Structural, thermal and electrochemical properties of layered perovskite SmBaCo2O5+d, a potential cathode material for intermediate-temperature solid oxide fuel cells

The synthesis, conductivity properties, area specific resistance (ASR) and thermal expansion behaviour of the layered perovskite SmBaCo₂O_5+d (SBCO) are investigated for use as a cathode material for intermediate-temperature solid oxide fuel cells (IT-SOFCs). The SBCO is prepared and shows the expected orthorhombic pattern. The electrical conductivity of SBCO exhibits a metal–insulator transition at about 200 °C. The maximum conductivity is 570 S cm⁻¹ at 200 °C and its value is higher than 170 S cm⁻¹ over the whole temperature range investigated. Under variable oxygen partial pressure SBCO is found to be a p-type conductor. The ASR of a composite cathode (50 wt% SBCO and 50 wt% Ce_0.9Gd_0.1O_2−d, SBCO:50) on a Ce_0.9Gd_0.1O_2−d (CGO91) electrolyte is 0.05 Ω cm² at 700 °C. An abrupt increase in thermal expansion is observed in the vicinity of 320 °C and is ascribed to the generation of oxygen vacancies. The coefficients of thermal expansion (CTE) of SBCO is 19.7 and 20.0 × 10⁻⁶ K⁻¹ at 600 and 700 °C, respectively. By contrast, CTE values for SBCO:50 are 12.3, 12.5 and 12.7 × 10⁻⁶ K⁻¹ at 500, 600 and 700 °C, that is, very similar to the value of the CGO91 electrolyte.     

A potential interconnect material for solid oxide fuel cells: Nd0.75Ca0.25Cr0.98O3−δ

Chromium-deficient Nd_0.75Ca_0.25Cr_1−xO_3−δ (0.02 ≤ x ≤ 0.06) oxides are synthesized and assessed as a novel ceramic interconnect for solid oxide fuel cells (SOFCs). At room temperature, all the samples present single perovskite phase after sintering at 1600 °C for 10 h in air. Cr-deficiency significantly improves the electrical conductivity of Nd_0.75Ca_0.25Cr_1−xO_3−δ oxides. No structural transformation occurs in the Nd_0.75Ca_0.25Cr_1−xO_3−δ oxides in the temperature range studied. Among all the samples, the Nd_0.75Ca_0.25Cr_0.98O_3−δ sample with a relative density of 96.3% exhibits the best electrical conductivity of 39.0 and 1.6 S cm⁻¹ at 850 °C in air and hydrogen, respectively. The thermal expansion coefficient of Nd_0.75Ca_0.25Cr_0.98O_3−δ sample is 9.29 × 10⁻⁶ K⁻¹ in the temperature range from 30 to 1000 °C in air, which is close to that of 8 mol% yttria stabilized zirconia electrolyte (10.3 × 10⁻⁶ K⁻¹) and other cell components. The results indicate that Nd_0.75Ca_0.25Cr_0.98O_3−δ is a potential interconnect material for SOFCs.     

Vapour/liquid fractionation of rare earths,Y, Na,K, NH4, Cl,HCO3, SO4 and borate in fluids from the Piancastagnaio geothermal field,Italy

Vapour/liquid fractionation of rare earth elements and yttrium (REY), Na⁺, K⁺, NH₄⁺, HCO₃⁻, SO₄²⁻, Cl⁻ and borate in geothermal fluids from the Piancastagnaio geothermal field (Mt. Amiata geothermal area, Tuscany, central Italy) were evaluated based on the chemistry of collected liquids and condensed vapours. Apparent vapour–liquid partitioning factors (^appD^V/L) of REY vary from 0.3 to 0.01. These factors are much higher than those of Na (<0.001) and K (∼0.001). Volatile components are ion pairings such as NH₄HCO₃^o, NH₄Cl^o, NaHCO₃^o, CaSO₄^o and REYO(HCO)₃^o ⇔ REY(OH)CO₃^o. In vapour, REY and NH₄⁺ are negatively correlated. High and low ^appD^V/L(REY) indicate variations of NH₄⁺ concentrations in liquids. The results of this study are relevant to the understanding of element migration and deposition under hydrothermal boiling conditions.     

Determination of glazing area in direct gain systems for three different climatic zones

This study determines the glazing area in direct gain passive systems needed to ensure thermal comfort inside a building (room air temperature 20 ± 2°C). A 4 m × 4 m × 3 m single zone isolated house is analyzed in three different types of climates namely composite (8°C to 20°C, New Delhi), cold-cloudy (−2°C to 5°C, Srinagar), and cold-sunny (−14°C to −3°C, Leh). The analysis is based on the periodic solution of the heat conduction equations describing heat transmission in the building components, floor, walls, and roof, and the Fourier representation of the ambient temperature vnd the total solar radiation intercepted by the building envelope. Two types of construction are analyzed: the first type is a traditional construction with 22-cm-thick brick wall, plastered 15 mm on both the sides (U = 2.0 W m⁻² K⁻¹); and the second one is of the same type but with 10 cm of expanded polystyrene insulation on all the four walls and the roof (U = 0.31 W m⁻² K⁻¹). It is found that for traditional construction with U = 2.0 W m⁻² K⁻¹, the glazing U value has almost no effect on the room temperature even for large variation of the glazing area (10% to 40%, expressed in terms of percentage of floor area). For a well-insulated house (U = 0.31 W m⁻² K⁻¹), the glazing U value has no effect upon the room air temperature if the glazing area is small (less than 10%). The position of the insulation on the external surfaces is more effective in reducing large inroom air temperature. Finally, for an insulated house, we recommended glazing is 30%, 20%, and 10% for cold-sunny, cold-cloudy, and composite climates, respectively.     

Sodium/lithium ratio in water applied to geothermometry of geothermal reservoirs

We propose here a new geothermometer for natural waters. Analyses from many explored geothermal fields allow us to define two empirical thermometric relationships.One is for waters of low to moderate salinity (Cl⁻< 0·3 M) log Na/Li = 1000/T −0·38 and one for marine waters and brines (Cl⁻ > 0·3 M) log Na/Li = 1195/T + 0·38 These relationships, which at present are not well understood, result mainly from the increase of Li concentrations in waters with temperature.Equation (a) proved to be adequate for spring waters from mostly known geologic origin; this is an important feature in geochemical surveys for geothermal prospecting.Furthermore, when comparison between springs and drillhole chemistry of a given geothermal field is possible, the Na/Li geothermometer gives more reliable temperature estimates from the spring compositions than do classical geothermometers.     

Simulation and model validation of a horizontal shallow basin solar concentrator

Salt removal from drainage water is becoming increasingly important for sustainable irrigated arid land agriculture, where inadequate drainage infrastructure exists. Solar evaporation and concentration systems are currently in development in California for this purpose. The thermal behavior and evaporation rates of a horizontal shallow basin solar concentrator were modeled for design purposes and investigated experimentally in order to validate the model. Three different evaporation rate models were evaluated and compared. Measured and predicted peak brine temperatures differed by as much as 5 °C when using prescribed literature coefficients without calibration. Model prediction was improved by calibration so that peak brine temperature deviated less than 3 °C when tested against independent data sets.Minimum root mean square error was used to calibrate the mass transfer coefficient and absorptance of the collector surface for solar radiation, which are the main factors affecting the heat transfer associated with the solar concentrator. Calibrated collector surface absorptance for solar radiation declined while mass transfer coefficients were increased from reported literature values. Under calibration, the absorptance of the collector surface was adjusted from 0.8 to 0.61, and mass transfer coefficients estimated by Newell et al. [Newell, T.A., Smith, M.K., Cowie, R.G., Upper, J.M., Cler, C.L., 1994. Characteristics of a solar pond brine reconcentration system. Journal of Solar Energy Engineering 116 (2), 69–73] from 1.36 × 10⁻⁶(1.9 + 1.065V) to 1.70 × 10⁻⁶(1.84 + 1.0V) kg m⁻² s⁻¹ mm Hg⁻¹, by Manganaro and Schwartz [Manganaro, J.L., Schwartz, J.C., 1985. Simulation of an evaporative solar salt pond. Industrial & Engineering Chemistry Process Design and Development 24, 1245–1251] from 0.0208(1 + 0.224V) to 0.0233(1 + 0.214V) kg m⁻² h⁻¹ mm Hg⁻¹, and by Alagao et al. [Alagao, F.B., Akbarzadeh, A., Johnson, P.W., 1994. The design, construction, and initial operation of a closed-cycle, salt-gradient solar pond. Solar Energy 53 (4), 343–351] from 2.8 + 3.0V to 3.0 + 3.33V W m⁻² °C⁻¹. The calibrated models were tested using an independent data set. Maximum deviation between measured and predicted brine temperatures differed by less than 3 °C. The measured and predicted peak evaporation rates were between 1.2 and 1.4 kg m⁻² h⁻¹.The calibrated Newell model was used to predict the monthly productivity and daily maximum evaporation rates at Five Points, California for the year 2004. The productivity from April to September and from March to October was 80.7% and 94.3% of the total annual productivity, respectively.     

PCM-facade-panel for daylighting and room heating

Double glazings combined with phase change materials (PCM) result in daylighting elements with promising properties. Light transmittances in the range of 0.4 can be achieved with such facade panels. Compared to a double glazing without PCM, a facade panel with PCM shows about 30% less heat losses in south oriented facades. Solar heat gains are also reduced by about 50%. This results in calculated U_eff-values of −0.3 to −0.5 W m⁻² K⁻¹, depending on PCM used. For an optimised panel, we calculated an U_eff-value of −0.6 W m⁻² K⁻¹. Although the U_eff-value of a double glazing is −0.8 W m⁻² K⁻¹, the PCM-systems may prove advantageous in lightweight constructed buildings due to their equalised energy balance during the course of day. Facade panels with PCM improve thermal comfort considerably in winter, especially during evenings. In summer, such systems show low heat gains, which reduces peak cooling loads during the day. Additional heat gains in the evening can be drawn off by night-time ventilation. If a PCM with a low melting temperature of up to 30 °C is used, thermal comfort in summer will also improve during the day, compared to a double glazing without or with inner sun protection. A homogeneous appearance of the PCM-systems is achievable by use of a concealment, like a screen-print glazing.     

Ex situ measurements of through-plane thermal conductivities in a polymer electrolyte fuel cell

In this paper thermal properties for materials typically used in the proton exchange membrane fuel cell (PEMFC) are reported. Thermal conductivities of Nafion membranes were measured ex situ at 20 °C to be 0.177 ± 0.008 and 0.254 ± 0.016 W K⁻¹ m⁻¹ for dry and maximally wetted membranes respectively. This paper also presents a methodology to determine the thermal conductivity of compressible materials as a function of applied load. This technique was used to measure the thermal conductivity of an uncoated SolviCore porous transport layer (PTL) at various compaction pressures. For the dry PTL at 4.6, 9.3 and 13.9 bar compaction pressures, the thermal conductivity was found to be 0.27, 0.36 and 0.40 W K⁻¹ m⁻¹ respectively and the thermal contact resistivity to the apparatus was determined to be 2.1, 1.8 and 1.1 × 10⁻⁴ m² K W⁻¹, respectively. It was shown that the thermal contact resistance between two PTLs is negligible compared to the apparatus’ thermal contact resistivity. For a humidified PTL, the thermal conductivity increases by up to 70% due to a residual liquid saturation of 25%.     

Characterization of Pr1−xSrxCo0.8Fe0.2O3−δ (0.2 ≤ x ≤ 0.6) cathode materials for intermediate-temperature solid oxide fuel cells

Cathode materials consisting of Pr_1−xSr_xCo_0.8Fe_0.2O_3−δ (x = 0.2–0.6) were prepared by the sol–gel process for intermediate-temperature solid oxide fuel cells (IT-SOFCs). The samples had an orthorhombic perovskite structure. The electrical conductivities were all higher than 279 S cm⁻¹. The highest conductivity, 1040 S cm⁻¹, was found at 300 °C for the composition x = 0.4. Symmetrical cathodes made of Pr_0.6Sr_0.4Co_0.8Fe_0.2O_3−δ (PSCF)–Ce_0.85Gd_0.15O_1.925 (50:50 by weight) composite powders were screen-printed on GDC electrolyte pellets. The area specific resistance value for the PSCF–GDC cathode was as low as 0.046 Ω cm² at 800 °C. The maximum power densities of a cell using the PSCF–GDC cathode were 520 mW cm⁻², 435 mW cm⁻² and 303 mW cm⁻² at 800 °C, 750 °C and 700 °C, respectively.     

ZnO-doped BaZr0.85Y0.15O3−δ proton-conducting electrolytes: Characterization and fabrication of thin films

ZnO-doped BaZr_0.85Y_0.15O_3−δ perovskite oxide sintered at 1500 °C has bulk conductivity of the order of 10⁻² S cm⁻¹ above 650 °C, which makes it an attractive proton-conducting electrolyte for intermediate-temperature solid oxide fuel cells. The structure, morphology and electrical conductivity of the electrolyte vary with sintering temperature. Optimal electrochemical performance is achieved when the sintering temperature is about 1500 °C. Cathode-supported electrolyte assemblies were prepared using spin coating technique. Thin film electrolytes were shown to be dense using SEM and EDX analyses.     

Preparation of sulfonated poly(ether ether ketone)s containing amino groups/epoxy resin composite membranes and their in situ crosslinking for application in fuel cells

A series of amino-containing sulfonated poly(aryl ether ketone)/4,4′-diglycidyl(biphenyl) epoxy resin (DGBP) composite membranes for proton exchange membranes fuel cells (PEMFCs) are prepared by solution blending and casting. The reaction kinetics and the effects of introduction of DGBP content on the properties of the composite membranes are thoroughly investigated. The crosslinked composite membranes after treatment at either 120 °C or 200 °C have improved oxidative and dimensional stability than those without crosslinking. Despite the fact that crosslinked membranes generally have lower proton conductivity in comparison with the original ones, the proton conductivities of the membranes treated at 120 °C are above 2.22 × 10⁻² S cm⁻¹ at room temperature and 9.42 × 10⁻² S cm⁻¹ at 100 °C. Even for the samples treated at 200 °C, their proton conductivities are still higher than 1.26 × 10⁻² S cm⁻¹ at room temperature and higher than 8.67 × 10⁻² S cm⁻¹ at 100 °C, which are well satisfied with elementary requirement of fuel cells. In addition, all the evaluated membranes have low methanol permeability. For example, the methanol permeability of AP6FSPEEK/DGBP1 cured at 200 °C is 0.33 × 10⁻⁶ cm² s⁻¹, which is an order magnitude lower than Nafion 117. Therefore, these novel crosslinked composite membranes could be potential usage in fuel cells.     

Deposition of amorphous silica in porous packed beds — predicting the lifetime of reinjection aquifers

Predicting deposition rates of dissolved silica in geothermal reinjection aquifers is difficult due to a lack of reliable scaling rates and the complexity of modelling fluid transport simultaneously with deposition. In order to develop techniques, understand the problems and improve our predictive capabilities, we have undertaken field experiments at Wairakei geothermal field, New Zealand, to determine amorphous silica deposition rates in 25 mm diameter pipes packed with 2 mm diameter zirconia beads. These pipes served as model aquifers. Five experiments using flashed fluid containing 530 ppm total silica were completed at temperatures between 71 and 129°C and at flowrates between 0.002 and 0.02 kg s⁻¹. The residence times in the pipes were shorter than the induction period required for silica polymerisation from solution. The scaling rates in the beds, measured over a month, were about 12 mg cm⁻² year⁻¹ and independent of flowrate between 80 and 129°C. Scaling at 129°C was unexpected, because the dissolved silica was expected to be undersaturated with respect to amorphous silica. At 71°C the rates were higher (up to 23 mg cm⁻² year⁻¹) and were proportional to flowrate. At Wairakei the 130°C fluid used in these experiments is disposed of by injection into a reservoir at 80°C. Using our field deposition rates, we estimate that 2.6×10⁵ kg of amorphous silica would precipitate in 10 years around the injection well, assuming an injection rate of 50 kg s⁻¹ into a 100 m thick reservoir of radius 500 m with permeability 100 mdarcy and a porosity of 0.2.     

Rock-water interactions in the Fenton Hill, new Mexico, hot dry rock geothermal systems I. fluid mixing and chemical geothermometry

The chemistry of fluids circulated through an artificially-stimulated, hot dry rock (HDR) fractured geothermal reservoir system in granitic rock is described in terms of mixing phenomena, geothermometry, and approach to saturation with reservoir rock minerals. Based on the similar dynamic behavior of Na⁺, K⁺, Li⁺, CI⁻, and B species and other isotopic evidence, the presence of a concentrated in-situ pore fluid was identified. Mixing and displacement of this in-situ fluid with meteoric make-up water is responsible for the observed behavior of the major dissolved species in the circulated fluid of this HDR system.     

Synthesis and characterization of oxygen-rich delafossite CuYO2+x—Application to H2-photo production

Here we report the synthesis and photo electrochemical properties of super oxides CuYO_2.50 and CuYO_2.25 prepared from the delafossite CuYO₂, respectively, by thermal oxidation at 380 °C under O₂-flow and soft chemistry in NaBrO solution (5 N). Their applications as catalysts for H₂ evolution upon visible light were investigated. The oxygen insertion was accompanied by partial oxidation of Cu⁺. For CuYO_2.25, the chemical analyses revealed the presence of mixed valent states containing at least formally an equal number of Cu⁺ and Cu²⁺. The thermal analysis (TGA) under reducing atmosphere indicates that oxygen is inserted in different crystallographic sites, for CuYO_2.25 it exhibits a two-step reduction mechanism with restoration of the parent oxide. In air, CuYO_2+x is thermally stable up to 500 °C above which it undergoes irreversible conversion into Cu₂Y₂O₅. They display p-type behavior ascribed to oxygen insertion and the conduction occurs by hopping mechanism between mixed copper valences. Under illumination, the oxides are stabilized by hole consumption reactions involving SO₃²⁻ and S²⁻ as holes scavengers. The flat-band potentials, lying between 0.17 and 0.26 V_SCE, allow a spontaneous H₂-photo formation. The rate of H₂-evolution is altered by the oxygen insertion and the best photo activity (1.33 μmol h⁻¹ mg⁻¹) was obtained over CuYO_2.25 immersed in S²⁻ solution (0.025 M); CuYO₂ is also reported for a comparison goal. Over time, the photoactivity is slowed down because of the competitive reduction of H₂O with the final products namely S₂O₆²⁻ and S_n²⁻.     

Synthesis of LiFePO4/polyacenes using iron oxyhydroxide as an iron source

LiFePO₄/polyacenes (PAS) composite is synthesized by iron oxyhydroxide as a new raw material and phenol–formaldehyde resin as both reducing agent and carbon source. The mechanism of the reaction is outlined by the analysis of XRD, FTIR as well as TG/DSC. The results show that the formation of LiFePO₄ is started at 300 °C, and above 550 °C, the product can be mainly ascribed to olivine LiFePO₄. The electrochemical properties of the synthesized composites are investigated by charge–discharge tests. It is found that the prepared sample at 750 °C (S750) has a better electrochemical performance than samples prepared at other temperatures. A discharge capacity of 158 mAh g⁻¹ is delivered at 0.2 C. Under high discharge rate of 10 C, a discharge capacity of 145 mAh g⁻¹ and good capacity retention of 93% after 800 cycles are achieved. The morphology of S750 and PAS distribution in it are investigated by SEM and TEM.     

Thermal cycle stability of BaO–B2O3–SiO2 sealing glass

Thermal cycle stability is very important for glass seals in planar solid oxide fuel cell (pSOFC) applications. In the present study, thermal cycle stability of a thermally stable sealing glass is investigated using a sealing fixture from 150 °C to 700 °C. SS410 alloy with the TEC (thermal expansion coefficient) of 12.2 × 10⁻⁶ K⁻¹ (room temperature to 700 °C) is used to evaluate the effect of TEC mismatch on the thermal cycle stability. The leak rates increase with thermal cycles and appear to be two different stages. Microstructure examinations are performed to investigate the degradation mechanism of the thermal cycle stability. It is found that the sealing glass interacts chemically with the SS410 alloy and the formation of BaCrO₄ new phase results in the rapid increase of the leak rates.     

Carbon-coated graphite for anode of lithium ion rechargeable batteries: Graphite substrates for carbon coating

Anode performance in lithium ion rechargeable batteries (LIBs) was studied on four kinds of graphite powders, including synthetic graphite. Carbon-coated synthetic graphite gave a smaller irreversible capacity of about 20 mAh g⁻¹ and a better cyclic performance in an electrolyte solution of EC/DMC than natural graphite, though its discharge capacity of about 300 mAh g⁻¹ is a little smaller than natural graphite. Even in a PC-containing solution as EC/PC = 3/1, carbon-coated synthetic graphite had almost the same anode performance as in the solution without PC. Carbon coating of above 5 mass% on graphite particles was found to be effective to improve the anode performance at a low temperature of −5 °C, high retention in discharge capacity of about 90% being obtained. On both natural and synthetic graphite powders, carbon coating by the amount of 3–10 mass% at a temperature of 700–1000 °C was found to be optimum for the improvement of anode performance in LIBs, to have a lower irreversible capacity and higher retention in discharge capacity at −5 °C than without carbon coating.     

Stable, easily sintered BaCe0.5Zr0.3Y0.16Zn0.04O3−δ electrolyte-based protonic ceramic membrane fuel cells with Ba0.5Sr0.5Zn0.2Fe0.8O3−δ perovskite cathode

A stable, easily sintered perovskite oxide BaCe_0.5Zr_0.3Y_0.16Zn_0.04O_3−δ (BCZYZn) as an electrolyte for protonic ceramic membrane fuel cells (PCMFCs) with Ba_0.5Sr_0.5Zn_0.2Fe_0.8O_3−δ (BSZF) perovskite cathode was investigated. The BCZYZn perovskite electrolyte synthesized by a modified Pechini method exhibited higher sinterability and reached 97.4% relative density at 1200 °C for 5 h in air, which is about 200 °C lower than that without Zn dopant. By fabricating thin membrane BCZYZn electrolyte (about 30 μm in thickness) on NiO–BCZYZn anode support, PCMFCs were assembled and tested by selecting stable BSZF perovskite cathode. An open-circuit potential of 1.00 V, a maximum power density of 236 mW cm⁻², and a low polarization resistance of the electrodes of 0.17 Ω cm² were achieved at 700 °C. This investigation indicated that proton conducting electrolyte BCZYZn with BSZF perovskite cathode is a promising material system for the next generation solid oxide fuel cells.     

Novel composite sorbent for resorption systems and for chemisorption air conditioners driven by low generation temperature

The utilization of a composite sorbent (NaBr and expanded graphite) in chemisorption air conditioning systems driven by low-grade heat source, and in resorption systems with simultaneous heating and cooling effects was experimentally investigated using bench-scale prototypes. The mass of ammonia desorbed and adsorbed was measured, and used to calculate the specific cooling capacity. The sorbent produced 219 kJ kg⁻¹ of cooling at 5 °C and 510 kJ kg⁻¹ at 15 °C, when the heat source temperature was 65 °C and the heat sink temperature was 30 °C. The air conditioning system mean specific cooling power (SCP), and mean coefficient of performance (COP) were calculated based on the desorbed and adsorbed masses, and on the variation of temperature in the reactors. For the same heat source and heat sink temperatures mentioned above, the air conditioning system had a SCP of 129 ± 7 W kg⁻¹ and a COP of 0.46 ± 0.01, when cooling occurred at 15 °C. Regarding the utilization of the composite sorbent in resorption machines, the prototype was tested for production of cooling/heating at −5/50 °C, and at 10/70 °C. In the former condition, the COP was only 0.02, but in the latter condition, there was a tenfold increase in the COP, and the combined coefficient of performance and amplification reached 1.11, which indicates the energy saving potential of resorption systems using the studied sorbent.     

Co-free, iron perovskites as cathode materials for intermediate-temperature solid oxide fuel cells

We have developed a Co-free solid oxide fuel cell (SOFC) based upon Fe mixed oxides that gives an extraordinary performance in test-cells with H₂ as fuel. As cathode material, the perovskite Sr_0.9K_0.1FeO_3−δ (SKFO) has been selected since it has an excellent ionic and electronic conductivity and long-term stability under oxidizing conditions; the characterization of this material included X-ray diffraction (XRD), thermal analysis, scanning microscopy and conductivity measurements. The electrodes were supported on a 300-μm thick pellet of the electrolyte La_0.8Sr_0.2Ga_0.83Mg_0.17O_3−δ (LSGM) with Sr₂MgMoO₆ as the anode and SKFO as the cathode. The test cells gave a maximum power density of 680 mW cm⁻² at 800°C and 850 mW cm⁻² at 850 °C, with pure H₂ as fuel. The electronic conductivity shows a change of regime at T ≈ 350 °C that could correspond to the phase transition from tetragonal to cubic symmetry. The high-temperature regime is characterized by a metallic-like behavior. At 800 °C the crystal structure contains 0.20(1) oxygen vacancies per formula unit randomly distributed over the oxygen sites (if a cubic symmetry is assumed). The presence of disordered vacancies could account, by itself, for the oxide-ion conductivity that is required for the mass transport across the cathode. The result is a competitive cathode material containing no cobalt that meets the target for the intermediate-temperature SOFC.