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The solubilities of the rare earth chlorides REECl3, where REE = (La, Nd, Er), were measured in HCl bearing water vapor from 350 to 425 °C with water partial pressures ranging from 8 to 170 bar. Solubility data were fit to the Pitzer-Pabalan quasi-chemical model in order to extract thermodynamic parameters for the formation of the gaseous REE-chloride-water clusters REECl3(H2O)n. The data show that the solubility of the REE chlorides are orders of magnitude higher than salts such as NaCl or CuCl at low water fugacities, despite their sublimation energies being substantially higher. This enhanced solubility is likely due to the high enthalpy associated with binding a single water molecule to form the species REECl3(H2O), with derived enthalpies ranging from −378 to −465 kJ/mol. Addition of further water molecules to form higher order clusters (n > 1) involves enthalpy changes of ~−20 kJ/mol, and are in effect thermodynamically suppressed over the temperature range 350–425 °C. Despite the enhanced solubility of small REECl3 water clusters, simulations of boiling processes demonstrate that the REE show highly conservative behavior, partitioning strongly into the dense aqueous phase. Not surprisingly, the presence of phosphates in the system makes this effect even more pronounced, completely immobilizing the REE. This would reduce transport in both the vapor and aqueous phase to negligible levels. However, we suggest that vapor phase transport of the REE may play a significant role in systems having a relatively low partial pressure of water (below the saturation point), where the relatively high stability of the first hydrated REE chloride clusters (REECl3(H2O) and REECl3(H2O)2) will give a preference for gas transport of the REE relative to other elements. This can likely happen in systems involving a gas/melt exchange in fumarolic exhalations, where water vapor discharges at relatively low (close to atmospheric) pressures.

The lunar surface is a typical vacuum environment, and its harsh heat rejection conditions bring great challenges to the thermal control technology of the exploration mission. In addition to the radiator, the sublimator is recommended as one of the promising options for heat rejection. The sublimator makes use of water to freeze and sublimate in a porous medium, rejecting heat to the vacuum environment. The complex heat and mass transfer process involves many physical phenomena such as the freezing and sublimation phase change of water in the porous medium and the movement of the phase-change interface. In this paper, the visualized ground-based experimental approaches of space sublimation cooling were presented to reveal the moving law of three-phase point and the growth phenomenon of ice-peak and icicle in microchannels under vacuum conditions. The visualized experiments and results prove that the freezing ice is divided into the porous ice-peak and the transparent icicle. As the sublimation progresses, the phase-change interface moves downward steadily, the length of the ice-peak increases, but the icicle decreases. The visualized experiments of space sublimation cooling in the capillary have guiding significance to reveal the sublimation cooling mechanism of water in the sublimator for lunar exploration missions.

The evolutions of the phase composition, microstructure, and thermoelectric properties of BaFe4Sb12 materials at 773 K in vacuum were investigated to evaluate their long-term thermal stabilities. It was observed that the interior of the BaFe4Sb12 exhibited excellent thermal stability, while the surface decomposed into FeSb2, Sb, and Ba5Sb3. However, the decomposition rate sharply declined with increasing annealing time, and the thicknesses of the decomposition layer was approximately 49 μm after annealing for 30 days. Thermoelectric performances negligibly changed during the annealing process, and the dimensionless figure of merit remained in the range of 0.61 ± 0.02 at 800 K. The unique decomposition layer, wherein Ba5Sb3 compounds enriched in the outermost layer and along the FeSb2 grain boundaries, served as a dense protective cover to effectively retard the Sb sublimation, resulting in excellent long-term thermal stability. This work provides a plausible explanation for the long-term thermal stability of Fe4Sb12-based filled skutterudites.

A novel indirect solar receiver/volatile extractor concept was considered for thermally extracting H2O(s) from lunar regolith in the permanently shadowed regions on the Moon. The modeled indirect solar receiver/H2O(s) extractor consisted of a rigid, highly conductive chamber that was partially embedded in the lunar surface. Solar selective and non-selective absorbers were examined to efficiently capture concentrated solar irradiation and effectively transfer heat to icy regolith to drive H2O sublimation. A detailed heat and mass transfer model was developed in ANSYS Fluent to assess the feasibility of thermal extraction from permanently shadowed regions near the lunar poles with 5 wt% of H2O(s). The maximum H2O(v) collected after 10 terrestrial h of simulation time was 2789 g for the solar selective coated receiver and 1035 g for the non-selective receiver. The addition of a solar selective coating was observed to significantly enhance H2O(s) thermal extraction. The low lunar regolith thermal conductivity was shown as the major bottleneck for thermal extraction.

Antimony selenide (Sb2Se3) is a promising light absorber material for solar cells because of its superior photovoltaic properties. However, the current performance of the Sb2Se3 solar cell is much lower than its theoretical value (∼32%) due to its low open-circuit voltage (VOC). In this paper, we have demonstrated inorganic vanadium oxides (VOx) as a hole transport layer (HTL) for Sb2Se3 solar cells to enhance efficiency through the VOC improvement. Here, a solution-processed VOx through the decomposition of the triisopropoxyvanadium (V) oxide is deposited on the Sb2Se3 absorber layer prepared by close-spaced sublimation (CSS). With VOx HTL, the built-in voltage (Vbi) is significantly increased, leading to improved VOC for the Sb2Se3 solar cell devices. As a result, the efficiency of the device increases from an average efficiency of 5.5% to 6.3% with the VOx.

Black phosphorus (BP) is an emerging two-dimensional semiconductor material, which has interesting structural features and broad application prospects in the fields of optoelectronic devices, energy storage, and biomedicine. However, a large amount of evidence is still needed to clarify the potential mechanism for the synthesis of high-quality BP crystals in chemical vapor transport (CVT) reactions. In this work, High-purity BP crystal was synthesized by CVT method in amorphous Red Phosphorus (aRP), Sn and I2 system. We found that the synthesis of BP experienced three stages of structural transformation of aRP-P4-Hittorf’s Phosphorus (HP)-BP. First, the phase transition of aRP and P4 molecules was reversible in the sublimation stage; then, the P4 molecules were gradually transformed into the HP structure in the transportation and deposition stage; however, the nucleation of BP quickly inhibited the growth of HP and completed the phase transition quickly; Finally, the remaining P4 molecules were transformed into BP structure, which promoted the growth of BP crystals. This crystallization kinetics explained the nucleation mechanism during the formation of BP, and the competitive nucleation between HP and BP provided the possibility for the bottom-up preparation of BP nanobelts.

Nanodiamonds (NDs) were prepared under ambient pressure by sublimation decomposition of silicon carbide in an intermediate frequency furnace for only 8 min. The synthesis proceeded in the temperature range of 2600-2800°C without any catalyst or highly active gas components (such as H2, alkane, and halogen). The conversion began at 2600°C and produced NDs with particle sizes in the range of 1-5 nm with a uniform particle shape and excellent dispersion. The linear reaction kinetics allowed for rapid transformation to any depth with reasonable control of the temperature. The linear rate constant (Kl) for the reaction at 2800°C was 37.5 mm/h, which is 31.2 times that of the reaction at 2600°C. The SiC sublimation decomposition produced carbon atoms that filled the SiC lattice vacancies or were combined with the suspended carbon chain bonds to form sp3 carbon, while the diffusion of amorphous carbon atoms promoted nucleation and growth of diamond. High-resolution transmission electron microscopy analysis indicated that the NDs were separated from the SiC matrix by break-off due to propagation of the reaction front. This SiC sublimation decomposition method is considered simple, fast, environmentally friendly and promising for industrial-scale production.

Recent studies on supercritical nitrogen revealed clear changes in structural markers and dynamical properties when the coordination number approaches its maximum value. The line in P and T space where these changes occur is referred to as the Frenkel line. Here, we qualitatively reproduce such changes in the supercritical regime using the popular “optimized potential for liquid simulation” (OPLS) classical force field for molecular dynamics. Unfortunately, at 160 K, OPLS nitrogen predicts sublimation rather than producing a liquid phase; therefore, we developed our own force field to achieve quantitative agreement with experimental data. We confirm the asymptotic behavior of the coordination number on crossing the Frenkel line and note an associated change in the diffusion constant, consistent with the non-rigid to rigid liquid-like character of the “transition”. The simulations allow us to track the Frenkel line to subcritical temperatures and demonstrate that it terminates at the triple point. This establishes the experimentally measurable changes, which could unequivocally determine the Frenkel line in other systems.

Such paradigms of the coupled classical metastability and nonclassical criticality as the existence of a unified EOS (common for both gas and liquid phases) with its mean-field (mf), so-called Andrews-van der Waals’ critical point (CP) should be questioned to recognize the realistic stratified structure of a mesoscopic liquid phase. It exists supposedly in the wide range of temperatures located between about zero , K and up to the singular first Boyle’s point . Its opposite, also singular second Boyle’s point corresponds to the alternative origin for the crossover continuous bounds separating the specific structural strata of a mesoscopic liquid. The region of a heterogeneous l-phase spanning the whole temperature range can be termed the non-Gibbsian phase (due to its discrete cluster-like structure) without any appeals to the concept of a spinodal decomposition. The respective metastable liquid stratum is formed by three segments of supercritical , subcritical and sublimation metastable states of a formally incompressible liquid constrained by the pair of fixed extensive parameters (N,V). Its location on the CVL-diagram is restricted by the new introduced here ml-bound and by the known Zeno-line (ZL) bound. Thus, all above-mentioned strata belong to the region of soft fluid with the dominance of interparticle attraction. The remaining parts of CVL-diagram are spanned either by the real gas state-points and solid state-points (crystalline and/or amorphous) or by the region of hard fluid in the classification proposed by Ben-Amotz and Herschbach.

Some studies in recent years have shown the possibility of extending the application temperature of the natural refrigerant carbon dioxide (CO2) below its triple point. Thus, CO2 could be a potential alternative refrigerant for R-23 in ultralow-temperature (ULT) refrigeration systems. This paper introduces a special cascade system, whose lower stage can be switched between a CO2 sublimation cycle and a conventional R-23 cycle, so that both cycles can be compared directly under the same ambient conditions. The sublimation system features a unique sublimation heat exchanger, which allows the operation with an extra carrier fluid in order to improve the heat transfer and reduce the blockage by solid CO2. In this study, experiments were carried out using HFE-7500 as the carrier fluid (“wet sublimation”) as well as without the carrier fluid (“dry” sublimation). The system was able to be operated continuously in both operating mode. A refrigerating capacity of 600 W was achieved at a sublimation temperature of -79°C. The transient behavior and blocking issues of the system are discussed. The efficiency of the sublimation system during stable operations are compared with the result of the reference R-23 system. It shows that there is still large potential for improvement on the system performance of the CO2 sublimation system.

1,2-Oxazines were synthesised via a copper-catalysed aerobic acyl nitroso Diels–Alder reaction from 1,4-disubstituted 1,3-dienes and N-Boc-hydroxylamine. From this, 1,2-oxazinanes were obtained in a novel follow-up reaction path. The stability of several 1,2-oxazines and 1,2-oxazinanes towards organometallic compounds was tested to rate their operability as cyclic chiral Weinreb amide auxiliaries. 3,6-Di-tert-butyl-1,2-oxazinane gave the best results and was introduced as a chiral Weinreb amide-type auxiliary to yield chiral α-substituted ketones in a diastereomeric ratio of up to 98:2. The removal of the auxiliary can be performed with BuLi to form unsymmetrical α-chiral ketones. Thereafter, the chiral auxiliary can be re-isolated and purified by sublimation under vacuum.

The experimental data of sublimation properties is limited to important materials, encouraging the development and assessment of theoretical models. Here, such properties were evaluated from period...

Thermodynamic quantities in the coexistence of the liquid and the solid phases for Frost–Kalkwarf vapor- and sublimation-pressure equations are investigated at an isobaric process. Gibbs free energy changes in the gaseous and the liquid phases, ΔG GL, has been derived from the Frost–Kalkwarf vapor-pressure equation. Similarly, Gibbs free energy changes in the gaseous and the solid phases, ΔG GS, may be estimated by the Frost–Kalkwarf sublimation-pressure equations which are determined by data of sublimation pressures and temperatures for 24 substances. In coexistence between the liquid and the solid phases, Gibbs free energy changes in the liquid and the solid phases, ΔG LS, may be expressed as the difference of ΔG GL and ΔG GS. The melting temperatures and enthalpy changes of melting are evaluated by numerical calculations for 24 substances. The behaviors of H2O for the neighborhood at the melting and the boiling points are investigated. The Gibbs free energy indicates two polygonal lines. Entropy, volume and enthalpy jump from the solid to the liquid phase at the melting point and from the liquid to the gaseous phase at the boiling point. The heat capacity does not diverge to infinity but shows a finite discrepancy at the melting and the boiling points. This suggests that first-order phase transitions at the melting and the boiling points may occur.

Flash spark plasma sintering (FSPS) of SiC was carried out using additives (10 vol%) with different electrical conductivities: alumina (insulator), boron carbide (semiconductor), and titanium carbide metallic (conductor). The electrical conductivity of the additives plays a determinant role on the FSPS process, it controls the electrical SPS power dissipation, the development of gaseous/liquids/solid phases and time needed to complete densification. The microstructure of FSPSed SiC samples confirmed localized heating in the case of Al2O3 additive, resulting in undesired carbothermal reduction and formation of gaseous species. In the presence of TiC additive, solid state sintering led to SiC sublimation without achieving a complete densification. The presence of B4C as an additive led to a liquid phase formation, which promoted sintering contributing and the densification of the samples. The present study rationalizes the selection FSPS sintering additives based on their electrical and chemical compatibility with the SiC matrix.

Experimental data on the saturated vapor pressure and melting of dicarbonyl(hexafluoroacetylacetonato)iridium [Ir(CO)2(hfac)] were obtained. Thermodynamic characteristics of its melting and sublimation were calculated. A unified processing of p‒T dependences, the reduction of sublimation parameters to the standard temperature, and the thermodynamic modeling of the composition of condensed phases in the precursor‒gas‒ reagent system were carried out for three iridium(I) compounds: [Ir(CO)2(hfac)], [Ir(CO)2(acac)], and [Ir(cod)(hfac)] (acac– = acetylacetonate ion, cod = cyclooctadiene-1,3). The results form the basis for selection of a precursor and determination of the optimal deposition conditions for iridium(I)-based coatings.

Vapor pressures for the main component of the biodiesel – methyl oleate were measured by using the static method. For this purpose, a new setup for vapor pressure measurements in the range (0.1 to 1000) Pa and the elevated temperatures up to 450 K has been designed and tested using the reference materials benzoic acid and naphthalene. Absolute vapor pressures and sublimation (vaporization) enthalpies for the tested compounds were in a good agreement with the most reliable literature data.

The limiting temperature of an In2O3 thin film sensor is much lower than its melting point. Herein, the failure modes of In2O3 thin films at high temperatures, including sublimation and changes in composition, have been studied. The edge and surface layer sublimation rates increased dramatically at 1350 °C, indicating that it is the limiting temperature of no-protection In2O3 films. In addition, oxygen atoms will escape from In2O3 thin films at high temperatures, forming oxygen vacancies. As the main current carrier type in In2O3, the increasing number of oxygen vacancies affects the resistance of In2O3 thin film sensors. To solve these problems and promote the high temperature performance of In2O3 thin films, protection methods based on Al2O3 and ZrO2 layers have been investigated. The ZrO2 protective layer alleviated the serious considerable sublimation of In2O3 thin films at high temperatures, and the Al2O3 protective layer was beneficial for reduction the escape of oxygen atoms. Finally, different protection layers were evaluated by in-situ resistivity measurements of In2O3 thin films at high temperatures. The resistance of the In2O3 thin film resistor with a protective multilayer consisting of Al2O3 and ZrO2 remained stable at 1360 °C, verifying the protection method effectively increased the thermal stability of In2O3 thin films.

The crystal structures of number of azoles were modeled using the quantum chemical and Atom-Atom potential methods. The crystal packing was carried out by the local minimization of the crystal structure in the experimental space group, for which purpose the energy of the crystalline lattice was described by a set of van der Waals interactions in the form of the Buckingham 6-exp potential and Coulomb electrostatic interactions. The enthalpies of sublimation of the calculated and experimental crystals are satisfactorily consistent. The prediction for the compounds with earlier unknown enthalpies of sublimation was performed on the basis of the obtained data.

By combining highly resolved Scanning Tunneling Potentiometry with the exceptional sample homogeneity of graphene on SiC epitaxially grown by polymer-assisted sublimation growth, we reveal local variations in the resistance associated with substrate steps. We quantify these variations and show that they are an intrinsic property of graphene on SiC. Furthermore, we trace back their origin to variations in the electronic structure of the interface and, thereby, demonstrate the crucial impact of intrinsic proximity effects in graphene on SiC. Moreover, we find a correlation of the step resistance with the local conductivity and show that at room temperature, the step resistance decreases with increasing local conductivity, whereas at low temperatures, it increases with increasing local conductivity. We attribute this inversion to an interplay between the reduction in electron-phonon scattering and potential scattering with decreasing temperature, and the efficiency of the built-up of an almost completely charge carrier depleted zone at the position of the substrate step.

The thermal management function of high-quality graphene, which is expected to maximize in-plane thermal conductivity at cryogenic temperature, was demonstrated by cryogenic transmission electron microscopy (cryo-TEM) equipped with electron energy loss spectroscopy (EELS). Vitreous ice, observed under the cryo-TEM, suffers from electron beam irradiation, and gradually becomes thinner by sublimation. The ice thickness decreases exponentially with respect to the irradiation time of electron beam with and without graphene, according to the time series of thickness measurement by EELS. Direct contact between graphene and ice effectively dissipates the heat of the ice through graphene, which significantly suppresses the sublimation behavior. The heat dissipation by graphene is effective for thinner ice rather than thicker one. The lifespan of ice on graphene against electron beam irradiation extends to about 40%, showing substantial improvement compared to that without graphene. The graphene provides a new stream for effective thermal management in cryo-TEM analysis.

Thermogravimetry, differential scanning calorimetry, and flow methods were used to investigate thermal properties of a series of cobalt(II) β-iminoketonates [R2C(NR1)CHC(O)R2]. The consecutive order of their volatility was determined. The complexes do not decompose up to melting and do not undergo phase transitions. For the complex (R1 = Н, R2 = Me) the temperature dependence of sublimation ln (p/p0) = 32.02 ‒ 16822/T(K) at 402.6‒433.7 K was measured and the values of ΔsublH°Т* = 140±4 kJ/mol and ΔsublS°Т* = 266±10 J/(K·mol) were calculated.

The L-tryptophan sublimation was studied by high-temperature mass spectrometry in the temperature range 395–493 K. The compound evaporates congruently in the form of monomeric molecules. The saturated vapor pressure at 485 K was determined by the Knudsen effusion method. In combination with mass spectrometric data, the pressure equation ln (p, Pa) = –(19943±304)/T + (40.568±0.688) is recommended for the temperature range 395–493 K. The enthalpy of 167.5±1.6 kJ/mol for sublimation at 298.15 K was determined on the basis of the second and third laws of thermodynamics.

The enthalpies of sublimation of five substituted pyridine N-oxides were determined by the Knudsen effusion method with mass spectrometric control of the vapor composition within the framework of the second law of thermodynamics. The sublimation enthalpy of mono-substituted compounds 4-X-PyO depends on the nature of the substituent X and increases in the order CH3→NO2→OCH3. A difference is noted in the nature of dissociative ionization of disubstituted derivatives 2-CH3-4-NO2PyO and 3-CH3-4-NO2PyO. The relationship between the packing of molecules in crystals and the ΔH°subl values is considered.

A series of nondestructive assay measurements were performed before, during, and after localized heating of an industrial standard 12B cylinder of uranium hexafluoride to replicate dose variations previously observed on commercial 30B cylinders. While cylinders represent a closed system, enrichment measurements may be impacted by altered uranium and daughter product distributions due to sublimation. A series of measurements were performed to examine localized heating impacts on dose rates, ratios of uranium and daughter product distributions, and measured 235U enrichment as calculated by two different approaches. The less complex enrichment meter approaches were found to be more robust and less prone to deviation than isotope ratio approaches such as FRAM, but the impact can be minimized by using observable dose changes to avoid impacted areas.

A mononuclear complex [Fe(tBu2qsal)2] has been obtained by a reaction between an Fe(II) precursor salt and a tridentate ligand 2,4-di(tert-butyl)-6-((quinoline-8-ylimino)methyl)phenol (tBu2qsalH) in the presence of triethylamine. The complex exhibits a hysteretic spin transition at 117 K upon cooling and 129 K upon warming, as well as light-induced excited spin-state trapping at lower temperatures. Although the strongly cooperative spin transition suggests substantial intermolecular interactions, the complex is readily sublimable, as evidenced by the growth of its single crystals by sublimation at 573 → 373 K and ∼10-3 mbar. This seemingly antagonistic behavior is explained by the asymmetric coordination environment, in which the tBu substituents and quinoline moieties appear on opposite sides of the complex. As a result, the structure is partitioned in well-defined layers separated by van der Waals interactions between the tBu groups, while the efficient cooperative interactions within the layer are provided by the quinoline-based moieties. The abrupt spin transition is preserved in a 20 nm thin film prepared by sublimation, as evidenced by abrupt and hysteretic changes in the dielectric properties in the temperature range comparable to the one around which the spin transition is observed for the bulk material. The changes in the dielectric response are in excellent agreement with differences in the dielectric tensor of the low-spin and high-spin crystal structures evaluated by density functional theory calculations. The substantially higher volatility of [Fe(tBu2qsal)2], as compared to a similar complex without tBu substituents, suggests that asymmetric molecular shapes offer an efficient design strategy to achieve sublimable complexes with strongly cooperative spin transitions.

Physically-based snow models provide valuable information on snow cover evolution and are therefore key to provide water availability projections. Yet, uncertainties related to snow modelling remain large as a result of differences in the representation of snow physics and meteorological forcing. While many studies focus on evaluating these uncertainties, issues still arise, especially in environments where sublimation is the main ablation process. This study evaluates a case study in the semi-arid Andes of Chile and aims to compare two snow models with different complexities, SNOWPACK and SnowModel, at a local point, over one snow season. Their sensitivity relative i) to physical calibration for albedo and fresh snow density and ii) to forcing perturbation is evaluated based on ensemble approaches. Results indicate larger uncertainty depending on the model calibration than between the two models (even though the significant differences in their physical complexity). We also confirm the importance of albedo parameterization, even though ablation is driven by sublimation. SnowModel is particularly sensitive to this choice as it strongly affects both the sublimation and the melt rates. However, the day of snow-free snow surface is not sensitive to the parameterization as it only varies every eight days. The albedo parameterization of SNOWPACK has stronger consequences on melt at the end of the season leading to a date difference of the end of the season of 41 days. However, despite these differences, the sublimation ratio ranges are in agreement for the two models: 42.7–63.5 % for SnowModel and 51.3 and 64.6 % for SNOWPACK, and are related to the albedo calibration choice for the two models. Finally, the sensitivity of both models to the forcing data was in the same order of magnitude and highly influenced by the precipitation uncertainties.

A small-scale plasma ablation facility was employed to test the C/C-SiC composite material for investigating the thermal performance and ablation characteristics under two heat flux conditions, 3593.54 kW·m−2 and 5644.86 kW·m−2. The morphology of post-test specimens was analyzed with the ablation rates calculated. The average mass ablation rates of two group specimens were 0.01735 and 0.10620 g·s−1 respectively with average linear ablation rate of 0.00680 and 0.09407 mm·s−1. Specimen surface could be divided into three regions with typical layered structure characteristics. For the stagnation point ablation test, the structural deformation in the ablation surface area featured in vertical layering and lateral regionality, forming an ablation pit near the stagnation point. In the center region, sublimation occured primarily, accompanied by a serious jet scouring of the molten liquid phase, as well as a small amount of oxidation reaction; Jet erosion with thermal sublimation was the main factor for the mass loss in the transitional region; Thermochemical reactions were mainly carried out in the marginal region. The SiO2 generated from the thermochemical reaction of the material filled the interspace well and prevented the thermochemical reaction from penetrating deeper through the crack. The protective layer in the molten state with high viscosity reduced the damage of the high-speed jet impact material.

The performance of a superstrate TiO2/Sb2Se3 solar cell, fabricated by close-spaced sublimation technique (CSS), was improved after the deployment of a seed layer. The seed layer caused columnar Sb2Se3 film growth with texture coefficient analysis (TC) showing increased presence of crystal planes, which are inclined towards the [001] crystal direction. Given the highly anisotropic properties of Sb2Se3, preferential growth of (Sb4Se6)n ribbons along the [001] direction is best suited for effective charge collection. Hence, grain orientation of Sb2Se3 films was studied more closely via measurement of pole figures by XRD and orientation distribution maps by electron backscatter diffraction (EBSD). Although the measurements did not reveal strong preferred orientation, it was observed that the columnar Sb2Se3 growth enhanced texture along the [001] direction. Temperature-dependent admittance spectroscopy (TAS) and capacitance–voltage (CV) profiling were performed on the seed-assisted TiO2/Sb2Se3 solar cell to evaluate carrier density and deep defects in the Sb2Se3 absorber. TAS study revealed a deep defect with activation energy of 0.39 eV. CV profiles indicated that the density of defects could be as high as 1017 cm−3, which needs to be addressed by post-deposition treatments.

The high temperature thermodynamic properties of chalcogenides materials based on BaS remain elusive. Herein the pseudo binary BaS-La2S3 is investigated above 1573 K. The liquid properties of BaS-La2S3 are measured by means of high resolution in-situ visualization coupled with thermal arrest measurements in a thermal imaging furnace. This enables to report the first observation of such melts in a container-less setting. The melting points of BaS and La2S3 are revisited at 2454 K and 2004 K respectively. La2S3 demonstrates a high stability in its liquid state, in strike difference with the sublimation observed for BaS. BaS is however partially stabilized with the addition of few percents of La2S3. The remarkable chemical and thermal stability of La2S3-rich samples contrasts with the partial decomposition and high vapor pressure observed for BaS-rich samples. Observations and analysis of the solidified samples suggest three different solid solutions. Solid and liquid densities are investigated along the different compositions, supporting a first estimate of the volumetric thermal expansion coefficient for La2S3.

An analytical review on the study of structural changes in membranes is presented. Ultrafiltration films of polytetrafluoroethylene membranes in the temperature range from 30 to 500°С are investigated by thermogravimetry. An analysis of the thermal data is carried out, which indicates that in the temperature range from 100 to 215°C, the first stage of destruction occurs, where the value of the lost mass for the air-dry sample is 33%, and for the water-saturated sample, the mass loss is 10%, which is 3 times less than the first sample. For the working sample, a slow process of mass change is observed in a wide temperature range from 100 to 410°C, which with total weight loss is about 9%. The second stage of destruction occurs in the temperature range from 410 to 500°C with a loss of mass for an air-dry sample of 61 and 85% for a water-saturated sample, and the working sample loses 86% of its mass. The data on X-ray crystallography (X-ray crystallography) allow us to conclude that the effect of water and transmembrane pressure leads to a significant change in the morphology of polymer molecules at the supramolecular level. If for an air-dry sample of a polytetrafluoroethylene ultrafiltration membrane, a diffuse nature of the reflection with a maximum at 2θ = 12° is observed, then for a water-saturated sample an intense diffraction peak appears at 2θ = 17° against the background of an amorphous halo. For the working sample, the reflection has a compact structure with a sharp asymmetric peak at 2θ = 13.8°. Complementary methods of TG (thermogravimetry), DSC (differential scanning calorimetry), X-ray diffraction analysis (XRD), and gravimetry have established that conformational changes in molecules in the polytetrafluoroethylene-membrane matrix occur as a result of the detachment of side monomers or oligomers and their sublimation from the film volume under the influence of transmembrane pressure and the interaction of water molecules.

Investment Casting (IC), using the wax pattern, produces metal parts with a high surface finish and complex geometries within acceptable tolerances. However, removing the wax patterns can have processing challenges, such as thermal expansion during wax melting for pattern removal leading to shell cracking defects, the release of hydrocarbons from melting wax, and the burnt residue from this process. To overcome these challenges, it has been proposed to replace wax with ice as a pattern material. Ice has an inherent benefit of reduction of volume during its phase change from solid to liquid. It helps to reduce cracking due to expansion. Rapid Freeze Prototyping (RFP) and Freeze Cast Process (FCP) can produce the ice pattern. In the process of Rapid Ice Investment Casting (RIIC), the ice pattern is invested with a low-temperature ceramic slurry to make ceramic shells for metal casting. Sublimation is used for ice pattern evacuation at sub-zero conditions using a vacuum. Estimating various properties like time for total sublimation, concentration gradient, and energy usage are vital for process characterization and optimization. A diffusion-based mathematical model has been proposed and experimentally verified to sublimate the ice patterns in this research. Experimental results show a close correlation (96.74%) with the theoretical model. The demonstration of ice investment casting has been carried out, and it reported close dimensional accuracy.

The thermal stability of CeO2 nanomaterials can directly impact both the uniformity of the supported catalysts and the catalytic behavior of CeO2 itself. However, knowledge about the thermal stability of CeO2 is still deficient. Here, we conduct in-situ transmission electron microscopy experiments and theoretical calculations to elucidate the thermal stability of CeO2 nanomaterials under different environments. A sinter ( 700 °C) are observed within CeO2 nanoflowers under O2. The sinter firstly occurs among the nanoflowers’ monomers and then the sintered nanoparticles structurally decompose to tiny nanoparticles from the strain interface. Under a vacuum environment, the CeO2 nanoflowers firstly undergo a transition from cubic fluorite CeO2 to hexagonal Ce2O3, accompanied by the oxygen release. The Ce2O3 nanoparticles further atomically sublimate from the edges to the center under high temperatures. Theoretical calculation results reveal a considerably lower energy barrier for the structural decomposition under O2 and for the sublimation under vacuum. This work provides a perspective on the structural design and performance optimization of CeO2-based catalysts.

Theodor W. Adorno resisted Sigmund Freud’s explanation of artistic creation as the sublimation of the artist’s libidinal drives. It focuses too much on the artist rather than the work and is in the service of accommodation to the status quo. But Adorno also questioned the simple reversal of Freud’s formula, pointing out the dangers of unmediated desublimation. The artist, he suggested, should sublimate his or her rage instead. No less significant was the retrospective cultural sublimation of objects from exhausted devotional or cultic contexts, which preserved the unfulfilled yearnings originally expressed in them.

When impurities are removed from crude lead by metallic zinc, a silver foam (SF) containing lead, zinc, and silver forms on the melt surface along. Vacuum distillation can be used to separate the SF components, since it is one of the most environmentally friendly and highly efficient technologies in pyrometallurgy. Phase diagrams are used to choose the system temperature and pressure and to estimate the efficiency of the separation of the components during vacuum distillation. The aim of this work is to calculate VLE (vapor–liquid equilibrium) states, including the temperature dependence of the phase composition (T–x), at a given pressure for binary Zn–Ag alloys during vacuum distillation using MIVM (molecular interaction volume model) and SMIVM (simple molecular interaction volume model), which contains a smaller number of variable system parameters, in particular, for fixed values of coordination numbers Zi and molecular volume Vmi of the alloy components. As a result, the adequacy of SMIVM used in the calculation is confirmed. Information on the influence of the temperature and the residual pressure in the system on the sublimation and separation of the metals from Zn–Ag alloys of variable composition is obtained. The saturated vapor pressures (Pa) for zinc ( $$p_{{{\text{Zn}}}}^{*}$$ = 5.79 × 102–3.104 × 104) and silver ( $$p_{{{\text{Ag}}}}^{*}$$ = 5.25 × 10–9–5.1 × 10–5) at T = 823–1073 K are determined. The large differences between $$p_{{{\text{Zn}}}}^{*}$$ and $$p_{{{\text{Ag}}}}^{*}$$ cause high values of separation coefficient log βZn = 8.32–12.18 and imply the possibility of separation of zinc by sublimation into the gas phase (βZn > 1) and the concentration of silver in the liquid phase. An increase in the mole fraction of silver in the alloy composition from 0.1 to 0.9 and or in the system temperature from 823 to 1073 K leads to an increase in the mole fraction of silver in the gas phase from 1 × 10–15 to 8.5 × 10–7. The following thermodynamic functions are calculated for the equilibrium state of the liquid and gas phases of the Zn–Ag system: $$G_{{\text{m}}}^{E}$$ = 0.08–1.36 kJ/mol, – $$H_{{\text{m}}}^{E}$$ = 1.52–5.73 kJ/mol, and $$S_{{\text{m}}}^{E}$$ = (1.57–5.38) × 10–3 J/(mol K). The equilibrium VLE diagrams of a Zn–Ag alloy can be used at the preliminary stages of designing pilot equipment for vacuum distillation and to choose the temperature and pressure ranges in the system in order to manufacture Zn- and Ag-containing products of a given composition.

Ganymede's atmosphere is produced by charged particle sputtering and sublimation of its icy surface. Previous far-ultraviolet observations of the O{\small I\,}1356-{\AA} and O{\small I\,}1304-{\AA} oxygen emissions were used to infer sputtered molecular oxygen (O$_2$) as an atmospheric constituent, but an expected sublimated water (H$_2$O) component remained undetected. Here we present an analysis of high-sensitivity spectra and spectral images acquired by the Hubble Space Telescope revealing H$_2$O in Ganymede's atmosphere. The relative intensity of the oxygen emissions requires contributions from dissociative excitation of water vapor, indicating that H$_2$O is more abundant than O$_2$ around the sub-solar point. Away from the sub-solar region, the emissions are consistent with a pure O$_2$ atmosphere. Eclipse observations constrain atomic oxygen to be at least two orders of magnitude less abundant than these other species. The higher H$_2$O/O$_2$ ratio above the warmer trailing hemisphere compared to the colder leading hemisphere, the spatial concentration to the sub-solar region, and the estimated abundance of $\sim$10$^{15}$ H$_2$O/cm$^{2}$ are consistent with sublimation of the icy surface as source., Comment: published in Nature Astronomy (2021) (reformatted for arXiv)

In current study, oleogel containing surface-active (sodium caseinate) and non-surface active biopolymers (xanthan gum) prepared in different concentrations through emulsion template (containing 60% canola oil) and dried by freeze-drying. Results showed that biopolymer content affects the oleogel structure: applying the biopolymer combination with increased concentration mainly sodium caseinate, resulted in lower droplet size in emulsions and obtained oleogels with higher firmness and less oil loss. Therefore, samples containing 4% sodium caseinate with 0.2% and 0.4% xanthan were selected as the superior formulas for examining deeply the drying methods' effects (freeze and vacuum-oven drying) on oleogel's physicochemical properties such as hardness, rheology, XRD, color, and oxidative stability. Freeze-drying with higher content of xanthan (0.4% w/w) generated a high mechanical strength oleogel. However, reducing xanthan concentration (0.2% w/w) reduced the gel strength, probably due to not enough viscoelasticity in oil droplets interface. Nevertheless, the charm of freeze-drying method is high-quality dried products in optimized biopolymer concentration due to the water removal by sublimation of ice crystals. Contrariwise, vacuum-oven revealed soft-discolored materials even in high biopolymers concentrations due to the higher temperature and structural collapse. Independence of biopolymer concentration and drying method, no significant difference in XRD patterns, and oxidative stability was observed. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s13197-021-05214-1.

The purpose of present study was to formulate and Evaluate Sustained release floating tablet of losartan Potassium using Camphor and Polyethylene Oxide as Pore formation for floating and release retarding agent respectively to improve gastric residence time and patient compliance in management of hypertension. The tablet was prepared by direct compression by using HPMC K4 as dry binder. Camphor and PEO as floating and release retarding agent for sustained release floating tablet. Post compression was done to increase the hardness and floating time of tablet. Release modifier was used to speed up the release of drug from sustained release floating tablet. The effect of two independent variables like amount of Sublimating agent (camphor) and amount of Polyethylene oxide (PEO) on Q30min, Q360min, and Q720min was optimized using 32 factorial design and analyzed using the software design expert 10.0.3. The observed (actual values) responses were coincided well with the predicted values, given by the optimization technique. The floating tablet were characterized by FTIR for drug excipient compatibility. Keywords: Losartan Potassium, Polyethylene Oxide (PEO), Camphor pore, Floating tablet

Freeze-drying is an effective method for aortal preservation. However, there are few studies on heat and mass transfer of aortal freeze-drying. In this study, the contactless weighing device was us...

Vapor pressure data and evaporation/sublimation rate of liquid and solid samples are key parameters for designing new process units in terms of design, operability, and safety. In addition, for the case of hazardous materials, health and environmental aspects become essential. Conventional methods for obtaining these data mostly require significant material, time, and energy. Thermal analysis methods including differential scanning calorimetry (DSC) and thermogravimetry (TG) can both offer a platform for studying transition behavior of liquids/solids to the vapor phase. Yet, there are limitations, operational considerations, and analysis precautions to be accounted for in order to obtain highly valuable data. In particular, specific cautions should be taken for the case of liquid mixtures. Therefore, it is essential that the fundamentals and underlying principles of using DSC and TG methods for vapor pressure data generation are comprehensively understood so that one can effectively tune the methods according to the specific nature of the study. The dynamic nature of these methods develops a quasi-equilibrium state, where one should attempt to optimize the conditions as such that the temperature program effect becomes negligible on the initial condition of the sample. In this work, an integrative approach is followed to discuss the fundamentals and operational aspects of using DSC and TG for generating accurate vaporization and vapor pressure data of liquid samples. Specific attention is dedicated to elaborate on optimizing not only the experimental conditions to achieve isothermal boiling, but also data analysis step. Therefore, different considerations regarding post-run analysis are discussed. Moreover, due to the high importance of hydrocarbons, specific attention is also given to the application of these two methods to obtain vapor pressure data of hydrocarbons. The constructive discussions in this work develop an overview of the fundamentals of the method, provide the most significant contributions to the topic in a unifying manner, and suggest inputs and highlight the limitations of the techniques for future studies.

Chemistry - a European journal 27(49), 12558 - 12565 (2021). doi:10.1002/chem.202101260, echanochemistry, as a synthesis tool for inorganic materials, became an ever-growing field in material chemistry. The direct energy transfer by collision of the educts with the milling media gives the possibility to design environmental-friendly reactions. Nevertheless, the underlying process of energy transfer and hence the kinetics of mechanosynthesis remain unclear. Herein, we present in situ synchrotron X-ray diffraction studies coupled with pressure measurements performed during the formation of ZnS and the subsequent phase transition (PT) from the hexagonal to the cubic modification. Milling Zn and S$_8$ results in the sublimation of S$_8$, observed by a sudden pressure increase. Simultaneously, the hexagonal metastable ZnS-modification (wurtzite) forms. Via detection of the pressure maximum, the exact start of the wurtzite formation can be determined. Immediately after the formation of wurtzite, the structural PT to the thermodynamic stable cubic modification sphalerite takes place. This PT can be described by the Prout-Tompkins equation for autocatalytic reactions, similar to thermally induced PT in sulfur vapor at high temperatures (T>1133 K). The increase in the reactivity of the wurtzite formation is explained by the reaction in sulfur vapor and the induction of defect structures by the collisions with the milling media., Published by Wiley-VCH, Weinheim

Snowflakes are a natural subject for microscopy, but the conditions under which they form, and the minutes-long working time imposed by sublimation, are substantial technical barriers to field microscopy of snow crystals. Building on the work of earlier pioneers, we developed a portable, actively cooled, semi-automated microscope system capable of making z-stacked images of individual snowflakes and small groups of crystal specimens at ultrahigh resolution. Field trials of the system in Alaska and Canada produced encouraging results and also suggested directions for further improvement.

The results of recent studies of the structural morphological transformations of Si(111) and Si(100) surfaces using in situ ultrahigh-vacuum reflection electron microscopy (UHV REM) are presented. It is established that high-temperature sublimation from extremely wide Si(111) terraces occurs at a smaller activation energy (3.77 eV) than from the vicinal surface (4.04 eV). A nonmonotonic change in the kinetics of step bunching during a smooth transition from sublimation to growth on the Si(100) surface is recorded. The structural transformations caused by electromigration of positively charged Sn adatoms on the reconstructed Si(111) surface are demonstrated. It is shown that Si(111) surface etching under exposure to a Se molecular beam occurs in a layer-by-layer mode due to the desorption of SiSe2 molecules with activation energy of 2.65 eV.

Sr2FeMoO6-δ double perovskites are widely-recognized due to several important factors: high electronic conductivity and electrocatalytic activity, structural stability under reducing atmospheres, high transition temperature, enormous magnetoresistance, reasonable tolerance to carbon formation, and their desirable capacity to avoid sulfur poisoning. One of the methods most commonly-used to synthetize these perovskites is solid-state reaction. The precursor phases usually associated with this method are the oxides SrMoO4 and SrFeO3-δ when Fe2O3, SrCO3, and MoO3 are the initial reagents used. Morphological, XRD (Rietveld), and thermogravimetry (calcination and reduction) analyses are steps or routes towards achieving the final result. While recent studies suggest that the temperature of calcination is always 900 °C and that reduction occurs at 1200 °C, they fail to explain why this occurs. This article demonstrates, according to the results of thermogravimetric analysis (TGA), that as calcination advances weight loss increases until a temperature of 850 °C is reached. In addition, it stresses the importance of the ball milling technique at ambient temperature to prevent sublimation of the MoO3 compound at 700 °C in the later steps of synthesis, such as calcination and reduction. According to the kinetic study, the values of activation energy (Ea) and reaction order (n) were 130.47 kJ/mol and 1 respectively.

The heat release kinetics in thermally initiated polymerization of 1,4-diethynylbenzene suggested as fuel dispersant in gas generator engines was studied under isothermal conditions in the temperature interval 90–150°С in the melt–vapor two-phase closed system. The enthalpies and entropies of melting, vaporization, and sublimation of 1,4-diethynylbenzene and the kinetics of a decrease in its vapor pressure in the course of polymerization in the melt were determined. Specific features of pressure and temperature variation in the course of propagation of the 1,4-diethynylbenzene combustion front in a cylindrical specimen in a Crawford bomb at the initial pressure of 2 MPa were studied.

We consider sublimation in M–X (M = Mg, Cr, Sm, Eu; X = impurity with a preset activation energy for diffusion) model systems, for which the Peclet number Ре = wr/(ρD) (where D is the diffusion coefficient, w is the mass vaporization rate, ρ is the density of the substance, and r is a size factor) is calculated as a function of temperature by a semiempirical method. The Pe(T) temperature dependence is shown to exhibit complex behavior. Knowledge of the Peclet number as a function of temperature allows one to use it for calculating sublimation refining of a substance in the case of an impurity with a given separation factor and get an idea of how the sublimation refining process depends on temperature.