A host glass matrix composed of potassium bismuth borosilicate that has been reinforced with 2, 4, 8, and 16 mol% La2O3 to act as a gamma-ray shield. Thermal, optical, and shielding qualities have ...been impacted by the penetration of La2O3 into the suggested host glass, which fills the interstitial spaces. The density increases from 4.304 g/cm3 to 6.384 g/cm3 with an increase in La2O3 while (Vm) decrease. The glass under consideration demonstrated a high degree of thermal stability as the content of La2O3 increased. When La3+ ions are added, the resulting glasses' optical transparency improves to above 77 %. The origin of these glasses is non-metallic. Gamma-ray attenuation of the glasses was developed with increasing amounts of La2O3. The glass containing 16 mol% La2O3 is a promising candidate for protective shields in various nuclear applications due to its high thermal stability, transparency, and effective capability to reduce gamma rays.
•Potassium bismuth borosilicate glasses containing La2O3 that were manufactured.•The density increases from 4.304 g/cm3 to 6.384 g/cm3Vm).•The glass containing 16 mol% La2O3 is a promising candidate for protective shields.
Recovery of iron values from the Barsua iron ore slimes containing 56% Fe, 4.8% SiO2, 7.2% Al2O3 and 7.0% LOI by the addition of synthetic colloidal magnetite and oleate colloidal coating followed by ...high gradient magnetic separation technique was investigated. The effects of concentration of colloidal magnetite, pH, and magnetic field strength were studied. The detailed characterization studies of the slime samples carried out by SEM, FTIR, and AFM analysis suggested the coating of magnetic material on iron oxide surface. AFM studies of slime and slime coated with colloidal magnetite provided information about the average height and roughness on the calculated area. The image profile of iron ore slimes equilibrated by oleate colloidal magnetite indicated the maximum height due to the presence of an oleate group, which has a strong affinity for iron atoms. Finally, an iron concentrate of 62.6% Fe, 2.0% SiO2, and 3.5% Al2O3 with 72% recovery was achieved at pH7 and at colloidal magnetite concentration of 10–40g/t at 12kG, whereas the recovery was only 62.4% without the addition of colloidal magnetite at the same magnetic field intensity.
Display omitted
•Recovery of iron values from iron ore slimes using selective magnetic coating•Colloidal magnetite and oleate colloidal magnetite used as the coating agents•FTIR and AFM studies confirm preferential magnetic coating on hematite.•Iron recovery enhanced compared to conventional magnetic separation.
Display omitted
•We investigate evaporation characteristics of palm methyl ester (PME) droplet.•Results for PME, diesel fuel and n-hexadecane droplets were compared.•Thermogravimetric and ...differential thermal analyses were also conducted.•Droplet lifetime of PME is longer than that of diesel fuel and n-hexadecane.•Exothermic polymerization reactions occur during PME droplet evaporation.
To investigate the evaporation characteristics of a palm methyl ester (PME) droplet at high ambient temperatures, droplet evaporation experiments were conducted. Thermogravimetric and differential thermal analyses (TG–DTA) were also conducted to investigate the presence of exothermic reactions during fuel evaporation. The results for PME were compared with those for diesel fuel and n-hexadecane. The results show that the initial heating period decreases and the average evaporation coefficient increases with increasing ambient temperature for all fuels. As a results, the droplet lifetime decreases with increasing ambient temperature for all fuels. It was found that the droplet lifetime of PME is longer than that of diesel fuel and n-hexadecane. The average evaporation coefficients of PME and diesel fuel are almost equal. The longer initial heating period of PME due to the higher boiling points of the components leads to the longer droplet lifetime. It was also found that exothermic reactions occur during PME droplet evaporation. The exothermic reactions are considered to be polymerization reactions of the unsaturated fatty acid methyl esters. The volume of the residue formed by the polymerization reactions decreases with increasing ambient temperature due to the shorter reaction time before complete evaporation.
•A proposal of hydration degree calculation for blended cement pastes is presented.•The method is based both on the contributions of various authors and on DTA–TG results.•Paste and mortar specimens ...with BFS, FA and SF mineral admixtures were used.•The evaluation of CH gives information on hydration and pozzolanic reactions.•The assessment of α provides an insight into future strength evolution.
The degree of hydration assessment of cement paste from differential thermal and thermogravimetric analysis data has been performed by several authors that have offered a number of proposals for technical application to blended cements. In this paper, two calculation methods are studied in detail. Then, a proposal of the degree of hydration calculation for blended cements, based on the analysis of experimental results of DTA–TG, is presented. The proposed method combines the contributions of the authors and allows straightforward calculation of the degree of hydration from the experimental results. Validation of the methodology was performed by macroscopic and microstructural tests through paste and mortar specimens with blast furnace slag, flying ash and silica fume mineral admixtures bei(g)ng used. Tests of scanning electron microscopy with an energy dispersive analyser on paste specimens, and of mechanical strength on mortar specimens with the same percentages of substitution, were performed. They showed good agreement with the information derived from the differential thermal and thermogravimetric analysis data.
Nano-spinel zinc ferrites (ZnFe2O4) with substitution of diamagnetic magnesium (Mg2+) ions were synthesized using solution-gelation (sol-gel) self ignition route. The thermal, structural, spectral, ...optical and N2-physisorption properties of the prepared Zn–Mg ferrite nanoparticles were analyzed by standard characterization techniques. The temperature dependent spinel phase formation and percentage weight loss was studied by thermogravimetric and differential thermal analysis (TG-DTA). The analysis of the room temperature X-ray diffraction (XRD) patterns showed the formation of cubic spinel structure with single phase in the Zn–Mg ferrites. The crystallite size decreasing from 27 nm to 20 nm with Mg2+ substitution confirmed the nanocrystalline formation of the Zn–Mg ferrites. The two characteristics vibrational modes of interstitial sub-lattice sites corresponding to the spinel structure were observed within the desired wavelength range of the FT-IR spectra. The optical band gap values estimated from the UV–Visible data analysis is found to be in the scope of 1.96 eV–2.39 eV. The photoluminescence (PL) spectra showed the broader emission band in the visible region (around 525 nm) for all the samples of Zn–Mg ferrites. The BET isotherms were recorded by the N2 adsorption-desorption and the surface area, pore volume, average pore radius etc surface parameters were deduced. The BET surface area and average pore radius values were obtained in the range of 5.6–24.8 m2/gm and 2.61–4.52 nm respectively.
•The AHMP+.AMBA− compound was synthesized by the slow evaporation technique.•The present compound was characterized by SCXRD, FTIR and DFT analyses.•The O⋅⋅⋅H and H⋅⋅⋅H contacts are observed as ...significant interactions.•TG and DTA analyses show thermal stability up to 168 ºC of the present salt.•AHMP+.AMBA− is suitable for the fabrication of optoelectronic and photonic devices.
The organic crystal (AHMP+.AMBA−) of the AHMP and AMBA organic compounds was successfully synthesized and grown by the slow evaporation solution process. The present work focuses on the crystal structure, Hirshfeld surface, spectroscopic and DFT analyses of the title salt. The crystal geometry of AHMP+.AMBA− monohydrated salt was characterized by the single-crystal XRD technique. The synthesized salt crystallizes in the triclinic crystal system and P-1 space group. The identification of the functional groups of the compound has been done by FTIR spectroscopy and DFT/B3LYP-D3/6–311++G(d,p) level of theory. Further, Hirshfeld surface mapping and its associated two-dimensional fingerprint plots predict that the O⋅⋅⋅H and H⋅⋅⋅H interactions are dominant for stabilizing the crystal structure. TG-DTA reveals the crystal is thermally stable up to 168 ºC. The optical studies have been performed by the time-dependent DFT (TD-DFT) and UV–Vis spectroscopic methods. Moreover, the Z-scan experiment has been done to obtain third-order NLO properties. Additionally, the HOMO-LUMO energy gap, MEP maps and theoretical NLO parameters have also been calculated.
Display omitted
In this manuscript, a new method for the synthesis of CaCu3Ti4O12 (CCTO) perovskite was adopted via co-precipitation followed by calcination processes. The co-precipitation route was employed to ...synthesize calcium and copper oxalates precipitated on the TiO2 surfaces and the calcination technique at different temperatures was utilized to follow the single-phase formation. Differential thermal analysis-thermogravimetry (DTA-TG) were used to estimate the proper calcination temperatures and to follow the precursor′s decomposition stages. X-ray diffraction (XRD) revealed the initiation of titanate formation at 700 °C. The complete formation of single-phase was achieved at 1100 °C. In agreement with the XRD measurements, FT-IR spectra confirmed the formation the different phases at different calcination temperatures. The prepared titanate showed giant dielectric properties with values higher than reported in literature. The conductivity measurement indicated semi-conducting properties and revealed a transition agreed well with that obtained in the dielectric properties measurements vs. temperature, attributed to the orientional polarization or change in the entire conduction mechanism from hopping to ionic conduction. The obtained electrical properties enhances the utilization of the entire titanate as capacitors.
•A new organic cocrystal of AHMP.DMBA was synthesized by a slow evaporation method.•The grown cocrystal was characterized by single crystal XRD.•FTIR, NMR, UV–vis and TG/DTA studies were ...presented.•Hirshfeld surface analysis and DFT/B3LYP calculations were also performed.
A newly synthesized organic cocrystal (AHMP.DMBA) of 2-amino-4‑hydroxy-6-methylpyrimidine (AHMP) and 2,4-dimethylbenzoic acid (DMBA) was successfully grown by the slow evaporation method. The current report focuses on the molecular structure, vibrational study, thermal analysis and electronic properties of the grown crystal. The crystal structure analysis of AHMP.DMBA cocrystal was done by single crystal X-ray diffraction (SCXRD) technique. The given cocrystal crystallizes in the orthorhombic system space group Pnma. 3D Hirshfeld surface map and its associated 2D fingerprint plots have been generated for understanding the noncovalent interactions which stabilized the crystal pacing. Further, FTIR spectroscopy and B3LYP-D3/6-311++G(d,p) theory have been used to examine the vibrational modes present in the synthesized complex. The observed and simulated 13C and 1H NMR spectral analyses have also supported the structural analysis. The experimental absorption spectra and optical band gap are obtained by UV–Vis absorption spectroscopy and the theoretical electronic spectrum is computed using time dependant density functional theory (TD-DFT) method. The thermal profiles of the given sample have been recorded by thermal gravimetric/differential thermal analysis (TG/DTA). Additionally, the molecular properties i.e., HOMO-LUMO, MEP and non-linear optical parameters are also discussed.
Display omitted
The kinetics and mechanism of the development of nepheline (NaAlSiO4) through thermal transformation of sodalite (Na4Al3Si3O12Cl) was studied by means of differential thermal analysis at different ...heating rates (10°C min−1 to 50°C min−1) to control the evolution of the crystallization fraction. The conversion of sodalite (cubic crystal) to pure nepheline (hexagonal crystal) took place in the 800°C–900°C interval. The activation energy for nepheline crystallization from sodalite was determined by isothermal and non‐isothermal methods. The ratio t0.75/t0.25, together with the Avrami exponent (n) and the numerical factor of the dimensionality of crystal growth (m) parameters indicated that dominant crystallization mechanism in nepheline development is bulk crystallization mechanism controlled by interface reaction.
Display omitted
•Metakaolin improves strength characteristics of NHL mortars.•In general a decrease of strength with ageing was observed with MK incorporation.•Carbonation is the main hardening ...reaction in all curing conditions.
This paper investigates the mechanical and mineralogical characteristics of natural hydraulic lime NHL3.5 (NHL) mortars with different% of lime replacement by metakaolin (MK) under different laboratory and natural marine curing conditions.
Tests were conducted at different curing ages, using compressive and flexural strength tests and thermogravimetric and X-ray diffraction techniques.
NHL mortars cured at high humidity levels in natural and artificial environments present interesting results and some could be used in old masonries repair.
The incorporation of MK improves the NHL mortars strength, being this increase mostly associated to the pozzolanic reaction.
PDF