Crystalline Solid Solutions Research Articles

Solid-liquid equilibrium of free form of oil contaminants (3-MCPD and glycidol) in lipidic systems

Esters of 3-monochloropropane-1,2-diol (3-MCPD) and glycidol are reported vegetable fats and oils contaminants formed during processing. During digestion, esterified forms are hydrolyzed making the free forms, with high toxicity to human health, possibly available in the digestive system, which could depend, among other factors, on the phase condition stablished in the gastrointestinal tract between contaminants and lipids. Therefore, this work was aimed at evaluating the solid–liquid equilibrium (SLE) of binary and pseudobinary mixtures of fatty acids (palmitic, oleic and stearic), triacylglycerols (tripalmitin, triolein and tristearin) and a partial acylglycerols, with 3-MCPD and glycidol, by differential scanning calorimetry (DSC) and thermodynamic modeling with Margules 2 and 3 suffixes, UNIFAC and ideal models. Melting properties of the contaminants were determined by DSC thermograms, with microstructure micrographs and compared to some predictive group contribution models (GC). 14 complete SLE phase diagrams could be determined. Results showed that the lipid compounds had high affinity with the free contaminants with probably the formation of liquid crystalline structures and/or solid solutions. The Margules 3 suffixes model showed the best fit with the lowest average relative deviations, no higher than 1%, although the parameters probably incorporated the non-ideality promoted by the crystalline phase behavior. The formation of mesophases and/or solid solutions with very high melting temperature probably means a difficulty of separating the contaminants from the lipid matrix in which, on the other hand, could avoid separation process or affect (probably decreasing) their absorption during digestion.

7．結晶性複合酸化物の超微粒子化と助触媒への応用

7．結晶性複合酸化物の超微粒子化と助触媒への応用

Ionic Conductivity of Pb0.67Cd0.33F2 Ceramics Obtained by Mechanical Synthesis and by Grinding of a Crystalline Solid Solution

Ionic Conductivity of Pb0.67Cd0.33F2 Ceramics Obtained by Mechanical Synthesis and by Grinding of a Crystalline Solid Solution

Enantiotropic inconstancy, crystalline solid solutions and co-crystal in the salicylic acid-anthranilic acid system.

The phase boundaries and thermodynamic properties of crystal phases in the salicylic acid (SA) - anthranilic acid (AA) system have been determined experimentally. The complete binary T-X diagram reveals a total of four crystalline phases, including a co-crystal and three crystalline solid solutions. The two eutectics were determined through triplicate DSC analyses at 33 compositions. By adding a liquid solvent and generating a ternary phase diagram, a methodology is introduced to determine the solid-state miscibility limits of the solid solutions at 20 and 55 °C. The crystalline solid solutions exhibit substantial differences in physical properties relative to the pure components, including solubility enhancements that are relevant for chemical processing and material properties. The thermodynamic relationships of the three polymorphs of AA have been resolved showing an enantiotropic transition temperature of 50-55 °C between Form I and III of pure AA. However, as a result of the solid solutions with SA, the enantiotropic transition temperature was suppressed by around 30 °C at the eutectoid. In addition, a co-existence envelope is formed, wherein the two AA polymorph solid solutions exist in equilibrium with one another over a wide range of temperatures and compositions.

Revisiting glass formation in Zr-Cu-Al alloys

In the last decade, it was demonstrated that certain composition windows exist (the well-known PHS and PHSS models), within which the glass-forming ability peaks, although the underlying causes for the existence of this window has not been satisfactorily established. While these models predict a number of compositions where the glass forms, they also identify multiple compositions as good glass-formers, where experimentally, it has been shown that intermetallics form as opposed to metallic glasses or crystalline solid solutions. We postulate that this drawback in the PHS and the PHSS can be satisfactorily addressed by considering the formation of the intermetallic phase. This proposition is tested theoretically in the Zr-Cu-Al system and our model predictions tested against experimental results available in the literature. We demonstrate that a good glass-forming parameter can be developed only if we identify techniques for determining composition ranges where an intermetallic is difficult to nucleate.

Influence of the Degree of Phase Transition Diffuseness on the Depolarization Temperature in Relaxors of Different Types

The relationship between the temperatures of depolarization (Td) and morphotropic phase transition (TF-R) in crystalline relaxor solid solutions of various types, such as PbMg1/3Nb2/3O3-29PbTiO3 (PMN-29PT), PbZn1/3Nb2/3O3-9PbTiO3 (PZN-9PT) and NaBi1/2Ti1/2O3-xBaTiO3 (x=5,7.5%) (NBT-xBT) has been studied. For this purpose, dielectric measurements of polarized samples were carried out, and the process of induction of the ferroelectric phase in an electric field applied below the TF-R temperature was also studied. It was found that the structure of the low-temperature phases in these compounds is different, which leads to significant differences not only in the induction of the ferroelectric phase, but also to different relative positions of the temperatures Td and TF-R. In PMN-29PT, the formation of ferroelectric phases is preceded by some delay time, which is one of the hallmarks of a non-ergodic glassy phase, and in this case the temperatures Td and TF-R coincide. In PZN-9PT and NBT-5BT, the ferroelectric phase is induced immediately after the field is applied without a delay time, which indicates that below the TF-R temperature, the non-ergodic glassy phase does not appear, and the temperatures Td and TF-R do not coincide in them. The results obtained are discussed from the point of view of different degrees of diffuseness of the phase transition and different sizes of the polar regions. It is suggested that the coincidence of temperatures Td and TF-R is a consequence of the non-ergodic glassy phase and the small sizes of the polar regions. Keywords: relaxors, phase transitions, degree of smearing, depolarization temperature.

Влияние степени размытия фазового перехода на температуру деполяризации в релаксорах разного типа

The relationship between the temperatures of depolarization (Td) and morphotropic phase transition (TF-R) in crystalline relaxor solid solutions of various types, such as PbMg1/3Nb2/3O3-29PbTiO3 (PMN-29PT), PbZn1/3Nb2/3O3-9PbTiO3 (PZN- 9PT) and NaBi1/2Ti1/2O3-xBaTiO3 (x=5.7.5%) (NBT-xBT) has been studied. For this purpose, dielectric measurements of polarized samples were carried out, and the process of induction of the ferroelectric phase in an electric field applied below the TF-R temperature was also studied. It was found that the structure of the low-temperature phases in these compounds is different, which leads to significant differences not only in the induction of the ferroelectric phase, but also to different relative positions of the temperatures Td and TF-R. In PMN-29PT, the formation of ferroelectric phases is preceded by some delay time, which is one of the hallmarks of a non-ergodic glassy phase, and in this case the temperatures Td and TF-R coincide. In PZN-9PT and NBT-5BT, the ferroelectric phase is induced immediately after the field is applied without a delay time, which indicates that below the TF-R temperature, the non-ergodic glassy phase does not appear, and the temperatures Td and TF-R do not coincide in them. The results obtained are discussed from the point of view of different degrees of diffuseness of the phase transition and different sizes of the polar regions. It is suggested that the coincidence of temperatures Td and TF-R is a consequence of the non-ergodic glassy phase and the small sizes of the polar regions.

Photocatalytic Radical Addition to Levoglucosenone

AbstractUsing photocatalysis with tetra‐n‐butylammonium decatungstate (TBADT), alkanes, cyclic acetals, cyclic ethers, formamide and aldehydes were added in a stereoselective way to levoglucosenone (LGO). A hydrogen atom is transferred from the donor compound to the photochemically excited TBADT, and the resulting radicals add onto LGO in a stereoselective way. In the case of the addition of adamantane, two regio‐isomers were obtained which form a crystalline solid solution. Cyrene™, obtained by hydrogenation of LGO, was added under the same conditions. In this case, only two of 32 possible isomers of the resulting Cyrene™ dimer were formed. The regio‐selectivity of the HAT step is discussed in detail. For this purpose, bond dissociation energies and partial charges have been calculated. Transition state calculations of the radical addition to LGO explain the stereospecificity of this reaction step.

Synthesis of FePt Nanoparticles by Photoreduction and Chemical Reduction in Poly(ethyleneimine).

Using poly(ethyleneimine) (PEI) polymer substrates, spherical FePt nanoparticles (NPs) with diameter <10 nm have been synthesized by photoreduction and chemical reduction in aqueous media at room temperature. In the photoreduction approach, PEvI acts as both the template into which the metal ions are coordinated and as a reductant when irradiated by ultraviolet light. In the chemical reduction method, PEI acts as only a template, with NaBH4 as the reductant. The as-prepared NPs were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), and vibrating sample magnetometry (VSM). Starting from the same precursor state and relative concentrations, the as-prepared NPs from both methods are spherical, crystalline solid solutions with a chemically disordered face-centered cubic (fcc) structure. The as-prepared NPs from both methods are superparamagnetic with some contribution from a ferromagnetic phase. The photoreduced NPs have broad size distribution of (5 ± 1.0 nm), an expanded lattice (3.913 Å), and relatively lower magnetic moment (0.02 emu/g) compared to the narrower size distribution (4 ± 0.7 nm), shortened lattice (3.890 Å), and a dominant moment (15 emu/g) of the chemically reduced NPs. The difference in the rate of particle formation apparently leads to a low efficiency of FePt NP formation via photoreduction compared to chemical reduction.

Synthesis, structure and spectroscopy of Fe2+:MgAl2O4 transparent ceramics and glass-ceramics

We report on a comparative study of a transparent Fe:MgAl2O4 (spinel) ceramics and a transparent nanophase Fe:MgAl2O4-based glass-ceramics. The 0.1 mol% Fe:MgAl2O4 ceramics was synthesized by hot pressing (at 1500 °C/50 MPa) of powders obtained by the sol-gel method using LiF as a sintering aid. The Fe:MgAl2O4 ceramic is a single-phase material (cubic structure, sp. gr. Fd3‾m, a = 8.083 Å) with a mean grain size of ~50 μm. The ceramic exhibits a broadband transparency of 0.2–6.0 μm and a high in-line transmission at ~1 μm of 74.4%. The iron ions are presented in the ceramics in the single state of Fe2+ species in tetrahedral (Td) sites. A broad absorption band spanning from ~1.2 to 3.7 μm assigned to the 5E → 5T2 (5D) transition of Fe2+ ions in Td sites is observed, corresponding to a ground-state absorption cross section of 0.28 × 10−18 cm2 at 1.90 μm. The glass-ceramics were prepared by secondary two-stage heat-treatments of the magnesium aluminosilicate glass nucleated by titanium oxide and doped with 0.1 mol% FeO. Transparent Fe:MgAl2O4-based glass-ceramics obtained at the temperature of the second stage of 800–1000 °C were multi-phase materials containing two crystalline nanophases, i.e., spinel (mean size: 3.7–7.4 nm) and magnesium aluminotitanate solid solution (mean size: 6.4–20.6 nm), as well as residual silica-rich glass. Glass-ceramics obtained at the temperature of the second stage of 1050 °C were transparent and based on Fe-doped sapphirine. For glass-ceramics, absorption has a much more complex character as it is caused by interplay of iron and titanium ions in different valence states, coordination sites and locations. The iron ions enter the spinel nanocrystals but unlike the ceramic, in the form of both VIFe2+ and IVFe2+ species. The developed ceramics and glass-ceramics are promising for saturable absorbers of mid-infrared (2–3 μm) lasers.

Corrosion Characteristics of TiNbMoMnFe High Entropy Thin Film Deposited on AISI316L for Biomedical Applications

High entropy alloys (HEAs) have received tremendous attention in different applications because of their excellent corrosion resistance and superior mechanical properties. In the present work, a novel TiNbMoMnFe high entropy alloy system was synthesized and deposited on AISI 316L by DC magnetron sputtering system. The microstructure of the resulting thin film was evaluated by grazing incidence X-ray diffraction and field emission electron microscope. It was found that the thin film microstructure is composed of a crystalline solid solution (grain size of 76 nm) and an amorphous phase. The electrochemical investigations in Ringer’s solution revealed that a thin film of 670 nm thick high entropy alloy has a low corrosion current density of 0.024 μA cm−2, approximately 30% lower than that of the uncoated 316L. Meanwhile, the HEA thin film showed the highest pitting corrosion resistance and stability of the passive film. The wettability examinations exhibited that the coated sample has a high contact angle of 90° in contrast to 60° for the uncoated ones. In summary, the TiNbMoMnFe high entropy alloy thin film shows great potential for use in biomaterial applications.

Electrolytic Formation of Solid Crystalline UO2–ThO2 and UO2–ThO2–ZrO2 Solutions from Salt Melts

For the first time, crystalline solid solutions of UO2–ThO2 and UO2–ThO2–ZrO2 have been electrolytically prepared. The mechanism of their formation in molten halides is presented. The influence of the electrolysis current density on the compositions of the cathode deposits has been established and explained. We also established the effect of zirconium ions on the ThO2 content in the UO2–ThO2–ZrO2 cathode deposits.

Investigation of the power peaking factor Kr in the fuel assembly during the maneuvering mode of the VVER-1000 reactor

The aim of this thesis paper is to analysis the power peaking factors Kr of the VVER-1000 reactor. Power peaking factor is important for the safety operation of the VVER-1000 power reactor. The maintenance of the core power distribution in a nuclear power plant is a precondition for the safety operation of a reactor. In this investigation used boron carbide. Boron carbide is a compound that contains boron and carbon, especially B4C; an extremely hard, non-metallic, black crystalline compound or solid solution. Only diamond is harder. In addition to its hardness property, boron carbide has the physical properties of corrosion resistance, heat strength, low specific gravity and high elastic modulus. It is used as an abrasive, neutron absorber for nuclear reactors, and as an alloying agent in composite structural materials. For this reason, when need to change the power of a reactor then the boron carbide (B4C) control insert the reactor core. In this step investigated the power picking factors and its deviation using the Boron carbide (B4C). Power peaking factors are connecting between the thermal-hydraulics and the nutronics of the nuclear power plant core. This power peaking factors was calculated by the comprehensive nutronics calculation program GETERA-93.

Thermal Stability and Mechanical Properties of Sputtered (Hf,Ta,V,W,Zr)-Diborides

Non-reactive magnetron sputtering of a diboride target composed of HfB2, TaB2, VB2, W2B5, and ZrB2 with equimolar composition leads to the formation of crystalline single-phase solid solution diboride thin films, (Hf,Ta,V,W,Zr)B2, with a high-entropy metal-sublattice. Their growth morphology (dense and fine-fibrous), crystal structure (AlB2-type), as well as mechanical properties (indentation modulus E of ~580 GPa and hardness H of ~45 GPa), and chemical compositions are basically independent of the substrate bias potential applied (varied between -40 and -100 V) during the deposition at 450 °C.Detailed X-ray diffraction (XRD) and atom probe tomography (APT) studies indicate that the (Hf,Ta,V,W,Zr)B2 thin films remain single-phase AlB2-structured (with randomly distributed metal elements) during vacuum-annealing at temperatures up to 1200 °C. Only when increasing the annealing temperature to 1400 °C, the formation of small orthorhombic structured (V,W)B-based regions can be detected, indicating the onset of decomposition of (Hf,Ta,V,W,Zr)B2 thin films into (Hf,Ta,Zr)B2 and (V,W)B. This decomposition is accompanied with the formation of confined B-rich boundary regions between the two phases. This leads to a decrease in H to ~39 GPa with Ta = 1500 and 1600 °C. After annealing at 1400 °C the hardness is still very high with ~44 GPa, as the volume fraction of the newly formed (V,W)B-rich domains is small and the majority of the coating is still solid-solution (Hf,Ta,V,W,Zr)B2 with severe lattice distortions.

Thermal stability and mechanical properties of sputtered (Hf,Ta,V,W,Zr)-diborides

Non-reactive magnetron sputtering of a diboride target composed of HfB2, TaB2, VB2, W2B5, and ZrB2 with equimolar composition leads to the formation of crystalline single-phase solid solution diboride thin films, (Hf,Ta,V,W,Zr)B2, with a high-entropy metal-sublattice. Their growth morphology (dense and fine-fibrous), crystal structure (AlB2-type), as well as mechanical properties (indentation modulus E of ~580 GPa and hardness H of ~45 GPa), and chemical compositions are basically independent of the substrate bias potential applied (varied between -40 and -100 V) during the deposition at 450°C.Detailed X-ray diffraction (XRD) and atom probe tomography (APT) studies indicate that the (Hf,Ta,V,W,Zr)B2 thin films remain single-phase AlB2-structured (with randomly distributed elements at the metal-sublattice) during vacuum-annealing at temperatures up to 1200°C. Only when increasing the annealing temperature to 1400°C, the formation of small orthorhombic structured (V,W)B-based regions can be detected, indicating the onset of decomposition of (Hf,Ta,V,W,Zr)B2 thin films into (Hf,Ta,Zr)B2 and (V,W)B, accompanied by the formation of confined B-rich boundary regions between these phases. After annealing at 1400°C the hardness is still very high with ~44 GPa, as the volume fraction of the newly formed (V,W)B-rich domains is small and the majority of the coating is still solid-solution (Hf,Ta,V,W,Zr)B2 with severe lattice distortions. Only at even higher Ta of 1500 and 1600 °C, H decreased to ~39 GPa.

Crystal-Glass High-Entropy Nanocomposites with Near Theoretical Compressive Strength and Large Deformability.

High-entropy alloys (HEAs) and metallic glasses (MGs) are two material classes based on the massive mixing of multiple-principal elements. HEAs are single or multiphase crystalline solid solutions with high ductility. MGs with amorphous structure have superior strength but usually poor ductility. Here, the stacking fault energy in the high-entropy nanotwinned crystalline phase and the glass-forming-ability in the MG phase of the same material are controlled, realizing a novel nanocomposite with near theoretical yield strength (G/24, where G is the shear modulus of a material) and homogeneous plastic strain above 45% in compression. The mutually compatible flow behavior of the MG phase and the dislocation flux in the crystals enable homogeneous plastic co-deformation of the two regions. This crystal-glass high-entropy nanocomposite design concept provides a new approach to developing advanced materials with an outstanding combination of strength and ductility.

Highly sensitive and selective ethylene gas sensors based on CeOx-SnO2 nanocomposites prepared by a Co-precipitation method

CeOx-SnO2 nanocomposites (NCs) with different Ce:Sn compositions of 0:100, 20:80, 25:75, 33:67, 50:50 and 100:0 were synthesized via a two-reactant co-precipitation method. The phase, morphology, particles size, elemental composition and chemical state of as-prepared CeOx-SnO2 nanoparticles (NPs) were characterized by X-ray diffraction, nitrogen adsorption, electron microscopy and X-ray spectroscopy. The results revealed that the highly crystalline solid solution phases structure of CeOx-SnO2 were formed exhibiting approximately round morphologies with average particles sizes of ~5–20 nm. The sensor properties towards ethylene gas were characterized in terms of response, response times, stability and selectivity. The gas-sensing data showed that the addition of CeOx to SnO2 provided significant enhancement of ethylene response and the CeOx-SnO2 NPs (Ce:Sn = 33:67) offered the highest response of 5.18 with a short response time of 12 s to 10 ppm ethylene at 350 °C. Additionally, the sensor exhibited a low minimum detectable ethylene concentration of 0.3 ppm, high ethylene selectivity and good stability. Therefore, the sensor based on coprecipitated CeOx-SnO2 NPs could ce a promising candidate for detection of ethylene in fruit-ripeness monitoring applications.

Li-doped Ni0.4Mg0.6−yLiyO film prepared by sol–gel method

Superior photoelectric thin film plays critical role in ultraviolet signal detection. In this paper, we display a simple and smooth sol–gel method to produce lithium doped Ni0.4Mg0.6−yLiyO film, and the X-ray diffraction pattern shows both the doped and undoped films inclined to crystal growth. The surface quality was investigated by scanning electron microscope, which reveals a close packed nanoparticle configuration with particle size about 10 nm. The optical bandgap of the films was found to decrease as the doping abundance increased, but no less than 4.1 eV even at the highest doping level. As a result, we obtained a crystalline solid solution composite film which possess wide bandgap and improved conductivity simultaneously, indicated a promising application toward deep UV photodetection, especially for solar-blind photon sensing.

Enhanced catalytic performance of cobalt and iron co-doped ceria catalysts for soot combustion

A series of promising Ce–Co–Fe catalysts were successfully synthesized using a cetyl-trimethylammonium-bromide-assisted co-precipitation method and investigated for diesel soot combustion. The surface morphological and structural properties were systematically examined using various techniques: X-ray diffraction, scanning electron microscope, N2 adsorption–desorption, Raman spectroscopy, temperature-programmed reduction and in situ diffuse reflection infrared Fourier transform spectroscopy. The catalyst–soot combustion activities were tested in O2 and NO + O2 using a temperature-programmed technique. Nanometer crystalline solid solutions were formed with high surface areas when the Fe and Co cations were co-doped in the ceria lattice. Transition metals doping played a key role in increasing oxygen vacancies and promoting the redox performance of Ce–Co–Fe catalysts. Co–Fe co-doping accelerated the oxidation of soot under both “tight” and “loose” contact conditions. Among all the ceria-based catalysts, Ce80Co15Fe5 showed superior activity with T10 = 256 °C and high selectivity with $$ S_{{{\text{CO}}_{ 2} }} \, = \,100\% $$ under tight a contact mode. The observed high catalytic activity following co-doping was proved to have occurred because of various reasons such as improved redox properties, increased oxygen vacancies and high surface area. The presence of NO in O2 also promoted soot oxidation, which follows the NO2-assisted mechanism. Moreover, the in situ DRIFTS performed under an isothermal condition in NO + O2 confirmed the strong adsorption capacity for NOx species on the doped ceria catalyst.

Broad Mid-Infrared Luminescence in a Metal-Organic Framework Glass.

Metal–organic framework (MOF) glasses are a newly discovered family of melt-quenched glasses. Despite considerable progress in understanding the nature of MOF glasses, their photonic functionalities have not been found so far. Here, we report on the first breakthrough regarding the photonic functionalities of MOF glasses, that is, finding of the luminescence in melt-quenched MOF glasses. The finding was achieved on a zeolitic imidazolate framework (ZIF) series, that is, the ZIF-62 series: Zn1–xCox(Im)1.7(bIm)0.3, x = 0, 0.1, and 0.5, where Co substitutes Zn in ZIF-62 forming single-phased solid solutions. Remarkably, we observed broadband mid-infrared (Mid-IR) luminescence (in the wavelength range of 1.5–4.8 μm) in both the crystalline and amorphous solid solutions. The intensity of the luminescence in ZIF glass is gradually enhanced by increasing the level of Co concentration. The observed Mid-IR emission originates from d–d transition of Co ions. The discovery of the luminescence in ZIF-62 glass may pave the way toward new photonic applications of bulk MOF glasses.