Different Degrees Of Crystallization Research Articles

Giant Thermopower of Hydrogen Ion Enhanced by a Strong Hydrogen Bond System.

Ionic thermoelectric materials based on organic polymers are of great significance for low-grade heat harvesting and self-powered wearable temperature sensing. Here, we demonstrate a poly(vinyl alcohol) (PVA) hydrogel that relies on the differential transport of H+ in PVA hydrogels with different degrees of crystallization. After the inorganic acid is infiltrated into the physically cross-linked PVA hydrogel, the ionic conductor exhibits a huge ionic thermopower of 38.20 mV K-1, which is more than twice the highest value reported for hydrogen ion transport thermoelectric materials. We attribute the enhanced thermally generated voltage to the movement of H+ in the strong hydrogen bond system of PVA hydrogels and the restrictive effect of the strong hydrogen bond system on anions. This ionic thermoelectric hydrogel opens up a new way for thermoelectric conversion devices using H+ as an energy carrier.

Simply synthesized apatites precipitated onto porous rice husk charcoal for the extraction of cadmium (II) and copper (II) ions

ABSTRACT A simple low-temperature method for the deposition of apatite on porous charcoal from rice husk is proposed. The deposition was carried out by impregnation and subsequent treatment of porous charcoal with inorganic compounds of phosphorus and calcium, followed by hydrothermal treatment at 120° C. The composites obtained in this way were investigated by XRD, electron microscopy, nitrogen porosimetry and ion-exchange adsorption of copper and cadmium ions. XRD of the synthesized composites showed the formation of hydroxyapatites with different degrees of crystallization. Electron microscopy showed the presence in the composites of pore-channels with a diameter of up to 10 microns in which apatite grains up to 300 nanometers in length are deposited. The study of the kinetics of ion exchange shows that the diffusion of ions into the grains of hydroxyapatite occurs slowly and does not end during 60 days. Adsorption of cadmium and copper ions during 24 hours occurs mainly on the surface of grains and is characterized by a high degree of ion adsorption and solution purification.

Crystallization processes and microwave absorption properties of amorphous LiZn ferrite hollow microspheres

In this work, amorphous Lithium-Zinc ferrite hollow microspheres (LiZn FHMs) were prepared by using self-reactive quenching technology with NaCl aqueous solution (15 wt%) as the quenching medium. Heat-treatment for 4 h at 300, 600, 900 and 1200 °C was used to obtain LiZn FHMs with different degree of crystallization. The morphology, phases and microwave absorption properties were investigated by SEM, XRD, and vector network analyzer. The results show that polarization increases first and decline then with the increasing of heat-treatment temperatures. So the value of eʺ also increases and then decline. Natural resonance is the magnetic loss mechanism of amorphous LiZn FHMs (room temperature) and those with heat-treatment at 300, 900 and 1200 °C. However, natural resonance and eddy current loss are the magnetic loss mechanism with heat-treatment at 600 °C. The microwave absorption properties increase first and decline then with the increasing of heat-treat temperature, which is caused by the decline of orientational polarization of electric dipole moment and increasing of space charge polarization.

Comparative study of crystallization and lamellae orientation of isotactic polypropylene by rapid heat cycle molding and conventional injection molding

Abstract The crystallization and orientation of isotactic polypropylene (iPP) molded by rapid heat cycle molding (RHCM) and conventional injection molding (CIM) were studied. Due to the varying cooling rates and shearing, the molded parts exhibited a multilayered structure (skin, shear and core) across the part thickness, reflecting different degrees of crystallization and lamellae orientation of iPP. The morphology evolution of RHCM products was discussed based on the comparative research of morphology and structure at multiple sites on the RHCM and CIM specimens. Scanning electron microscopy (SEM) and wide angle X-ray diffraction (WAXD) were used to analyze the thickness, crystallinity and lamellae orientation of these three distinct layers. The crystallization and lamellae orientation of iPP correlated strongly with the multilayered structure. In the RHCM process, one side of the mold is equipped with the rapid heat cycle function. The thickness and lamellae orientation next to the heated surface were less than that of the opposite skin layer without heating. Meanwhile, the crystallinity was greater than that of the opposite skin layer.

Influence of hygrothermal aging on dimensional stability of thin injection‐molded short glass fiber reinforced PA6 materials

ABSTRACTThe hygrothermal aging of short glass fiber reinforced polyamide 6 materials (PA6/GF) is a major problem for thin‐walled components used in the automotive sector. In this work, the thickness and glass fiber content of PA6/GF materials were varied and exposed to hygrothermal aging. The temperature and relative humidity were chosen to range from −40 to 85°C and 10% RH to 85% RH respectively, according to automotive requirements for components in the passenger compartment. For the absorption of moisture, the diffusion behavior could not be generally described by Fick's law. However, the results indicate that the diffusion behavior is dependent on the relative humidity and thickness of the PA6/GF material. The morphology of the test specimen, which is influenced by injection molding, was also found to affect the diffusion behavior. The states of equilibrium for moisture absorption are strongly dependent on the relative humidity during hygrothermal aging and less dependent on the temperature. The maximum absorbed humidity was found at a temperature of 65°C and 85% RH, which was higher than at 85°C and 85% RH because of reduced contrary aging processes, such as postcrystallization. In certain climatic conditions and test specimen thicknesses, there was a characteristic overshoot in the mass change. This behavior could be attributed to a different degree of crystallization and lower glass fiber content. Both moisture absorption and an overshoot of the mass affected the dimensional stability of the test specimens. This effect on dimensional stability could be correlated with the glass fiber orientation. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42245.

Geochemistry and zircon U-Pb geochronology of magmatic enclaves in trachytes from the Euganean Hills (NE Italy): further constraints on Oligocene magmatism in the eastern Southern Alps

This study presents the results of the geochemical and geochronological investigation of magmatic enclaves in trachytes from the Euganean Hills (NE Italy). The Euganean Hills magmatic district is the most recent (Eocene-Oligocene) volcanic distric within the Veneto Volcanic Province (VVP), which represents the main magmatic event in the eastern Southern Alps. The studied enclaves include intrusive and crystal mush types, the latter characterised by embayments of the host trachyte towards the core of the enclaves. Both types have zircon U-Pb ages of ~30–32 Ma, indicating that they are contemporaneous with the second Euganean magmatic phase. Amphibole-bearing intrusive enclaves (syenites and quartzo-monzonites) and crystal mushes have similar major and trace element compositions ( e.g. REE, Rb, Ba, K, Nb, Pb, Th and Y contents) as those of the host trachyte. They are interpreted as magma chamber solidification fronts with different degrees of crystallization, which were caught as enclaves by the trachytic magma during its ascent. Amphibole-free intrusive enclaves show peculiar trace element compositions (depletion in Th, U, Nb, Ta, MREE and HREE, and marked Eu positive anomaly), in contrast to the compositions of Euganean lavas and other studied enclaves, and are interpreted as cumulative rocks resulting from concentration of crystals fractionated during trachyte–rhyolite evolution. This study confirms that low-pressure fractional crystallisation played a primary role in the evolution of magma in the VVP. The first zircon U-Pb ages from the Euganean rocks prove a Lower Oligocene age for the second Euganean magmatic phase. The use of this robust chronometer should be extended to the Euganean lavas, to better constrain the chronological sequence of eruptive events.

LA-ICP-MS mineral chemistry of titanite and the geological implications for exploration of porphyry Cu deposits in the Jinshajiang – Red River alkaline igneous belt, SW China

The Jinshajiang–Red River alkaline igneous belt in the eastern Indian–Asian collision zone, of southwestern China, hosts abundant, economically important Cu–Mo–Au mineralization of Cenozoic age. Major- and trace-element compositions of titanites from representative Cu-mineralized intrusions determined by LA-ICP-MS show higher values for Fe2O3/Al2O3, ΣREE + Y, LREE/HREE, Ce/Ce*, (Ce/Ce*)/(Eu/Eu*), U, Th, Ta, Nb and Ga, and lower values for Al2O3, CaO, Eu/Eu*, Zr/Hf, Nb/Ta and Sr than those for titanites from barren intrusions. Different ΣREE + Y, LREE/HREE, U, Th, Ta and Nb values of titanites between Cu-mineralized and barren intrusions were controlled mainly by the coexisting melt compositions. However, different Sr concentrations and negative Eu anomalies of titanites between Cu-mineralized and barren intrusions were most probably caused by different degrees of crystallization of feldspar from melts. In addition, different Ga concentrations and positive Ce anomalies of titanites between Cu-mineralized and barren intrusions were most likely caused by different magmatic fO2 conditions. Pronounced compositional differences of titanites between Cu-mineralized and barren intrusions can provide a useful tool to help discriminate between ore-bearing and barren intrusions at an early stage of exploration, and, thus, have a potential application in exploration for porphyry Cu deposits in the Jinshajiang – Red River alkaline igneous belt, and to other areas.

Silicate melt inclusions in clinopyroxene phenocrysts from mafic dikes in the eastern North China Craton: Constraints on melt evolution

Silicate melt inclusions (SMIs) in magmatic minerals provide key information on the chemical and mineralogical evolution of source magmas. The widespread Cretaceous mafic dikes in the Jiaojia region of the eastern North China Craton contain abundant SMIs within clinopyroxene phenocrysts. The daughter minerals in these SMIs include amphibole, plagioclase, pyrite and ilmenite, together with CO2+CH4 and CH4 as the major volatile phase. The total homogenization temperatures of the SMIs range between 1280 and 1300°C. The host clinopyroxene phenocrysts in these dolerite dikes are dominantly augite with minor diopside. From LA-ICPMS analyses of the SMIs, we identify two compositional groups: (1) low-MgO (6.0–7.6 wt.%) SMIs and (2) high-MgO (11.2–13.9 wt.%) SMIs. The Low-MgO group exhibits higher concentrations of TiO2, Al2O3, Na2O, P2O5 and lower CaO and CaO/Al2O3 ratio as compared to the high-MgO SMIs. The trace element patterns of the two types of SMIs are similar to those of the host mafic dikes. However, the low-MgO SMIs and host mafic dikes are clearly more enriched in all the trace elements as compared to the high-MgO type, especially with regard to the highly incompatible elements. The estimated capture temperatures and pressures are 1351–1400°C and 1.6–2.1 GPa for the high-MgO SMIs and 1177–1215°C and 0.6–1.1GPa for the low-MgO type. The high-MgO and low-MgO SMIs were trapped at depths of ∼51–68km and ∼20–35km, respectively. Computations show that the parental melt is mafic with SiO2 content 49.6 wt% and Mg# 80.0 with relatively low total alkali contents (1.35 wt% Na2O+K2O) and high CaO (15.2 wt%). Exploratory runs with the program MELTS and pMELTS show that the low-MgO and high-MgO SMIs were derived from the same parental melt through different degrees of crystallization. Clinopyroxene and a small amount of olivine were the fractionating phases during the evolution from parental melts to high MgO melts, while the low MgO melts experienced significant fractional crystallization of olivine and clinopyroxene. We postulate the newly accreted lithospheric clinopyroxenite as the major source for the Jiaojia dolerite dikes, with melting of the source at a depth of ∼68–80km.

Solubility and mobility of phosphorus recycled from dairy effluents and pig manures in incubated soils with different characteristics

Phosphorus (P) nutrition of plants in croplands is managed by fertilization. Commercial P fertilizers are manufactured from phosphate rocks, which are non-renewable and the only fossil resource of P. As an alternative, P in human and animal wastes can be recovered and concentrated in products that can be used as P fertilizers. Here, we studied four recycled P products derived from pig manures (hereafter referred as “RPPM”) and another one derived from dairy effluents (“RPDE”). The RPDE product is composed of Ca–P (partly as hydroxyapatite, HA), while RPPM products include recovered struvite (ST) and Ca–P in variable proportions. The objective was to assess the ability of RPPM and RPDE products to increase available P in a range of soils differing in their characteristics (seven soils used), and to compare these recycled P products with a standard fertilizer [commercial triple super phosphates (TSP)], reference HA and reference ST. To this end, products were mixed to the soils and the mixtures were incubated at 75 % water holding capacity and 28 °C. After incubation, the amounts of phosphate ions (iP) in solution (QW) and isotopically exchangeable iP (E) in soils were quantified using an isotopic labeling (32P) and dilution procedure. In each soil, QW and E were significantly affected by treatments (control and P-treated soils) and increased due to the application of the different products. However, reference HA and RPDE products were generally less effective than TSP, reference ST and RPPM products. The soil response (variation in QW or E) in TSP treatment was compared to those in other treatments. It enabled the calculation of a relative effectiveness index. Relative effectiveness of HA and RPDE varied among soils (from 5 to 124 %) and increased with decreasing soil pH. Results however showed that the RPDE product tends to be more effective than reference HA, probably due to different degrees of crystallization of Ca–P. Relative effectiveness of RPPM products (80–116 %) was high in all soils and was similar to that of reference ST (90–104 %). To conclude, the present study suggests that RPDE products are effective only in acidic or slightly acidic soils. In contrast, P recycling from pig manures through chemical precipitation can provide effective P fertilizers, independently on soil conditions.

Preparation of lepidocrocites with different degrees of crystallization and their photocatalytic properties

Lepidocrocites with different degrees of crystallization were obtained, and the low-crystalline lepidocrocite showed higher adsorption and photocatalytic activity.

Anhydrous liquid line of descent of Yamato‐980459 and evolution of Martian parental magmas

AbstractWe report the results of nominally anhydrous equilibrium and fractional crystallization experiments on a synthetic Yamato‐980459 (Y98) bulk composition at 0.5 GPa. These experiments allow us to test a suggested fractional crystallization model, calculated using MELTS by Symes et al. (), in which a Y98‐like initial liquid yielded a magma closely resembling the bulk composition of QUE 94201. Although the two meteorites cannot be cogenetic owing to their age difference, they are thought to represent bona fide magmatic liquids rather than products of crystal accumulation, as are most Martian basaltic meteorites. Hence, understanding possible petrogenetic links between these types of liquids could be revealing about processes of melting and crystallization that formed the range of Martian basalts. We find that Y98 can, in fact, generate a residual liquid closely resembling QUE, but only after a very different crystallization process, and different degree of crystallization, than that modeled using MELTS. In addition, both the identity and sequence of crystallizing phases are very different between model and experiments. Our fractional crystallization experiments do not produce a QUE‐like liquid, and the crystallizing phases are an even poorer match to the MELTS‐calculated compositions than in the equilibrium runs. However, residual liquids from our experiments define a liquid line of descent that encompasses bulk compositions of parental melts calculated for several Martian basaltic meteorites, suggesting that the known Martian basaltic meteorites had their ultimate origin from the same or very similar source lithologies. These are, in turn, similar to source rocks modeled by previous studies as products of extensive crystallization of an initial Martian magma ocean.

Anomalous fading and crystalline structure: Studies on individual chondrules from the same parent body

Abstract Plagioclase feldspar is the major luminescent mineral in meteorites. Thermoluminescence (TL) characteristics, peak temperature (Tm), full width at half maximum (FWHM), ratio of high (HT) to low temperature (LT) peak, and TL sensitivity (TL/dose/mass) to an extent reflect degree of crystallinity of the mineral. The present study explores and establishes a correlation between quantum mechanical anomalous (athermal) fading and structural state by examining TL of individual chondrules. Chondrules were separated using freeze-thaw technique from a single fragment of Dhajala meteorite. The results show large variation in Tm (155−230°C), FWHM (80−210°C) and HT/LT (0.07–0.47) and seem to be positively correlated. TL sensitivity (ranging from 14 to 554 counts/s/Gy/mg) decreases with increasing Tm and FWHM. Large variations in TL parameters (Tm, FWHM, HT/LT, and Sensitivty) suggest that individual chondrules had different degree of crystallization. Thermal annealing experiments suggest that comparatively ordered form of feldspar can be converted to a disordered form by annealing the sample at high temperatures (1000°C) for long time (10 hr) in vacuum (1 mbar pressure) condition and rapidly cooling it. Measured anomalous fading suggest that fading rate increases as the crystal form changes from an ordered state to a disordered state. However, the fading rate becomes nearly negligible for the most disordered feldspars.

Fracture and creep of glass–ceramic solid oxide fuel cell sealant materials

The reliable operation of solid oxide fuel cell stacks depends strongly on the structural integrity of the sealing materials. In this respect, failure and deformation are aspects which need to be assessed in particular for glass–ceramic sealant materials. Bending tests and compressive tests were carried at room temperature and typical stack operation temperature for sintered bars and stack similar head-to-head joined glass–ceramic sealants specimens with different degree of crystallization and annealed temperature. The sealant material was screen printed onto the steel. Fracture stresses and creep data are reported. The results reveal a thickness dependent fracture stress and a decrease of the fracture stress for the partially crystallized sealant at operation relevant temperatures that can be associated with the residual stress state and viscous deformation of the material, respectively. A stable thickness independent fracture stress was obtained for the fully crystallized sealant. Fractographic based analysis gave insight into the failure origin.

Simulated body fluid electrochemical response of Zr-based metallic glasses with different degrees of crystallization

The bio-electrochemical response in simulated body fluid of the Zr53Cu30Ni9Al8 metallic glasses with different degrees of partial crystallization was systematically examined and discussed. Through thermal annealing, the volume fractions of the crystalline phases are determined to be 0, 34, 63, and near 100%. Based on the bio-corrosion voltage and current, as well as the polarization resistance, it is concluded that the fully amorphous alloy exhibits the highest bio-electrochemical resistance. With an increasing degree of partial crystallization, the corrosion resistance becomes progressively degraded. The passive current reveals that the fully amorphous metallic glasses can form a more protective and denser passive film on the metallic glass surface. The formation of reactive nanocrystalline phases in the amorphous matrix would reduce the bio-corrosion resistance.

Elevated temperature effects on the mechanical properties of solid oxide fuel cell sealing materials

A promising candidate to fulfil the solid oxide fuel cell sealant requirements with respect to gas tightness, high temperature stability and electrical insulation appear to be glass-ceramic sealing materials. However, the reliable operation of solid oxide fuel cell stacks depends strongly on the structural integrity of the sealing materials. In this respect failure and deformation are aspects which need to be assessed in particular for glass ceramic sealant materials. Bending tests were carried at room temperature and typical stack operation temperature for glass ceramic sealants with different degree of crystallization. Elastic moduli, fracture stresses and viscosity values are reported. In addition to sintered bars bending testing were carried out for steel specimens that were head-to-head joined with the glass ceramics similar as in a stack application, where the ceramic particle reinforced sealant material was screen printed onto the steel. The results reveal a decrease of the strength for the partially crystallized sealant at operation relevant temperatures that can be associated with the viscous deformation. Fractographic analyses based on a combination of optical, confocal and scanning electron microscopy gave insight into the failure origin.

Effect of Lipid Physical State of Palm Derivatives on β‐Carotene Bleaching

This research was addressed to study the effect of lipid physical state on bleaching kinetics of β-carotene. To this aim, β-carotene was added to palm oil and palm stearin and the samples were stored at increasing temperatures allowing different degree of crystallization. Phase transition properties of palm derivatives were studied by differential scanning calorimetry and synchrotron X-ray diffraction, whereas β-carotene bleaching kinetics were followed by measuring color changes. Bleaching proceeded at comparable rate in palm oil and palm stearin containing systems stored at 20 and -18 °C, whereas the color changes showed a maximum rate at 4 °C in palm stearin samples and at -7 °C in palm oil systems. Arrhenius plot clearly highlighted deviations from the linearity underlining the crucial role of lipid physical properties in determining the bleaching rate. The location and the compartmentalization of β-carotene in the fat lattice could affect its chemical stability.

Spontaneous Crystallization Behavior of Phosphosilicate Glasses

We studied the spontaneous crystallization behavior for 60.5SiO2-2.5Al2O3-3P2O5- 18Na2O-16RMgO-16(1-R)CaO system glasses during cooling of melts through changing the relative content of alkaline-earth oxides. Such compositional variation leads to the formation of different crystalline phases, as well as different degree of crystallization, with the help of X-ray diffraction (XRD), heat capacity (Cp) and scanning electron microscopy (SEM). It is found that the obtained glasses are opalescent due to formation of orthorhombic NaCaPO4 during cooling when R≤0.5, and the degree of crystallization increases with substituting MgO for CaO. On the other hand, the spontaneous crystallized phases is hexagonal NaCaPO4 for R=0.75 and is Na2MgSiO4 for R=1.0, respectively, and besides, the appearance become transparent.

Mechanothermal Solid-state Synthesis of Cobalt(II) Ferrite and Determination of its Heat Capacity by MTDSC

Cobalt ferrite (CoFe2O4) has been synthesized by a solid-state mechanothermal process, and its molar heat capacity has been determined. A stoichiometric mixture of CoC2O4 ・ 2H2O and FeC2O4 ・ 2H2O was subjected to a combination of mechanical activation (by high-energy milling) and thermal activation (by annealing at temperatures between 300 and 700 °C). The process was followed by thermogravimetric analysis and high-temperature X-ray powder diffraction. It has been shown that CoFe2O4 forms at all temperatures, though with different degrees of crystallization, while Co3O4 and Fe2O3 are the only products formed when starting from unmilled mixtures. The molar heat capacity of CoFe2O4 has been determined in the temperature range 60 - 400 °C by MTDSC. It has been shown that the molar CP values of CoFe2O4 samples produced at T ≥ 500 °C are close to each other while those of the samples produced at 300 and 400 °C are lower. Furthermore the CoFe2O4 samples prepared at T ≥ 500 °C show very similar microstructures.

Non-isothermal crystallization kinetic of poly(ethylene terephthalate)/fumed silica (PET/SiO 2) prepared by in situ polymerization

A number of poly(ethylene terephthalate) (PET) nanocomposites were prepared by in situ polymerization using different amounts (0.5, 1, 2, 3 and 4 wt%) of fumed silica (SiO 2). The polymerization of PET was carried out by the two-stage melt polycondensation method. From DSC studies it was found that the melting point of the nanocomposites was shifted slightly to higher temperatures by the addition of SiO 2 till 3 wt% while for PET–4 wt% SiO 2 nanocomposite the melting point was reduced. As the amount of SiO 2 was increased the crystallization became faster, and there was, also, a shifting of the temperature of the crystallization peak to higher values, this being evidence that SiO 2 can act as nucleating agent. At higher content (3 and 4 wt%) the temperature of the crystallization peak is lower than that of PET–2 wt% SiO 2 due to the formation of crosslinked macromolecules. The activation energy is calculated with the Friedman's method. PET/SiO 2 samples present lower activation energy compared to that of neat PET, except those of PET–4% SiO 2, in which the activation energy have a maximum value for α = 0.8 probably due to the second crystallization peak. Extensive crystallization studies by using Avrami, Ozawa and Malek methods verified that PET and its nanocomposites must be crystallized by two mechanisms with different activation energies taking place in different degrees of crystallization.

Novel Double-Layer Structure LTCC Substrate with Enhanced Flexural and Adhesions Strengths

To enhance both adhesive strength and flexural strength, a new structure consisting of two layers with different degree of crystallization was investigated as a substrate material for low-temperature co-fired ceramics (LTCC). A mixture system of silica-based glass and Al2O3 crystalline powder, which is known to be crystallized during the sintering process was used. Glasses with different compositions and various amounts of alumina filler were used for our new structure. Crystallization behavior was monitored by means of powder X-ray diffraction. The microstructure of sintered body after electroless plating was examined by scanning electron microscopy. It was observed that the degree of crystallization was strongly affected by glass composition and amount of alumina filler but sintering behavior depended on glass composition rather than amount of alumina. The combination of layers with 40 wt% alumina and 45 wt% alumina as an inner layer and outer layer, relatively, shows 362 MPa flexural strength and 1.74 kgf adhesion strength.