On the sol–gel synthesis and catalytic activity of Ce1−xAxO2−δ (A = Pr, Sm, Gd) SOFCs anode materials for reforming of methane

A sol–gel route to synthesize nanocrystalline praseodymium-, samarium- and gadolinium-doped ceria powders for solid oxides fuel Cells SOFCs is presented. The method involves metal nitrates with propionic acid (both as chelating ligand and solvent), gel formation, liquid nitrogen quenching, drying at 150 °C/24 h, and finally decomposition at 450 °C in nitrogen followed by calcination at 650 °C in air. TG–DTA, BET, XRD, FTIR, UV–vis and catalytic tests were used to characterize the samples. Ce_0.8Pr_0.2O_2?δ sample exhibited the best catalytic performance in methane steam reforming under water deficient conditions, closely followed by Ce_0.9Gd_0.1O_2?δ, Ce_0.8Sm_0.2O_2?δ and Ce_0.8Gd_0.2O_2?δ catalysts. The superior catalytic performance of Ce_0.8Pr_0.2O_2?δ sample was attributed to the existence of praseodymium species (Pr⁴⁺/Pr³⁺) strongly interacting with ceria. The two systems act synergistically in the catalytic steam reforming of methane.     

Preparation and characterization of ceria-Based electrolytes for intermediate temperature solid oxide fuel cells (IT-SOFC)

Solid-oxide fuel cells (SOFCs) can be used for clean, efficient and environment-friendly energy conversion with a variety of fuels at high temperature (1273 K). The high temperature operation accelerates unwanted reactions and creates materials challenges; so, intermediate-temperature SOFCs (IT-SOFCs) have been developed. Reduction of the operating temperature (between 873–1073 K) requires solid electrolyte materials with higher conductivities. In this study, partially substituted ceria as solid electrolyte is experimented systematically for use in solid oxide fuel cells operating below 1073 K (intermediate temperature range). Nine compositions namely, CeO₂, Ce_0.95Gd_0.05O_2-δ (CGO9505), Ce_0.90Gd_0.10O_2-δ (CGO9010), Ce_0.85Gd_0.15O_2-δ (CGO8515), Ce_0.80Gd_0.20O_2-δ (CGO8020), Ce_0.95Sm_0.05O_2-δ (SDC9505), Ce_0.90Sm_0.10O_2-δ (SDC9010), Ce_0.85Sm_0.15O_2-δ (SDC8515) and Ce_0.80Sm_0.20O_2-δ (SDC8020) were synthesized by Glycine Nitrate (GN) combustion technique and investigated. The physical properties and the other relevant features of the data obtained are analyzed with a view to use these alternate electrolyte materials in IT-SOFC.     

General and facile synthesis of ceria-based solid solution nanocrystals and their catalytic properties

Uniform Ce_1−xZr_xO₂ (x=0.2–0.8) nanocrystals with ultra-small size were synthesized through a thermolysis process, facilitated by the initial formation of precursor (hydrated (Ce,Zr)-hydroxides) at low temperature. TEM, XRD, EDAX, and Raman spectra were employed to study the formation of the solid solutions with various Ce/Zr ratios. Ultraviolet–visible (UV–vis) spectra showed that the ratios of Ce³⁺ to Ce⁴⁺ in both surface and bulk for the as-prepared Ce_1−xZr_xO₂ nanocrystals increased with the zirconium content x. The well-distributed Zr and Ce in the hydrated (Ce,Zr)-hydroxides before their thermolysis became the crucial factor for the structural homogeneity of the products. In addition, this strategy was extended to the synthesis of Ce_1−xGd_xO_1−x/2, Ce_1−xSm_xO_1−x/2, and Ce_1−xSn_xO₂ solid solutions. Catalytic measurements indicated that the ceria-based catalysts were active for CO oxidation at temperatures beyond 250 °C and the sequence of catalytic activity was Ce_0.5Zr_0.5O₂>Ce_0.8Zr_0.2O₂>Ce_0.2Zr_0.8O₂>Ce_0.5Sm_0.5O_1.75.     

Ce1－xNdxO2－δ固溶体的电子顺磁共振谱和阻抗谱的研究

利用溶胶-凝胶方法在800 ℃焙烧10 h后, 合成了固溶体Ce_1－xNd_xO_2－δ (x＝0.05～0.55), X射线衍射(XRD)测试表明固溶体已经形成立方萤石结构; 电子顺磁共振谱(EPR)研究表明在固溶体Ce_1－xNd_xO_2－δ中随着掺杂量x的增大, Ce^3＋离子含量减少, 说明掺杂Nd^3＋离子可以抑制Ce^4＋的还原; 交流阻抗谱的测量表明固溶体Ce_0.9Nd_0.1O_2－d 具有离子导电特性, 600和700 ℃时的电导率分别为4.25×10^－3和1.12×10^－2 S•cm^－1, 活化能为0.68 eV.     

Preparation and characterization of Ce1−xSmxO2−δ (x = 0.1–0.3) as electrolyte material for intermediate temperature SOFC

The effect of Sm doping on CeO₂ for its use as a solid electrolyte material for intermediate temperature solid oxide fuel cells (IT-SOFCs) has been explored here. Ce_1−xSm_xO_2−δ (x = 0.1–0.3) samples are successfully synthesized by carbonate co-precipitation method. TG–DTA, XRD, Raman, UV–Vis, FT-IR, SEM and ac-impedance are used for structural and electrical characterization. From the XRD patterns, well-crystalline cubic fluorite structured solid solution is confirmed. Lattice parameters increased with increase in Sm³⁺ while the crystallite size decreased. The optical absorption spectra exhibits a red shift for Sm³⁺ doped CeO₂. Raman spectra show an intense peak at 463 cm⁻¹, a characteristic peak for doped ceria. SEM shows cluster like particles. Based on ac-impedance data, the total oxygen ionic conductivity is highest for Ce_0.8Sm_0.2O_2−δ in the temperature range of 473–623 K.     

Study on Gd3+ and Sm3+ co-doped ceria-based electrolytes

Doped ceria electrolytes of Ce_1-aGd_a-ySm_yO_2–0.5a, wherein a=0.15 or 0.2, and 0ya, were prepared with the citrate method, and characterized by inductively coupled plasma–atomic emission spectrometry, energy dispersive spectrometry, scanning electron microscopy, powder X-ray diffraction, and AC impedance spectroscopy. The effect of composition on the structure and conductivity was studied. All the samples were fluorite-type ceria-based solid solutions. For the singly doped samples, the optimal composition was Ce_0.85Gd_0.15O_1.925 for Gd³⁺-doped ceria (CGO), which showed higher ionic conductivity than the best Sm³⁺-doped ceria (CSO) at 773–973 K. For the co-doped samples, the ionic conductivities were higher than those of the singly doped ones in the temperature range 673–973 K when a=0.15, but only better in 673–773 K when a=0.2. For the samples of Ce_0.85Gd_0.15-ySm_yO_1.925, wherein 0.05y0.1, much higher ionic conductivity was observed than those of the singly doped ceria at 773K~973 K. Therefore, these co-doped samples would be better than CGO and CSO to be the electrolytes of intermediate-temperature solid oxide fuel cells.     

Highly Dispersed Ce x Zr1−x O2 Nano-Oxides Over Alumina, Silica and Titania Supports for Catalytic Applications

We have been exploring the utilization of supported ceria and ceria–zirconia nano-oxides for different catalytic applications. In this comprehensive investigation, a series of Ce _x Zr_1−x O₂/Al₂O₃, Ce _x Zr_1−x O₂/SiO₂ and Ce _x Zr_1−x O₂/TiO₂ composite oxide catalysts were synthesized and subjected to thermal treatments from 773 to 1073 K to examine the influence of support on thermal stability, textural properties and catalytic activity of the ceria–zirconia solid solutions. The physicochemical characterization studies were performed using X-ray diffraction (XRD), Raman spectroscopy (RS), X-ray photoelectron spectroscopy (XPS), and high-resolution transmission electron microscopy (HREM), thermogravimetry and BET surface area methods. To evaluate the catalytic properties, oxygen storage/release capacity (OSC) and CO oxidation activity measurements were carried out. The XRD analyses revealed the formation of Ce_0.75Zr_0.25O₂, Ce_0.6Zr_0.4O₂, Ce_0.16Zr_0.84O₂ and Ce_0.5Zr_0.5O₂ phases depending on the nature of support and calcination temperature employed. Raman spectroscopy measurements in corroboration with XRD results suggested enrichment of zirconium in the Ce _x Zr_1−x O₂ solid solutions with increasing calcination temperature thereby resulting in the formation of oxygen vacancies, lattice defects and oxygen ion displacement from the ideal cubic lattice positions. The HREM results indicated a well-dispersed cubic Ce _x Zr_1−x O₂ phase of the size around 5 nm over all supports at 773 K and there was no appreciable increase in the size after treatment at 1073 K. The XPS studies revealed the presence of cerium in both Ce⁴⁺ and Ce³⁺ oxidation states in different proportions depending on the nature of support and the treatment temperature applied. All characterization techniques indicated absence of pure ZrO₂ and crystalline inactive phases between Ce–Al, Ce–Si and Ce–Ti oxides. Among the three supports employed, silica was found to stabilize more effectively the nanosized Ce _x Zr_1−x O₂ oxides by retarding the sintering phenomenon during high temperature treatments, followed by alumina and titania. Interestingly, the alumina supported samples exhibited highest OSC and CO oxidation activity followed by titania and silica. Details of these findings are consolidated in this review.     

Comparison of Electrochemical Synthesis of Ammonia by Using Sulfonated Polysulfone and Nafion Membrane with Sm1.5Sr0.5NiO4

Polysulfone (PSF) and sulfonated polysulfone (SPSF) were synthesized and characterized by IR spectrum. Sm_1.5Sr_0.5NiO₄ (SSN) and Ni‐Ce_0.8Sm_0.2O_2?δ (Ni‐SDC, Ni‐samarium doped ceria) were prepared and characterized by X‐ray diffraction (XRD) and scanning electron microscopy (SEM). Ammonia was synthesized from wet hydrogen and dry nitrogen with applied voltage, using SSN as cathode, Ni‐SDC as anode, Nafion and SPSF as proton membrane respectively. The performances of Nafion and SPSF membranes in ammonia synthesis were investigated and compared at atmospheric pressure and low temperature (25–100°C). The results demonstrated that the proton conducting performances of Nafion and SPSF membranes were similar and the highest rates of evolution of ammonia were up to 1.05×10^?8 and 1.03×10^?8 mol·cm^?2·s^?1 respectively at 80°C and 2.5 V.     

Structure and Catalytic Properties of Ceria-based Nickel Catalysts for CO<Subscript>2</Subscript> Reforming of Methane

Carbon dioxide reforming (CDR) of methane to synthesis gas over supported nickel catalysts has been reviewed. The present review mainly focuses on the advantage of ceria based nickel catalysts for the CDR of methane. Nickel catalysts supported on ceria–zirconia showed the highest activity for CDR than nickel supported on other oxides such as zirconia, ceria and alumina. The addition of zirconia to ceria enhances the catalytic activity as well as the catalyst stability. The catalytic performance also depends on the crystal structure of Ni–Ce–ZrO₂. For example, nickel catalysts co-precipitated with Ce_0.8Zr_0.2O₂ having cubic phase gave synthesis gas with CH₄ conversion more than 97% at 800 °C and the activity was maintained for 100 h during the reaction. On the contrary, Ni–Ce–ZrO₂ having tetragonal phase (Ce_0.8Zr_0.2O₂) or mixed oxide phase (Ce_0.5Zr_0.5O₂) deactivated during the reaction due to carbon formation. The enhanced catalytic performance of co-precipitated catalyst is attributed to a combination effect of nano-crystalline nature of cubic Ce_0.8Zr_0.2O₂ support and the finely dispersed nano size NiO _x crystallites, resulting in the intimate contact between Ni and Ce_0.8Zr_0.2O₂ particles. The Ni/Ce–ZrO₂/θ–Al₂O₃ also exhibited high catalytic activity during CDR with a synthesis gas conversion more than 97% at 800 °C without significant deactivation for more than 40 h. The high stability of the catalyst is mainly ascribed to the beneficial pre-coating of Ce–ZrO₂ resulting in the existence of stable NiO _x species, a strong interaction between Ni and the support, and an abundance of mobile oxygen species in itself. TPR results further confirmed that NiO _x formation was more favorable than NiO or NiAl₂O₄ formation and further results suggested the existence of strong metal-support interaction (SMSI) between Ni and the support. Some of the important factors to optimize the CDR of methane such as reaction temperature, space velocity, feed CO₂/CH₄ ratio and H₂O and/or O₂ addition were also examined.     

Thermal characterization of Er-doped and Er–Gd co-doped ceria-based electrolyte materials for SOFC

Ce_1?xEr_xO₂ and Ce_1?2xEr_xGd_xO₂ co-doped ceria electrolyte nanopowder materials were successfully prepared by sol–gel method. Depending on the temperature, the crystal structure changes were analyzed by X-ray diffraction. It was observed that the crystal size of the electrolytes decreased depending on the temperature and the time. X-ray diffraction results confirmed cubic fluorite structure in the samples. The microstructural properties of the samples were analyzed by scanning electron microscopy, and thermal stability measurement was performed by thermogravimetric and differential thermal analyses. The total electrical conductivity of the nanopowder electrolytes was determined by the dc four-point probe technique in air at temperatures ranging from room temperature to 1373 K. The four-probe conductivity results revealed that Ce_0.8Er_0.1Gd_0.1O₂ has a higher ionic conductivity compared to Ce_0.83Er_0.17O₂ at 1123 K. The four-probe conductivity results show that both Ce_1?xEr_xO₂ and Ce_1?2xEr_xGd_xO₂ solid electrolytes have potential application to oxide ionic conductor for solid oxide fuel cells.     

Electrical Properties of Sm‐doped Ceria (SDC) and SDC Carbonate Composite

This study prepared a dense Sm‐doped ceria (SDC) and an SDC carbonate composite (abbreviated as SDC‐C). The latter was prepared by immersing porous SDC with a formula of (Ce_0.8Sm_0.2)O_1.9 and a relative density of approximately 65‐70% into a molten mixture of carbonates containing 1:1 molar ratio of Li₂CO₃ and Na₂CO₃ at 500 °C. The relative density of the SDC‐C was close to 100%. In addition, SDC oxide without carbonates, which also has a relative density of close to 100%, was heat treated at 1600 °C. At 500 °C, the electrical conductivity and ionic transference number (t_i) of the SDC oxide were 1.79(5) × 10^?3 S·cm^?1 and 0.99(2), respectively, such that electronic conduction could be disregarded. Increasing the temperature caused a gradual decrease in the t_i of SDC. Following the addition of carbonates to SDC, the electrical conductivity reached 1.23(9) × 10^?1 S·cm^?1 at 500 °C. After 14 days (340 h), the electrical conductivity of the SDC‐C at 490 °C, leveled off at about 6 × 10^?2 S·cm^?1. SDC‐C could be used as a potential electrolyte in solid oxide fuel cells (SOFCs) at temperatures below 500 °C.     

Composite cathode materials Ag-Ba0.5Sr0.5Co0.8Fe0.2O3 for solid oxide fuel cells

Silver-Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3-δ (BSCF) cathodes were prepared in two ways. In the first method, Ag-BSCF composite powder was prepared in ethanol solution, where Ag nanoparticles serving as a component in the preparation of Ag-BSCF composite cathodes had been previously obtained via one-step synthesis in absolute ethanol using a neutral polymer (polyvinylpyrrolidone). To the best of our knowledge, this is the first study to use a Ag sol obtained by the above method for preparation of Ag-BSCF composite powder. Then, a paste containing this powder was screen-printed on a Sm_0.2Ce_0.8O_1.9 electrolyte and sintered at 1,000 °C. In the second technique, an aqueous solution of AgNO₃ was added to a previously sintered BSCF cathode, which was then sintered again at 800 °C. The oxygen reduction reaction at the quasi-point BSCF cathode on the Sm_0.2Ce_0.8O_1.9 electrolyte was tested by electrochemical impedance spectroscopy at different oxygen concentrations in three electrode setup. The continuous decrease of polarization resistance was observed under polarization ?0.5 V at 600 °C. The comparative studies of both obtained composite Ag-BSCF materials were performed in hydrogen-oxygen IT-SOFC involving samaria-doped ceria as an electrolyte and Ni-Gd_0.2Ce_0.8O_1.9 anode. In both cases, the addition of silver to the cathode caused an increase in current and power density compared with an IT-SOFC built with the same components but involving a monophase BSFC cathode material.     

Synthesis of ceria–zirconia mixed oxide from cerium and zirconium glycolates via sol–gel process and its reduction property

Ceria–zirconia mixed oxide was successfully synthesized via the sol–gel process at ambient temperature, followed by calcination at 500, 700 and 900 °C. The synthesis parameters, such as alkoxide concentration, aging time and heating temperature, were studied to obtain the most uniform and remarkably high‐surface‐area cubic‐phase mixed oxides. The thermal stability of both oxides was enhanced by mutual substitution. Surface areas of the Ce_xZr_1?xO₂ powders were improved by increasing ceria content, and their thermal stability was increased by the incorporation of ZrO₂. The most stable cubic‐phase solid solutions were obtained in the Ce range above 50 mol%. The highest surface area was obtained from the mixed catalyst containing a ceria content of 90 mol% (200 m²/g). Temperature programmed reduction results show that increasing the amount of Zr in the mixed oxides results in a decrease in the reduction temperature, and that the splitting of the support reduction process into two peaks depends on CeO₂ content. The CO oxidation activity of samples was found to be related to its composition. The activity of catalysts for this reaction decreased with a decrease in Zr amount in cubic phase catalysts. Ce₆Zr₄O₂ exhibited the highest activity for CO oxidation. Copyright © 2006 John Wiley & Sons, Ltd.     

Electroconduction and linear expansion of solid electrolytes Ce1? x Sm x O2?δ ( x = 0.10?0.30)

A complex investigation of solid electrolytes Ce_1−x Sm _x O_2−δ (x = 0.10−0.30) is performed in a broad temperature interval by methods of x-ray diffraction analysis, electroconduction, dilatometry, differential scanning calorimetry, and thermogravimetry. Ceramic technology is used for the synthesis. The density of the obtained specimens is no lower than 95%. The dilatometry measurements reveal the presence of singularities in the curves obtained at temperatures in the region of 180–230°C, which may be ascribed to a phase transition of the type order-disorder of hypothetical phase Ce₇SmO_15.5. The electroconduction and dilatometry methods also point to the presence of singularities in the temperature dependences in the temperature interval extending from 800 to 870°C. Original Russian Text ? E.G. Vaganov, V.P. Gorelov, N.M. Bogdanovich, I.V. Korzun, V.A. Kazantsev, 2007, published in Elektrokhimiya, 2007, Vol. 43, No. 6, pp. 695–698. Based on the report delivered at the 8th International Meeting on Fundamental Problems of Solid-State Ionics, Chernogolovka (Russia), 2006.     

Electrochemical synthesis of ammonia using a cell with a Nafion membrane and SmFe0.7Cu0.3?xNixO3 (x = 0?0.3) cathode at atmospheric pressure and lower temperature

Samaria-doped ceria Ce_0.8Sm_0.2O_2−δ (SDC) and SmFe_0.7Cu_0.3−x Ni _x O₃ have been synthesized by the sol-gel method and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The electrochemical synthesis of ammonia was investigated at atmospheric pressure and low temperature, using the SFCN materials as the cathode, a Nafion membrane as the electrolyte, nickel-doped SDC (Ni-SDC) as the anode and silver-platinum paste as the current collector. Ammonia was synthesized from 25 to 100°C when the SFCN materials were used as cathode, with SmFe_0.7Cu_0.1Ni_0.2O₃ giving the highest rates of ammonia formation. The maximum rate of evolution of ammonia was 1.13 × 10⁻⁸ mol·cm⁻²·s⁻¹ at 80°C, and the current efficiency reached as high as 90.4%. Supported by the National Natural Science Foundation of China (Grant No. 20863007)     

Characteristics of Pt Electrode Activated by Tb1 − xCexO2 − α Films in Contact with ZrO2 + 10 mol % Y2O3 Electrolyte

Porous platinum electrodes on ZrO₂ + 10 mol % Y₂O₃ solid electrolyte (YSZ) are activated by Tb_{1 ? x}Ce_xO_{2 ? α} (x = 0; 0.15; 0.33; 0.5; 1.0) mixed oxides by impregnation, and their polarization characteristics are studied. The activation is carried out under the conditions that an oxide activator nanofilm forms on the electrolyte surface as a result of heat treatment of the electrode. The activation is performed by impregnating the electrodes with low-concentrated alcohol solution of terbium and cerium nitrates (1.5% as recalculated to the oxides) and subsequent slow heating (≤50°C/h) to 850°C. An average thickness of the film on the electrolyte after a single activation (≈0.1 mg oxides/cm²) is estimated at 10–20 nm. The electrodes of Pt|YSZ|Pt cell activated by Tb_{1 ? x}Ce_xO_{2 ? α} films are studied by the impedance method in the oxidative and reductive atmospheres in the range of 700 to 500°C. The polarization conductivities of the activated electrodes increase by 2–3 orders of magnitude. The studied electrodes are discussed within the model of compact oxide electrodes, where platinum plays the role of collector. The advantage of these electrodes is that they can work both in the oxidative and reductive conditions. According to the aggregate of the properties, Tb_{1 ? x}Ce_xO_{2 ? α} compounds at x = 0.3–0.5 are recommended for activation.

     

A method for the estimation of the enthalpy of formation of mixed oxides in Al2O3-Ln2O3 systems

A new method is proposed for the estimation of the enthalpy of formation (Δ_oxH) of various Al₂O₃-Ln₂O₃ mixed oxides from the constituent binary oxides. Our method is based on Pauling's concept of electronegativity and, in particular, on the relation between the enthalpy of formation of a binary oxide and the difference between the electronegativities of the oxide-forming element and oxygen. This relation is extended to mixed oxides with a simple formula given for the calculation of Δ_oxH. The parameters of this equation were fitted using published experimental values of Δ_oxH derived from high-temperature oxide melt solution calorimetry. Using our proposed method, we obtained a standard deviation (σ) of 4.87 kJ mol⁻¹ for this data set. Taking into account regularities within the lanthanide series, we then estimated the Δ_oxH values for Al₂O₃-Ln₂O₃ mixed oxides. The values estimated using our method were compared with those obtained by Aronson's and Zhuang's empirical methods, both of which give significantly poorer results.     

Tuning Magnetic Properties of CeO2 by Fe Doping via an Electrochemical Deposition Route

Herein Ce_1?xFe_xO_2?δ nanocomposites were investigated for dilute magnetic semiconductor (DMS) properties. Ce_1?xFe_xO_2?δ nanospheres and porous nanostructures with high surface areas have been successfully prepared by electrochemical deposition at room temperature and atmospheric pressure. The structures and morphologies of Ce_1?xFe_xO_2?δ deposits were characterized by X‐ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and N₂ adsorption–desorption techniques. The magnetic properties of the prepared Ce_1?xFe_xO_2?δ nanospheres and porous nanostructures were studied, and they showed room‐temperature ferromagnetism and giant magnetic moments. In addition, the effects of morphologies and compositions on the magnetic properties of Ce_1?xFe_xO_2?δ deposits were studied.     

Beiträge zur Chemie der Oxidhalogenide von Molybdän und Wolfram. IX. Bildungsenthalpie und Sättigungsdruck des MoOBr3

From the enthalpy of solution of MoOBr₃ in NaOH/H₂O₂ the enthalpy of formation ΔH°(MoOBr₃,f,298) = ?109,5(±0,4) kcal/mol was derived. The sublimation of MoOBr₃ is connected with simultaneous decomposition (see “Inhaltsübersicht”). From the temperature function of the saturated vapor pressure the values ΔH°(subl., MoOBr₃, 298) = 36(±1,5) kcal/mol and ΔS°(subl., MoOBr₃, 298) = 56(±3) cl are calculated.     

Thermodynamic stability and hydration enthalpy of strontium cerate doped with yttrium

The standard molar enthalpy of formation of SrY_0.05Ce_0.95O_2.975 has been derived by combining the enthalpy of solution in 1 M HCl + 0.1 KI with auxiliary literature data, Δ_fH° (SrY_0.05Ce_0.95O_2.975, s, 298.15 K) = −1720.4 ± 3.4 kJ/mol. The formation enthalpy of SrY_0.05Ce_0.95O_2.975 from the mixture of binary oxides is Δ_oxH° (298.15 K) = −45.9 ± 3.4 kJ/mol and the enthalpy of reaction of SrY_0.05Ce_0.95O_2.975 with water forming Sr(OH)₂, CeO₂, and Y₂O₃ is Δ_rH° (298.15 K) = −85.5 ± 3.4 kJ/mol. Our data and the entropies of different substances show that SrY_0.05Ce_0.95O_2.975 is thermodynamically stable with respect to a mixture of SrO, Y₂O₃, CeO₂ and that the reaction of SrY_0.05Ce_0.95O_2.975 with water is thermodynamically favourable.