Crystal Water Research Articles

Thermal property characterization and modeling of SMAW electrode coating flux using ANN and regression analysis

The design and development of SMAW electrode coating fluxes, along with their thermal property characterization, are discussed. Using an extreme vertices design approach, 27 flux mixture combinations have been prepared. The TGA-DSC and hot disk analysis are done to quantify the thermal response of the fluxes. Results show that increase in CaF2 and SiO2 reduces weight loss. Increase in CaO increases weight loss, whereas increase in BaO shows minimal effect on weight loss. Enthalpy change of flux was found to influence mainly with CaF2 and CaO. Thermally stable flux has lower volatile compounds such as crystallization water and moisture, which helps to minimize gaseous entrapment in weld pool. An increase in CaF2 shows slight decreases and then increase in thermal diffusivity. The increase in thermal diffusivity leads to instant heat flow in the coating. Regression analysis is done, and the effect of individual and interaction of flux constituents on thermal properties is discussed. The artificial neural network is employed for predictive modeling in the domain of the mixture design approach, its prediction accuracy is compared with regression analysis. Water vapor solubility of slag was estimated between 3.169 and 3.947 and sulfide capacity of slag was − 2.479 to −1.892.

Dehydration behaviors and properties of anhydrite II prepared by phosphogypsum with low-temperature calcination

Certain concentration H+ can combine with the crystal water to form the H3O+, influencing the stability of the crystal water in dihydrate so that can be completely removed under lower temperature. Therefore, this paper introduces a method wherein sulfuric acid is employed as a medium, facilitating direct dry mixing and low calcination temperatures to produce anhydrite II. Initially, the low and high calcination temperatures were determined as 280°C and 500°C, respectively, through XRD analysis of the phase composition of calcination products under varying conditions. Subsequently, the influence of different sulfuric acid contents and concentrations on the calcination products at 280°C was investigated. Additionally, the impact of sulfuric acid on the dehydration behavior of PG was analyzed using TG-DSC and FTIR. The present work also assessed the physical-mechanical properties of anhydrite II at 280°C and 500°C, along with their hydration activity and microscopic morphology. The results indicated that the optimal sulfuric acid content and concentration were determined as 2 % and 40 wt%, respectively, yielding dehydration temperatures of 86.08°C and 146.95°C. The water requirement (WR) for normal consistency for anhydrite II at 280°C was 0.68, exhibiting higher flexural and compressive strength compared to calcination at 500°C (WR=0.58), and the hydration rate at 28 days reached 78.5 %. At 280°C, the dihydrate crystals formed by anhydrite II at 28 days exhibited a compact microstructure characterized by relatively small crystals with well overlapping.

Copper-doped zinc tartrate (Cu-ZnT) nanocrystals: Exploring their physical and antimicrobial properties

This study investigates the growth and properties of pure zinc tartrate (ZnT) and copper-doped zinc tartrate (Cu-ZnT) nanocrystals synthesized via a sol-gel technique using double-distilled water, sodium metasilicate, and tartaric acid. Controlled pH gels were prepared with the subsequent addition of zinc chloride and copper chloride solutions to facilitate nanocrystal formation. The synthesized nanocrystals were characterized using various techniques, including Energy-Dispersive X-ray analysis, Fourier Transform Infrared Spectroscopy, Thermogravimetric analysis, UV–visible-near infrared spectral analysis, X-ray diffraction (XRD), and Field Emission Scanning Electron Microscopy. EDAX confirmed the elemental composition of Zn, Cu, C, and O in the crystals. FTIR spectra revealed the presence of functional groups corresponding to water of crystallization, tartaric acid moieties, and potentially other compounds. TGA analysis indicated a two-stage decomposition process for ZnT and the formation of zinc copper oxide in Cu-ZnT. UV–vis-NIR analysis yielded a low cut-off wavelength of 285 nm for both crystals, suggesting electronic transitions below 350 nm. Both ZnT and Cu-ZnT nanocrystals are transparent in visible and near-infrared light, absorbing strongly in the ultraviolet. Copper doping enhances Cu-ZnT light absorption. While both act as insulators, Cu-ZnT exhibits significantly higher conductivity due to copper doping. XRD analysis estimated an average crystalline size of 42 nm, while FE-SEM images revealed a quasi-spherical morphology. Refractive index, extinction coefficient, and optical bandgap were further determined, highlighting the potential suitability of these nanocrystals for optoelectronic applications. Antibacterial and antifungal assays demonstrated moderate effectiveness against tested microorganisms compared to standard drugs.

Triple engineering boosts high-performance accordion-like vanadium oxide for practical aqueous zinc-ion batteries

Vanadium oxide is one of promising cathode materials for aqueous zinc-ion batteries (ZIBs), but the low electrical conductivity and slow ion diffusion kinetics of vanadium oxide lead to low practical capacity and poor cycling life, which limits further commercialization development. Herein, this study proposes a triple engineering strategy of N-doping, oxygen vacancies and crystal water to achieve the high-performance of V2O5 by a simple stirring method. N doping can improve the electrical conductivity of the materials, oxygen vacancies can modulate the electronic structure, and the crystal water can effectively shield the electrostatic effect. First-principles calculations confirmed that the incorporation of the triple engineering strategies can effectively reduce of the energy band gap and Zn2+ diffusion barrier of V2O5, and promote the intercalation dynamics of Zn2+. As a result, the prepared N-doped V2O5-x·nH2O achieves an outstanding specific capacity of 607.74 mAh/g at 0.1 A/g, and cycling stability. Moreover, based on the above advantages, the practical 21700-type cylindrical battery assembled with this N-doped V2O5-x·nH2O cathode and Zn foil anode, presenting a maximum capacity of 393.5 mAh at 0.4 A. This high performance of vanadium oxide cathode shows a good practical prospect in aqueous cylindrical ZIBs.

The radiation protection and high temperature performance of serpentine-magnetite mixed concrete

In this paper, the high density of magnetite and the high crystal water content of serpentine are used to configure concrete with high temperature resistance, gamma ray shielding and neutron shielding properties, and adjust the proportion of magnetite and serpentine to prepare five different proportions of serpentine magnetite mixed concrete, then studies the compressive strength of mixed concrete with different proportions; splitting tensile strength; quality loss; hydrogen content; γ radiation shielding performance; ultrasonic pulse velocity. The results show that the compressive strength of the mixed concrete increases from 31.5 MPa to 40 MPa, the linear attenuation coefficient of γ-ray increases from 0.17 to 0.259, and the hydrogen content decreases from 1.5989 % to 0.3778 % with the increase of magnetite content in the aggregate. Under different mix ratios, with the increase of heating temperature, various properties of mixed concrete gradually decrease, the minimum ultrasonic wave speed of concrete will drop to 24.1 % of the original wave speed, and the minimum compressive strength will drop to 25.1 % of the compressive strength at normal temperature. However, before the heating temperature of 600°C, the compressive strength can still be maintained at more than 75 % of the normal temperature compressive strength.The concrete above has good thermal stability.

High H2O-Assisted Proton Conduction in One Highly Stable Sr(II)-Organic Framework Constructed by Tetrazole-Based Imidazole Dicarboxylic Acid.

Solid electrolyte materials with high structural stability and excellent proton conductivity (σ) have long been a popular and challenging research topic in the fuel cell field. This problem can be addressed because of the crystalline metal-organic frameworks' (MOFs') high structural stability, adjustable framework composition, and dense H-bonded networks. Herein, one highly stable Sr(II) MOF, {[Sr(H2tmidc)2(H2O)3]·4H2O}n (1) (H3tmidc = 2-(1H-tetrazolium-1-methylene)-1H-imidazole-4,5-dicarboxylic acid) was successfully fabricated, which was structurally characterized by single-crystal X-ray diffraction and electrochemically examined by the AC impedance determination. The results demonstrated that the σ of the compound manifested a positive dependence on temperature and humidity, and the optimal proton conductivity is as high as 1.22 × 10-2 S/cm under 100 °C and 98% relative humidity, which is at the forefront of reported MOFs with ultrahigh σ. The analysis of the proton conduction mechanism reveals that numerous tetrazolium groups, carboxyl groups, coordination, and crystallization water molecules in the framework are responsible for the high efficiency of proton transport. This work offers a fresh perspective on how to create novel crystalline proton conductive materials.

The Temperature of Pretreatment on Microstructure Change of Lump Ore and Improvement of Metallurgical Properties

Goethite is one of the most common minerals in iron ore, and is the main source of internal crystal water generated during the heating process of lump ore. To address this challenge, three measures are proposed: first, minimizing the decomposition of crystalline water upon the introduction of lump ores into the furnace; second, reducing the heat absorption of water vapor within the furnace; and third, increasing the proportion of lump ores being introduced into the furnace. With this in mind, the lump ore preheating treatment technology is introduced. By preheating the lumps at different temperatures, the influence of pretreatment on the reduction and soft melting of the lumps is studied. The results show that at different preheating temperatures, due to the transformation of FeOOH to Fe2O3, the natural goethite gradually changes from natural granular to spherical at higher preheating temperatures. When the preheating temperature is 400–700 °C, the coexisting phase of goethite and hematite in the pores changes obviously. The metallurgical properties of lump ore change dramatically. When the temperature is lower than 400 °C or higher than 700 °C, almost all goethite in lump ore is transformed into hematite, and the morphology does not change.

Experimental study on suppression of thermal runaway propagation of lithium-ion battery by salt hydrate based dry powder extinguishants

To develop the high cooling effect, high fire extinguishing performance, non-conductive and low cost extinguishant for fighting lithium-ion battery (LIB) fire, seven salt hydrates with different amounts of crystal water were systematically studied as the dry powder extinguishants in this work. The results of the differential scanning calorimeter (DSC) measurement demonstrate that the highest endothermic enthalpies of the salt hydrates below 150 °C is larger than 800 kJ kg−1, which can effectively suppress the thermal runaway (TR) propagation between LIBs. Moreover, the heat absorption capacity of the salt hydrate can be enhanced by increasing the reaction entropy, which can be achieved by increasing the crystal water content. The electric breakdown voltages of the salt hydrates were ranged from 4 kV to 60 kV, which are mainly determined by the crystal water content and the melting point. Furthermore, the fire extinguishing performances of the salt hydrates have no obvious relationship with their heat absorption capacities, but are related to their chemical component. This work systematically studied the factors that affect the cooling effect, the fire extinguishing performance and the conductivity of the salt hydrates, which provides an essential basis for developing high performance salt hydrate based dry powder extinguishants in fighting LIB fire.

Influence of magnesium and calcium sulfate whisker on crystallization characteristics of poly (butylene adipate-co-terephthalate) and Poly(butylene succinate)

Inorganic fillers of whisker-like morphology are considered promising materials, and they have gained significant attention in recent years as a substitute for glass fibers due to their fibrous surface characteristics and extremely low bulk density. This study selected magnesium sulfate whiskers (MSWs) containing crystal water and pure calcium sulfate whiskers (CSWs) as fillers. They were physically blended with biodegradable polymers PBAT and PBS in a range of 0.1 wt.% to 2 wt.% to form composite materials. The non-isothermal crystallization behavior of the composite materials was studied using differential scanning calorimetry (DSC). The data indicated that with an increase in whisker content, the crystallization temperature (Tc) of composites increased, and the addition of a small amount of whiskers led to a reduction in the half-crystallization time of the composite materials, indicating the crystallization capacity of the materials has been enhanced to varying degrees. Analysis via POM unveiled a consistent pattern of decreased spherulite size and heightened spherulite count with the introduction of whiskers. This phenomenon is ascribed to the whisker fillers’ function as nucleating agents within the polymer matrices, thereby stimulating the crystallization process. Interestingly, the findings suggest that CSWs exert a more significant influence on crystallization than MSWs, likely due to the distinct single fiber morphology of the former filler.

Facile fabrication of mesoporous Ag-doped γ-MnO2 nanowires with rich oxygen defects for boosting performance of aqueous Zn-ion batteries

In recent years, the aqueous zinc-ion batteries (AZIBs) have attracted a remarkable attention due to their low cost, abundance, low toxicity and high safety. MnO2 is considered a potential electrode for AZIBs owing to its high theoretical capacity and abundance. However, MnO2 suffers a challenging issue of poor cyclability. Herein, mesoporous Ag-doped γ-MnO2 nanowires were fabricated for the first time by a facile room temperature co-precipitation method under the assistance of Ag+ and investigated electrochemically as cathode for AZIBs. The as-obtained sample electrode delivers a remarkable discharge specific capacity of 978 mAh g-1 at the 65th cycle at a current rate of 0.1 C to be steady at 804 mAh g-1 after 150 cycles and exhibits an excellent rate capability at high C-rate due to the surface-controlled capacitive process of the electrochemical reaction, which is attributed to the unique structure of Ag-doped γ-MnO2 nanowires with rich oxygen defects and crystal water for more active sites and stable structure. This work offers aspiration for the future cathode material engineering as AZIBs.

Continuous and Scalable Synthesis of Prussian Blue Analogues with Tunable Structure and Composition in Surfactant-Free Microreactor for Stable Zinc-Ion Storage.

We represent a segmented flow surfactant-free microfluidic strategy for continuous synthesis of Prussian blue analogues (PBAs) with high dispersity and high crystallization. Representative zinc hexacyanoferrate (ZnHCF) nanocubes were successfully synthesized in a microfluidic reactor within a few minutes via the cooperation method and possessed lower contents of crystal water and Fe(CN)6 3- vacancies than that of synthesis in bulk solution. The nucleation and particle growth process can be precisely controlled by the exploration of different flow rates and reaction temperatures during the formation of ZnHCF nanocubes in segmented flow microfluidic reactors. High crystallinity, low crystal water and vacancies in the ZnHCF structure were presented at relatively high temperatures for the crystal growth process. High-quality ZnHCF with a low content of crystal water showed excellent electrochemical activity and stability towards zinc-ion storage. The continuous and scalable synthesis approach can be extended to the fabrication of other PBAs such as NiHCF, CoHCF, MnHCF, and CuHCF with high dispersity without using any surfactants. The controllable construction of PBAs with tunable properties in microfluidic reactors provides a promising direction to minimize the gap between commercial reality and laboratory research.

Regular relations of the composition, structure and properties of crystals of hydrogen-containing compounds

Research subject. Crystals of hydrogen-containing compounds belonging to the superprotonic family. Aim. To obtain knowledge about regular relations between composition, atomic structure, real structure and physical properties of materials, with the purpose of elucidating processes occurring in condensed state and forming the basis for modification of known or obtaining new compounds. Materials and methods. Experimental data were obtained using a set of complementary physical methods, including structural analysis using X-rays, synchrotron radiation and neutrons, optical microscopy, and atomic force microscopy. Results. Experimental data on the atomic structure, real structure, and physical properties of superprotonic crystals, including systems of hydrogen bonds and their changes, were obtained. Conclusions. The physical properties of superprotonic crystals are significantly affected by hydrogen bonding systems and their changes, primarily by the formation of dynamically disordered hydrogen bonds with energetically equivalent positions of hydrogen atoms. When carrying out diagnostics of crystalline samples, account should be taken of their real structure, including the structure of surface layers and the presence of crystallization water. These factors may affect the measured physical parameters, the boundaries of existence of phases, the formation of a multiphase state under variations in temperature.

A nanochanneled silver-deficient oxalatocobaltate(III) complex anion with hydronium as counter cation: Synthesis, crystal structure, thermal analysis and magnetism

A novel cobalt(III) salt, (H3O)0.6[Ag2.4Co(C2O4)3]·6H2O (1), a member of the rare paramagnetic CoIII-open framework materials, has been synthesized in water and characterized by standard methods, including elemental and thermal analyses, IR, UV-Vis and EDX spectroscopies, and single-crystal X-ray diffraction. Compound 1 crystallizes in the monoclinic I2/a space group. In the crystal structure, the Co(III) centers are pseudo-octahedrally chelated by three oxalato ligands with usual propeller orientation. The structure can be best described as an anionic silver-deficient oxalatocobaltate(III) [Ag2.4Co(C2O4)3]0.6- framework with isolated nanochannels parallel to the a axis, hosting highly disordered water molecules carrying protons (hydronium ions). Thermal analysis showed significant weight losses corresponding to the elimination of crystal water molecules followed by the decomposition of the network. Temperature-dependence susceptibility measurements investigated in the temperature range 2–300 K revealed antiferromagnetic ordering at low temperatures (T ≤ 25 K), the Curie–Weiss constants being C = 1.60 emu Oe−1 K and θ = -50 K.

Construction of Adaptive Deformation Block: Rational Molecular Editing of the N-Rich Host Molecule to Remove Water from the Energetic Hydrogen-Bonded Organic Frameworks.

Energetic hydrogen-bonded organic frameworks (E-HOFs), as a type of energetic material, spark fresh vitality to the creation of high energy density materials (HEDMs). However, E-HOFs containing cations and anions face challenges such as reduced energy density due to the inclusion of crystal water. In this work, the modification of amino groups in N-rich organic units could form a smart building block of hydrogen-bonded frameworks capable of changing the volume of the void space in the molecule through adaptive deformation of E-MOF blocks, thus enabling the replacement of water. Based on the above strategy, we report an interesting example of a series of hydrogen-bonded organic frameworks (E-HOF 2a and 3a) synthesized using a facile method. The crystal structure data of all of the compounds were also obtained in this work. Anhydrous 2a and 3a exhibit higher density, good thermal stability, and low mechanical sensitivity. The strategy of covalent bond modification for the host molecules of energetic frameworks shows enormous potential in eliminating the crystalline H2O of hydration and exploring high energy density materials.

Influences of Recycled Polyethylene Terephthalate Microplastic on the Hygrothermal and Mechanical Performance of Plasterboard with Polymethylhydrosiloxane Content.

New composites produced with recycled waste are needed to manufacture more sustainable construction materials. This paper aimed to analyze the hygrothermal and mechanical performance of plasterboard with a polymethylhydrosiloxane (PMHS) content, incorporating recycled PET microplastic waste and varying factors such as PMHS dose, homogenization time, and drying temperature after setting. A cube-centered experimental design matrix was performed. The crystal morphology, porosity, fluidity, water absorption, flexural strength, and thermal conductivity of plasterboards were measured. The results showed that incorporating recycled PET microplastics does not produce a significant difference in the absorption and flexural strength of plasterboards. However, the addition of recycled PET reduced the thermal conductivity of plasterboards by around 10%.

WO3 nanostructures produced from tungsten welding electrode scraps: Temperature influence on optical and morphological characteristics

Methods to produce WO3 nanostructures have become important due to the possibility of using this material in a wide range of technological applications. In this context, a hydrated WO3.2H2O structure was produced by the electrochemical dissolution of welding electrode scraps in an alkali aqueous solution, followed by acid precipitation. The thermal treatment of this precursor structure at 550, 700, 850, and 1000 °C was able to produce γ phase WO3 materials with a monoclinic crystalline structure at all the temperatures used, as demonstrated by XRD and RAMAN characterization. However, different treatment temperatures can yield materials with diverse morphologies and optoelectronic properties. For example, the material produced at 1000 °C presented an elongated nanorod shape, with dimensions, from the base, ranging between 50 and 500 nm, a length of about 4 μm, and the lowest Eg value. The spectroscopic characterization also demonstrated that above 700 °C, the thermal treatment could eliminate the crystallization water and create oxygen vacancies, mainly at 850 and 1000 °C; explaining the decrease in the Eg values with increased temperature. As proof of concept, photocatalytic degradation of the Reactive Black 5 dye demonstrated that the material produced at 1000 °C was able to discolor ca. 50% of the initial color. Broad DFT analyses were performed, carefully describing the surface properties and the influence of morphology on the material properties. Therefore, we demonstrated that a simple, fast and low-cost two-step process was successfully developed aiming at a noble reuse of residues of this important material.

Insight into the Structure and Redox Chemistry of [Carbonatotetraamminecobalt(III)] Permanganate and Its Monohydrate as Co-Mn-Oxide Catalyst Precursors of the Fischer-Tropsch Synthesis

[Carbonatotetraamminecobalt(III)] permanganate monohydrate was synthesized first in the metathesis reaction of [Co(NH3)4CO3]NO3 and NaMnO4 in aqueous solution. Its thermal dehydration at 100 °C resulted in phase-pure [Co(NH3)4CO3]MnO4 (compound 1). Compounds 1 and 2 (i.e., the hydrated form) were studied with IR, far-IR, and low-temperature Raman spectroscopies, and their vibrational modes were assigned. The lattice parameters were determined by powder X-ray diffraction (PXRD) and single crystal X-ray diffraction (SXRD) methods for the triclinic and orthorhombic compounds 1 and 2, respectively. The detailed structure of compound 2 was determined, and the role of hydrogen bonds in the structural motifs was clarified. UV studies on compounds 1 and 2 showed the distortion of the octahedral geometry of the complex cation during dehydration because of the partial loss of the hydrogen bonds between the crystal water and the ligands of the complex cation. The thermal decomposition consists of a solid phase quasi-intramolecular redox reaction between the ammonia ligands and permanganate anions with the formation of ammonia oxidation products (H2O, NO, N2O, and CO2). The solid phase reaction product is amorphous cobalt manganese oxide containing ammonium, carbonate (and nitrate) anions. The temperature-controlled thermal decomposition of compound 2 in toluene at 110 °C showed that one of the decomposition intermediates is ammonium nitrate. The decomposition intermediates are transformed into Co1.5Mn1.5O4 spinel with MnCo2O4 structure upon further heating. Solid compound 2 gave the spinel at 500 °C both in an inert and air atmosphere, whereas the sample pre-treated in toluene at 110 °C without and with the removal of ammonium nitrate by aqueous washing, gave the spinel already at 300 and 400 °C, respectively. The molten NH4NO3 is a medium to start spinel crystallization, but its decomposition stops further crystal growth of the spinel phase. By this procedure, the particle size of the spinel product as low as ~4.0 nm could be achieved for the treatments at 300 and 400 °C, and it increased only to 5.7 nm at 500 °C. The nano-sized mixed cobalt manganese oxides are potential candidates as Fischer-Tropsch catalysts.

Statistical thermodynamics to assess probability of water channel formation in membrane

In this work, the probability of water channel formation was calculated for several polymeric materials, and with that information, the desalination capacity of each material was assessed. Using a 3D lattice model for a flat sheet, the Gibbs free energy change (ΔG) that results from the formation of the first water channel from the top to the bottom surface of the sheet was calculated as a function of the hydrophilicity/-phobicity of the polymeric material (w), the total fraction of water in the 3D lattice (x), and the thickness of the lattice (n). With this result, an equation was further derived to evaluate (xb) the fraction of water which is related to the channel formation, and (xb/x), the ratio of xb to x. It was found that the values of xb are closely related to the fractional free volume (FFV) measured by positron annihilation lifetime spectroscopy (PALS) and the percent free volume of percolated open spaces where water could pass through obtained by molecular dynamics simulation (MDS).These equations were then used to assess the usefulness of each material for making reverse osmosis membranes. When xb is too large, too many channels form, and those channels join to form large pores through which salt can pass, rendering reverse osmosis unsuccessful. On the other hand, when xb is too small, not enough water channels are formed, so reverse osmosis cannot occur then either. It was found that xb was too small for polyvinylidene fluoride (PVDF) and polyethersulfone (PES); suitable for cellulose acetate (CA), aromatic polyamide (APA) and aromatic polyamidehydrazide (APAH); and too large for cellophane (CE). This paper determines which circumstances allow water to form channels in a membrane, and it provides a novel method to assess a material's suitability for reverse osmosis.

Thermal-Induced Microstructure Deterioration of Egyptian Granodiorite and Associated Physico-Mechanical Responses.

Mineral transformations often induce microstructural deteriorations during temperature variations. Hence, it is crucial to understand why and how this microstructure weakens due to mineral alteration with temperature and the correlated physical and mechanical responses. Therefore, in this study, physical, chemical, thermal, petrographic, and mechanical analyses were carried out to comprehend better the thermal behaviors of Egyptian granodiorite exposed to temperatures as high as 800 °C. The experimental results indicate that the examined attributes change in three distinct temperature phases. Strength zone (up to 200 °C): During this phase, the temperature only slightly impacts the granodiorite mass loss and porosity, and the P-wave velocity and E slightly decrease. However, the rock structure was densified, which resulted in a minor increase in strength. After that, the transition zone (200-400 °C) was distinguished by the stability of most studied parameters. For instance, mass and porosity did not significantly alter, and the uniaxial compressive strength steadily increased with an axial failure mode. When the temperature rises, transgranular cracks cause the P-wave velocity and elastic modulus to decrease moderately. The decay zone started after 400 °C and continued to 800 °C. This zone is characterized by complicated factors that worsen the granodiorite properties, lead to color shift, and produce a shear failure mode. The properties of granodiorite became worse because of chemical reactions, structural and crystal water evaporation, rising thermal expansion coefficient variation, and quartz inversion at 575 °C (α to β, according to the differential thermal analysis). Thermal damage greatly affected granodiorite's physical and mechanical properties and microstructure at 800 °C. As a result, UCS measurements were extremely small with a complex failure pattern, making Vp and E unattainable.

Comprehensive study of O2 and H2O interaction with La0.9Sr0.1ScO3–δ oxide

In this paper we study the processes of O2 and H2O interaction with La0.9Sr0.1ScO3−δ. Using high temperature neutron powder diffraction (HT-NPD), the evolution of crystal structure and water uptake was investigated in the temperature range 25–700 °C at 21.3 kPa in O2 and O2 + D2O atmospheres. The results of HT-NPD show the influence of the water uptake by La0.9Sr0.1ScO3–δ bulk on the thermal expansion of the material. The kinetics of oxygen surface exchange was studied using pulsed isotope exchange technique. The measurements were carried out in the temperature range 300−900 °C at pO2 = 5.1, 12.2 and 21.3 kPa in dry and humid (pH2O = 2.6 kPa) conditions. For the first time the physical model describing the kinetics of oxygen surface exchange between the mixture of oxygen and water in the gas phase and a solid oxide has been suggested. The model includes following steps: oxygen dissociative adsorption, oxygen incorporation, hydrogen surface diffusion, water adsorption and dissociation. The rate-determining step of the exchange is considered. The influence of O2 humidification on the oxygen surface exchange is discussed.