Search

We present a quaternion representation of quantum mechanics that allows its ontological interpretation. The correspondence between classical and quaternion quantum equations permits one to consider the universe (vacuum) as an ideal elastic solid. Elementary particles would have to be standing or soliton-like waves. Tension induced by the compression and twisting of the elastic medium would increase energy density, and as a result, generate gravity forcing and affect the wave speed. Consequently, gravity could be described by an index of refraction. [ABSTRACT FROM AUTHOR]

Fick's diffusion equation represents physical reality that has been interpreted by Einstein and Smoluchowski. In this way, the question of interpretation of diffusion is answered in the affirmative. It gives rise to a new question critical for the understanding of our world: how broad is the spectrum of physical reality that diffusion could in principle give a complete account. The answer in this work is based on the elegant mathematical foundations formulated three decades before Fick by French mathematician Augustin Cauchy (~ 1822). It will be shown that the diffusion equation is a consequence of his model of the ideal elastic continuum. Namely, a product of the classical energy and momentum balance equations and their solutions. This demonstrates that the complete ontological construal of the diffusion theory exists. Explicitly, the interpretation of both, the diffusion equation and the flux constative formulae exist. The two terms in the flux equations, the driving forces defined by the potential gradients and the kinetic coefficients in front of the driving forces, are derived in this paper. Some fundamental consequences of all derived equations and relations for physics, chemistry and the prospects are presented. The ontological interpretation of the diffusion equation presented here provides evidence of the common roots of the chemistry and physics. [ABSTRACT FROM AUTHOR]

The problem of simultaneous growth and competition of intermediate phases during reactive diffusion is formulated and solved. In this paper, we compare existing models of steady state reaction diffusion and introduce the new one basing on the bi-velocity method. We extend old problem and propose method based on material (lattice) fixed frame of reference. It allows computing the material velocity in the reacting system in which reactions at several moving interfaces occur. All reactions lead to the lattice shift due to the difference of intrinsic diffusivities and different molar volumes. The following peculiarities are taken into account: (1) the deviation from local equilibrium at all interfaces; (2) the mobilities of the components in the bulk and interphase zone; and (3) the molar volumes of the components. We show the kinetic of the reactions, the non parabolic regime, the multiphase scale growth and present the practical application of the method. [ABSTRACT FROM AUTHOR]

Interdiffusion between two-phase ternary alloys is described analytically and numerically with self-consistent account of thermodynamical constraints and of morphology evolution. At that, growth/shrinking of minority phase precipitates and their flow with parent phase lattices are taken into account. Description scheme is multiscale (actually – double-scaled): it uses both coarsened scale for overall concentrations and phases redistribution, and it uses fine-scale for description of growth or shrinking of each precipitate. Natural constraints on the effective interdiffusivity matrices in coarsened scale are formulated (zero determinant). We show characteristic zigzag-type diffusion paths, horn-like paths and additional regimes with single-phase sublayers. Model enables to trace the history of deviations from the Local Equilibrium condition in both matrix phases and enables to predict the redistribution of precipitates in both matrix phases. [ABSTRACT FROM AUTHOR]

The problem of Kirkendall’s trajectories in finite, three- and one-dimensional ternary diffusion couples is studied. By means of the parabolic transformation method, we calculate the solute field, the Kirkendall marker velocity, and displacement fields. The velocity field is generally continuous and can be integrated to obtain a displacement field that is continuous everywhere. Special features observed experimentally and reported in the literature are also studied: (i) multiple Kirkendall’s planes where markers placed on an initial compositional discontinuity of the diffusion couple evolve into two locations as a result of the initial distribution, (ii) multiple Kirkendall’s planes where markers placed on an initial compositional discontinuity of the diffusion couple move into two locations due to composition dependent mobilities, and (iii) a Kirkendall plane that coincides with the interphase interface. The details of the deformation (material trajectories) in these special situations are given using both methods and are discussed in terms of the stress-free strain rate associated with the Kirkendall effect. Our nonlinear transform generalizes the diagonalization method by Krishtal, Mokrov, Akimov, and Zakharov, whose transform of diffusivities was linear. [ABSTRACT FROM AUTHOR]

The Poisson equation is used to calculate the drift velocity in the two-dimensional diffusion couple. This approach is based on the bi-velocity (Darken) method which combines the Darken and Brenner concepts that the volume velocity is essential in defining the local material velocity in multicomponent mixture at non-equilibrium. As an example the arbitrary binary system is considered. It is shown that (1) the two dimensional calculations should be applied with the stochastization method and (2) the drift term in mass conservation law does not affect the calculations. [ABSTRACT FROM AUTHOR]

Bi-velocity (Darken) method, which includes material drift and diffusion fluxes, is for the first time applied to describe mass transport in multiphase materials. The respective model is formulated in details and then applied for a ternary diffusion couple in which a two-phase zone can grow during isothermal diffusion. Thanks to the use of a phase-field order parameter, identified here with volume fraction of a chosen phase, the mass transport throughout both phases within a two-phase zone can be considered. The model allows smooth crossing of the type 1 boundary, which makes the mass transport equations valid in both single- and two-phase regions. The solution obtained for 1D geometry provides: (1) a diffusion path in the concentration triangle, (2) element-concentration profiles, (3) volume fractions of the phases in the two-phase zone and (4) drift-velocity distribution along x axis parallel to the mass transport. As an example, the interdiffusion in thediffusion couple of Type 0 boundary is modelled. The zigzag diffusion path is predicted and the profiles of the element concentrations are simulated. For the first time, the drift velocity for the diffusion in two-phase system is determined and correlated with the changes in volume fractions of the phases. [ABSTRACT FROM AUTHOR]

Abstract: An approach to the problem of interdiffusion in multicomponent–multiphase system is presented. It couples bi-velocity (Darken) method, in which the mass conservation and volume continuity laws are considered, with the phase field model and is a generalization of the model based on the diffusion equation implemented in Dictra. The proposed bi-velocity phase field method allows computing the kinetics of the process, diffusive mass transport in every phase, concentration profiles, diffusion paths, and Kirkendall effect. The example problem presented here is a fundamental problem concerning the reactive diffusion at high temperatures in Al–Cr–Ni ternary system. It is a starting point that will allow modeling the coating composition to reduce interdiffusion and stabilize a desired microstructure, i.e., to extend coating life time. [Copyright &y& Elsevier]

In this work we solve the problem of the simultaneous growth and competition of intermediate phases. The crystal lattice as the frame of reference for diffusion is defined, based on the volume continuity equation. It permits the computation of the material velocity in a system in which reactions at several moving interfaces occur. All reactions lead to the lattice shift due to the difference of diffusivities and molar volumes. We simulate the CVD process followed by annealing in a non-oxidizing atmosphere. The computed kinetics and concentration profiles are compared with experimental results. [ABSTRACT FROM AUTHOR]

A theory of stress and elastic deformation during interdiffusion is presented. It is shown that it is consistent with the general Darken analysis and linear irreversible thermodynamics. Special consideration is given to local entropy production. An expression is derived for the rate of entropy production during interdiffusion and practical computations presented of the internal energy and entropy densities and the entropy production. It is shown that the entropy produced by the diffusion of mass is positive, [image omitted], and it does not depend on the frame of reference. The results span the gap between the Darken method, linear irreversible thermodynamics and treatments by Larche, Cahn and Stephenson. [ABSTRACT FROM AUTHOR]

Abstract: The bi-velocity concept of separation of diffusion and drift flows allows one to combine the convection and dissipative contributions to the mass and energy fluxes. It is shown that the bi-velocity method combined with statements of the first law of thermodynamics and the Euler’s and Liouville theorems is consistent with linear irreversible thermodynamics. We apply the derived formalism in modeling the two-dimensional sedimentation between Bi and Sb and demonstrate the satisfactory agreement with experimental data. The method allows modeling the sedimentation of isotopes in solids. [Copyright &y& Elsevier]

Abstract: A thermodynamically consistent framework is developed to combine the convection and dissipative contributions with the mass and energy fluxes in multicomponent materials. The method, which is known as bi-velocity or Darken method, is based on the postulate of the unique (independent on the frame of reference) transport of the mass due to diffusion. In this work we merge: (i) the combined statements of the first and second laws of thermodynamics (linear irreversible thermodynamics) and (ii) the Euler and Liouville theorems. We derive an expression for the rate of the entropy production that does not depend on the frame of reference and is always positive. We show that the derived set of partial differential equations describing the mechanochemical mass transport is thermodynamically consistent and can be used in advanced modeling. [ABSTRACT FROM AUTHOR]

Abstract: The duration of the selective oxidation period is a key factor determining the life time of the corrosion resistant alloys. Diffusion processes during the selective oxidation of an alloy containing a noble metal (Pt, Au) and a oxidizable metal (Ni, Cu or Zn) were theoretically analyzed by C. Wagner. He had shown the analytical method to calculate the oxidation rate (growth of the scale) as a function of initial concentration of the reacting metal. Wagner simplified the problem of alloy oxidation assuming the constant concentration at the alloy∣oxide interface. In this work we extend the Wagner model by introducing (i) the time dependence of the reacting metal concentration at the alloy∣oxide interface and the instantaneous rate constant, (ii) the composition dependent diffusivities of the alloy components and (iii) the finite geometry of the oxidized alloy. The model can be applied to predict the life time, i.e., the critical consumption of the reacting element and the evolution of the components concentration in alloy and at its boundaries. We present the comparison of Wagner’s results and our extended analysis. [Copyright &y& Elsevier]

Abstract: In the present work we derive the volume continuity equation and demonstrate its use to define the volume frame of reference in the multicomponent, compressible systems. The volume velocity (material velocity) is a unique frame of reference for all internal forces and processes, e.g., the mass diffusion, heat flow, etc. No basic changes are required in the foundations of linear irreversible thermodynamics except recognizing the need to add volume to the usual list of extensive physical properties undergoing transport in every continuum. The volume fixed frame of reference allows the translation of the Newton’s discrete mass-point molecular mechanics into continuum mechanics and the use of the Cauchy linear momentum equation of fluid mechanics and Navier–Lamé equation of mechanics of solids. Our proposed modifications of Navier–Lamé and energy conservation equations are self-consistent with the literature for solid-phase continua dating back to the classical interdiffusion experiments of Kirkendall and their subsequent interpretation by Darken in terms of diffuse volume transport. We do show that the local diffusion processes do not change the centre of mass of the system and that the stress and viscosity depend only on the local volume velocity. [Copyright &y& Elsevier]

Abstract: The numerical simulations of steady-state potentials and impedance spectra of ion-selective membranes electrodes (ISEs) with ionic sites are presented. The set of Nernst–Planck–Poisson and continuity equations is solved numerically by means of the finite difference method and the Rosenbrock solver. Transient and steady-state solutions for ion-selective electrodes under open- or closed-circuit conditions are calculated. The Fourier transformation of the potential-time response to a current perturbation is used for determination of complex impedances. The paper presents simulations of ISEs as a function of varying the ionic concentrations in the “bathing” solution or the rates of ion transfer across the membrane/solution interfaces. It is shown that the non-Nernstian behaviour of passive membrane electrodes is a result of kinetic constraints at the interfaces, which are manifested in the appearance of an additional arc between the high-frequency bulk and the low-frequency (Warburg) arcs. The presented approach directly relates the transport properties of the bulk and interfaces (ionic diffusivities and heterogeneous rate constants of transport across interfaces) to the characteristic features of complex impedances (dimensions and characteristic radial frequencies), and allows non-linear effects to be simulated. [Copyright &y& Elsevier]

The work is concerned with the numerical analysis of kinetics and thermodynamics of lithium insertion into electrode materials. The two methods for simulating diffusion in electrode material are shown. The Nernst–Planck flux formula and the law of mass conservation were chosen as the governing equations in a variable diffusivity model (VDM). These equations were solved for the planar electrode and for the different initial and boundary value conditions by means of the finite difference method. The distribution of lithium in the electrode material and the change of the Li+/LiyM half-cell potential are computed. The VDM is compared with a constant diffusivity model (CDM), the results confirm that dependence of the chemical diffusivity of Li on thermodynamics in binary system, M-LiyM, cannot be neglected in practical computations. [Copyright &y& Elsevier]

We show that quaternion quantum mechanics has well-founded mathematical roots and can be derived from the model of the elastic continuum by French mathematician Augustin Cauchy, i.e., it can be regarded as representing the physical reality of elastic continuum. Starting from the Cauchy theory (classical balance equations for isotropic Cauchy-elastic material) and using the Hamilton quaternion algebra, we present a rigorous derivation of the quaternion form of the non- and relativistic wave equations. The family of the wave equations and the Poisson equation are a straightforward consequence of the quaternion representation of the Cauchy model of the elastic continuum. This is the most general kind of quantum mechanics possessing the same kind of calculus of assertions as conventional quantum mechanics. The problem of the Schrödinger equation, where imaginary 'i' should emerge, is solved. This interpretation is a serious attempt to describe the ontology of quantum mechanics, and demonstrates that, besides Bohmian mechanics, the complete ontological interpretations of quantum theory exists. The model can be generalized and falsified. To ensure this theory to be true, we specified problems, allowing exposing its falsity. [ABSTRACT FROM AUTHOR]

In this work we consider the one and multidimensional diffusional transport in an s-component solid solution. The new model is expressed by the nonlinear parabolic-elliptic system of strongly coupled differential equations with the initial and the nonlinear coupled boundary conditions. It is obtained from the local mass conservation law for fluxes which are a sum of the diffusional and Darken drift terms, together with the Vegard rule. The considered boundary conditions allow the physical system to be not only closed but also open. We construct the implicit finite difference methods (FDM) generated by some linearization idea, in the one and two-dimensional cases. The theorems on existence and uniqueness of solutions of the implicit difference schemes, and the theorems concerned convergence and stability are proved. We present the approximate concentrations, drift and its potential for a ternary mixture of nickel, copper and iron. Such difference methods can be also generalized on the three-dimensional case. The agreement between the theoretical results, numerical simulations and experimental data is shown. [ABSTRACT FROM AUTHOR]

A new method, which allows determination of intrinsic diffusivities values on the Kirkendall plane in multicomponent systems, is presented. The approach is based on the zero contribution of drift flux to the total flux value of i -th component, when calculated relatively to the Kirkendall plane position. The method allows precise determination of intrinsic diffusivities without limitations of Boltzmann-Matano based methods e.g. in situations when uphill diffusion occurs. The approach is validated on a number of theoretical and experimental systems. The results indicate that the method have a very high potential in application for multicomponent systems, including high entropy alloys. [ABSTRACT FROM AUTHOR]

The detection limit of ion-selective electrodes (ISEs) is of great interest because of the many possible practical applications of ISEs in trace analysis. Existing theoretical interpretations of the detection limit of ISEs are restricted by severe assumptions such as steady-state and electroneutrality, which hamper theorizing on this problem. For this reason, the Nernst-Planck-Poisson (NPP) equations are used to predict and visualize the detection limit variability under nonequilibrium conditions. For the first time, the NPP model is applied to the so-called inverse problem: finding the optimal measurement time and inner solution concentration for lowering the detection limit. [ABSTRACT FROM AUTHOR]

Over the last two decades, there have been tremendous advances in the computation of diffusion and today many key properties of materials can be accurately predicted by modelling and simulations. In this paper, we present, for the first time, comprehensive studies of interdiffusion in three dimensions, a model, simulations and experiment. The model follows from the local mass conservation with Vegard's rule and is combined with Darken's bi-velocity method. The approach is expressed using the nonlinear parabolic–elliptic system of strongly coupled differential equations with initial and nonlinear coupled boundary conditions. Implicit finite difference methods, preserving Vegard's rule, are generated by some linearization and splitting ideas, in one- and two-dimensional cases. The theorems on the existence and uniqueness of solutions of the implicit difference schemes and the consistency of the difference methods are studied. The numerical results are compared with experimental data for a ternary Fe-Co-Ni system. A good agreement of both sets is revealed, which confirms the strength of the method. [ABSTRACT FROM AUTHOR]

Possibility of formation of quinary and senary equimolar high entropy oxides from the Co-Cr-Fe-Mg-Mn-Ni-O system is presented. Different proposed compositions are synthesized using the solid-state reaction route at high temperatures (900−1100 °C) and quenched to room temperature. Phase composition of the samples is studied, showing tendency toward formation of two main phases: rock salt-structured Fm-3 m and spinel-structured Fd-3 m. It is documented that the annealing temperature has a profound effect on stability of both structures, and at 1100 °C usually the highest content of Fm-3 m phase is usually observed. Three different oxides, namely, (Co,Cr,Fe,Mn,Ni) 3 O 4 , (Co,Cr,Fe,Mg,Mn) 3 O 4 and (Cr,Fe,Mg,Mn,Ni) 3 O 4 are obtained as single-phase materials, which structure can be described as the high entropy Fd-3 m spinel one. The latter two compounds have not been previously reported in the literature. Activated character of the electrical conductivity dependence on temperature is observed, with relatively high total conductivity at high temperatures and corresponding high absolute values of Seebeck coefficient. [ABSTRACT FROM AUTHOR]

Defect structure and chemical diffusion in the (Co,Cr,Fe,Mn,Ni) 3 O 4 high entropy oxide is investigated. The material is synthesized by means of a solid-state reaction, through sintering mixture of composing oxides at 1273 K for 20 h. Presence of the single-phase, spinel-structured high entropy solid solution is confirmed with the use of X-ray diffraction method and scanning electron microscopy. Good thermal stability of the material is documented up to 1273 K. Modified marker experiment allows concluding that defects form predominantly in the oxygen sublattice. Based on thermogravimetric studies, general formula of (Co,Cr,Fe,Mn,Ni) 3 O 4±y is established, with the defect inversion phenomenon (i.e. change of the dominating type of defects from oxygen vacancies to interstitial oxygen) likely to occur at high oxygen partial pressures (p O 2 ). Chemical diffusion coefficient is calculated, based on the measured reequilibration kinetics, showing a very strong dependence on p O 2 and relatively small values under low oxygen pressures. [ABSTRACT FROM AUTHOR]

Abstract Interdiffusion studies in Co-Cr-Fe-Mn-Ni, Co-Fe-Mn-Ni, Co-Cr-Fe-Ni, and Co-Cr-Mn-Ni, as well as a reevaluation of the previous results obtained for Al-Co-Cr-Fe-Ni, were conducted. In the experimental part, diffusion couples were annealed at four different temperatures: 1230, 1270, 1310 and 1350 K for each system. Then, the results were evaluated with use of the optimization-based technique, combined with the Miedema's thermodynamic description, what allowed obtaining of tracer diffusion coefficients for all elements in all considered systems. The correctness of the applied approach was tested on the example of Co-Cr-Fe-Mn-Ni system, showing very good agreement of determined tracer diffusivities with the values obtained by other authors. Obtained values of diffusivities were compared with the available data for a number of conventional binary and ternary systems. No signs of diffusion retardation were observed in the absolute temperature scale. In the case of temperature scale normalized with respect to the melting point, an abnormal behavior, previously attributed to the HEAs' sluggish diffusion effect was observed. However, it occurred only for alloys with prominent manganese content and was completely independent of the number of components, being just as likely to occur in binary systems as in HEAs. Therefore, the alleged sluggishness of diffusion in HEAs should be treated just as a result of specific compositions of the previously studied alloys and cannot be generalized for all high entropy systems. Graphical abstract Image 1 Highlights • Diffusion was studied in Co-Cr-Fe-Mn-Ni, Co-Fe-Mn-Ni, Co-Cr-Fe-Ni, and Co-Cr-Mn-Ni. • Results for Al-Co-Cr-Fe-Ni were reevaluated. • Diffusion couples were evaluated with use of the optimization-based technique. • The observed sluggishness of diffusion was correlated with presence of Mn. • The observed sluggishness was independent of number of components. [ABSTRACT FROM AUTHOR]

A high-entropy (Co,Cr,Fe,Mn,Ni) 3 O 4 oxide, characterized by the Fd-3m single-phase, spinel structure, was synthesized for the first time. The material was based on the combination of Co, Cr, Fe, Mn and Ni elements, well known from the other group of high-entropy materials, namely high-entropy alloys. The microstructure of the material was studied using SEM + EDS and XRD methods, showing single-phase structure. Additional structural characterization was performed with use of Raman spectroscopy, also showing in the process, the usefulness of this method for characterization of high-entropy oxides. [ABSTRACT FROM AUTHOR]

Experimental and theoretical studies of diffusion in quinary Co-Cr-Fe-Mn-Ni and quaternary Co-Cr-Fe-Ni and Co-Fe-Mn-Ni FCC-structured high entropy alloys were performed. The diffusion couples, with thorium dioxide markers placed at initial joint positions, were annealed at temperature of 1350 K for 72 or 73 h. The concentration profiles obtained from the quinary system were used to determine tracer diffusivities of all components, by using a combinatorial approach, i.e. the Darken method with thermodynamic description provided by Miedema's scheme combined with the optimization method. The results showed good qualitative agreement with the tracer data from radiotracer experiments. The calculated thermodynamic factor, ranged from tens to hundreds of %, show importance of mixing enthalpy on interdiffusion kinetics. The values determined for 5-component system were then used a priori to simulate the concentration profiles for 4-component ones, showing very good agreement with the experimental data. The results indicate that change of components number did not influence the diffusion kinetics in the investigated systems and do not support existence of the sluggish diffusion effect. [ABSTRACT FROM AUTHOR]

Studies on the oxidation behavior of high entropy alloys from the Al-Co-Cr-Cu-Fe-Ni metallic system were conducted. Three different high entropy alloys were synthesized using arc-melting method: AlCoCrFeNi, AlCoCrCu 0.5 FeNi and AlCoCrCuFeNi, with their crystal structures being respectively BCC, BCC and BCC + FCC. All alloys were oxidized in the air atmosphere at temperature of 1273 K for different time periods. Basing on the thermogravimetric result, the oxidation rate of the materials decreased with the increase of Cu content and the values of parabolic constants were on the level similar to those observed in Ni-Al intermetallic alloys. In all cases the oxide scale consisted of α-Al 2 O 3 , which exhibited poor adhesion to the surface during the cooling process, what was especially visible in alloys with Cu addition. In all oxidized samples a tendency towards formation of the Al-depleted FCC phase directly beneath the scale was observed. The phase constitution of all materials changed significantly during the oxidation process, with multiple new phases appearing in the system. [ABSTRACT FROM AUTHOR]

A group of Al-Co-Cr-Fe-Ni alloys was synthesized for diffusion couple experiments that were performed in the temperature range of 1273–1373 K. The measured concentrations profiles were used to determine the tracer diffusion coefficients of the components, using Darken - Manning approach coupled with Levenberg–Marquardt or genetic algorithm methods of optimization. The approach was also validated against literature data obtained for diffusion in Co-Cr-Fe-Ni-Mn alloys. The results for both systems confirm the theory of sluggish diffusion in High Entropy Alloys, with the values of diffusion coefficients being significantly lower than in the case of conventional alloys. [ABSTRACT FROM AUTHOR]

Highlights: [•] Tritium escape from LiPb is estimated using bi-velocity diffusion model. [•] We performed experimental validation of the diffusion model. [•] We propose conception of LSS application to TPR in HCLL TBM measurement. [Copyright &y& Elsevier]

Abstract: A procedure for the development of a pen-like, multi-electrode potentiometric sensing platform is described. The platform comprises a seven-in-one electrode incorporating all-solid-state ion-selective and reference electrodes based on the conductive polymer (poly(3,4-ethylenedioxythiophene) (PEDOT)) as an intermediate layer between the contacts and ion-selective membranes. The ion-selective electrodes are based on traditional, ionophore-based membranes, while the reference electrode is based on a polymer membrane doped with the lipophilic salt tetrabutyl ammonium tetrabutyl borate (TBA-TBB). The electrodes, controlled with a multichannel detector system, were used for simultaneous determination of the concentration of Pb2+ and pH in environmental water samples. The results obtained using pH-selective electrodes were compared with data obtained using a conventional pH meter and the average percent difference was 0.3%. Furthermore, the sensing system was successfully used for lead-speciation analysis in environmental water samples. [Copyright &y& Elsevier]

The interdiffusion process in thin and thick (500 nm–60 µm) Au–Ni layers deposited on different substrates is studied using the EDS technique. In-depth X-ray analysis based on the Pouchou and Pichoir method is applied for obtaining the concentration profiles in nanometre scale multi-layers. A theoretical analysis using the Darken method is employed for modelling interdiffusion in the Au–Ni system. Computer simulations, where intrinsic diffusivities of the Au and Ni are functions of composition, are presented and compared with experimental results. [ABSTRACT FROM AUTHOR]

A series of the high-entropy (Co,Cu,Mg,Ni,Zn) 1- x Li x O oxides with a lithium substitution level of x = 0, 0.05, 0.10, 0.15, 0.20, 0.25, and 0.30 is evaluated in terms of the crystal structure, morphology and transport properties, with thorough studies aimed at elucidation of the nature of different contributions to the total electrical conductivity. It is found that cubic Fm -3 m structure is preserved in the whole investigated series, with (Co,Cu,Mg,Ni,Zn) 0.8 Li 0.2 O composition showing a high internal strain, supporting to some degree one of the so-called core effects, anticipated for the high-entropy materials. For samples with Li content x > 0.20 the strain is relaxed by formation of the oxygen vacancies. As unambiguously evidenced by DC polarization experiments and measured impedance spectroscopy data with ionically-blocking Au and reversible Li electrodes used, the previously reported in the literature transition to the lithium superionic conductivity in the Li-rich compounds, up to σ i ≈ 1–10⋅10−3 Scm−1, is more complex, with emergence of the electronic conduction as well, reaching similar magnitude for (Co,Cu,Mg,Ni,Zn) 0.7 Li 0.3 O. The observed behavior upon increase of lithium concentration (x) can be explained by a qualitative change of the nature of the electronic and ionic defects present in (Co,Cu,Mg,Ni,Zn) 1- x Li x O series, with initial oxidation of 3 d metals (mainly Co), followed by possible formation of the interstitial lithium, and final emergence of the oxygen vacancies. Furthermore, the recorded electrochemical properties of (Co,Cu,Mg,Ni,Zn) 0.7 Li 0.3 O lithium cell electrode, suggesting presence of intercalation-like behavior at the initial stages of lithiation, confirm the proposed mixed ionic-electronic conductivity. [Display omitted] [ABSTRACT FROM AUTHOR]