High Water Vapor Pressure Research Articles

Pressurized Steam Torrefaction of Biomass: Focus on Solid, Liquid, and Gas Phase Distributions

Torrefaction is a thermal pretreatment of biomass feedstocks aimed at their conversion into a commodity solid fuel with more uniform and standard properties. Pressurized torrefaction—a novel concept—deserves consideration because of its possible advantages with respect to the atmospheric process, in particular the establishment of favorable conditions for generation of valuable condensed products. The objectives of this research are (i) an investigation on the feasibility of the pressurized, steam-assisted, batch torrefaction of some agro-industrial biomass residues and (ii) the conversion of these latter into solid and liquid products to be used in energy production or chemical processes, with improved characteristics with respect to the raw biomass. The results reported in this article prove that the operation under pressure allows maintaining high water vapor pressure in the system, enhancing the solid biomass conversion to liquid products. The recovery of valuable liquid compounds from the solid resid...

The role of water in reducing WO3 film by hydrogen: Controlling the concentration of oxygen vacancies and improving the photoelectrochemical performance

H2O, as a product of reduced reaction by H2, may affect the chemical equilibrium according to the changing of the pressure ratio of H2O/H2 in the system. Meanwhile, the performance may also be influenced by adsorption of H2O on the surface of the material. In this work, the effect of H2O is studied by reducing plate-like array WO3 films under different pressure ratio of H2O/H2. It is controlled by changing the water temperature in the washing bottle through which the Ar/H2 (80:20) gas flows. The higher water vapor pressure not only decreases the content of W5+ but also increases the content of surface hydroxyl groups in the WO3 films. Moreover, the excess water vapor improves the crystallinity. The WO3 film shows hydrophobicity with adhesive property and high contact angle hysteresis after reduction, and the wettability increases with the increase of the pressure ratio of H2O/H2. Additionally, a built-in electric field may form by dissociation of the surface hydroxyl group and absorption of O− species, which promotes the charge separation, showing better photoelectrochemical (PEC) performance. Thus, water influences the coverage of chemical species on the surface of hydrogen reduced WO3 film, which affects the wettability and PEC performance.

Pressure, hydrolytic degradation and plasticization drive high temperature blistering failure in moisture saturated polyimides

Polyimides and polyimide matrix composites are used in electronics, automotive, aerospace and other applications, particularly in situations where high temperature resistance and low weight are required. Under conditions in which polyimides have absorbed water, either by exposure to high humidity or by direct immersion, if the material is rapidly heated it may fail by high pressure water vapor induced blistering and/or delamination. Such hygrothermal failures can be a limiting factor to the use of polyimides and their composites in extreme environments. Despite prior experimental studies, the mechanisms of such failures remain a question due to the lack of complete material model for polyimide. In this work, a novel time, temperature and moisture dependent constitutive model is developed and presented for the first time. This model is built on previous experimental and modeling studies of high temperature viscoelastic and viscoplastic deformation in the polyimide HFPE-II-52 and on studies of the effects of moisture degradation on the mechanical properties. The model is implemented in a finite element simulation providing a means for the study of blistering under different heating rates and moisture levels. The results show for the first time that high temperature blistering failures are driven not only by steam pressure and thermal softening but by the synergy of pressure loading and material softening due to hydrolytic degradation and plasticization.

Modeling of the lithium hydride hydrolysis under low relative humidity

A reactional mechanism describing the hydrolysis of lithium hydride (LiH) under moist atmosphere is proposed and modeled. It involves the formation of lithium oxide (Li2O) at low vapor pressure and both lithium oxide and lithium hydroxide (LiOH) at higher vapor pressures, with diffusion of water in these layers. A numerical model based on this mechanism is implemented with COMSOL Multiphysics to simulate the hydrolysis of LiH particles in open system (constant water vapor pressure). Kinetic parameters such as rate constant of reactions and diffusion coefficient of water in Li2O and LiOH are first fitted against experimental data. The best agreements are obtained when the diffusion coefficient of water is 10 times higher in LiOH than in Li2O. The resulting model accurately predicts the hydrolysis rates experimentally measured for a wide range of water vapor pressures (0.3–17 Pa). The hydrolysis mechanisms are compatible with a Li2O production limited by water diffusion and a LiOH production governed by the kinetics. Finally, simulation suggest that the thickness of the Li2O layer does not depends much on the water vapor pressure whereas that of LiOH increases drastically at high water vapor pressures.

Crystal structure, chemical stability and electrical properties of Sr2MnNbO6 − δ, Sr2Cr0.5Mn0.5NbO6 − δ and Sr2CuNbO6 − δ perovskites

The 3d-cation-substituted perovskites Sr2MnNbO6 − δ, Sr2Cr0.5Mn0.5NbO6 − δ and Sr2CuNbO6 − δ were synthesized using the solid state technique. Conductivity measurements showed that the investigated phases exhibited mixed-electronic-ionic conductivity, and the total conductivity decreased in the row Sr2MnNbO6 − δ–Sr2Cr0.5Mn0.5NbO6 − δ–Sr2CuNbO6 − δ. The O2−-conductivity was measured by oxygen permeation technique, and it was found that the Cu- and Cr-containing samples exhibited ∼0.5 order of magnitude higher ionic conductivities at 500 °C, and lower activation energies, 0.85 ± 0.02 and 0.90 ± 0.02 eV, respectively, than Mn-containing compound Sr2MnNbO6 − δ (1.16 ± 0.03 eV). The conductivity, thermogravimetry and Raman measurements showed that these compositions did not intercalate the water and did not exhibit proton conductivity, but showed good chemical stability at high water vapour pressure. In contrast, the solid solution Sr2.9 − x Cu x Nb1.1O5.65 (x = 0.07; 0.15) with double perovskite structure was able to water uptake and to proton transport, but had a low chemical stability.

Advanced Proton Conducting Ceramic Cell as Energy Storage Device

Ba-based protonic ceramic cell (PCC) was investigated under galvanostatic electrolysis and reversible Fuel cell / electrolysis cycles modes. Such PCC has been made by industrial wet chemical routes (tape casting and screen-printing methods) and by using NiO-BaCe0.8Zr0.1Y0.1O3-δ (BCZY81) as anode material layer / BCZY81–ZnO (5 mol%) as electrolyte, Ba0.5Sr0.5Co0.8Fe0.2O3-δ (BSCF) – BCZY81) as air electrode and BSCF as current collector. The optimization of key parameters of both fuel cell and electrolysis operating conditions such as water feed content, fuel utilization, temperature operation allow to validating promising electrical cell performances (>0.25 W/cm², 0.7V under fuel cell mode; 0.5A/cm², 1.3V under electrolysis mode) and reliability during more than 3500 h with limited electrical degradation (<2%/kh) at 700°C. The evolution of on line Electrochemical Impedance Spectroscopy measurements reveals that the total electrical resistances of PCC are lower under electrolysis mode than under fuel cell mode, in particular the ohmic resistance (electrolyte). But in the same time, the polarization resistance of the cell (air electrode interface) is higher under electrolysis mode. With time, the combination of high temperature and water vapor pressure can induce negative reaction able to accelerate the Ba-based materials aging. In any case, such highlights pave the way to the use of PCC technology as high efficient energy storage candidate.

The influence of water on the thermal simulation experiment of hydrocarbon generation and expulsion

ABSTRACTThermal simulation experiment of hydrocarbon generation and expulsion is an important method for the study of source rock evolution. The role played by water in organic material evolution was clarified by summarizing the effect of water on different pyrolysis systems. According to the results, the hydrous experiment has a better hydrocarbon generation rate than the anhydrous experiment in the closed system. In the semi-open system, high-pressure water vapor has good effect to gas generation, while near-critical water (NCW) improves the oil and total hydrocarbon productive rate. So, it is inferred that NCW improves the conversion of kerogen to hydrocarbon reactions, and increases the dissolving capacity of hydrocarbons.

Estimation of grass reference evaporation and sensible heat flux using surface renewal and Monin-Obukhov similarity theory: A simple implementation of an iterative method

An iterative method was applied to daily crop reference evaporation ETo. The method correctly evaluated the slope of the saturation water vapour pressure vs temperature relationship between surface temperature and air temperature. Using daily meterological data spanning several decades from four selected locations in Australia, South Africa and USA, differences in ETo estimates were noted with and without the iteration method applied. The largest difference, which occurred under high water vapour pressure deficit conditions, ranged from 1.65mm/day for Griffith, Australia to 0.51mm/day for Pretoria, South Africa. The aerodynamic component of the ETo equation was more affected by not applying the spreadsheet iterative procedure compared to the radiative component. Other spreadsheet examples of the iterative method employed included obtaining the roots of a depressed cubic polynomial in the air temperature surface renewal (SR) ramp. This value was used for the measurement of sensible heat flux using surface renewal. An iterative method, together with Monin-Obukhov similarity theory (MOST) and surface-layer scintillometer (SLS) measurements in a mesic grassland, was also used to calculate the sensible heat flux. The simple iterative method is quick, accurate and convenient, easy to repeat following changes to equations or data, allows easy manipulation and allows convenient visual inspection of data and graphics. Sub-hourly measurements of sensible heat flux for the mesic grassland using SR and SLS MOST iterative methods compared favourably with Bowen ratio and eddy covariance measurements.

Advanced Proton Conducting Ceramic Cell as Energy Storage Device

Ba-based protonic ceramic cell (PCC) was investigated under galvanostatic electrolysis and reversible Fuel cell/electrolysis cycles modes. Such PCC has been made by industrial wet chemical routes (tape casting and screen-printing methods) and by using NiO-BaCe0.8Zr0.1Y0.1O3-δ (BCZY81) as anode/BCZY81–ZnO (5 mol%) as electrolyte, Ba0.5Sr0.5Co0.8Fe0.2O3-δ (BSCF) – BCZY81) as air electrode and BSCF as current collector. The optimization of key parameters of both fuel cell and electrolysis operating conditions such as water feed content, fuel utilization, temperature operation allow to validating promising electrical cell performances (>0.25 W/cm², 0.7 V under fuel cell mode; 0.5 A/cm², 1.3 V under electrolysis mode) and reliability during more than 3500 h with limited electrical degradation (<2%/kh) at 700°C. The evolution of Electrochemical Impedance Spectroscopy measurements reveals that the total electrical resistances of PCC are lower under electrolysis than under fuel cell mode, in particular the ohmic resistance (electrolyte). But in the same time, the polarization resistance of the cell (air electrode interface) is higher under electrolysis mode. The combination of high temperature and water vapor pressure can induce negative reaction able to accelerate the Ba-based materials aging. In any case, it highlights the use of PCC technology as high efficient energy storage candidate.

Emission Properties of Porous Silicon Electron Emitters Formed by Pulsed Anodic Etching

Porous silicon (PS) layers were formed by pulsed anodic etching and subsequently processed by electrochemical oxidization (ECO) and high-pressure water vapor annealing (HWA), and their morphologies and oxidation degrees were analyzed. The electron emitters based on these PS layers were fabricated, and their emission properties were investigated. The experimental results show that a PS layer formed by pulsed anodic etching has a better pore-diameter homogeneity in the longitudinal direction, and it can obtain good oxidation quality more easily by the combined treatment of ECO and HWA. The as-formed PS electron emitters have better emission properties in comparison with those based on PS layers prepared by constant-current anodic etching.

A hybrid hydrolytic hydrogen storage system based on catalyst-coated hollow glass microspheres

Hydrogen-pressurized hollow glass microspheres (HGMs) in combination with a hydride bear the potential of storing hydrogen in feasible amounts. Therefore, the approximately 20-µm diameter spheres are heated up and pressurized with hydrogen at a pressure of 85 MPa, so hydrogen diffuses into the spheres. After the spheres are cooled down, hydrogen can be stored at room temperature without excessive security measures. To release the stored hydrogen, heat has to be applied again to reach temperatures of about 250 °C (523.15 K). To reach this temperature, it is suggested in this work to use an exothermal chemical reaction, which produces hydrogen as a by-product. In this case, an NaBH4–water reaction will be discussed, which has to be initialized by a catalyst deployed on the HGMs. It will be shown that hydrogen storage densities of up to 20 wt% and 50 kg/m3 can be theoretically achieved with the proposed hydrogen storage system consisting of hydrogen-pressurized HGMs and a hydride, that is, NaBH4. Volumetric storage density and other aspects, such as water management, temperature restriction, stoichiometric restriction and hydrogen diffusion through glass, will be discussed. Due to resulting high water vapour pressures, a pressure vessel will still be needed in the concept. This paper shall give an overview of theoretically achievable storage densities with the proposed system. Experiments were carried out regarding catalytic promoted hydrolysis with HGMs, and resulting storage densities were determined. These experiments show good agreement with theory. However, they will be addressed only briefly in the outlook of the paper because a detailed discussion would go beyond the scope of this work. Copyright © 2016 John Wiley & Sons, Ltd.

Enhancement in Chemical Stability of Proton Conducting Solid Oxide Electrolysis Cell (SOECs)

Developments of fuel cell technology are a great achievement for researcher’s to fulfill the need of clean and renewable energy. Among the various type of fuel cells, high temperature ceramic fuel cells inherit several advantages such as high efficiency, fuel flexibility and no precious-metal catalyst [1], but the solid oxide fuel cell (SOFC) typically uses yttria-stabilized zirconia (YSZ) at operating temperature of 800-1000°C, resulting in high cost, cell degradation and material compatibility issues. Many researchers investigated protonic ceramic conducting fuel cells (PCFCs) and have presented their possibility as intermediate temperature ceramic fuel cells [2, 3]. Proton-conducting oxides due to high conductivity with lower activation energy (0.3-0.6eV) can be operated at lower temperature of 400-600°C, which increases the cell life-time and reduces the fabrication cost. Compared with SOFCs when operating on hydrocarbon fuel, particularly CH4 conversion rate is high due to direct conversion of proton (hydrogen). A few studies try to use solid oxide electrolysis cell (SOEC) to produce hydrogen by electrolyzing steam at the IT range. [4]. In conventional oxygen-ion SOECs, steam is fed into the fuel electrode side, then the oxygen-ions move toward the air electrode, while the hydrogen is produced at fuel electrode side. One of the technical issues in SOECs is the oxidation of Ni based electrode in steam conditions, resulting in cell degradation. In proton-conducting SOECs, steam is fed at air electrode and hydrogen is produced at fuel electrode. In IT-SOFCs, the BSCF cathode is considered to be as an excellent material [5], but it can be degraded and decompose in high humid air condition. Hence, we should develop durable materials against high water vapor pressure. In this study we design the electrode material to develop highly durable cathode materials for SOECs. Moreover, in order to investigate the practical use of these cell, the accelerating durability test is designed and carried out. The durability test is conducted by periodically repeated both in fuel cell and electrolysis modes. To find the degradation analysis of the cell, micro-structural analysis is performed with SEM, TEM and XRD [6, 7], the impedance spectra and over-potential analysis are performed. E. D. Wachsman, and K. T. Lee, Science , 334, 935 (2011).C. Duan, J. Tong, M. Shang, S. Nikodemski, M. Sanders, S. Ricote, A. Almansoori and R. O’Hayre, Science, 349, 6254 (2015).L. Bi, S. Boulfrad and E. Traversa, J. Chem. Soc. Rev., 43, 8255 (2014).M. Ni, M. K. H. Leung and D. Y.C. Leung, Int. Ass. Hydrogen Eng., 33, 4040 (2008).P. K. Lohsoontorn, D. J. L. Brett, N. Laosiripojana, Y. M. Kim, J-M. Bae, Int. J. Hydrogen energy, 35, 3958 (2010).G. Kim, N. Lee, K. -B. Kim, B. -K. Kim, H. Chang, S. J. Song, J. -Y. Park, Int. J. Hydrogen energy, 38, 1571 (2013).H. Xiao, T. L. Reitz, M. A. Rottmayer, J. Power sources, 183, 49 (2008). * Corresponding authors: jyoung@sejong.ac.kr (J.-Y. Park)

Enhanced Ultraviolet Luminescence of ZnO Nanorods Treated by High-Pressure Water Vapor Annealing (HWA)

Zinc oxide nanorods (ZnO NRs), synthesized by a low temperature chemical method, were postannealed at 260 °C in air and under high pressure water vapor (HWA) at 1.3–3.9 MPa. We found that the UV luminescence intensity increased by a factor of 2–3 after HWA annealing compared to that observed after annealing in air. Structural analysis of the nanorods in relation with their optical properties by means of Raman and XPS spectroscopies, transmission and scanning electron microscopies allow to conclude that the origin of the UV luminescence enhancement is due to the transformation of the Zn(OH)2 surface–layer into ZnO, but also to the growth of a new thin ZnO layer at the surface of the rods. This layer is 1–2 nm thick and its presence leads to surface reconstruction of the nanorods. In addition, we show that the size and the density of the nanopores within the ZnO NRs are reduced upon HWA annealing with respect to air annealing.

Current Collapse Reduction in AlGaN/GaN HEMTs by High-Pressure Water Vapor Annealing

We have demonstrated for the first time a remarkable reduction of current collapse in AlGaN/GaN high-electron-mobility transistors (HEMTs) by high-pressure water vapor annealing (HPWVA). The device subjected to HPWVA exhibited considerably low dynamic ON-resistance (R <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ON</sub> ), suggesting highly improved performance of these devices. Analyses of the results on normalized dynamic R <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ON</sub> experiments have shown the elimination of deeper traps by HPWVA, leading to the substantially reduced current collapse. X-ray photoelectron spectroscopy (XPS) studies revealed a significant increase in the oxygen core-level O 1s peak. Moreover, angle-resolved XPS suggested the formation of surface oxide layer. These results indicate that the effective reduction of current collapse in the HPWVA-processed samples is likely due to the incorporation of active oxygen species generated by the HPWV into the AlGaN surface. These oxygen atoms eventually fill up near-surface nitrogen vacancies and promote the formation of Ga <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> native oxide and possibly Ga <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O suboxide, which is known to be an excellent III-V surface passivant. HPWVA is a relatively simple, low-damage, and low-temperature process, and hence, it is found to be a highly feasible and promising alternative for realizing AlGaN/GaN HEMTs with improved performance.

Effect of Feed Temperature on the DCMD Performances in Treating Synthetic Textile Wastewater

This article discussed the effect of feed temperature on the performance of direct contact membrane distillation (DCMD) in treating synthetic textile wastewater containing dissolved dye and salt. The DCMD experiments were conducted using an in-house made composite hollow fiber membrane made of organic polyvinylidene fluoride (PVDF) and inorganic Cloisite 15A. Prior to dyeing solution treatment process, the influence of feed temperature on membrane permeability was first investigated using deionized water. Then, the membrane was tested using synthetic solution containing 50 mg L-1 acid red 1 and 60 g L-1 sodium chloride. The inlet temperature of the feed solution was varied in the range of 50 to 90°C while the temperature of permeate solution was kept constantly at 20°C. The results showed that the vapor fluxes of membrane increased with increasing the feed temperature and maximum flux (Jv = 20.88 kg m-2 h-1) was obtained at 90°C.This is mainly due to the higher water vapor pressure sensitivity at the feed side of a higher operating temperature. With respect to separation performance, it is reported that DCMD process could easily achieve excellent rejection for both dye compound and dissolved salts, recording more than 99% rejection.

Surface passivation and bandgap widening in poly-Si treated by using high-pressure water-vapor annealing

Cast-grown polycrystalline silicon (poly-Si) was treated by using high-pressure water-vapor annealing (HWA) at various temperatures and pressures. The effective carrier lifetime (τeff) was measured by using the microwave photo-conductance decay, and the number of dangling bonds was monitored by using the electron spin resonance (ESR). As the annealing temperature and the pressure were increased, the ESR signal due to dangling bonds disappeared at (600 ℃, 0.1 MPa), but τeff increased only at higher pressures. The Si-O-Si vibration peaks measured by using Fourier-transform infrared spectroscopy appeared under the conditions where τeff was increased, and the binding energy measured by using X-ray photoemission spectroscopy and the refractive index measured by using ellipsometry showed that SiO2 was formed at the surface. These results show that the bandgap widening due to the formation SiO2 and to the passivation of dangling bonds is responsible for the increased τeff.

High Mean Water Vapour Pressure Promotes the Transmission of Bacillary Dysentery

Bacillary dysentery is an infectious disease caused by Shigella dysenteriae, which has a seasonal distribution. External environmental factors, including climate, play a significant role in its transmission. This paper identifies climate-related risk factors and their role in bacillary dysentery transmission. Harbin, in northeast China, with a temperate climate, and Quzhou, in southern China, with a subtropical climate, are chosen as the study locations. The least absolute shrinkage and selectionator operator is applied to select relevant climate factors involved in the transmission of bacillary dysentery. Based on the selected relevant climate factors and incidence rates, an AutoRegressive Integrated Moving Average (ARIMA) model is established successfully as a time series prediction model. The numerical results demonstrate that the mean water vapour pressure over the previous month results in a high relative risk for bacillary dysentery transmission in both cities, and the ARIMA model can successfully perform such a prediction. These results provide better explanations for the relationship between climate factors and bacillary dysentery transmission than those put forth in other studies that use only correlation coefficients or fitting models. The findings in this paper demonstrate that the mean water vapour pressure over the previous month is an important predictor for the transmission of bacillary dysentery.

Electron emission properties of cold cathodes based on porous silicon layer processed by electrochemical oxidation and high-pressure water vapor annealing

Porous silicon (PS) layers were processed by electrochemical oxidation (ECO) and high-pressure water vapor annealing (HWA) after they were prepared on n+-type silicon substrates with the double-cell anodic etching technique. The cathodes with a multilayer structure of Pt/PS layer/n+-Si/ohmic-contact electrode were fabricated, and their electron emission properties were investigated. The experimental results showed that it is difficult to get a sufficient and uniform oxidation for a PS layer by merely using ECO, while HWA can assist ECO to improve the oxidation quality of the PS layer, and the emission current density and efficiency of the porous silicon cathode can be increased by the combined treatment of HWA and ECO.

Hydration thermodynamics of the proton conducting oxygen-deficient perovskite series BaTi1-xMxO3-x/2 with M = In or Sc.

This article establishes the effect of structure and composition on water uptake and the hydration and proton transport properties of the oxygen-deficient perovskite series BaTi1-x(In,Sc)xO3-x/2, with 0.2 ≤ x ≤ 0.7. The equilibrium water uptake is determined by thermogravimetry, while combining thermogravimetry with differential scanning calorimetry allows for direct determination of the materials' hydration thermodynamics. Proton and oxide ion transport properties are characterized by means of ac impedance measurements up to 1000 °C. In general, the hydration thermodynamics of the scandates are more favorable than that of the indates and are also affected by changes in crystal structure throughout the series. The more favorable hydration thermodynamics of cubic scandates increase their proton conductivity at higher temperatures compared to their indate counterparts. In contrast to the BaTi1-xInxO3-x/2 series, the BaTi1-xScxO3-x/2 (0.5 ≤ x ≤ 0.7) materials retain their cubic structures upon full saturation by protons and show no signs of chemical instability upon exposure to 1 atm H2O(g) down to 100 °C. The BaTi1-xScxO3-x/2 materials with 0.5 ≤ x ≤ 0.7 may therefore find application in, for instance, steam electrolysis or similar processes involving high water vapor pressures.

Protonation and structural/chemical stability of Ln2NiO4+δ ceramics vs. H2O/CO2: High temperature/water pressure ageing tests

Mixed ionic-electronic conductors (MIEC) such as rare-earth nickelates with a general formula Ln2NiO4+δ (Ln=La, Pr, Nd) appear as potential for energy production and storage systems: fuel cells, electrolysers and CO2 converters. Since a good electrode material should exhibit important stability in operating conditions, the structural and chemical stability of different nickelate-based, well-densified ceramics have been studied using various techniques: TGA, dilatometry, XRD, Raman scattering and IR spectroscopy. Consequently, La2NiO4+δ (LNO), Pr2NiO4+δ (PNO) and Nd2NiO4+δ (NNO) have been exposed during 5days to high water vapor pressure (40bar) at intermediate temperature (550°C) in an autoclave device, the used water being almost free or saturated with CO2. Such protonation process offers an accelerating stability test and allows the choice of the most pertinent composition for industrial applications requiring a selected material with important life-time. In order to understand any eventual change of crystal structure, the ceramics were investigated in as-prepared, pristine state as well as after protonation and deprotonation (due to thermal treatment till 1000°C under dry atmosphere). The results show the presence of traces or second phases originating from undesirable hydroxylation and carbonation, detected in the near-surface layers. The proton/water insertion modifies the structure symmetry and the unit-cell volume whatever the low amount (<0.5wt% equivalent H2O). This result is consistent with long range interaction and in contradiction with the formation of hydroxyl species hypothesis. The reaction mechanisms evidenced after autoclave treatment may be useful to understand the reaction occurring at the electrode surface in SOFC/HTSE systems.