Ac conductivity and dielectric properties of CuFe1−xCrxO2 : Mg delafossite

Lalanne, Maëva; Demont, Philippe; Barnabé, Antoine

doi:10.1088/0022-3727/44/18/185401

Cited by 28 publications

(12 citation statements)

References 29 publications

(38 reference statements)

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“…(4) are equal not only at the high frequency limit but also at ω = ω 0 , then in these cases, from Eqs. (2), (3) and (4) with ω = ω 0 we find σ 0 = ε 0 ω 0 ε ′′ (ω 0 )/2 (5) and…”

Section: Theoretical Considerationsmentioning

confidence: 75%

AC and DC conductivity correlation: The coefficient of Barton–Nakajima–Namikawa relation

Tsonos

Kanapitsas

Kechriniotis

et al. 2012

Journal of Non-Crystalline Solids

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It has been some time since an empirical relation, which correlates DC with AC conductivity and contains a loosely defined coefficient thought to be of order one, was introduced by Barton, Nakajima and Namikawa. In this work, we derived this relation assuming that the conductive response consists of a superposition of DC conductivity and an AC conductivity term which materialized through a HavriliakNegami dielectric function. The coefficient was found to depend on the Havriliak-Negami shape parameters as well as on the ratio of two characteristic time scales of ions motion which are related to ionic polarization mechanism and the onset of AC conductivity. The results are discussed in relation to other relevant publications and they also applied to a polymeric material. Both, theoretical predictions and experimental evaluations of the BNN coefficient are in an excellent agreement, while this coefficient shows a gradual reduction as the temperature increases.

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Section: Theoretical Considerationsmentioning

confidence: 75%

AC and DC conductivity correlation: The coefficient of Barton–Nakajima–Namikawa relation

Tsonos

Kanapitsas

Kechriniotis

et al. 2012

Journal of Non-Crystalline Solids

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“…Due to the very limited Mg 2+ solubility range in the delafossite CuCrO 2 structure and then to prevent the precipitation of a secondary spinel phase which can affect the physical properties, 26,38,39 the Mg content in Mg-doped CuCrO 2 was fixed to 3at% in this study. Polycrystalline CuCr 0.97 Mg 0.03 O 2 powder (denoted as Mg-doped CuCrO 2 in the manuscript) was prepared by grinding and mixing the starting commercial oxides, Cu 2 O, Cr 2 O 3 and MgO.…”

Section: Preparation Of Mg-doped Cucro 2 Sputtering Target Materialsmentioning

confidence: 99%

p-Type conducting transparent characteristics of delafossite Mg-doped CuCrO₂ thin films prepared by RF-sputtering

et al. 2015

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“…Such a better description of the Cu−Fe−O phase diagram is crucial because it will permit one not only both to minimize the experimental effort and to improve the general understanding of the processes for producing these phases with the delafossite structure, 60,61,67−69 but also to optimize the remarkable properties of CuFeO 2 by a better understanding of the complex relationships between the structure and properties. [13][14][15][16][17][18][19][20][21][22][23]70 One can note that, because some major applications of CuFeO 2 materials concern the surface properties, it also should be interesting to consider similar analysis on film. Even if thinfilm materials could be characterized by an ad-hoc method, the equilibrium conditions are generally not satisfied because of, for instance, an almost instantaneous transition of the elements of the very high-temperature plasma to a crystalline solid phase at low temperature in the physical vapor deposition process.…”

Section: Introductionmentioning

confidence: 99%

Insights on the Stability and Cationic Nonstoichiometry of CuFeO₂ Delafossite

et al. 2019

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CuFeO 2 , the structure prototype of the delafossite family, has received renewed interest in recent years. Thermodynamic modeling and several experimental Cu−Fe−O system investigations did not focus specifically on the possible nonstoichiometry of this compound, which is, nevertheless, a very important optimization factor for its physicochemical properties. In this work, through a complete set of analytical and thermostructural techniques from 50 to 1100°C, a fine reinvestigation of some specific regions of the Cu−Fe−O phase diagram under air was carried out to clarify discrepancies concerning the delafossite CuFeO 2 stability region as well as the eutectic composition and temperature for the reaction L = CuFeO 2 + Cu 2 O. Differential thermal analysis and Tammann's triangle method were used to measure the liquidus temperature at 1050 ± 2°C with a eutectic composition at Fe/(Cu + Fe) = 0.105 mol %. The quantification of all of the present phases during heating and cooling using Rietveld refinement of the high-temperature X-ray diffraction patterns coupled with thermogravimetric and differential thermal analyses revealed the mechanism of formation of delafossite CuFeO 2 from stable CuO and spinel phases at 1022 ± 2°C and its incongruent decomposition into liquid and spinel phases at 1070 ± 2°C. For the first time, a cationic off-stoichiometry of cuprous ferrite CuFe 1−y O 2−δ was unambiguous, as evidenced by two independent sets of experiments: (1) Electron probe microanalysis evidenced homogeneous micronic CuFe 1−y O 2−δ areas with a maximum y value of 0.12 [i.e., Fe/(Cu + Fe) = 0.47] on Cu/Fe gradient generated by diffusion from a perfect spark plasma sintering pristine interface. Micro-Raman provided structural proof of the existence of the delafossite structure in these areas. (2) Standard Cu additions from the stoichiometric compound CuFeO 2 coupled with high-temperature X-ray diffraction corroborated the possibility of obtaining a pure Cu-excess delafossite phase with y = 0.12. No evidence of an Fe-rich delafossite was found, and complementary analysis under a neutral atmosphere shows narrow lattice parameter variation with an increase of Cu in the delafossite structure. The consistent new data set is summarized in an updated experimental Cu−Fe−O phase diagram. These results provide an improved understanding of the stability region and possible nonstoichiometry value of the CuFe 1−y O 2−δ delafossite in the Cu−Fe−O phase diagram, enabling its optimization for specific applications.

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Ac conductivity and dielectric properties of CuFe_1−xCr_xO₂ : Mg delafossite

Cited by 28 publications

References 29 publications

AC and DC conductivity correlation: The coefficient of Barton–Nakajima–Namikawa relation

AC and DC conductivity correlation: The coefficient of Barton–Nakajima–Namikawa relation

p-Type conducting transparent characteristics of delafossite Mg-doped CuCrO₂ thin films prepared by RF-sputtering

Insights on the Stability and Cationic Nonstoichiometry of CuFeO₂ Delafossite

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Ac conductivity and dielectric properties of CuFe1−xCrxO2 : Mg delafossite

Cited by 28 publications

References 29 publications

AC and DC conductivity correlation: The coefficient of Barton–Nakajima–Namikawa relation

AC and DC conductivity correlation: The coefficient of Barton–Nakajima–Namikawa relation

p-Type conducting transparent characteristics of delafossite Mg-doped CuCrO2 thin films prepared by RF-sputtering

Insights on the Stability and Cationic Nonstoichiometry of CuFeO2 Delafossite

Contact Info

Product

Resources

About

Ac conductivity and dielectric properties of CuFe_1−xCr_xO₂ : Mg delafossite

p-Type conducting transparent characteristics of delafossite Mg-doped CuCrO₂ thin films prepared by RF-sputtering

Insights on the Stability and Cationic Nonstoichiometry of CuFeO₂ Delafossite