Synthesis And Characterization Of Two New Antimony Phosphates Co0,5alsb(PO4)3 And Mg0,5fesb(PO4)3

Two new antimony phosphates Co0,5AlSb(PO4)3 and Mg0,5FeSb(PO4)3 were synthesized for the first time by the solid-state reaction method. Their crystal structures have been refined at room temperature from X-ray powder diffraction data using Rietveld method. Co0,5AlSb(PO4)3 crystallizes in the space group R-3c (N°167) (ah = 8.23±0.01Ǻ, ch = 21.94±0.02Ǻ). Mg0,5FeSb(PO4)3 crystallizes in the monoclinic space group P21/n (N°14) (am =11.54 Ǻ, bm = 8.83± 0.02 Ǻ, cm = 8.39± 0.01 Ǻ, β = 96.67°± 0.09). Raman and infrared spectra were recorded and assignments of the stretching and bending vibrations of the PO43- tetrahedra were made. The number of the peaks observed is in good agreement with that predicted by the factor group analysis of the R-3c et P21/n space group respectively. Vibrational spectral studies of two antimony phosphates were collected in-situ at room-pressure and at elevated temperatures, up to 430 oC. At elevated temperatures in air, Mg0,5FeSb(PO4)3 seems to be stable, but Co0,5AlSb(PO4)3 show a transition at 380°C and decomposes at 930°C. This result has been confirmed by differential scanning calorimetric study (DSC).Two new antimony phosphates Co0,5AlSb(PO4)3 and Mg0,5FeSb(PO4)3 were synthesized for the first time by the solid-state reaction method. Their crystal structures have been refined at room temperature from X-ray powder diffraction data using Rietveld method. Co0,5AlSb(PO4)3 crystallizes in the space group R-3c (N°167) (ah = 8.23±0.01Ǻ, ch = 21.94±0.02Ǻ). Mg0,5FeSb(PO4)3 crystallizes in the monoclinic space group P21/n (N°14) (am =11.54 Ǻ, bm = 8.83± 0.02 Ǻ, cm = 8.39± 0.01 Ǻ, β = 96.67°± 0.09). Raman and infrared spectra were recorded and assignments of the stretching and bending vibrations of the PO43- tetrahedra were made. The number of the peaks observed is in good agreement with that predicted by the factor group analysis of the R-3c et P21/n space group respectively. Vibrational spectral studies of two antimony phosphates were collected in-situ at room-pressure and at elevated temperatures, up to 430 oC. At elevated temperatures in air, Mg0,5FeSb(PO4)3 seems to be stable, but Co0,5AlSb(PO4)3 show a transition at 380°C and decomposes at 930°C. This result has been confirmed by differential scanning calorimetric study (DSC)

Sorption of Cd(II), Ni(II) and Zn(II) on natural, sodium-, and acid-modified clinoptilolite-rich tuff

Sorption of Cd2+, Ni2+and Zn2+ions on natural (ZPCli), sodium modified (ZPCliNa) and acid modified (ZPCliH) zeolites have been investigated in function of the contact time, pH, and metal concentration by the batch technique. The characterization of ZPCIi, ZPCliNa, and ZPCliH materials was performed using X-ray powder diffraction, scanning electron microscopy and energy dispersive X-ray spectroscopy techniques. The surface area (BET) and the pHpzcwere also determined. The pH in the point of the zero charge of ZPCli, ZPCliNa, and ZPCliH zeolites was 8.25, 8.00, and 2.05, respectively. The kinetic sorption data for ZPCli, ZPCliNa and ZPCliH were well fitted to the pseudo-second order model (R2> 0.99). The linear model described the Cd, Ni and Zn sorption isotherms for ZPCliH, while for ZPCliNa and ZPCliH it was the Freundlich model. The unmodified and modified zeolitic materials showed the highest sorption capacity for Cd2+, lower for Zn2+ and Ni2+

Synthesis, structure, magnetic, optical and Mössbauer properties of Na2FeSn(PO4)3

The phosphate Na2FeSn(PO4)3, obtained by solid state reaction, was found to be isotypic with Na2CrTi(PO4)3, with space group R-3c and unit cell parameters a = 8.6617(2)Å, c=22.0161(7)A, V = 1430.47(5)Å3, Z=6. The structural parameters refined using Rietveld method showed that the Na+ ions occupy totally the M1 sites and partially the M2 sites and sharing faces with the [Sn/FeO6] octahedra. The presence of the unique valence of ferric iron in the reported phosphate was confirmed using UV-visible diffuse-reflectance spectroscopy, magnetic measurements and Mössbauer spectroscopy

A Reitveld quantitative XRD phase-analysis of selected composition of the Sr

Qualitative XRD phase-analysis of four (x = 0.10, 0.20, 0.30, 0.40) selected compositions of the Sr(0.5+x)Sb(1−x)Fe(1+x)(PO4)3(0 < x < 0.50) system was undertaken. XRD data shows the absence of a continuously solid solution. In fact, each composition is composed only of a mixture of the two end members, Sr0.50SbFe(PO4)3 (R$\bar{3}$ space group) and SrSb0.50Fe1.50(PO4)3 (R$\bar{3}$c space group), type-phases. Rietveld refinement method, using the XRPD technique, has been used for a quantitative phase-analysis of these compositions. In order to evaluate the relative errors of this experimental result, a set of standard phase-mixtures of both end compositions of the system was also quantified by the Rietveld method. Obtained results show the usefulness of this method for quantitative phase-analysis, particularly in geology including other classes of materials such clay and cement

Effect of BaO-Bi2O3-P2O5 glass additive on structural, dielectric and energy storage properties of BaTiO3 ceramics

International audienceA phosphate BaO-Bi2O3-P2O5 (BBP) glass is added to BaTiO3 ceramics (BT) to investigate its influence on densification, rearrangement of structural units, and dielectric properties of the elaborated composites. The BT ceramic is elaborated by the solid-state method while the glasses BaO-Bi2O3-P2O5 (BBP) are synthesized by the melting-quench process. The synthesized composites are labeled BT-xBBP (x = 2.5, 5, and 7.5 wt %) where x stands for the glass content in weight percent. The density was measured to determine the appropriate sintering temperature of the composites, it was found that the glass addition induces a decrease in their densification and helps their sintering at lower temperatures, the suitable sintering temperature (SST) obtained for all the composites is 900 degrees C. Raman spectroscopy and X-ray Diffraction are performed to study the structural approach of the BBP glass addition to BT ceramics. The scanning electron microscopy was used to examine the morphology of pure BT and sintered composites. It was observed that the BT-(x = 5) composite had a uniform small grains microstructure. The composition dependence of the dielectric properties shows that a material BT-(x = 5) has the highest dielectric constant at room temperature. The P-E plots were carried out and the energy storage parameters (density and efficiency) of the composites are determined. These parameters are affected by the porosity and the remnant polarization of the composites

Structural, optical, and dielectric properties of Bi2O3-K2O-TiO2-P2O5 glasses and related glass-ceramics

International audienceThe glasses in the Bi2O3-K2O-TiO2-P2O5 system were elaborated by the conventional quenching method. Their structure was studied by Raman spectroscopy, and additional information is determined from density measurements and thermal analysis. The optical absorption of the glasses is investigated and it is found that the optical gap and the Urbach energy decrease and increase, respectively, with increasing Bi2O3 content. The crystallization of the glasses was performed under controlled heat treatments to develop glass-ceramics. Their dielectric constants are carried out by impedance spectroscopy. The variations of the permittivity (epsilon(r)) and the dielectric loss (tan delta) versus frequency and temperature are determined. It is evidenced that the introduction of Bi2O3 in the glasses diminished the dispersion at low frequencies. The presence of bismuth oxide in the materials is also beneficial since it allowed the formation of glass-ceramics with high dielectric constant and low dielectric loss

Punica granatum leave extract as green corrosion inhibitor for mild steel in Hydrochloric acid

Leave of Punica granatum extract (LPGE) as green inhibitor for the corrosion of mild steel in 1M HCl solution was studied using weight-loss and potentiodynamic polarization measurements. The results obtained revealed that LPGE has fairly good inhibiting properties for mild steel corrosion in 1M HCl solution, with efficiency of around 94 % at a concentration of 1 g/l. The inhibition was of a mixed anodic–cathodic nature. The film which is formed over the metal surface was analysed by FT-IR spectroscopy. Further examination using X-ray diffraction confirms the role of LPGE as an effective corrosion inhibitor for mild steel in acid media

An experimental investigation on morphological, mechanical and thermal properties of date palm particles reinforced polyurethane composites as new ecological insulating materials in building

The rigid polyurethane (PU) with apparent density about 40 kg/m3 was prepared using commercial polyols and polyisocyanate. This reference petrochemical formulation was modified with natural and renewable components such as date palm particles (DPP). The goal of this investigation was to reduce the environmental impacts, and reduce the cost of the petroleum based polyurethane (PU) by obtaining polyurethane/date palm particles (PU-DPP) composites with the heat insulating and mechanical properties similar or better as in the case of the reference material (PU). The composites were prepared with different (DPP) loading; 5%, 10%, and 20% (by weight). The results showed that heat insulating and mechanical properties of the (PU-DPP) composites were comparable with those from reference petrochemical formulation (PU). On the other hand these mechanical and thermal performances are competitive with those of other insulating material available on the market. Hence the (PU-DPP) is a good candidate for development of efficient, low cost, and safe insulating materials

Mechanical and thermal conductivity properties of hemp fiber reinforced polyurethane composites

The aim of the present work is to introduce natural hemp fiber as reinforcement in the preparation of partially biodegradable green composites. Composite of rigid polyurethane (PU) and hemp fiber (H.F) ​​were prepared at different loading rates in (H.F) ​​(5%, 10%, 15%, 20%, 25% and 30%). Water absorption, thermal conductivity, and mechanical properties of composite were investigated as a function of fiber content. The results show that, the thermal conductivity of composites increases linearly with density. The mechanical properties of composites with 15% wt fibers loading provided a 40% increase in strength. Measured properties showed that polyurethane- hemp fibers composite present good insulating properties compared to the traditional insulation materials (glass wool, mineral wool etc.). Therefore, (PU-HF) insulation may provide a promising solution for building insulation. Keywords: Hemp fiber, Polyurethane, Resin, Green composites, Thermal conductivity, Mechanical properties, Water absorptio