni 0.58 In 0.1 O 4 which is nearest to the tetragonal/cubic phase boundary. It is concluded that the Mn 3 concentration on octahedral sites increases due to aging. The domain configuration changes with increasing Ni content: samples with low Ni content reveal domain laths ($100 nm width) with internal twinning (<10 nm), samples near to the boundary exhibit finer scaled (5±10 nm), weakly curved domains without twinning and for high Ni contents a slightly increased domain width of 5±15 nm is observed. With the exception of x 0:58, all aged samples show the same microstructure as the corresponding non-aged ones, whereas aged Mn 2.32 Ni 0.58 In 0.1 O 4 is more comparable with Mn 2.40 Ni 0.50 In 0.1 O 4 . Consequently, the choice of composition with respect to the phase boundary is decisive for the electrical and microstructural behaviour.

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Investigations on electronically conducting oxide systems XX. MgNiMnO4 and properties of MgzNiMn2−zO4 spinels

Cited by 13 publications

References 28 publications

Exceptionally Active and Stable Spinel Nickel Manganese Oxide Electrocatalysts for Urea Oxidation Reaction

Exceptionally Active and Stable Spinel Nickel Manganese Oxide Electrocatalysts for Urea Oxidation Reaction

Studies of the Temperature and Frequency Dependent Impedance of an Electroceramic Functional Oxide NTC Thermistor

Microstructure and Electrical Properties of Mn-Ni-In Spinels

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