Crystalline Phase Composition Research Articles

Crystallization behavior, structure and properties of glasses in SrO–Fe2O3–P2O5 system

Crystallization behavior, structure and properties of the glasses in SrO–Fe2O3–P2O5 ternary system, with the content of P2O5 fixed to be 60, 50 and 40 mol%, were studied systematically. For vitreous samples, thermal expansion coefficients (TEC) and characteristic temperature were obtained by using a thermal dilatometer, while their thermal stability was examined by using a differential scanning calorimeter (DSC). Accordingly, their heat treatment schedules were determined. Furthermore, their chemical durability was characterized according to the dissolution rate (DRwater) in distilled water at 90 °C. Glass forming region of the SrO–Fe2O3–P2O5 ternary system at 1250 °C has been identified. It was found that crystallization behavior, crystalline phase compositions, structure and properties of the samples are closely related to the ratios of O/P and Fe/P. Specifically, the iron phosphate glasses were explored as the host matrices to immobilize high-level radioactive wastes (HLWs) with high contents of 90Sr.

Phytosynthesis and Characterization of Copper Oxide Nanoparticles using the Aqueous Extract of Beta vulgaris L and Evaluation of their Antibacterial and Anticancer Activities

With an objective of developing sustainable metallic nanoparticles from bioresources, intended for biomedical applications; herein we have fabricated copper oxide nanoparticles through a green chemistry approach. Copper oxide nanoparticles (BvCuONPs) were successfully achieved from an aqueous extract of Beta vulgaris. Synthesized BvCuONPs measure absorbance at 310 nm in UV–Visible Spectrophotometer which is characteristic of copper oxide nanoparticles. Fourier Transform Infrared Spectroscopy (FTIR) identified the responsible functional groups involved in reducing and stabilizing BvCuONPs. Transmission electron microscopy (TEM), atomic force microscopy (AFM) energy dispersive analysis spectroscopy (EDAX) displayed the morphology; crystalline phase and elemental composition of BvCuONPs. Further, we have performed the antibacterial activity of BvCuONPs against tested pathogens. Subsequently, we performed anticancer efficacy of BvCuONPs in A549 cells through cell viability assay and BvCuONPs induce apoptosis in A549 cell line with an IC50 value 25 µg/mL. In addition, BvCuONPs arrest cell cycle in G2/M phase in A549 cells; revealed by flow cytometer analysis. Therefore, it is presumed that BvCuONPs could be developed as a nano drug for infectious diseases and tumor studies.

Influence of La/B ratio on the structure, sinterability and crystallization of La2O3–B2O3–CaO glass–ceramics

To have a better understanding on the characteristics of La2O3–B2O3–CaO (LBC) glass–ceramics designed for low temperature co-fired ceramic applications, LBC glass–ceramics with La/B ratio changing from 1:6.0 to 1:3.0 were prepared, and the network structure, sinterability, crystalline phase composition and crystallization kinetics of synthesized LBC glass–ceramics were investigated. The increase of La/B ratio would reduce the content of [BO4] units in the network structure, and decrease the glass transition temperature as well as the softening temperature of LBC glass–ceramics. But low La/B ratio of glass could cause serious foaming during sintering process. The change of La/B ratio would influence the position as well as intensity of crystalline peaks on DSC curves, and the composition and microstructure of crystalline phases were also affected. The crystallization activation energies of LBC glass–ceramics were 157.9–498.7 kJ/mol, which raised up with the increase of La/B ratio.

Preparation and characterization of glass-ceramics via co-sintering of coal fly ash and oil shale ash-derived amorphous slag

Abstract A novel preparation method of glass-ceramics from coal fly ash (CFA) and oil shale ash-derived amorphous slag (OSAS) was developed in this study. Effects of important factors such as OSAS/CFA ratio and sintering temperature on the crystalline phase compositions, microstructure, mechanical-chemical properties, heavy metals leaching characteristics, and potential ecological risk assessment of glass-ceramics were investigated. The results showed that the properties of glass-ceramics increased with increasing OSAS/CFA ratio and sintering temperature, and S4 glass-ceramics (100% OSAS) showed the most superior product performances, followed by the S3 (80%OSAS-20%CFA), S2 (60%OSAS-40%CFA), and S1 (100% CFA). As for the products from the mixed sources, the best product properties of S2 glass-ceramics (density, 2.00 ± 0.04 g/cm 3 ; water absorption, 3.11 ± 0.22%; and compressive strength, 106.67 ± 28.42 MPa) were achieved at 1085 °C. S3 glass-ceramics showed the highest density of 2.16 ± 0.04 g/cm 3 , and lowest water absorption of 0.22 ± 0.01%, and highest compressive strength of 195.99 ± 23.85 MPa at 1085 °C. Specially, the overall energy consumption for preparing S2 and S3 glass-ceramics was estimated to be reduced 23.66–27.00% and 11.67–13.50%, respectively, compared to that of S4 glass-ceramics. In addition, the good chemical stability, low heavy metals leaching concentrations and low potential ecological risk of OSAS-CFA-derived glass-ceramics further confirmed its potential and feasibility as building material in engineering application.

Structural and photocatalytic properties of silicon carbide powder and nanowires modified by gold nanoparticles

Commercial bulk powder of SiC and SHS-synthesized SiC nanowires were studied. Gold nanoparticles were deposited onto a surface of both samples. Basic properties, such as crystalline structure, phase composition, morphology and photocatalytic activity with the chromatographic analysis of the reaction products, were determined. Obtained silicon carbides are crystalline materials of hexagonal (commercial SiC) and cubic (synthesized SiC nanowires) structures. The presence of gold nanoparticles was proven through Raman spectroscopy, inductively coupled plasma mass spectrometry and transmission electron microscopy. No gold phase was detected as a separate crystalline component in both Au-modified samples. The neat nanowires were indicated as a catalyst rather accumulating intermediate organic substances than commercial SiC which enables shifting equilibrium to the generation of gaseous products (CO and CH4). The gold-containing SiC nanowires demonstrated an essential enhancement of photocatalytic activity keeping Au nanoparticles on the surface after the reaction.

Influence of Replacement Level of Coal-series Kaolin on Hydration of Ordinary Portland Cement by X-ray Diffraction/Rietveld Method

The influence of replacement level of calcined coal-series kaolin (CCK) on hydration of ordinary Portland cement (OPC) was studied by X-ray diffraction(XRD)/Rietveld method. X-ray diffraction/Rietveld method was used to quantify the crystalline phase composition of the hydrated samples. Additionally, the morphology of hydrated samples was observed by scanning electron microscopy (SEM). The results showed that, calcium hydroxide (CH), ettringite (AFt) and amorphous phase content in hydrated samples decreased as the replacement level of CCK increased, while AFm and stratlingite increased, which was caused by the combination of dilute, physical and pozzolanic effects. The hydration of anhydrous cement phases was accelerated by physical effect but hindered by the retardation effect of CCK. The role of each effects was discussed in detail to analyze the mechanism of OPC hydration with CCK addition. The SEM images showed that the shortening of AFt at 1 day and the denser texture at 28 days was observed with CCK addition, which was caused by the physical and pozzolanic effects, respectively.

Magnetic Properties of FeNi₃ Nanoparticle Modified Pinus radiata Wood Nanocomposites.

Magnetic FeNi3 nanoparticles were synthesized in the internal structure of wood through an in situ fabrication approach. The morphology, crystalline phase and chemical composition of the FeNi3 modified wood was investigated by X-ray powder diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) with energy-dispersive X-ray (EDX) analysis and X-ray photoelectron spectroscopy (XPS). SEM confirmed that the magnetic nanoparticles were densely dispersed in the wood matrix. The magnetic hysteresis loops showed that the magnetism of composites is dependent on the amount of FeNi3 loading. The saturation magnetization of magnetic wood increases from 6.3 to 10.8 emu/g with an increase of FeNi3 loading from 12 to 18 wt %. Furthermore, magnetic wood showed significant directional dependence. The presented work will provide a feasible pathway for producing wood composite products.

Microstructure and Strength of Alkali-Activated Bricks Containing Municipal Solid Waste Incineration (MSWI) Fly Ash Developed as Construction Materials

Alkali-activated materials (AAM) are widely applied in the field of building materials and civil engineering to substitute cement materials. This study used two types of municipal solid waste incineration fly ash (MSWI-FA): grate-firing fly ash (GFFA) and fluidized bed fly ash (FBFA) as brick raw materials. Various weight ratio of 20%, 30%, and 40% GFFA and FBFA were added to coal fly ash (CFA), GGBFs (Ground Granulated Blast-Furnace Slag), and an alkali-activating reagent to produce alkali-activated bricks. Microstructure and crystalline phase composition were observed to analyze their compressive strength, and a leaching test was used to prove the material’s safety for the environment. It can be seen from the results of this study that the alkali-activated bricks containing FBFA had higher compressive strength than those containing GFFA in the same amount. Considering the engineering properties, the alkali-activated bricks containing FBFA are more suitable to be used as building materials. The difference in the compressive strength resulted from the large amount of calcium compounds and chloride salts present in the GFFA. From SEM analysis, it was observed that there was a large number of pores in the microstructure. It was also found from the results of XRD that the bricks containing GFFA contained a large amount of chloride salt. From the results of the two leaching tests, it was found that the amounts of six heavy metals detected in the leachates of the bricks in this study met the corresponding regulation standards. This described MSWI-FA is suitable for use as alkali-activated material, and its products have potential to be commercially used in the future.

Synthesis of Tribological WS2 Powder from WO3 Prepared by Ultrasonic Spray Pyrolysis (USP)

This paper describes the synthesis of tungsten disulfide (WS2) powder by the sulfurization of tungsten trioxide (WO3) particles in the presence of additive potassium carbonate (K2CO3) in nitrogen (N2) atmosphere, first at lower temperature (200 °C) and followed by reduction at higher temperature (900 °C). In addition, the ultrasonic spray pyrolysis of ammonium meta-tungstate hydrate (AMT) was used for the production of WO3 particles at 650 °C in air. The HSC Chemistry® software package 9.0 was used for the analysis of chemistry and thermodynamic parameters of the processes for WS2 powder synthesis. The crystalline structure and phase composition of all synthesized powders were analyzed by X-ray diffraction (XRD) measurements. The morphology and chemical composition of these samples were examined by scanning electron microscopy (SEM) combined with energy dispersive X-ray analysis (EDX).

High temperature molten flux growth, structural and optical characteristics of KTiOPO4:Ho and KTiOPO4:Er single crystals

KTiOPO4:Ho and KTiOPO4:Er single crystals are grown by a top-seeded solution growth method from potassium phosphate and MoO3 flux. The crystalline phase, packing structure and chemical composition of the crystals are analyzed by X-ray diffraction (XRD), energy dispersive spectrum (EDS). The doping of Ho and Er induced strain in the crystal is determined from Williamson–Hall relation. The bonding between titanium and oxygen of Ho and Er doping in the KTP crystal is changing the pseudo-symmetrical deviation in the lattice. The bonding of O and Ti decreases with doping Ho and Er and Ti3+ content in the crystal. The bonding, distortion of the TiO6-TiO6 chain and change in inter-atomic distances by erbium and holmium doping are assessed by Raman spectroscopy and low temperature ESR spectroscopy which evidences the low concentration of Ti3+ presence in the crystal. The KTiOPO4:Ho and KTiOPO4:Er single crystal shows second harmonic generation properties which shows that the efficiency ratio of ηKTiOPO4:Ho/η KTiOPO4 = 0.63 and ηKTiOPO4:Er/η KTiOPO4 = 0.80.

Improved photocatalytic performance of reduced zinc oxide (ZnO) novel morphology of astray like microstructure under solar light irradiation

Zinc oxide (ZnO) microstructures were successfully fabricated by using the template free hydrothermal growth method. Crystalline phase, morphology, and elemental composition had been characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), and energy dispersive X-ray spectroscopy (EDS). FESEM graphs had showed that hexagonal astray like morphology along micro sized particles. Synthesized microstructures of ZnO were hydrogenated at high temperature 500 °C to get reduced ZnO microstructures. Furthermore, ultraviolet-visible-near infrared (UV–Vis-NIR) spectroscopy had been employed to determine the optical absorbance of ZnO microstructures. The direct optical band gap of 2.1 eV was acquired by using Davis-Mott model for reduced ZnO microstructures. Hydrogenation of ZnO microstructures made the material photoactive under visible light region. Visible light active (VLA) performance of reduced ZnO microstructures improved photocatalytic degradation of pollutants under solar light irradiation. Photocatalytic performance of prepared ZnO microstructures and reduced ZnO microstructures were investigated by using methyl orange under solar light irradiation.

Templated Growth of Crystalline Mesoporous Materials: From Soft/Hard Templates to Colloidal Templates.

Mesoporous non-siliceous materials, in particular mesoporous transition metal oxides (m-TMOs), are of interest due to their fascinating electronic, redox, and magnetic properties for a wide range of applications in catalysis and energy storage. Control of the porosity (e.g., pore size, wall thickness, and surface area) and the crystalline degree (e.g., phase composition, crystallinity, and crystal grain size) of m-TMOs are critical for those applications. To crystallize TMOs, high temperature annealing is often needed to remove the amorphous defects and/or tune the compositions of different crystalline phases. This has brought many challenges to surfactant or block copolymer templates used in the process of evaporation-induced-self-assembly to prepare m-TMOs. In this review, we summarize the most recent achievements including the findings in our own laboratory on the use of organosilicate-containing colloids for the templated growth of mesoporous materials. We review a few key examples of preparing crystalline mesoporous oxides using different templating methods. The colloidal templating method by which mesoporous nanostructures can be stabilized up to 1,000°C is highlighted. The applications of m-TMOs and meso metal-oxide hybrids synthesized using organosilicate-containing colloidal templates in photocatalysis and high-temperature catalysis are also discussed.

Evaluation of in vitro properties of 3D micro-macro porous zirconia scaffolds coated with 58S bioactive glass using MG-63 osteoblast-like cells

A new family of bioceramic scaffolds consisting of zirconia foam-like structures with 58S bioactive glass (BG) coating was developed. Three open-cell structures fabricated by the foam replica method were coated via immersion in a sol-gel solution. The coating technique was optimised controlling the sol viscosity, condensation time, and the number of immersions in order to increase the coating thickness. The scaffolds chemical and structural characteristics were evaluated before in vitro tests, including the Ca/P ratio, crystalline phase composition, pH change, pore diameter and microporosity of the scaffolds struts. In vitro tests were performed by culturing MG-63 human osteoblast-like cells. An increase in cell proliferation of 100% was found with the decrease in pore size from 700 to 120 μm. Also, with the presence of the 58S-BG coating, an increase of cell proliferation was reached, which indicates the positive effect of the BG coating on the otherwise bioinert ceramic scaffold.

The effects of the nature of TiO2 supports on the catalytic performance of Rh–Mn/TiO2 catalysts in the synthesis of C2 oxygenates from syngas

Four types of TiO2 with different rutile/anatase crystalline phase compositions were used as supports, and the effect of the TiO2 phase composition on the catalytic properties of supported Rh catalysts in the synthesis of C2 oxygenates from syngas was studied.

The novel synthesis and luminescence studies of CuO and Fe2 O3 embedded(8-hydroxyquinoline)zinc nanocomposites

The present study investigates the synthesis of novel luminescent polymer nanocomposite through the incorporation of CuO and Fe2 O3 into a C18 H12 N2 O2 Zn host polymer matrix. The observed green electroluminescence behavior originates mainly from the shift in the HOMO-LUMO energy gap of the polymer matrix caused by the inclusion of oxidized metal/oxygen ions from the incorporated metal oxides into the pyridyl and phenyl groups of the host polymer. The existence of oxidized metal/oxygen ionic states in the polymer matrix is successfully confirmed through X-ray photoelectron spectroscopic analysis. The FTIR analysis is utilized to verify the presence of pyridyl and phenyl groups in the host polymer matrix. The successful incorporation of CuO and Fe2 O3 into the host polymer matrix is examined through FESEM and HRTEM analyses. XRD, EDS, and XPS analyses are employed in order to confirm the exact crystalline phase and material compositions of the samples prepared.

Morphology, Crystalline Structure and Chemical Composition Of MAO Treated Ti-15Zr-Mo Surfaces Enriched with Bioactive Ions

In this study, MAO treatment was used to enrich, with bioactive Ca, Mg and P atoms, as-casted and heat-treated Ti-15Zr-xMo (x = 0, 5, 10 and 15 wt%) alloys, for potential use as advanced metallic biomaterials. The chemical composition of the surface was evaluated by EDS and XPS measurements. The morphology and microstructure was analyzed by OM and SEM images. Crystalline structure and phase composition were characterized by XRD measurements. The results indicated that the oxide layers were porous, with microstructural features of the bulk (grain size and secondary phases) slightly affecting the surface characteristics (pore size, chemical and phase composition). The crystalline structure of the oxide layers were composed by a mixture of anatase and rutile phases (TiO2), with a minority of tetragonal zirconia (ZrO2) and traces of CaCO3 and P2O3 compounds. Chemical analysis indicated that the oxide layers were composed mainly by Ti and Zr oxides, with successful incorporation of the bioactive elements. The obtained results evidenced that the surface characteristics of MAO-treated Ti surfaces can be properly adjusted by the addition of alloying elements and implementation of specific heat treatments on the substrate. This finding can be quite useful for the development of novel biomedical implants.

Annealing Control on the Anatase/Rutile Ratio of Nanostructured Titanium Dioxide Obtained by Sol-Gel

According to the different phases at which titanium dioxide (TiO2) crystallizes, previous studies have shown that anatase is more efficient for photocatalysis than rutile. Nowadays, the synergetic effect is well-accepted between anatase and rutile as having an effect in increasing performance in photocatalysis. In the present work, control over the anatase/rutile ratio was performed in three experimental steps. Initially, amorphous-anatase TiO2 powders were synthesized by the sol-gel method. For the crystallization of anatase, the powders were annealed at 250 °C for 2 h in ambient atmosphere. The final step was performed by using different annealing times, ranging from 35 up to 200 min at a temperature of 475 °C. The powders were characterized by Raman spectroscopy, UV–VIS, SEM and TEM techniques to determine the crystalline phase, band gap, morphology, and elemental composition, respectively. It was possible to control the anatase/rutile ratio on the nanostructured TiO2 powders from 100% of anatase until a complete transformation to rutile through the variation of the annealing time. The band gap calculated using the Tauc’s model was found in the range of 2.56 to 2.93 eV. However, no direct relationship between the anatase/rutile ratio, and the band gap was found.

Photoluminescence investigation of novel reddish-orange phosphor Li2NaBP2O8:Sm3+ with high CP and low CCT

The exploration of appropriate inorganic phosphors with high color purity (CP) and low correlated color temperature (CCT) has always been a hot issue for solid state light applications. In this work, we have developed series of Sm3+ doped Li2NaBP2O8 (abbreviated as: LNBP) phosphors by means of the solid state synthesis route. The crystalline phase compositions, micromorphology, valence state of elements as well as photoluminescence properties were systematically illustrated. Upon the excitation wavelength at 400 nm, emission peaks are located at 561，597，643 and 699 nm, corresponding to the 4G5/2 → 6H5/2, 6H7/2, 6H9/2 and 6H11/2 transitions of Sm3+ in the same order. The optimal doping amount of Sm3+ ions is 2 mol% for the reddish-orange photoluminescence of the LNBP:Sm3+ phosphor system. The critical energy transfer distance, mechanism of concentration quenching, CIE chromaticity coordinate, CP, CCT and internal quantum efficiency were extensively investigated. The title product might be considered as a promising candidate of phosphor in near UV-based warm white LEDs.

Diatomite-based porous ceramics with high apparent porosity: Pore structure modification using calcium carbonate

High apparent porosity ceramics have a wide range of applications in chemical, environmental, and automotive sectors as reactors, absorbers, and cleaning devices due to their large specific surface area and excellent permeability for fluids. In this paper, porous ceramics with high apparent porosity were successfully fabricated from diatomite. Importantly, the pore structure of this ceramic was further modified by calcium carbonate (CaCO3). The results showed that the pores of the modified ceramic were in the space between the loose particles, and the position originally occupied by the calcium carbonate. An addition of 0–50 wt% CaCO3 improved the apparent porosity up to 67.53% and enlarged the pore size from ~0.7 to ~26.6 µm due to the decomposition of CaCO3, generating new pores and further transforming isolated pores to interconnected ones. The crystalline phase composition of the ceramic was found to change from cristobalite to the combination of cristobalite, wollastonite and larnite with the addition of CaCO3. The results also showed that an addition of more than 40 wt% of CaCO3 did not give much further increase in the apparent porosity due to the densification process. The modified ceramics were found to have a good mechanical strength; the ceramic with the highest apparent porosity (67.53%) had a compressive strength of 7.33 ± 0.28 MPa.

Novel solid–solid phase-change cascade systems for high-temperature thermal energy storage

In this work, we investigate novel solid–solid phase-change cascade systems based on mixtures of lithium and sodium sulfates. Solid–solid phase-change materials (PCMs) can be coupled with concentrated solar power technologies. They present several advantages over solid–liquid PCMs including lower thermal expansion, lower or no corrosiveness, and no need for encapsulation. In solid–solid PCMs, the energy is stored during crystal structure transitions. Specifically, lithium sulfate undergoes a crystal structure transition (monoclinic to cubic) at 576 °C, which is a suitable temperature for concentrated solar thermal technologies. Due to the high cost of lithium sulfate, we evaluated the potential of mixing lithium with sodium sulfate to create solid–solid cascaded PCM systems to provide higher thermal storage densities. We used differential scanning calorimetry, high-temperature in situ X-ray diffraction and thermogravimetric analysis to evaluate the phase-transition temperature, phase-change enthalpy, specific heat capacity, crystalline phase composition and thermal expansion. The obtained values for heat capacity and enthalpies of phase transitions showed good agreement with available thermodynamic databases. Therefore, further calculations of thermodynamic properties of each mixture in the system were performed for designing cascaded latent thermal energy storage system. From the PCM mixtures studied, NaLiSO4 shows the greatest stability under ambient conditions. A mixture of 59.17% NaLiSO4 and 40.83% Li2SO4 allows an optimum charge of both PCMs for power cycles such as supercritical CO2. Economic assessment revealed that this cascade system has an estimated cost of $50.2 kWhth−1.