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The various structural and conductive attributes of barium cerate, BaCeO3 position it as a highly promising matrix for energy storage purposes. The current study illustrates that barium cerate can be effectively tailored by introducing trivalent praseodymium ions, thereby enhancing its optical properties as well. In this work, single-phased orthorhombic crystalline powders of barium cerate incorporated with Pr3+ (BaCeO3: Pr3+) were synthesized using the gel combustion procedure, followed by calcination. We conducted a comprehensive investigation into their crystal structure, vibrational characteristics, optical properties, and potential applications in wLEDs. The structure refinement indicates that Pr3+ occupies Ce4+ site, which results in the expansion of the cell and facilitates the generation of defects such as Pr Ce ′ and oxygen vacancies V O ⋅ ⋅ . By correlating information gathered from diffuse reflectance spectra with that obtained from photoluminescence spectra, we gained a deeper understanding of the electronic level structure and the mechanism of energy transfer. We successfully achieved a finely tuned cool white light emission with very low color purity (CP), a high color rendering index (CRI), and a high correlated color temperature (CCT) with a quantum efficiency of 36.3 % by exciting the material with a 321 nm wavelength. Because of the transfer of energy within activators through dipole–dipole interaction, luminescence quenching occurs when Pr3+ concentration reaches 1 wt%. To the best of our knowledge, this is the initial investigation of luminescence properties of Pr-incorporated barium cerate perovskites. [ABSTRACT FROM AUTHOR]

BaZr 0.1 Ce 0.7 Y 0.1 Yb 0.1 O 3-δ (BZCYYb) as a potential candidate for protonic ceramic fuel cells (PCFCs) electrolytes, often suffers from its high sintering temperature, making it deviate from the stoichiometric ratio and present a poor electrochemical performance than expected. Here, we reported a Ba evaporation inhibition strategy to fabricate stoichiometric BZCYYb electrolyte. By using this strategy, Ba evaporation and Y 2 O 3 /Yb 2 O 3 segregation can be effectively suppressed. The electrolyte's average grain size is ∼5.29 μm, significantly promoting grain growth. An improvement of 60 % in total conductivity is accomplished at 700 °C in humid air, approaching 2.7 × 10−2 S cm−1. By constructing the proton transport model, the reasons for the enhanced electrochemical performance are explained from both bulk and grain boundary. Finally, at 700 °C, an anode-supported single cell with stoichiometric BZCYYb electrolyte demonstrates a maximum power density of 0.65 W cm−2, showing that the barium evaporation inhibition strategy is a powerful tool to fabricate PCFCs with high performance. • Stoichiometric BZCYYb electrolyte is obtained by a Ba evaporation inhibition strategy. • Large grain size (∼5.29 μm) of BZCYYb electrolyte is obtained. • Enhanced electrical conductivity reaches to 2.7 × 10−2 S cm−1 at 700 °C in humid air. [ABSTRACT FROM AUTHOR]

An innovative bidirectional (up and down) luminescence conversion agent (BaCeO3: Dy3+) which transforms UV and near-infrared lights into visible lights, is synthesized by the solution combustion method. The structure and phase of the crystal samples were examined from XRD and Rietveld refinement analysis. Surface morphology and elemental configuration were analyzed using FESEM, EDS, and elemental mapping techniques. Raman spectral analysis revealed corresponding vibrational bands of both host and dopant ions incorporated lattice. The optical band gaps of the samples were determined through UV–Visible diffuse reflection study. The luminescence characteristics, including up and down conversions (UC and DC) of the samples have been investigated on the basis of excitation and emission spectra. Upon 350 nm down conversion, the low-symmetric site of Dy3+within the host lead to a sharp emission peak at 578 nm (yellow) which dominates blue emission at 479 nm. Additionally, a peak at 654 nm is observed upon 980 nm up conversion. These findings recommend that the obtained material can be a potential candidate for solar spectral conversion materials in solar cell applications. The presence of these nanoparticles makes solar cells indirectly exploit UV and near-infrared lights in solar illuminations thus enhancing light absorption range and improving the solar energy utilization rate.

Here, BaCe 0.97 M 0.03 O 3-δ (M = Sm, Gd) perovskite electrolyte materials were synthesized via a semi-organic combustion route by employing the synergetic role of biomolecules and bio-chelating agent of lemon juice for IT-SOFC. The synthesized BaCe 0.97 M 0.03 O 3-δ (M = Sm, Gd) electrolyte was compared to BaCe 0.97 M 0.03 O 3-δ (M = Sm, Gd) synthesized with a typical chemical combustion route. The structural analysis confirmed the orthorhombic phase of all perovskite electrolytes while the microstructural analysis revealed dense microstructure for electrolytes synthesized with bio-chelating agents compared to those synthesized with chemical combustion route. The compositional analysis confirmed the presence of all elements and the thermal analysis established the stability within the SOFC operating temperature range of BaCe 0.97 M 0.03 O 3-δ (M = Sm, Gd) synthesized with both routes. The electrochemical measurements exhibited a maximum power density of 0.47 W cm−2 for BaCe 0.97 M 0.03 O 3-δ (M = Sm) synthesized with lemon juice as a chelating agent suggesting its potential use as an efficient electrolyte for IT-SOFCs. The outcomes show that the semi-organic route can be successfully used for the synthesis of perovskite structure materials with minimal negative impact on the environment compared to chemical routes. [ABSTRACT FROM AUTHOR]

The development of intermediate-temperature solid oxide fuel cells (IT-SOFCs) is currently a focus of research, as it has the potential to improve their operational characteristics, lower their cost, and enhance their stability. However, achieving high-performance functional materials at working temperatures of 600–800 °C poses a significant challenge. Barium cerate (BaCeO 3) has been identified as a promising material for the solid electrolyte of IT-SOFCs due to its high proton conductivity among A2+B4+O 3 -type perovskites. Nevertheless, producing a single-phase and dense ceramic based on BaCeO 3 with high conductivity in the intermediate-temperature range remains a challenge. This study employed the hydrazine-nitrate combustion method to obtain BaCeO 3 precursor powder, which was then used to produce dense proton-conducting ceramics by isostatic pressing and subsequent isothermal sintering at temperatures of 1100–1500 °C. The resulting samples were characterized using various techniques, including XRD, SEM, Vickers microhardness, TMA, LFA, and impedance spectroscopy. The findings indicate that the proposed hydrazine-nitrate approach was successful in producing ceramic samples with an average crystallite size of 95–220 nm, an average grain size of 4.8–9.9 μm, and a relative density of 70.7–91.2% depending on the sintering conditions. The most densely sintered sample (91.2%) exhibited the highest mechanical and functional properties, with Vickers microhardness values of 3.0 GPa (R T.), a coefficient of thermal expansion of 8.7 × 10–6 (R T.-1000 °C), thermal conductivity of 1.51–1.06 W/m·°C (R.T.-1000 °C), and logarithmic conductivity of −3.37 to −6.35 S/cm (675–980 °C). Thus, the proposed hydrazine-nitrate approach shows promise for producing high-performance conducting ceramic materials for IT-SOFCs. [ABSTRACT FROM AUTHOR]

BaCe 0.8 Y 0.2 O 3-δ proton conductor powder was prepared by sol-gel method, and the effects of sintering temperature and sintering aids addition on the mechanical properties and hydrogen permeability of BaCe 0.8 Y 0.2 O 3-δ proton conductor were investigated. XRD tests showed that when the addition of sintering aid Co 2 O 3 reached 5%, the BaCe 0.8 Y 0.2 O 3-δ proton conductor still showed a good perovskite phase. The sintering temperature of the sample with sintering aid is significantly lower than that of the blank sample. SEM shows that the addition of Co 2 O 3 , the proton conductor grains are closely arranged, the mechanical properties are increased, and the hydrogen permeability is significantly improved. • Co 2 O 3 was selected as an important sintering aid material. • The effect of sintering aid Co 2 O 3 on the mechanical properties of BCY was discussed. • The effect of sintering aid Co 2 O 3 on the hydrogen permeability of BCY was discussed. [ABSTRACT FROM AUTHOR]

As electrolyte materials for proton conductive fuel cells, perovskite-type materials such as barium cerates and barium zirconates have received a lot of attention due to their high protonic conduction at intermediate temperatures. Yet, the crystalline structure and the microstructure of the electrolyte layers are of the utmost importance that define the resulting protonic conductivity. The aim of this research was to investigate the formation of doped/undoped BCO and BZO thin films using e-beam vapor deposition and to analyze the influence of the formation parameters on the microstructural and crystallographic properties. Crystalline structure and microstructure were investigated by X-ray diffractometer and scanning electron microscope, while the elemental composition of the resulting thin films was analyzed by an energy-dispersive X-ray spectroscope. It was found that the formed thin films were highly dense and consisted of the oriented columnar grains. The crystallinity of the thin films was strongly expressed with the predominant crystallographic orientations for undoped/doped barium cerates. Yttrium dopant had an influence on the lattice parameters and crystallite sizes. With the chosen technological parameters allowed to both, barium cerates and barium zirconates did not form carbonates and did not experience the degradation process. [ABSTRACT FROM AUTHOR]

Solid oxide fuel cells based on proton-conducting ceramic electrolytes, i.e., protonic ceramic fuel cells (PCFCs), are promising in operating at intermediate to low temperature. BaZr 0.8 Y 0.2 O 3-δ (BZY) and BaZr 0.1 Ce 0.7 Y 0.2 O 3-δ (BZCY) are two typical electrolyte materials for PCFCs. However, there is still a lack of basis for making a choice between the two materials. In this paper, we present a comparison investigation on practical BZY and BZCY electrolytes with NiO of 2 mol.% as sintering aid. Their crystal structure, sinterability, microstructure, and electrical conductivity in humid air and hydrogen (3% H 2 O) are measured and analyzed. Anode-supported PCFCs based on the two electrolyte materials are prepared and their electrochemical performances are tested and analyzed in association with an examination on their microstructure. The results show that both materials can be densified after sintered with NiO aid at 1400 °C for 6h. Ni is doped into the interstitial of BZY while it occupies the B site of perovskite lattice of BZCY. The sintered BZY has small grains and many grain boundaries while BZCY has large grains and much fewer grain boundaries, resulting in lower conductivity of BZY than that of BZCY. A PCFC with BZY electrolyte gives a peak power density of 360 mW cm−2 at 700 °C, while this value for a PCFC with BZCY is 855 mW cm−2. Although the performances of BZCY seems much better than those of BZY, a stability test in 10% CO 2 -containing Ar at 650 °C shows BZY is stable while BZCY reacts with CO 2 to form BaCO 3 and CeO 2. [ABSTRACT FROM AUTHOR]

In the present work, preceramic nanocrystallite barium cerate (BaCeO3) was successfully synthesized using the hydrazine-nitrate combustion method. Using carbon-free hydrazine (N2H4) as fuel significantly reduced the formation of carbonate by-products. Subsequent annealing of combustion products in the air atmosphere at temperatures in the range of 500–1000 °С yielded preceramic powders based on chemically and phase-pure BaCeO3. Characterization of the as-received powders was performed by X-ray diffraction, energy-dispersive X-ray spectroscopy (EDXS), scanning electron microscopy (SEM), simultaneous thermal analysis (DTA-TGA) and adsorption-structural analysis (N2, 77 K). Thermophysical properties of the sample annealed at 1000 °С were investigated using laser flash analysis (LFA) in the temperature interval of 1000 °С. As a result of a comprehensive study, the sequence of chemical and phase transformations that lead to the formation of barium cerate with a rhombic structure (Pnma, a = 6.2145 Å, b = 8.7776 Å, c = 6.2337 Å) during the thermal processing of combustion products was investigated. It was established that the average size of the obtained nanocrystals is 38 ± 3 nm and that they form micron-sized agglomerates with a specific surface area of the powder of 4.8 m2/g. It was shown that the sintered sample of barium cerate is characterized by thermal diffusivity values of 0.28 to 0.20 mm2/s and thermal conductivity values of 0.41–0.35 W/mK, depending on temperature. These results, given the impact of porosity on the sample (~40%), show very good agreement with the thermophysical characteristics of densely sintered ceramics based on BaCeO3—a solid oxide electrolyte SOFC. Consequently, the proposed method of hydrazine-nitrate synthesis of barium cerate presents itself as a promising approach to obtaining preceramic powders and ceramics in the area of solid oxide fuel cells. Highlights: Novel hydrazine-nitrate combustion route was proposed to synthesize BaCeO3 nanopowder. Thermal treatment of combustion products leads to chemically and phase pure BaCeO3. Crystallite size and its aggregation outperform those for conventional approaches. Thermophysical performance of BaCeO3 powders makes it promising for SOFC ceramics. [ABSTRACT FROM AUTHOR]

Protonic ceramic fuel cells are a promising technology for energy conversion and chemical synthesis in the intermediate temperature range (400–600 °C). Nevertheless, a major restriction to their wider implementation concerns their relatively high cathode polarisation resistance that can become performance limiting as working temperatures decrease. As potential new cathode materials, high order nickelates can be attractive candidates as they exhibit high electrical conductivities at lower temperatures due to their metallic behaviour. In the current work, we investigate the performance of La 4 Ni 3 O 10±δ and La 4 Ni 3 O 10±δ –BaCe 0.9 Y 0.1 O 3-δ composite cathodes, deposited on a BaCe 0.9 Y 0.1 O 3-δ (BCY10), proton-conducting electrolyte in the temperature range 350–550 °C. The study is performed in symmetrical cell configuration to permit separation of the electrode performance from the overall cell behaviour. For such experiments, possible internal short-circuiting of the electrolyte in oxidising conditions can arise from the presence of p-type electronic conductivity in the BCY10 electrolyte, causing underestimation of measured polarisation resistances. The current work corrects for such factors by knowledge of the transference numbers of the BCY10 electrolyte and the use of a parallel short-circuiting resistor in the equivalent circuit model. The results underscore that the cathode characteristics are highly dependent on the electronic leakage, especially at higher temperatures, and that suitable correction of data is imperative before discussion. Corrected values for polarisation resistance in wet O 2 reveal the composite cathode shows an improvement of total polarisation resistance by a factor of 1.5. The analysis on the oxygen reduction reaction mechanism allows the rate-limiting processes between the electrodes to be differentiated, with the low-frequency term, corresponding to surface processes, being the dominant polarisation resistance and the most improved on formation of the composite. Overall performance analysis indicates that the results from this work are in line with some of the best cathodes currently reported. • Electronic short-circuiting in oxidising conditions with increasing temperature. • Equivalent circuit modelling allows for correction of the electronic leakage. • LNO-BCY10 cathode shows decreased R p in comparison to that of pure LNO. • LNO-BCY10 cathode shows one of the best performances among PCFC cathodes. [ABSTRACT FROM AUTHOR]

As electrolyte materials for proton conductive fuel cells, perovskite-type materials such as barium cerates and barium zirconates have received a lot of attention due to their high protonic conduction at intermediate temperatures. Yet, the crystalline structure and the microstructure of the electrolyte layers are of the utmost importance that define the resulting protonic conductivity. The aim of this research was to investigate the formation of doped/undoped BCO and BZO thin films using e-beam vapor deposition and to analyze the influence of the formation parameters on the microstructural and crystallographic properties. Crystalline structure and microstructure were investigated by X-ray diffractometer and scanning electron microscope, while the elemental composition of the resulting thin films was analyzed by an energy-dispersive X-ray spectroscope. It was found that the formed thin films were highly dense and consisted of the oriented columnar grains. The crystallinity of the thin films was strongly expressed with the predominant crystallographic orientations for undoped/doped barium cerates. Yttrium dopant had an influence on the lattice parameters and crystallite sizes. With the chosen technological parameters allowed to both, barium cerates and barium zirconates did not form carbonates and did not experience the degradation process.

Proton conducting Y‐doped BaZrO3, BaCeO3 and their solid solutions are receiving increasing attention due to their promising application as electrolytes in ceramic fuel cells and electrolysis cells. However, the literature indicates a clear tendency that the performance of the cells increases with increasing Ce content in the electrolyte. In this work, to elucidate this phenomenon, a systematic work is performed on investigating the phase, hydration, and transport behaviors of BaZr0.8−xCexY0.2O3−δ (BZCY20). The results reveal that in the temperature range between 500 and 700 °C, with increasing Ce content, the dehydration temperature elevates and the proton concentration increases, showing that the Ce component favors the stabilization of protons. Furthermore, the transport number of hole conduction decreases, whereas the transport number of ionic conduction increases with the increasing Ce content. By further separating the contribution of oxide ions and protons, it is found that the oxide ion conductivity increases with the increasing Ce content at higher temperatures of 600 and 700 °C. Such decreased hole conductivity and increased oxide ion conductivity result in the enhancement of the ionic conduction of BZCY20 with increasing Ce content, and therefore improve the performance of fuel cells and electrolysis cells. [ABSTRACT FROM AUTHOR]

Y‐doped BaZrO3, BaCeO3 and BaZr1‐xCexO3 show high proton conductivity at intermediate temperature and are promising electrolyte candidates in electrochemical devices. However, in most cases, the present cell fabrication process seems to be unavailable to avoid the addition of NiO, which is either added to improve the sinterability of these electrolyte or diffuses from the electrode substrate during co‐sintering. In this work, a systematic investigation was performed to study the effect of NiO on BaZr0.8‐xCexY0.2O3‐δ (BZCY20) covering the full Ce range from 0 to 0.8. The results revealed that regardless of the composition of BZCY20, both the dehydration temperature and proton concentration decreased by adding NiO, which further greatly decreased the ionic conductivity and the transport number. And it is found that the redox cycles in Ce‐rich samples containing Ni makes the grain boundary conductivity worse and the electrolyte brittle. The conclusion is that NiO is detrimental to the performance of the electrochemical cells using these materials as the electrolyte, although compromise might be achieved in certain degree by tuning the Ce content. However, it should be noted that to further improve the cell performance, a new sintering additive or new processing for cell fabrication is essential. [ABSTRACT FROM AUTHOR]

Featured Application: The results of the study can be used for the development of the production technology of cathode-supported SOFCs with a thin-film electrolyte using the electrophoretic deposition method. This paper presents the study of electrophoretic deposition (EPD) of a proton-conducting electrolyte of BaCe0.89Gd0.1Cu0.01O3-δ (BCGCuO) on porous cathode substrates of LaNi0.6Fe0.4O3−δ (LNFO) and La1.7Ba0.3NiO4+δ (LBNO). EPD kinetics was studied in the process of deposition of both a LBNO sublayer on the porous LNFO substrate and a BCGCuO electrolyte layer. Addition of iodine was shown to significantly increase the deposited film weight and decrease the number of EPD cycles. During the deposition on the LNFO cathode, Ba preservation in the electrolyte layer after sintering at 1450 °C was achieved only with a film thickness greater than 20 μm. The presence of a thin LBNO sublayer (10 μm) did not have a pronounced effect on the preservation of Ba in the electrolyte layer. When using the bulk LBNO cathode substrate as a Ba source, Ba was retained in a nominal amount in the BCGCuO film with a thickness of 10 μm. The film obtained on the bulk LBNO substrate, being in composition close to the nominal composition of the BCGCuO electrolyte, possessed the highest electrical conductivity among the films deposited on the various cathode substrates. The technology developed is a base step in the adaptation of the EPD method for fabrication of cathode-supported Solid Oxide Fuel Cells (SOFCs) with dense barium-containing electrolyte films while maintaining their nominal composition and functional characteristics. [ABSTRACT FROM AUTHOR]

The aim of this work was to determine the influence of glassy Ba–Ce–Y–Si–P–O phase, prepared by sol-gel method and introduced into the BaCe 0.9 Y 0.1 O 3 host material on the selected properties of obtained materials. Three composite materials with different content of modifying phase (3, 6 and 18 wt%) were prepared. It was found that the introduction of an additional amorphous phase leads to the decrease of the electrical conductivity in the measured temperature range, both in grain interior and grain boundary regions. The observed change of conduction mechanism can be explained by the modification of the chemical composition of BaCe 0.9 Y 0.1 O 3 due to reaction with modifying phase at the stage of material preparation. Based on obtained results further optimisation of modifier phase composition and the preparation conditions leading to the materials with improved properties can be proposed. [ABSTRACT FROM AUTHOR]

The vaporization/decomposition of single-phase BaCeO3 samples was studied by the Knudsen Effusion Mass Spectrometry technique in the overall temperature range 1647–1923 K. The partial pressures of the gaseous species BaO(g), CeO2(g) and CeO(g) were monitored as a function of temperature. The formation of reduced form of cerium oxide as a product of the high temperature decomposition of BaCeO3 under the given experimental conditions was suggested by the low value of the measured CeO2(g)/CeO(g) pressure ratio and confirmed by the XRD spectra of the vaporization residues. The equilibrium data were tentatively processed according to various heterogeneous equilibria that may be established in the cell: (i) BaCeO3(s) = BaO(g) + CeO2(s); (ii) BaCeO3(s) + CeO(g) = BaO(g) + Ce2O3(s); (iii) BaCeO3(s) = BaO(g) + CeO2(g). The corresponding enthalpy changes were calculated by the third-law method and the enthalpy of formation of BaCeO3 derived thereafter. The thermodynamic analysis confirms that the decomposition process forming CeO2(s) is very unlikely to occur under the high temperature, high vacuum conditions used in the present study. The analysis of process BaCeO3(s) = BaO(g) + CeO2(g), not involving solid products, was selected as the most reliable and leads to a value for the enthalpy of formation of barium cerate (Δf (BaCeO3) = –1688.7 ± 6.2 kJ/mol) in agreement with the available calorimetric determinations. [ABSTRACT FROM AUTHOR]

Wet vacuum impregnation method was applied in order to evaluate the possibility of the formation of the material in BaCe0.9Y0.1O3−δ–V2O5 system. Single-phase BaCe0.9Y0.1O3−δ samples, synthesised by solid-state reaction method, were impregnated with the solution of vanadium(V) oxide precursor. Multi-step, multi-cycle impregnation procedure was applied to enhance the impregnation efficiency. Partial decomposition of Y-doped BaCeO3 in contact with the solution of the precursor, resulting in the formation of vanadium containing phases (CeVO4 and BaV2O6) on the materials surface, was observed. However, the presence of vanadium was also confirmed for the inner parts of the materials. The synthesised materials were submitted for exposition test to evaluate their chemical stability towards CO2/H2O. All BaCe0.9Y0.1O3-based materials modified by impregnation revealed higher chemical stability in comparison with single-phase un-modified BaCe0.9Y0.1O3−δ, since the amount of barium carbonate formed during the exposition was significantly lower. The total electrical conductivity of the received multi-phase materials was generally slightly lower than for the reference BaCe0.9Y0.1O3−δ sample, since the presence of the additional phases had a blocking effect on materials conductivity. The values of BaCeO3 lattice parameters and the Seebeck coefficient did not show the modification of the defects structure of Y-doped BaCeO3 during applied synthesis procedure. [ABSTRACT FROM AUTHOR]

Wet vacuum impregnation method was applied in order to evaluate the possibility of the formation of the material in BaCe0.9Y0.1O3−δ–V2O5 system. Single-phase BaCe0.9Y0.1O3−δ samples, synthesised by solid-state reaction method, were impregnated with the solution of vanadium(V) oxide precursor. Multi-step, multi-cycle impregnation procedure was applied to enhance the impregnation efficiency. Partial decomposition of Y-doped BaCeO3 in contact with the solution of the precursor, resulting in the formation of vanadium containing phases (CeVO4 and BaV2O6) on the materials surface, was observed. However, the presence of vanadium was also confirmed for the inner parts of the materials. The synthesised materials were submitted for exposition test to evaluate their chemical stability towards CO2/H2O. All BaCe0.9Y0.1O3-based materials modified by impregnation revealed higher chemical stability in comparison with single-phase un-modified BaCe0.9Y0.1O3−δ, since the amount of barium carbonate formed during the exposition was significantly lower. The total electrical conductivity of the received multi-phase materials was generally slightly lower than for the reference BaCe0.9Y0.1O3−δ sample, since the presence of the additional phases had a blocking effect on materials conductivity. The values of BaCeO3 lattice parameters and the Seebeck coefficient did not show the modification of the defects structure of Y-doped BaCeO3 during applied synthesis procedure. [ABSTRACT FROM AUTHOR]

High-temperature impregnation of solid single-phase Y-doped BaCeO 3 with melted WO 3 was performed towards the evaluation of the possibility of formation of chemically stable material with relatively high electrical conductivity in this system. Impregnation was performed at 1470 °C as a function of time. Due to the relatively high reactivity in solid BaCe 0.9 Y 0.1 O 3-δ - liquid WO 3 system the reactive and the inner layers were distinguished and analysed. The obtained results clearly indicate the decomposition of Y-doped BaCeO 3 in contact with melted WO 3. X-ray diffraction method together with SEM observation, EDS analysis and EIS measurements results were applied to discuss the mechanism of this multi-stage process and the influence of the reaction time on materials structure and microstructure. As it was observed, partial incorporation of tungsten into the barium cerate structure can process not only on the surface of the materials but also in the inner layer of the synthesised materials. This donor-type doping of the perovskite structure finds reflection in both, materials electrical properties and chemical stability towards CO 2 /H 2 O. The decrease of proton defects concentration was observed together with the significant increase of the materials chemical stability in comparison to un-modified single-phase BaCe 0.9 Y 0.1 O 3-δ. The calculated values of activation energy of conductivity confirm the change in the conduction mechanism. Also, the presence of an additional phase in the intergranular voids of doped BaCeO 3 was postulated. • Decomposition of BaCe 0.9 Y 0.1 O 3 in the contact with melted WO 3. • Incorporation of tungsten into Y-doped BaCeO 3 structure. • The increase of the activation energy of conductivity - conduction mechanism change. [ABSTRACT FROM AUTHOR]

Syngas has been produced from carbon dioxide (CO 2) and steam using a proton ceramic electrolyser cell. Proton-conducting electrolytes which exhibit high conductivity can suffer from low chemical stability. In this study, to optimize both proton conductivity and chemical stability, barium cerate and doped barium cerate are synthesized using solid state reaction method: BaCeO 3 (BC), Ba 0.6 Sr 0.4 CeO 3-α (BSC), Ba 0.6 Sr 0.4 Ce 0.9 Y 0.1 O 3-α (BSCY), and BaCe 0.6 Zr 0.4 O 3-α (BCZ). The BC, BSC, and BSCY are calcined at 1100 °C for 2 h and BCZ is calcined at 1300 °C for 12 h, respectively. All samples exhibit 100% perovskite and crystallite sizes equal 37.05, 28.46, 23.65 and 17.46 nm for BC, BSC, BSCY and BCZ, respectively. Proton conductivity during steam electrolysis as well as catalytic activity toward the reverse water gas shift reaction (RWGS) is tested between 400 and 800 °C. The conductivity increases with temperature and the values of activation energy of conduction are 64.69, 100.80, 103.78 and 108.12 kJ mol−1 for BSCY, BC, BSC, and BCZ, respectively. It is found that although BCZ exhibits relatively low conductivity, the material provides the highest CO yield at 550–800 °C, followed by BSCY, BSC, and BC, correlating to the crystallite size and BET surface area of the samples. Catalytic activity toward RWGS of composited Cu and electrolytes is also measured. Additional Cu (60 wt%) significantly increases catalytic activity. The CO yield increases from 3.01% (BCZ) to 43.60% (Cu/BCZ) at 600 °C and CO can be produced at temperature below 400 °C. There is no impurity phase detected in BCZ sample after exposure to CO 2 -containing gas mixture (600 °C for 5 h) while CeO 2 phase is detected in BSC and BSCY and both CeO 2 and BaO are observed in BC sample. • Sr3+ and Zr4+ doped BaCeO 3 was synthesized using solid state reaction. • Ba 0.6 Sr 0.4 Ce 0.9 Y 0.1 O 3-α exhibits the lowest activation energy of conduction. • The BaCe 0.6 Zr 0.4 O 3-α provides the highest CO yield at 550–800 °C. • Additional Cu (60 wt%) significantly increases catalytic activity of the materials. • The BCZ was stable after exposed to CO 2 -containing gas mixture at 600 °C for 5 h. [ABSTRACT FROM AUTHOR]

Abstract In this work the reactivity in solid BaCe 0.9 Y 0.1 O 3-δ - liquid V 2 O 5 system was investigated in order to evaluate the possibility of composite formation in this system. Impregnation of melted vanadium(V) oxide into solid Y-doped BaCeO 3 was performed in various temperature and time conditions. Due to the relatively high reactivity of components in this system an analysis of the synthesized materials was divided into discussion of the properties of the reactive layer and the inner part. As was shown, decomposition of Y-doped BaCeO 3 in contact with melted vanadium(V) oxide occurs already at temperature 700 °C and results in formation of CeVO 4 as one of the main phases. Moreover, the presence of Ba 8 V 7 O 22 as the intermediate phase was observed. The extension of reaction time and increase of temperature resulted in significant changes in the microstructure and chemical composition of the reactive layer. The incorporation of vanadium into yttrium doped BaCeO 3 structure for inner parts of the synthesized materials was postulated based on the modification of the materials electrical properties and chemical stability towards CO 2 and H 2 O. Also, the presence of additional phase in the intergranular voids of doped-BaCeO 3 was suggested. [ABSTRACT FROM AUTHOR]

Several orthorhombic perovskite products with nominal chemical formula BaCe 0.85 Gd 0.15 O 3–δ (BCGO), doped with variable amounts (0–5 mol%) of CuO and characterized by high total ionic conductivities, were synthesized by a sol-gel method followed by a calcination step at 1200 °C to induce the formation of a perovskite single phase. The products were characterized by X-ray Diffraction (XRD), Rietveld refinement, Scanning Electron Microscopy (SEM), Raman spectroscopy and Electrochemical Impedance Spectroscopy analysis (EIS). The powders were sintered into highly dense bodies (greater than 99 % for the best sample) through a relatively mild sintering process, i.e. 1350 °C for 6 h. The positive effect of copper as a sintering aid was revealed when a threshold content value (around 2 mol%) was e. Indeed, beyond such a limit, by calcination at 1200 °C, a secondary phase, a mixed oxide of Cu, Ba and Gd (very likely with chemical formula GdBa 4 Cu 3 O 9.18) appears in the precursor powders strongly enhancing the densification process, reasonably via partial liquid-phase sintering. Finally, remarkable grain growth also occurred, enhancing the overall conductivity of BCGO due to the positive effect of the reduction of grain boundary dimensions. • 5 % Cu-doped BCGO electrolyte was sintered at 1350 °C, reaching a relative density> 99 %. • A threshold of 2 mol% CuO was identified for Cu dissolution in BCGO at 1200 °C. • The beneficial effects of CuO contents higher than the threshold upon BCGO sintering were demonstrated. • Partial liquid-phase sintering promotes enhanced Cu-doped BCGO densification. • The overall conductivity of highly Cu-doped BCGO is enhanced due to major grain growth. [ABSTRACT FROM AUTHOR]

The Eu3+ doped barium cerate had been made using the Glycine nitrate combustion technique. The prepared powder's characterization reveals that it is made entirely of orthorhombic nanopowder that has been crystallized. The generated nanopowder's emission spectra were used to calculate the Judd-Ofelt parameter intensities, which confirmed that the added Eu3+ replaced the Ce4+ in the perovskite structure and that it was positioned in the 4b, non-centrosymmetric Wyckoff position. By using complex impedance spectroscopy, the produced nanopowder's electric characteristics were investigated in the temperature range of 480–650 °C (CIS). The obtained doped barium cerate has an unusual activation energy (0.28 eV between 562 and 650 °C) and conductivity of 2673 10−5 Ω−1 cm−1 at 650 °C in the temperature range under consideration. • Eu3+ doped BaCeO 3 perovskite was made using the glycine nitrate combustion technique. • The resultant oxide can conduct protons since the Eu3+ doping created oxygen vacancies. • The conductivity significantly increases with temperature, according to the impedance spectra. • The created rare earth-doped perovskites could be considered as potential SOFC electrolyte options. • It operates at moderate temperatures and emits a promising luminophore in the red-orange spectrum. [ABSTRACT FROM AUTHOR]

This paper presents the study of electrophoretic deposition (EPD) of a proton-conducting electrolyte of BaCe0.89Gd0.1Cu0.01O3-δ (BCGCuO) on porous cathode substrates of LaNi0.6Fe0.4O3−δ (LNFO) and La1.7Ba0.3NiO4+δ (LBNO). EPD kinetics was studied in the process of deposition of both a LBNO sublayer on the porous LNFO substrate and a BCGCuO electrolyte layer. Addition of iodine was shown to significantly increase the deposited film weight and decrease the number of EPD cycles. During the deposition on the LNFO cathode, Ba preservation in the electrolyte layer after sintering at 1450 °C was achieved only with a film thickness greater than 20 μm. The presence of a thin LBNO sublayer (10 μm) did not have a pronounced effect on the preservation of Ba in the electrolyte layer. When using the bulk LBNO cathode substrate as a Ba source, Ba was retained in a nominal amount in the BCGCuO film with a thickness of 10 μm. The film obtained on the bulk LBNO substrate, being in composition close to the nominal composition of the BCGCuO electrolyte, possessed the highest electrical conductivity among the films deposited on the various cathode substrates. The technology developed is a base step in the adaptation of the EPD method for fabrication of cathode-supported Solid Oxide Fuel Cells (SOFCs) with dense barium-containing electrolyte films while maintaining their nominal composition and functional characteristics.

In this work, BaCe 0.6 Zr 0.2 Y 0.2-x Yb x O 3-δ and BaCe 0.6 Zr 0.2 Gd 0.2-x Yb x O 3-δ (x = 0–0.20), proton conducting materials are prepared by the freeze-drying precursor method. The sintering conditions were optimized by adding Zn(NO 3 ) 2 ·6H 2 O as sintering additive. The materials are thoroughly characterized by different structural and microstructural techniques, including X-ray diffraction, scanning and transmission electron microscopy, and thermogravimetric-differential thermal analysis. The addition of Zn favours the phase formation and densification at lower sintering temperatures; however, it leads to the segregation of a Zn-rich secondary phase, with general formula BaLn 2 ZnO 5 (Ln˭Y, Gd and Yb), which is identified and quantified for the first time. All samples with Zn as sintering aid exhibit cubic structure; however, the samples without Zn crystallize with orthorhombic or cubic structure, depending on the composition and thermal treatment. The electrical properties are studied by impedance spectroscopy. A deep analysis of the bulk and grain boundary contributions to the conductivity has revealed that the bulk conductivity remains almost unchanged along both series over Yb-doping; however, the grain boundary resistance decreases. The highest conductivity values are found for the intermediate members of both series, BaCe 0.6 Zr 0.2 Y 0.1 Yb 0.1 O 3-δ and BaCe 0.6 Zr 0.2 Gd 0.1 Yb 1 O 3-δ , with 33 and 28 mS cm −1 at 750 °C, respectively. [ABSTRACT FROM AUTHOR]

The aim of this work was to determine the influence of chemical composition on thermal and electrical properties of selected glass from the BaO-CeO2-Y2O3-P2O5-SiO2 system. Properties of the investigated glasses were optimized in terms of glass-BaCe0.9Y0.1O3 composite protonic conductor preparation. Three types of glasses with different P2O5/SiO2 ratio were prepared and investigated. The DSC and XRD measurements indicated limited tendency to crystallization of obtained glasses up to T = 1023 K. The dilatometry measurements led to determination of the thermal expansion coefficients (TEC) and the softening point. It was found that obtained glasses soften in temperature range of 903-923 K, depending on the composition which is advantageous from the viewpoint of further preparation and formation of the composite material. The Electrochemical Impedance Spectroscopy measurements done as a function of temperature and gas atmosphere allowed to determine the activation energy of the electrical conductivity. Observed fluctuations of the activation energy with gas atmosphere suggest the possible role of the protonic defects in total conductivity. Based on the obtained results it can be stated that proposed glass system may be considered as the modifying phase for improvement of BaCe0.9Y0.1O3-based materials. [ABSTRACT FROM AUTHOR]

The aim of this work was to determine the influence of chemical composition on thermal and electrical properties of selected glass from the BaO-CeO2-Y2O3-P2O5-SiO2 system. Properties of the investigated glasses were optimized in terms of glass-BaCe0.9Y0.1O3 composite protonic conductor preparation. Three types of glasses with different P2O5/SiO2 ratio were prepared and investigated. The DSC and XRD measurements indicated limited tendency to crystallization of obtained glasses up to T = 1023 K. The dilatometry measurements led to determination of the thermal expansion coefficients (TEC) and the softening point. It was found that obtained glasses soften in temperature range of 903-923 K, depending on the composition which is advantageous from the viewpoint of further preparation and formation of the composite material. The Electrochemical Impedance Spectroscopy measurements done as a function of temperature and gas atmosphere allowed to determine the activation energy of the electrical conductivity. Observed fluctuations of the activation energy with gas atmosphere suggest the possible role of the protonic defects in total conductivity. Based on the obtained results it can be stated that proposed glass system may be considered as the modifying phase for improvement of BaCe0.9Y0.1O3-based materials. [ABSTRACT FROM AUTHOR]

Yttrium-doped BaCeO 3 is one of the most promising electrolyte candidates for solid oxide fuel cells because of its high ionic conductivity. Nd and Y co-doped BaCeO 3 strategy is adopted for the further optimization of Y-doped BaCeO 3 electrolyte properties. X-ray diffraction results indicate that the structure of BaCe 0.8 Y 0.2-x Nd x O 3-δ (x = 0, 0.05, 0.1, 0.15) with orthorhombic perovskite phase becomes more symmetric with increasing Nd concentration. The scanning electron microscope observation demonstrates that the densification and grain size of the sintered pellets significantly enhance with the increase of Nd doping level. Whether in dry and humid hydrogen or air, the increase of Nd dopant firstly increases the conductivities of BaCe 0.8 Y 0.2-x Nd x O 3-δ (x = 0, 0.05, 0.1, 0.15) and then decrease them after reaching the peak value at x = 0.05. Electrochemical impedance spectra at 350 °C can distinguish clearly the contribution of grain and grain boundary to total conductivity and the highest conductivity of BaCe 0.8 Y 0.15 Nd 0.05 O 3-δ ascribes to the decrease in bulk and grain boundary resistances due to the synergistic effect of Nd and Y doping. The anode-supported single cell with BaCe 0.8 Y 0.15 Nd 0.05 O 3-δ electrolyte shows an encouraging peak power density of 660 mW cm −2 at 700 °C, suggesting that BaCe 0.8 Y 0.15 Nd 0.05 O 3-δ is a potential electrolyte material for the highly-efficient proton-conducting solid oxide fuel cell. [ABSTRACT FROM AUTHOR]

For the first time solution enthalpies of BaCe 0.8 Y 0.1 Gd 0.1 O 2.9 , BaCe 0.8 Y 0.1 Lu 0.1 O 2.9 and mixtures of BaCl 2  + 0.8CeCl 3  + 0.1YCl 3  + 0.1GdCl 3 , BaCl 2  + 0.8CeCl 3  + 0.1YCl 3  + 0.1LuCl 3 in 1 mol dm −3 HCl with 0.1 mol dm −3 KI have been measured. On the basis of experimental data obtained and literature data the standard molar enthalpies of formation and stabilization energies were calculated. Using Born-Haber cycle the lattice energies were calculated. It was established that lattice energy was increased from BaCe 0.8 Y 0.1 Gd 0.1 O 2.9 to BaCe 0.8 Y 0.1 Lu 0.1 O 2.9 . It correlates with decreasing of ion radius of rare earth element from gadolinium to lutetium. Increasing of lattice energy with decreasing of ion radius of rare earth element was explained with modified formula of Kapustinskii. [ABSTRACT FROM AUTHOR]

The nanoparticles of BaCeGdO (BCGO) with x = 0.01 and 0.02 mol% Gd respectively, were synthesized by the polymeric precursor method. The nanocrystals analyzed by X-ray diffraction (XRD) displayed an orthorhombic perovskite-type structure. The sintered samples were characterized using Archimedes method, field emission scanning electronic microscopy (FE-SEM), and dilatometric measurements are reported. The values obtained relative to the average crystallite sizes calculated by the Scherrer equation were found to be dependent on Gd dopant concentration in the samples under investigation. The samples were sintered via both conventional and microwave sintering methods at 1480 °C for 4 h and at 1370 °C for 1 h respectively. By applying a heating rate of 50 °C min in a microwave oven, a satisfactory final density (95.1% of the theoretical density) was obtained using relatively lower temperatures compared to the conventional method. Both sintering methods were successfully employed towards obtaining dense BCGO ceramic. Comparatively, however, domestic microwave sintering was found to bear advantages over conventional sintering. Among such advantages include rapid heating, selective material coupling in addition to the enhancement of reaction kinetics. These relevant merits, in essence, render microwave sintering suitably more attractive for the synthesis of diverse ceramic materials. [ABSTRACT FROM AUTHOR]

BaCeO 3 –based protonic conductors may be considered as perspective materials for construction of various electrochemical devices as fuel cells, gas sensors, electrochemical pumps, separators or membrane chemical reactors. The desired properties, as high electrical conductivity or chemical stability of these materials may be further improved by formation of composite, by introduction of modifying phase as BaWO 4 into the host Y-doped BaCeO 3 material. The high temperature process of composite formation requires the recognition of chemical reactivity between the used component. In this work the mutual reactivity and reaction mechanism in the solid BaCe 0.9 Y 0.1 O 3 – liquid BaWO 4 system were investigated. The synthesis of BaCe 0.9 Y 0.1 O 3 and BaWO 4 compounds was done by solid-state reaction method. The formation of BaCe 0.9 Y 0.1 O 3 – BaWO 4 materials was obtained by high temperature impregnation of melted BaWO 4 into solid BaCe 0.9 Y 0.1 O 3 with different impregnation time applied (2, 4 and 8 h). The evolution of crystal structure, phase composition, microstructure, chemical composition and electrical properties with impregnation time, for surface and interior of the samples allowed to analyse the mutual reactivity of composite components and to propose the multi-step reaction mechanism in the solid BaCe 0.9 Y 0.1 O 3 – liquid BaWO 4 system. [ABSTRACT FROM AUTHOR]

Many of the challenges in solid oxide fuel cell technology stem from chemical and mechanical incompatibilities between the anode, cathode and electrolyte materials. Numerous attempts have been made to identify compatible materials. Here, these challenges are circumvented by the introduction of a working single layer fuel cell, fabricated from a composite of proton conducting BaCe 0.6 Zr 0.2 Y 0.2 O 3-δ and a mixture of semiconducting oxides – Li 2 O, NiO, and ZnO. Structural and electrical properties of the composite, related to its fuel cell performance are investigated. The single layer fuel cell shows a maximum OCV of 0.83 V and a peak power density of 3.86 mW cm −2 at 600 °C. Activation and mass transport losses are identified as the major limiting factor for efficiency and power output. [ABSTRACT FROM AUTHOR]

Processes of thermal desorption of oxygen molecules and water from BaCeMO, where M= Nd, Sm, and Gd, presintered in air at the temperature of 650°C are studied. It is found that oxygen is desorbed only from neodymium-doped barium cerate and is almost not evolved from barium cerate doped by samarium and gadolinium. The amount of desorbed oxygen features a square dependence on cationic doping by neodymium. At similar degrees of cationic doping, the amount of water desorbed from neodymium-doped barium cerate is always lower than that from the cerate doped by samarium and gadolinium. The obtained experimental data on thermal desorption and analysis of literature data served as a basis for the conclusion as to the mixed valency of neodymium Nd(III)-Nd(IV) in BaCeNdO. In this case, at similar doping degrees x, the hydration degree of BaCeNdO is lower and the oxygen index is higher than in BaCe1(Sm,Gd)O. The differences become more pronounced at high degrees of cationic doping and must decrease at an increase in temperature. [ABSTRACT FROM AUTHOR]

BaCeO 3 -based materials exhibit high electrical conductivity, however undergo degradation in CO 2 and H 2 O containing atmospheres. In this work the BaCe 0.9 Y 0.1 O 3 -BaWO 4 composites were prepared by co-sintering and via impregnation methods. The main motivation was to locate the barium tungstate on the grain boundary of Y-doped barium cerate and enhance the functional properties of final material comparing to single phase BaCe 0.9 Y 0.1 O 3 − δ . It was found that used synthesis procedures lead to two phase materials with doped barium cerate as the main phase and BaWO 4 as the second one. The Electrochemical Impedance Spectroscopy (EIS) measurements performed at dry air, 100% HR air and 5% H 2 in Ar atmospheres for temperature range 200–700 °C allowed to determine the electrical conductivity of synthesized materials. Introduction of BaWO 4 second phase into host BaCe 0.9 Y 0.1 O 3 − δ modified the electrical properties of bulk and grain boundary for materials synthesized by both co-sintering and for impregnation method. However, the effect of synthesis procedure was observed mainly for grain boundary contribution. Chemical resistance of composites toward CO 2 and water vapour was estimated based on the CO 2 /H 2 O exposure test in which samples were exposed to CO 2 and H 2 O rich atmosphere at 25 °C for 700 h. It was observed that chemical stability of composites in corrosive atmosphere was significantly higher comparing to single phase BaCe 0.9 Y 0.1 O 3 − δ regardless to the synthesis procedure. [ABSTRACT FROM AUTHOR]

Barium cerate with additions of rare-earth or 3- d metal oxides is widely used for production of solid electrolytes, ionic, and electron–ionic conductors. Knudsen effusion mass spectrometry was used to study vaporization processes and thermodynamic properties of solid solutions in the BaO – CeO 2 system at the temperature 2000 K. Ba, BaO, CeO and CeO 2 were found as the main vapor species over the samples studied. Activity values and Gibbs energy of BaO and CeO 2 in the samples studied were calculated. The activities of barium and cerium oxides in the concentration range of the homogeneous melt (70–32 mol. % of BaO) and in the region from 32 to 5 mol % of BaO (solid solution of CeO 2 + liquid) have low negative deviations from the ideal case. The determined value of the standard formation enthalpy of solid barium cerate is equal to −1692 ± 17 kJ/mol. [ABSTRACT FROM AUTHOR]

Most of investigated ceramic proton materials exhibit insufficient conductivity and/or chemical stability. In this work the formation of composite BaCe 0.9 Y 0.1 O 3 –Ba 3 (PO 4 ) 2 proton conductor via impregnation route, leading to the improvement of functional properties, was undertaken. It was assumed that introduction of additional phase would lead to the modification of grain boundaries, being responsible for poor chemical stability and electrical conductivity of already tested materials based on BaCeO 3 . The influence of phosphate modifying phase on crystal structure, microstructure, chemical stability and electrical properties of BaCe 0.9 Y 0.1 O 3 -based materials was investigated. It was found that introduction of phosphate into the material has changed the electrical conductivity of BaCe 0.9 Y 0.1 O 3 –Ba 3 (PO 4 ) 2 composite comparing to the BaCe 0.9 Y 0.1 O 3−δ single phase material. Also, the formation of composites has improved the chemical stability. The observed dependencies were discussed in terms of structure and microstructure modification, indicating that synthesis of BaCe 0.9 Y 0.1 O 3 -based composite proton conductors is a promising way of improvement. [ABSTRACT FROM AUTHOR]

In this study, the effects of Ti substitution for Ce on chemical and structural stability and electrical properties of proton-conducting solid electrolyte membrane BaCe 0.8 − x Ti x Sm 0.2 O 3 − δ (BCST) are investigated. Our results show that both chemical and structural stability of the BCST samples in CO 2 containing and moist atmospheres are remarkably enhanced with increasing the content of Ti which is higher electronegative than Ce. However, the proton conductivity of the sample decreases with increasing Ti content, which may be due to the increasing difficulty of lattice hydration and smaller grain size (corresponding to more grain boundaries) caused by Ti doping. The activation energy for proton migration increases with Ti content, which is mainly related with the weaker hydrogen bond. The results show that the BaCe 0.75 Ti 0.05 Sm 0.2 O 3 − δ has a great electrical conductivity (1.03×10 −2 S cm −1 at 650 °C) and it also demonstrates good chemical and structural stability in CO 2 and water containing atmospheres. Therefore, BaCe 0.75 Ti 0.05 Sm 0.2 O 3 − δ can be considered as a promising proton conducting electrolyte for intermediate temperature solid oxide fuel cells. [ABSTRACT FROM AUTHOR]

In this work, Sr 2 + and Y 3 + co-doped BaCeO 3 -based perovskite Ba 0.9 Sr 0.1 Ce 0.85 Y 0.15 O 3 − δ (BSCY) was synthesized by solid-state reaction method, and its mass transport behavior was studied using electrical conductivity relaxation (ECR) measurements in 600–800 °C range with respect to variations in oxygen partial pressure ( p O 2 ) and water vapor pressure ( p H 2 O). During oxidation/reduction process, the electrical conductivity showed a monotonic relaxation behavior and in − 2.65 ≤ log( p O 2 /atm) ≤ − 0.67 range the values of oxygen chemical diffusivity ( D ˜ vO ) and surface exchange coefficient ( κ vO ) varied in 10 − 6 –10 − 4 cm 2 ⋅ s − 1 and 10 − 4 –10 − 2 cm ⋅ s − 1 range, respectively. However, during hydration/dehydration process, the electrical conductivity showed a non-monotonic twofold relaxation behavior, and hydrogen, and oxygen chemical diffusivities ( D ˜ iH ) and ( D ˜ vH ) values were in 10 − 5 –10 − 3 and 10 − 6 –10 − 4 cm 2 ⋅ s − 1 range, respectively, whereas hydrogen and oxygen surface exchange coefficient ( κ iH ) and ( κ vH ) values were in 10 − 3 –10 − 2 and ~ 10 − 4 –10 − 2 cm ⋅ s − 1 range, respectively. The comparison of H and O diffusivities of BSCY with BaCe 0.85 Y 0.15 O 3 − δ (BCY) showed that during hydration/dehydration the diffusivities of BSCY were lower than that of BCY. The long-term electrical conductivity measurement for ~ 800 h in humidified conditions showed a gradual decrease, which might be due to the gradual appearance of rhombohedral phase in otherwise orthorhombic BSCY, as confirmed by the X-ray diffraction (XRD) measurements. [ABSTRACT FROM AUTHOR]

Barium cerate (BaCeO 3 ) was synthesized using conventional precipitation and ultrasonic-assisted precipitation. The effect of precipitation parameters (precipitation precursor, precipitation agent, agent concentration and temperature) significantly affected %perovskite formation and crystallite size of the product. Precipitation with 1 M (NH 4 ) 2 C 2 O 4 induced the formation of a single-phase BaCeO 3 while precipitation with 5–20 M NaOH provided a mixed phase of BaCeO 3 and CeO 2 . The %perovskite increased as increasing precipitation temperature; however, the crystallite size of the product also increased. Increasing ultrasonic intensity (30 and 150 W cm −2 ) during precipitation was found to increase the %perovskite and to reduce crystallite size. The precipitation with 1 M (NH 4 ) 2 C 2 O 4 agent, using ultrasonic intensity at 150 W cm −2 , provided single phase BaCeO 3 with crystallite size of 18.4 nm after calcination at 900 °C for 4 h. The electrochemical performance of the BaCeO 3 cell under steam electrolysis condition (controlled voltage from OCV to 1.5 V; 20% H 2 O, 40% H 2 , and 40% N 2 ) was measured (600–800 °C) and the activation energy of conduction was calculated to be 0.78 eV. [ABSTRACT FROM AUTHOR]

A novel hybrid route, combining simple co-precipitation and conventional solid state reaction, is proposed for the first time to synthesize BaCe 0.4 Zr 0.4 Y 0.2 O 3− δ powders at a temperature as low as 1150 °C. This temperature is much lower than that used for conventional solid state reaction method and even comparable to that used in sol–gel route. The reasons for the low calcination temperature are analyzed in detail from the macroscopic to microscopic viewpoints. Moreover, with the powders made by the novel method, dense ceramic could be easily obtained. Further, impedance data illustrated that its electrical conductivity in wet H 2 at 750 °C is up to 1.39 × 10 −2 S/cm, which is the highest among all the samples prepared by the three different methods and much higher than the reported results related to BCZY proton conductors. Also, the new method is particularly suitable for other multi-component oxides. [ABSTRACT FROM AUTHOR]

Barium cerate based compounds are promising candidates for construction of different electrochemical devices. Previously published papers were focused on improvement of chemical stability and on increase of protonic conductivity of BaCeO 3 –based materials. Different approaches: aliovalent doping, formation of solid solutions or modification of synthesis method have been tested in order to develop the optimal material with desired properties. Recently, the concept of the composite material formation was implemented in order to improve the properties of BaCeO 3 –based protonic ceramic materials. In this work the results concerning the influence of barium phosphate and barium tungstate on the electrical properties of BaCeO 3 – based materials were presented and discussed. Our previous studies have shown that such modification leads to the improvement of chemical stability. In this work the electrical properties of developed BaCe 0.9 Y 0.1 O 3 –Ba 3 (PO 4 ) 2 and BaCe 0.9 Y 0.1 O 3 –BaWO 4 composites were determined using Electrochemical Impedance Spectroscopy (EIS). It was found that introduction of barium phosphate into the BaCeO 3 leads mainly to modification of grain boundaries, while the introduction of tungstate phase modifies the electrical properties of both bulk and grain boundaries. The discussion concerning the influence of used modifiers on crystallographic structure, microstructure and electrical properties of developed materials and observed correlation is also presented. [ABSTRACT FROM AUTHOR]

Proton-conducting electrolyte with Sm and Y co-doped BaCeO (BaCeSmYO, BCSY) were prepared by sol-gel combustion method. The characterization of proton-conducting electrolyte was evaluated in saturated humidity by structure identification, such as X-ray diffraction (XRD). Anode-supported cell with configuration of Ni-BCSY/BCSY/SSC (SmSrCoO) were fabricated. The cell with cathode after two coats and sintering temperature of 1,050 °C showed superior electrical performance. It was achieved with open circuit voltage (OCV) of 0.99 V and P of 220 mW/cm at 600 °C when humidified (3 vol.% HO) hydrogen as fuel and oxygen as oxidant. [ABSTRACT FROM AUTHOR]

A new composite cathode used for protonic ceramic fuel cells was developed, which consisted of BaZr 0.1 Ce 0.7 Y 0.1 Yb 0.1 O 3 − δ (BZCYYb), a protonic conductor, and Nd 1.95 NiO 4 + δ (NNO), a mixed oxygen ionic and electronic conductor. The symmetrical cell investigation under different oxygen and water partial pressures demonstrated that the cathode polarization resistance came from proton transport between electrolyte and cathode, charge transfer and the diffusion of O ad − , and the latter two played the dominant roles. The polarization resistance of BZCYYb-NNO composite cathode decreases with increasing NNO content and the composite cathode with 60 wt% NNO shows the lowest polarization resistance, which is 0.43 Ω cm 2 at 750 °C. The power density of 154 mV cm −2 is achieved with anode-supported cell NiO-BZCYYb | BZCYYb (∼60 μm) | BZCYYb-60NNO when humidified hydrogen is used as the fuel and ambient air as the oxidant. [ABSTRACT FROM AUTHOR]