Intrinsic Ionic Conductivity Research Articles

Effect of carbon coating methods on structural characteristics and electrochemical properties of carbon-coated lithium iron phosphate

The potential of LiFePO4 as cathode material has not been fully exploited due to its intrinsic poor electronic and ionic conductivities. Attempts have been made to improve these properties of which coating of the active carbon on the particle surface is the most viable method so far. Phase-pure LiFePO4 and two LiFePO4/C composites were synthesized by mechanical activation process employing two different methods: (i) direct addition of acetylene black carbon and (ii) addition of sucrose as carbon precursor. The samples were well characterized by various techniques like elemental analysis, Brunauer-Emmett-Teller (BET) method, scanning electron microscopy (SEM), X-ray powder diffraction (XRD), and Raman spectroscopy to establish their composition, morphology, particle size and surface area. The structure of these samples is investigated as olivine structure space group Prima by X-ray powder diffraction. Transmission electron microscopy (TEM) confirms that the carbon nanocoating on the LiFePO4 particles has no visible dislocations and fractures. The electrochemical performance of LiFePO4/C is significantly affected by the nature of the carbon nanocoating, which in turn is affected by the choice of synthesis method.

Long-Term Modulation of A-Type K+Conductances in Hippocampal CA1 Interneurons in Rats After Chronic Intermittent Ethanol Exposure During Adolescence or Adulthood

Chronic alcohol use, especially exposure to alcohol during adolescence or young adulthood, is closely associated with cognitive deficits that may persist into adulthood. Therefore, it is essential to identify possible neuronal mechanisms underlying the observed deficits in learning and memory. Hippocampal interneurons play a pivotal role in regulating hippocampus-dependent learning and memory by exerting strong inhibition on excitatory pyramidal cells. The function of these interneurons is regulated not only by synaptic inputs from other types of neurons but is also precisely governed by their own intrinsic membrane ionic conductances. The voltage-gated A-type potassium current (IA ) regulates the intrinsic membrane properties of neurons, and disruption of IA is responsible for many neuropathological processes including learning and memory deficits. Thus, it represents a previously unexplored cellular mechanism whereby chronic ethanol (EtOH) may alter hippocampal memory-related functioning. Using whole-cell electrophysiological recording methods, we investigated the enduring effects of chronic intermittent ethanol (CIE) exposure during adolescence or adulthood on IA in rat CA1 interneurons. We found that the mean peak amplitude of IA was significantly reduced after CIE in either adolescence or adulthood, but IA density was attenuated after CIE in adolescence but not after CIE in adulthood. In addition, the voltage-dependent steady-state activation and inactivation of IA were altered in interneurons after CIE. These findings suggest that CIE can cause long-term changes in IA channels in interneurons and thus may alter their inhibitory influences on memory-related local hippocampal circuits, which could be, in turn, responsible for learning and memory impairments observed after chronic EtOH exposure.

Iberiotoxin-sensitive and -insensitive BK currents in Purkinje neuron somata

Purkinje cells have specialized intrinsic ionic conductances that generate high-frequency action potentials. Disruptions of their Ca or Ca-activated K (KCa) currents correlate with altered firing patterns in vitro and impaired motor behavior in vivo. To examine the properties of somatic KCa currents, we recorded voltage-clamped KCa currents in Purkinje cell bodies isolated from postnatal day 17-21 mouse cerebellum. Currents were evoked by endogenous Ca influx with approximately physiological Ca buffering. Purkinje somata expressed voltage-activated, Cd-sensitive KCa currents with iberiotoxin (IBTX)-sensitive (>100 nS) and IBTX-insensitive (>75 nS) components. IBTX-sensitive currents activated and partially inactivated within milliseconds. Rapid, incomplete macroscopic inactivation was also evident during 50- or 100-Hz trains of 1-ms depolarizations. In contrast, IBTX-insensitive currents activated more slowly and did not inactivate. These currents were insensitive to the small- and intermediate-conductance KCa channel blockers apamin, scyllatoxin, UCL1684, bicuculline methiodide, and TRAM-34, but were largely blocked by 1 mM tetraethylammonium. The underlying channels had single-channel conductances of ∼150 pS, suggesting that the currents are carried by IBTX-resistant (β4-containing) large-conductance KCa (BK) channels. IBTX-insensitive currents were nevertheless increased by small-conductance KCa channel agonists EBIO, chlorzoxazone, and CyPPA. During trains of brief depolarizations, IBTX-insensitive currents flowed during interstep intervals, and the accumulation of interstep outward current was enhanced by EBIO. In current clamp, EBIO slowed spiking, especially during depolarizing current injections. The two components of BK current in Purkinje somata likely contribute differently to spike repolarization and firing rate. Moreover, augmentation of BK current may partially underlie the action of EBIO and chlorzoxazone to alleviate disrupted Purkinje cell firing associated with genetic ataxias.

Electrochemical analysis of a PPV derivative thin film doped with ß-ketoimine calix[4]arene in the dark and under illumination for the detection of Hg2+ ions

Conducting polymer can be used as the polymer matrix of the ion sensitive membrane (containing electroactive sites), which would exhibit intrinsic mixed ionic and electronic conductivity. In this work, a soluble poly(p-phenylene vinylene) derivative (MEH-PPV) has been used as the electroconducting polymer to immobilize the ß-ketoimine calix[4]arene derivative. Indium-thin oxide (ITO) electrode coated with the thin films of MEH-PPV and composite MEH-PPV/ß-ketoimine Cal[4] are designed for the determination of trace amounts of Hg2+ ions. Surface morphology properties were examined by atomic force microscopy (AFM) and scanning electron microscopy (SEM). The presented results show that the incorporation of calixarene derivative into MEH-PPV polymer improved the surface smoothness. Contact angle measurements were used to study hydrophobicity and surface energy properties of thin films. We observed that the best adhesion on the ITO surface is for the MEH-PPV/ß-ketoimine Cal[4] surface due to the presence of (OH) groups coming from the molecules of derivative calix[4]arene. Thin films were characterized by electrochemical impedance spectroscopy (EIS) in the dark and under illumination. The impedance behavior of the modified electrodes is modeled by an equivalent electrical circuit using the Z-View software. From the impedance plots, the bulk resistance and ionic conductivity of the membranes is an important factor determining the ability of ions to pass across the membrane. Marked differences in the ionic conductivity are observed as a function of the light excitation. The charge transfer processes at the electrode/electrolyte interface was carefully examined in the dark and under illumination. Optical excitation of both membranes revealed that the sensing activity of the MEH-PPV/ß-ketoimine Cal[4] modified electrode can improve the measuring sensitivity of Hg2+ ions compared to the MEH-PPV modified electrode.

Closed-Loop Measurements of Iso-Response Stimuli Reveal Dynamic Nonlinear Stimulus Integration in the Retina

Neurons often integrate information from multiple parallel signaling streams. How a neuron combines these inputs largely determines its computational role in signal processing. Experimental assessment of neuronal signal integration, however, is often confounded by cell-intrinsic nonlinear processes that arise after signal integration has taken place. To overcome this problem and determine how ganglion cells in the salamander retina integrate visual contrast over space, we used automated online analysis of recorded spike trains and closed-loop control of the visual stimuli to identify different stimulus patterns that give the same neuronal response. These iso-response stimuli revealed a threshold-quadratic transformation as a fundamental nonlinearity within the receptive field center. Moreover, for a subset of ganglion cells, the method revealed an additional dynamic nonlinearity that renders these cells particularly sensitive to spatially homogeneous stimuli. This function is shown to arise from a local inhibition-mediated dynamic gain control mechanism.

Understanding and recent development of carbon coating on LiFePO4cathode materials for lithium-ion batteries

Olivine-structured LiFePO4 has been the focus of research in developing low cost, high performance cathode materials for lithium ion batteries. Various processes have been developed to synthesize LiFePO4 or C/LiFePO4 (carbon coating on LiFePO4), and some of them are being used to mass produce C/LiFePO4 at the commercial or pilot scale. Due to the low intrinsic electronic and ionic conductivities of LiFePO4, the decrease of particle size and the nano-layer of carbon coating on LiFePO4 particle surfaces are necessary to achieve a high electrochemical performance. Significant progress has been made in understanding and controlling phase purity, particle size and carbon coating of the C/LiFePO4 composite material in the past. However, there are still many challenges in achieving a high quality product with high consistency. In this review, we summarize some of the recent progress and advances based on selected reports from peer-reviewed journal publications. Several typical synthesis methods and the effect of carbon coating quality on the properties of C/LiFePO4 composite are reviewed. An insight into the future research and further development of C/LiFePO4 composite is also discussed.

Enhanced and Reversible Contact Angle Modulation of Ionic Liquids in Oil and under AC Electric Field

Liquid actuation and manipulation using electrowetting is a rapidly growing field of research and has generated considerable interest in developing technologies such as microfluidic devices, liquid optics and displays. Electrowetting is conventionally carried out with (saline) aqueous solution under DC electric field. However, drawbacks such as evaporation and the inconvenient addition of inorganic salts to enhance the electric conductivity have inevitably limited its application. Therefore, development of new and robust media for electrowetting is highly desirable. Ionic liquids (ILs), a novel class of versatile solvents and soft materials possessing unique physicochemical properties, including negligible vapor pressure, being liquid over a wide temperature range, intrinsic ionic conductivity and acceptable electrochemistry stability, and so forth, have recently been developed as a promising alternative medium for electrowetting by Millefiorini et al. and other groups. In comparison with saline, IL-based electrowetting systems may be run under some extreme conditions such as in vacuum, or at temperatures either above 373 K or below 273 K. Recently, studies of electrowetting of ILs in air and under DC electric fields showed some unconventionality compared to saline such as low electrowetting efficiency (contact angle decrease or modulation) and cation/anion-dependent asymmetric behavior, although for the latter there is no unanimity among the different authors. Some effort has also been devoted to the initial applications of electrowetting of ILs as microreactor or microfluidics. Despite its promising potential, the reported electrowetting of ILs exhibits lower efficiency than that of saline with poor reversibility and a narrow range of contact angle modulation (<488). Herein, we presented greatly improved electrowetting efficiency of ILs using oil as the ambient and under AC electric field. Electrowetting behavior of ILs in this case, in particular at a high frequency of 1 kHz, shows greatly enhanced, sensitive, and reversible contact angle modulation in comparison to that in air or under DC electric field.

Efficient Thickness of Solid Oxide Fuel Cell Composite Electrode

The efficient thickness of a composite electrode for solid oxide fuel cells was directly calculated by developing a physical model taking into account of the charge transfer process, the oxygen ion and electron transportation, and the microstructure characteristics of the electrode. The efficient thickness, which is defined as the electrode thickness corresponding to the minimum electrode polarization resistance, is formulated as a function of charge transfer resistivity, effective resistivity to ion and electron transport, and three-phase boundary length per unit volume. The model prediction is compared with the experimental reports to check the validity. Simulation is performed to show the effect of microstructure, intrinsic material properties, and electrode reaction mechanism on the efficient thickness. The results suggest that when an electrode is fabricated, its thickness should be controlled regarding its composition, particle size of its components, the intrinsic ionic and electronic conductivities, and its reaction mechanisms as well as the expected operation temperatures. The sensitivity of electrode polarization resistance to its thickness is also discussed.

Control of the Firing Patterns of Vibrissa Motoneurons by Modulatory and Phasic Synaptic Inputs: A Modeling Study

Vibrissa motoneurons (vMNs) generate rhythmic firing that controls whisker movements, even without cortical, cerebellar, or sensory inputs. vMNs receive serotonergic modulation from brain stem areas, which mainly increases their persistent sodium conductance (g(NaP)) and, possibly, phasic input from a putative central pattern generator (CPG). In response to serotonergic modulation or just-suprathreshold current steps, vMNs fire at low rates, below the firing frequency of exploratory whisking. In response to periodic inputs, vMNs exhibit nonlinear suprathreshold resonance in frequency ranges of exploratory whisking. To determine how firing patterns of vMNs are determined by their 1) intrinsic ionic conductances and 2) responses to periodic input from a putative CPG and to serotonergic modulation, we construct and analyze a single-compartment, conductance-based model of vMNs. Low firing rates are supported in extended regimes by adaptation currents and the minimal firing rate decreases with g(NaP) and increases with M-potassium and h-cation conductances. Suprathreshold resonance results from the locking properties of vMN firing to stimuli and from reduction of firing rates at low frequencies by slow M and afterhyperpolarization potassium conductances. h conductance only slightly affects the suprathreshold resonance. When a vMN is subjected to a small periodic CPG input, serotonergically induced g(NaP) elevation may transfer the system from quiescence to a firing state that is highly locked to the CPG input. Thus we conclude that for vMNs, the CPG controls firing frequency and phase and enables bursting, whereas serotonergic modulation controls transitions from quiescence to firing unless the CPG input is sufficiently strong.

Li+Ionic Diffusion in LiCuO2Exposed to Heating-Cooling Cycles

The temperature dependence of 7 Li NMR line widths and electrical conductivity of LiCuO 2 have been measured to elucidate the Li + ionic diffusion in disordered layer structure. The line widths were constant below around 380 K, while the narrowing of line widths attributed to the Li + ionic diffusion was observed above 380 K in a heating-cooling cycle. The temperature dependence of conductivity shows hysteresis in the first heating-cooling cycle. It is strongly affected by the extrinsic conduction induced by the CuO phase produced at high temperatures. Therefore, it is difficult to extract the intrinsic ionic conduction from the electrical conductivity. However, the motional narrowing of 7 Li line widths is explained with a thermal activation model for Li + ion hopping, which yields the activation energy of around 0.22 eV through the heating-cooling cycle. It indicates that the Li + ionic diffusion occurs even in LiCuO 2 which has undergone the local change in structure produced by exposure to the heating...

Thin film solid oxide fuel cells with copper cermet anodes

Thin film solid oxide fuel cells (SOFCs), composed of thin coatings of 8 mol% Y 2O 3-stabilized ZrO 2 (YSZ) and thick substrates of (La 0.8Sr 0.2) 0.98MnO 3 (LSM)–YSZ cathodes, are fabricated using the conventional tape casting and tape lamination techniques. Densification of YSZ electrolyte thin films is achieved at 1275 °C by adjusting the cathode tape formulation and sintering characteristics. Two types of copper cermets, CuO–YSZ–ceria and CuO–SDC (Ce 0.85Sm 0.15O 1.925)–ceria, are compared in terms of the anodic performance in hydrogen and propane. Maximum power densities for hydrogen and propane at 800 °C are 0.26 W cm −2 and 0.17 W cm −2 for CuO–YSZ–ceria anodes and 0.35 W cm −2 and 0.22 W cm −2 for CuO–SDC–ceria anodes, respectively. Electrochemical impedance analysis suggests that CuO–SDC–ceria exhibits a much lower anodic polarization resistance than CuO–YSZ–ceria, which could be explained by the intrinsic mixed oxygen ionic and electronic conductivities for SDC in the reducing atmosphere.

Adaptation of chicken vestibular nucleus neurons to unilateral vestibular ganglionectomy

Vestibular compensation refers to the behavioral recovery after a unilateral peripheral vestibular lesion. In chickens, posture and balance deficits are present immediately following unilateral vestibular ganglionectomy (UVG). After three days, most operated chickens begin to recover, but severe deficits persist in others. The tangential nucleus is a major avian vestibular nucleus whose principal cells are vestibular reflex projection neurons. From patch-clamp recordings on brain slices, the percentage of spontaneous spike firing principal cells, spike discharge rate, ionic conductances, and spontaneous excitatory postsynaptic currents (sEPSCs) were investigated one and three days after UVG. Already by one day after UVG, sEPSC frequency increased significantly on the lesion side, although no differences were detected in the percentage of spontaneous spike firing cells or discharge rate. In compensated chickens three days after UVG, the percentage of spontaneous spike firing cells increased on the lesion side and the discharge rate increased bilaterally. In uncompensated chickens three days after UVG, principal cells on the lesion side showed increased discharge rate and increased sEPSC frequency, whereas principal cells on the intact side were silent. Typically, silent principal cells exhibited smaller persistent sodium conductances and higher activation thresholds for the fast sodium channel than spiking cells. In addition, silent principal cells on the intact side of uncompensated chickens had larger dendrotoxin-sensitive potassium conductance, with a higher ratio of Kv1.1 surface/cytoplasmic expression. Increased sEPSC frequency in principal cells on the lesion side of uncompensated chickens was accompanied by decreased Kv1.2 immunolabeling of presynaptic terminals on principal cell bodies. Thus, both intrinsic ionic conductances and excitatory synaptic inputs play crucial roles at early stages after lesions. Unlike the principal cells in compensated chickens which showed similar percentages of spontaneous spike firing cells, discharge rates, and sEPSC frequencies bilaterally, principal cells in uncompensated chickens displayed gross asymmetry in these properties bilaterally.

Crosslinked and quaternized poly(4-vinylpyridine)/polypyrrole composite as a potential candidate for the detection of low humidity

Poly(4-vinylpyridine) was crosslinked and quaternized with 1,4-bromobutane to form a polyelectrolyte humidity sensitive film on an interdigitated gold electrode, which was further coated with a layer of polypyrrole by a facile method of vapor phase polymerization. The composite so prepared was characterized by UV–vis spectroscopy and scanning electron microscopy. The investigations on the humidity sensitive properties of the composite revealed that it exhibited an impedance as low as 10 5 Ω even at 0%RH due to the existence of intrinsic conducting polypyrrole, thus conquering the difficulties in measuring low humidity with resistive-type humidity sensors. The impedance of the composite changed linearly with humidity in the range of 0–60%RH with good sensitivity. In addition, its response time ( t 90%) for adsorption and desorption between 33% and 97%RH was estimated to be 33 s and 110 s, respectively, and a hysteresis of 5%RH was observed. All these suggest it is promising as a sensitive material for low humidity detection. The effect of concentration and ratio of oxidizing agent to doping agent, polymerization temperature of pyrrole on the humidity sensitive properties of the composite have been investigated. A sensitive mechanism of the composite was proposed by taking into account the contribution of both the intrinsic electronic conduction and ionic conduction.

Charge and momentum transfer in supercooled melts: Why should their relaxation times differ?

The steady-state values of the viscosity and the intrinsic ionic conductivity of quenched melts are computed, in terms of independently measurable quantities. The frequency dependence of the ac dielectric response is estimated. The discrepancy between the corresponding characteristic relaxation times is only apparent; it does not imply distinct mechanisms, but stems from the intrinsic barrier distribution for alpha-relaxation in supercooled fluids and glasses. This type of intrinsic "decoupling" is argued not to exceed four orders in magnitude for known glassformers. The origin of the discrepancy between the stretching exponent beta, as extracted from epsilon(omega) and the dielectric modulus data, is explained. The actual width of the barrier distribution always grows with lowering the temperature. The contrary is an artifact of the large contribution of the dc-conductivity component to the modulus data. The methodology allows one to single out other contributions to the conductivity, as in "superionic" liquids or when charge carriers are delocalized, implying that in those systems, charge transfer does not require structural reconfiguration.

Ionic/Electronic Conducting Characteristics of LiFePO[sub 4] Cathode Materials

+ion diffusion coefficient of lithium iron phosphate LiFePO4 cathode materials should not be measured by the standard method because there is no composition variation but the movement of the LiFePO4/FePO4 interface during Li insertion/ extraction. A method to measure the intrinsic electronic and ionic conductivity of mixed conductive LiFePO4 was reported, for the first time, based on the conductivity measurements of mixed conductive solid electrolyte using blocking electrodes. The conductivities of the three LiFePO4 materials mixed electronic/ionic conductor, electronic conductor, and ionic conductor, were measured using the proposed method, and the electronic and ionic conductivities were linked with their electrochemical reaction kinetics and rate capabilities. These LiFePO4 samples have the same X-ray diffraction crystal structure and similar particle size, but different rate performance due to the difference in the ionic/electronic conductivity. The rate performance of the mixed electronic/ionic conductive LiFePO4 is much higher than that of the electronic conductive LiFePO4 and the ionic conductive

Chemistry and electrochemistry of nanostructured iron oxyhydroxides as lithium intercalation compounds for energy storage

The structural characterization and electrochemical performance of three nanosized iron oxyhydroxides (β-FeOOH, γ-FeOOH and δ-FeOOH) are reported in this work. The interest of having small particle sizes is to be able to circumvent the low intrinsic ionic conductivity of these materials through the increase of the active volume proportion of the operating grain, during the insertion process. Low temperature synthesis routes, in aqueous media, were thus used to obtain such crystallites with nanometer dimensions. The theoretical specific capacity of these materials is as high as 300 mA h g−1 which is actually very interesting for lithium batteries applications. However, the electrochemical behaviour greatly depends on the structure of the compounds. A phase transformation was, for example, evidenced in the case of γ-FeOOH first lithiation whereas the best performance were obtained with β-FeOOH, which develops a stable capacity of 180 mA h g−1, after 10 cycles, at C/10.

Intrinsic ionic conductances mediate the spontaneous electrical activity of cultured mouse myotubes

Mouse skeletal myotubes differentiated in vitro exhibited spontaneous contractions associated with electrical activity. The ionic conductances responsible for the origin and modulation of the spontaneous activity were examined using the whole-cell patch-clamp technique and measuring [Ca 2+] i transients with the Ca 2+ indicator, fura 2-AM. Regular spontaneous activity was characterized by single TTX-sensitive action potentials, followed by transient increases in [Ca 2+] i. Since the bath-application of Cd 2+ (300 μM) or Ni 2+ (50 μM) abolished the cell firing, T-type ( I Ca,T) and L-type ( I Ca,L) Ca 2+ currents were investigated in spontaneously contracting myotubes. The low activation threshold (around −60 mV) and the high density of I Ca,T observed in contracting myotubes suggested that I Ca,T initiated action potential firing, by bringing cells to the firing threshold. The results also suggested that the activity of I Ca,L could sustain the [Ca 2+] i transients associated with the action potential, leading to the activation of apamin-sensitive SK-type Ca 2+-activated K + channels and the afterhyperpolarization (AHP) following single spikes. In conclusion, an interplay between voltage-dependent inward (Na + and Ca 2+) and outward (SK) conductances is proposed to mediate the spontaneous pacemaker activity in cultured muscle myotubes during the process of myogenesis.

Grain boundary and grain interior conduction in γ′-Bi 2MoO 6

Impedance spectroscopy of fine grained (<10 μm) γ′-Bi 2MoO 6 samples, in the frequency range of 0.1 Hz–250 kHz, relevant to sensor applications, up to 800 °C, has been used to characterize grain boundary and grain interior contributions to conduction. Above 500 °C, the grain boundary contribution is no longer rate limiting and conduction is dominated by the grain interior component. The corresponding activation energies are 0.98 eV for grain boundary and 0.73 eV for grain interior components. The weak dependence of conductivity on oxygen partial pressure below 500 °C can be attributed to electrode–electrolyte interface phenomena, whereas the robust response to ethanol is commensurate with changes in intrinsic ionic conductivity.

Frequency-temperature response of ferroelectromagnetic Pb(Fe1∕2Nb1∕2)O3 ceramics obtained by different precursors. Part I. Structural and thermo-electrical characterization

With the purpose of fabricating ceramics where ferroelectric and magnetic order coexist, ceramics of Pb(Fe1∕2Nb1∕2)O3 have been prepared using the traditional ceramic method following three different routes. The first is a direct via starting from oxide reagents and the other two use different kinds of FeNbO4 precursors with either monoclinic or orthorhombic structures. Crystallographic and surface morphological studies were carried out by the powder x-ray diffraction and scanning microscopy techniques. The presence of Fe2+, detrimental to the ferroelectric and magnetic performance, was evaluated by x-ray photoelectron spectroscopy. The samples showed no structural differences, uniformly distributed grains, a ferro-paraelectric transition temperature at 110°C and a normal diffuse phase transition (nonrelaxor behavior). Differences in the degree of diffuseness, densities and grain size were observed depending on the kind of precursor. Measurements of dc and ac electrical resistivity, dielectric constant and dielectric loss were made as functions of temperature from room temperature to 250°C, at different frequency values (between 20Hz and 1MHz). Four conduction mechanisms were identified: hopping charge corresponding to low temperatures, small polarons and oxygen vacancies conduction at intermediate temperatures, and intrinsic ionic conduction at high temperatures. The best set of values of dielectric loss and dielectric constant, from the ferroelectricity point of view, were obtained when the precursor with orthorhombic structure was employed.

Synthesis of ceria based ion conducting mesoporous membranes by soft-chemistry

Ce0.9Gd0.1O1.95 (CGO) nanophase materials and related porous supported membranes were synthesized by a soft-chemistry route. One of the membranes was post-impregnated with Pt nanoparticles. The CGO average crystallite size is in the range 9–22 nm and the specific surface area varies from 43.4 to 6.7 m2/g in the intermediate temperature domain between 500 and 700 °C. The gas permeation properties of Pt-free and Pt post-impregnated CGO porous membranes were studied up to 500 °C. Although, the intrinsic bulk ionic conduction properties of the CGO material cannot be expected to contribute to oxygen transport at such a low temperature, attractive surface diffusion effects have been evidenced, which were clearly enhanced by a dispersion of Pt particles. The observed inversion of O2/N2 selectivity (α>1) compared to the Knudsen selectivity αK(O2/N2)=0.935 was attributed to the effect of the nanophase CGO material. Insertion of Pt nanoparticles increased oxygen surface diffusion at low temperature independently of the CGO effect. The barrier effect of the membranes and the induced solid/gas contact time were considered as key parameters to develop these porous nanophase ceramic membranes.