Outgassing Temperature Research Articles

Additively Manufactured Ceramics for Compact Quantum Technologies

AbstractQuantum technologies are advancing from fundamental research in specialized laboratories to practical applications in the field, driving the demand for robust, scalable, and reproducible system integration techniques. Ceramic components can be pivotal thanks to high stiffness, low thermal expansion, and excellent dimensional stability under thermal stress. Lithography‐based additive manufacturing of technical ceramics is explored, especially for miniaturized physics packages and electro‐optical systems. This approach enables functional systems with precisely manufactured, intricate structures, and high mechanical stability while minimizing size and weight. It facilitates rapid prototyping, simplifies fabrication and leads to highly integrated, reliable devices. As an electrical insulator with low outgassing and high temperature stability, printed technical ceramics such as and AlN bridge a technology gap in quantum technology and offer advantages over other printable materials. This potential is demonstrated with CerAMRef, a micro‐integrated rubidium D2 line optical frequency reference on a printed micro‐optical bench and housing. The frequency instability of the reference is comparable to laboratory setups while the volume of the integrated spectroscopy setup is only . Potential for future applications is identified in compact atomic magnetometers, miniaturized optical atom traps, and vacuum system integration.

On the Low-Pressure Hysteresis (LPH) in Gas Sorption Isotherms of Porous Carbons.

This study investigates the origin of low-pressure hysteresis (LPH) in the adsorption and desorption of three different probe molecules: carbon dioxide, nitrogen, and argon, across various adsorption temperatures (from cryogenic to room temperature), and within five different carbon materials: synthetic carbons (pristine and one post-synthetically oxidized) and natural coal. Significant attention is dedicated to elucidating LPH in oxidized samples outgassed at various temperatures (120-350°C). Experimental results show that insufficient outgassing temperature can lead to unreliable data due to artificial LPH and significantly underestimated textural properties, primarily caused by porosity blockage from substances like moisture. Conversely, in samples where heteroatoms have a stabilizing effect on texture, such as natural coal, careful consideration of outgassing temperature is crucial due to the risk of thermal degradation. Other factors contributing to LPH are adsorption temperature, and especially, kinetic limitations at cryogenic temperatures for cellulose-based carbons. Minor factors responsible for LPH are the physical state of the sample (monolith vs powder) and the flexibility of the porous system, both studied by carbon dioxide sorption. This study constitutes an important piece in the evaluation of LPH, providing practical recommendations and underlining the importance of experimental design, with implications for further research in this complex field.

Effect of the heating rate on the degassing and combustion of cylindrical Li-Ion cells

The thermal runaway (TR) of 18650 Li-ion cells under constant heating rate is investigated in a cone calorimeter. The effect of the heating rate was observed on the outgassing and cell casing temperatures, as well as on the thermal power of the flames produced and resulting smoke characteristics. Time-resolved analysis of outgassing composition based on four main gases was carried out using mass spectrometry and the size distribution of the particulate emission was measured with aerosol spectrometers. The results revealed that the heating rate had an impact on the course of TR events, with high heating rates resulting in more violent TR. The initial temperature of the first venting also increased with higher heating rates. Mass spectrometry measurements revealed that the first venting mainly released vaporized electrolyte (dimethyl carbonate, DMC) with a small quantity of CO2. During the combustion associated with the major venting event, the gases released were mainly CO2 and H2O, with small quantities of H2 and DMC, and sporadic detection of C3H6 and C6H6. The high-resolution size distributions obtained for the particulate emission showed a bimodal distribution, characteristic of very rich diffusion flames, but no significant effect of the heating rate.

Development of a simple setup for temperature dependent mass spectrometric measurements for the investigation of outgassing effects in polymeric materials for solar application

A simple experimental setup for temperature dependent mass spectrometric measurements has been constructed. It consists of a heated sample chamber and a mass spectrometer and allows for measurements under inert gas and ambient air. Based on initial measurements on two extruded polystyrene (XPS) samples a methodology for the data analysis has been developed. With this methodology the outgassing temperature of volatile compounds, which were used as blowing agents, has been identified. Furthermore, the composition of the blowing agents has been analyzed by temperature dependent mass spectra. The results indicate the use of ambient air in one material and a mixture of the banned blowing agents R142b and R22, both hydrochlorofluorocarbons (HCFC), in the other material. The here described methodology provides an easy to use approach to identify such compounds, for example as part of environmental or quality control.

The importance of outgassing conditions when using water vapour to characterize activated carbons

The singular mechanism of water adsorption in carbon pores has been roughly elucidated due to the intense research conducted in this field in the last years. Thus, it has been demonstrated that the surface chemistry of the carbon material plays a crucial role in the initialization of the water sorption process. However, the potential changes induced in the surface properties, and therefore in the water isotherm, during the outgassing of the sample prior to the water sorption measurement, have not been addressed yet. On the contrary, the same preparation protocol used for the analysis of non-associating simple fluids (N2, CO2, Ar) is commonly followed. Aiming at filling this gap, two activated carbons with different textural and surface properties have been outgassed under different conditions of time and temperature and subsequently characterized by H2O, N2 and CO2 isotherms and thermogravimetric analysis. The obtained results show that the optimal conditions of the outgassing treatment are not necessarily the same for all the adsorbates tested and will highly depend on the characteristics of the sample. In this regard, the recommended outgassing temperature for water sorption isotherms of nanoporous carbons seems to be lower than for other adsorbates and may not exceed 100 °C.

The Effect of Pulsed Current and Organic Additives on Hydrogen Incorporation in Electroformed Copper Used in Ultrahigh Vacuum Applications

The presence of hydrogen in electroformed copper from two different acidic copper sulfate solutions was evaluated: an additive-free solution and a solution including a sugar. D-xylose addition is found to inhibit H incorporation and allows the use of higher cathodic pulses before the copper diffusion limited range starts. TDS experiments show that hydrogen is trapped in the copper samples in two different forms. Hydrogen diffused from copper vacancies was found on all samples at an outgassing temperature of around 450°C. For samples with long pulse times, an additional H2 outgassing peak was found at around 600°C. XRD measurements allowed us to determine the preferential orientation of the plated samples and to monitor lattice parameter evolution with increasing temperature.

The Effect of Pulsed Current and Organic Additives on the Hydrogen Incorporation in Electroformed Copper Used in High Vacuum Applications

The presence and influence of hydrogen on electroformed copper from two different acidic copper sulfate solutions was evaluated: an additive-free solution and a solution including a sugar. D-xylose addition is found to inhibit the H2 formation and allows using higher cathodic pulses before the starting of the copper diffusion limited range. TDS experiments show the release of hydrogen trapped into the copper under two different forms. Hydrogen diffused from copper vacancies was found on all samples at an outgassing temperature around 450°C. For samples with long pulse times, an additional H2 outgassing peak was found around 600°C. XRD measurements allowed us to determine the preferential orientation of the plated samples and to monitor the lattice parameter evolution with increasing temperature.

Methane and CO2 Adsorption Capacities of Kerogen in the Eagle Ford Shale from Molecular Simulation.

Over the past decade, the United States has become a world leader in natural gas production, thanks in part to a large-fold increase in recovery from unconventional resources, i.e., shale rock and tight oil reservoirs. In an attempt to help mitigate climate change, these depleted formations are being considered for their long-term CO2 storage potential. Because of the variability in mineral and structural composition from one formation to the next (even within the same region), it is imperative to understand the adsorption behavior of CH4 and CO2 in the context of specific conditions and pore surface chemistry, i.e., relative total organic content (TOC), clay, and surface functionality. This study examines two Eagle Ford shale samples, both recovered from shale that was extracted at depths of approximately 3800 m and having low clay content (i.e., less than 5%) and similar mineral compositions but distinct TOCs (i.e., 2% and 5%, respectively). Experimentally validated models of kerogen were used to the estimate CH4 and CO2 adsorption capacities. The pore size distributions modeled were derived from low-pressure adsorption isotherm data using CO2 and N2 as probe gases for micropores and mesopores, respectively. Given the presence of water in these natural systems, the role of surface chemistry on modeled kerogen pore surfaces was investigated. Several functional groups associated with surface-dissociated water were considered. Pressure conditions from 10 to 50 bar were investigated using grand canonical Monte Carlo simulations along with typical outgassing temperatures used in many shale characterization and adsorption studies (i.e., 60 and 250 °C). Both CO2 and N2 were used as probe gases to determine the total pore volume available for gas adsorption spanning pore diameters ranging from 0.3 to 30 nm. The impacts of surface chemistry, outgassing temperature, and the inclusion of nanopores with diameters of less than 1.5 nm were determined for applications of CH4 and CO2 storage from samples of the gas-producing region of the Eagle Ford Shale. At 50 bar and temperatures of 60 and 250 °C, CH4 adsorption increased across all surface chemistries considered by 60% and 2-fold, respectively. In the case of CO2, the surface chemistry played a role at both 10 and 50 bar. For instance, at temperatures of 60 and 250 °C, CO2 adsorption increased across all surface chemistries by 6-fold and just over 2-fold, respectively. It was also found that at both 10 and 50 bar, if too low an outgassing temperature is used, this may lead to a 2-fold underestimation of gas in place. Finally, neglecting to include pores with diameters of less than 1.5 nm has the potential to underestimate pore volume by up to 28%. Taking into consideration these aspects of kerogen and shale characterization in general will lead to improvements in estimating the CH4 and CO2 storage potential of gas shales.

How accessible is the specific surface area of minerals? A comparative study with Al-containing minerals as model substances

The specific surface area (SSA) is a principal characteristic for the assessment of the sorption capacity of minerals. In addition to size, the accessibility of the surface area is of importance, which is primarily affected by porosity. In particular the micropore surface area of soil minerals may be inaccessible due to too small pore entrances or their clogging by organic material. In this study, SSA and micropore surface area of three minerals (Al oxide, Al hydroxide and kaolinite), acting as model materials for oxides, hydroxides and clay minerals, respectively, were measured by gas adsorption methods with both N2 at 77.35K or CO2 at 273.15K and the retention of the polar liquid ethylene glycol monoethyl ether (EGME). Moreover, porosity was assessed by 129Xe nuclear magnetic resonance (NMR) spectroscopy. A NaY zeolite was used as microporous reference material. 129Xe NMR spectroscopy and the determination of SSA by physisorption of N2 (BET-N2 SSA) were performed after sample pretreatment at various outgassing temperatures because BET-N2 SSA and porosity are significantly affected by the outgassing temperature due to the loss of adsorbed water molecules. For all minerals investigated, the highest SSA was obtained by EGME retention. The gas adsorption methods exhibited differences in SSA and micropore surface area depending on the gas and pretreatment temperature. Thereby, increased pretreatment temperatures resulted in increased SSA and micropore surface area. 129Xe NMR spectra revealed that this increase in surface area was mainly ascribed to an increase in porosity. It appeared that the accessibility of surface area was limited by surface hydration. This implies that at environmental conditions, partly saturated pores will yield a reduced sorption capacity compared to the one that may be expected from SSA measurements. Consequently, porosity and hydration of the mineral surfaces have to be considered for an improved assessment of the sorption capacity of minerals and soils.

Pillared montmorillontes from unusual antiperspirant aqueous solutions: Characterization and catalytic tests

Pillared clays (PILCs) based on montmorillonite clay were obtained using antiperspirant solution with different mmol of aluminum/g clay ratios at 80°C or at room temperature. The physico-chemical characterization of the intercalated clays and their pillared counterparts were performed by the following techniques: XRD, TGA/DTA, solid magic angle NMR, elemental analysis and nitrogen adsorption. The acidity of the pillared clays was estimated by the desorption of cyclohexylamaine and FTIR of pyridine desorption. The pillaring led to changes in the basal spacing of montmorillonite and stabilization of the smectite structure at higher temperature about 700°C. The total and micropore surface areas were improved with a creation of mesopores. The intercalated aluminum species were easily exchanged with decylamine, which was not the case of the aluminum oxide in the pillared clays after calciantion. The acidity of the pillared clays depended on the aluminum contents and to the outgassing temperatures, with strong Bronsted and Lewis acid sites up to 300°C. These acid sites played an important role in the hydro-isomerization of n-heptane.

<i>In Situ</i> Fabrication of Particles Reinforced Al-Si-Al<sub>2</sub>O<sub>3</sub> Composites by Hot Isostatic Pressing

Particles reinforced Al-xwt.%Si-Al2O3 (x=10,20) composites are fabricated through in situ reaction sintering of Al and SiO2 powder by hot isostatic pressing. Outgassing process and the microstructure of composites under different sintering processes are studied.XRD analysis confirms that the best hot outgassing temperature is 500°C,in situ reaction achieves completely and samples A2 and B2 have better microstructure at 550°C then heating-up to 700°C only for 1h.The microstructure analysis indicates that the reinforcement particulates distribute uniformly in the aluminum matrix.The mechanical properties test results show that the tensile strength of A2 is higher than B2. when x=10,the Al-Si-Al2O3 composites have better performance.

FTIR studies of adsorption and photocatalytic decomposition under UV irradiation of dimethyl sulfide on calcium hydroxyapatite

The adsorption and photocatalytic decomposition under UV irradiation of dimethyl sulfide ((CH 3) 2S: DMS) on synthetic colloidal calcium hydroxyapatite (Ca 10(PO 4) 6(OH) 2: Hap) particles were examined by in vacuo IR measurements. The adsorption isotherms of DMS on Hap exhibited the Langmuir type. The saturated adsorbed amount of DMS was increased with increasing the outgassing temperature of Hap, showing a maximum of 2.4 molecules/nm 2 at 250 °C. Similar tendency could be observed for change in area intensity of surface P-OH bands of Hap estimated from in vacuo IR measurements against outgassing temperature. By adsorption of DMS, the surface P-OH bands of Hap weakened while the CH bands due to DMS appeared. These results revealed that the DMS was adsorbed on surface P-OH groups of Hap. When the UV light was irradiated to the DMS-adsorbed Hap, the surface P-OH bands revived and the CH bands weakened. This fact strongly indicated the photocatalytic decomposition of DMS took place on surface P-OH groups of Hap, which was thought to be due to the formation of surface P-OH radicals by UV irradiation.

Effect of outgassing temperature on the performance of porous materials

This work illustrates the consequences of an inadequate outgassing temperature of porous materials of different nature (zeolites and activated carbons) on their performance on gas storage and wastewater remediation. Outgassing at low temperature in thermally stable materials leads to an incomplete cleaning of the porous surface; as a result, the gas storage ability based on adsorption isotherms is underestimated. In contrast, outgassing at elevated temperature in temperature-sensitive materials provokes irreversible changes in their composition and structure, which also affects strongly their stability and performance. Two examples illustrating wrong interpretation data on CO 2 capture on zeolites and wastewater treatment using activated carbons are addressed. The results show how the performance of a given material can be significantly modified or misunderstood after the outgassing pretreatment.

Influence of thermal treatment on the structure and adsorption properties of layered zinc hydroxychloride

Layered zinc hydroxychloride (Zn 5(OH) 8Cl 2·H 2O) synthesized by hydrolyzing the ZnO particles in aqueous ZnCl 2 solutions at 100 °C for 48 h was outgassed at different temperatures ranging from 100 to 250 °C for 2 h and the structure and adsorption properties of the products were examined by various means. Outgassing at 100–150 °C eliminated the H 2O molecules in interlayer of zinc hydroxychloride. The layered structure of zinc hydroxychloride was disintegrated at 175 °C by breaking the OH⋯Cl hydrogen-bond in interlayer to form curled thin films composed of poorly crystallized β-Zn(OH)Cl and ZnO, leading to the increment of the specific surface area from 4 to 39 m 2/g. The β-Zn(OH)Cl was decomposed at 225 °C to form ZnO. The crystallinity of ZnO was increased on elevating the outgassing temperature, giving rise to the UV absorption property. The H 2O and CO 2 adsorption measurements revealed that the zinc hydroxychloride outgassed at 100–150 °C possessed a high H 2O and CO 2 adsorption selectivity, and the selectivity diminished by the formation of thin films of ZnO above 175 °C.

Innovative Molecular Bonding in Newly Developed Elastomer Materials Enhances Outgassing, Permeability and High Temperature Performance

not Available.

Influence of heating and drying history on micropores in dry wood

To investigate the influence of heating and drying history on the microstructure of dry wood, in addition to the dynamic viscoelastic properties, CO2 adsorption onto dry wood at ice.water temperature (273 K) was measured, and the micropore size distribution was obtained using the Horvath-Kawazoe (HK) method. Micropores smaller than 0.6 nm exist in the microstructures of dry wood, and they decreased with elevating out-gassing temperature and increased again after rewetting and drying. Dry wood subjected to higher temperatures showed larger dynamic elastic modulus (E′) and smaller loss modulus (E″). This is interpreted as the result of the modification at higher temperature of the instability caused by drying. Drying history influenced the number of micropores smaller than 0.6 nm in dry wood not subjected to high temperature, although the difference in the number of micropores resulting from the drying history decreased with increasing out-gassing temperature. A larger number of micropores smaller than 0.6 nm exist in the microstructure of dry wood in more unstable states, corresponding to smaller E′ and larger E″ than in the stable state. Consequently, unstable states are considered to result from the existence of temporary micropores in the microstructures of dry wood, probably in lignin.

An EPR study of physi- and chemisorption of NO on MgO: Effect of outgassing temperature and nature of surface sites

The interaction of NO molecules with the surface of MgO has been studied by EPR as a function of outgassing temperature. Two different types of paramagnetic species are identified by EPR: physisorbed NO and chemisorbed NO22−. They are formed upon specific adsorption of NO on Lewis acidic Mg2+ and basic O2− sites, respectively. The concentration of NO and NO22− radicals depends on the outgassing temperature of MgO reaching a maximum at 1073K. FT-IR measurements suggest that sites liberated upon thermal outgassing by removal of OH and carbonate groups adsorbed on MgO play a significant role in the increase of the concentrations of NO and NO22− radicals. The latter are possibly formed on low coordinated oxide ions close to cationic vacancies or O4C2− of monoatomic step and O3C2− from kinks and divacancies.

Surface Structure, Hydration, and Cationic Sites of Nanohydroxyapatite: UHR-TEM, IR, and Microgravimetric Studies

A multi-technique study devoted to investigate the surface features of nanosized hydroxyapatite (HA) was carried out. UHR-TEM observation provided evidence that HA nanoparticles are constituted by a crystalline core, elongated in the direction of the crystallographic c-axis, coated by an amorphous layer 1−2 nm thick. By means of IR spectroscopy and microgravimetry, the amount of water and hydroxy groups on the surface was evaluated. For the as-prepared material, it was found that the first hydration layer is mainly constituted by H2O molecules interacting through a coordinative bond with Ca2+ in a 1:1 ratio, while hydroxy groups account only for ca. 20% of surface hydration species. Outgassing at increasing temperatures up to 300 °C resulted in a complete surface dehydration, accompanied by a decrease of the capability to readsorb water. Possible changes of the local structure of surface Ca2+ ions were probed by IR spectra of adsorbed CO. The combination of these data with rehydration tests suggested that a significant part of surface Ca2+ ions, once dehydrated, can undergo a relaxation inward the surface, progressively more irreversible as the outgassing temperature increases.

Specific Surface Area of Barrier Mixtures at Various Outgas Temperatures

Specific surface area (SSA) values for Fe–smectite alone and mixtures comprising varying proportions of glacial till were determined by nitrogen-adsorption Brunauer–Emmett–Teller analysis under different outgassing temperatures. Additionally, the extent to which the SSA of a mixture was related to the SSA of its components was investigated. A theoretical value for mixture SSA can be computed by summing the products of component SSA and the corresponding weight fraction. This theoretical estimate may not always yield the same value as measured because of a variety of physical and chemical interactions that can lead to either aggregation or dispersion of the constituent matrix. The results are explained in terms of these interactions and within the context of SSA relevance to barrier performance. For mixtures comprising 90% glacial till and 10% Fe–smectite, measured specific surface areas were consistently higher than predicted values for outgassing temperatures beyond 100°C, with a maximum departure of 4 m...

二硫化モリブデン結晶中への水素拡散の観察

Permeation of hydrogen into the molybdenum disulfide crystal (MoS2) in the hydrogen atmosphere is investigated from a view point of gas release by cleavage. MoS2 crystals are exposed to H2 or D2 gas at temperatures between RT and 600°C, followed by the cleavage at the same temperatures after evacuation of H2 or D2 gas. The dependence of amount of outgassing on the exposed temperature shows similar tendency in H2 and D2 except maximum outgassing temperature. The concentration of hydrogen in the bulk increases at the temperature of 400 or 500°C due to permeation from the surface to the bulk. Beyond the temperatures the concentration in the bulk decreases due to thermal desorption. Regardless of the exposure to D2 gas, many D atoms are detected. The concentration of dissociated hydrogen atoms in MoS2 depends on the exposure temperatures.