Characterization of micro-crystalline lead tungstate with different morphologies produced by the sonochemical process

Micro-crystalline PbWO₄ was sonochemically produced using Pb(CH₃COO)₂ · 3H₂O and Na₂WO₄ · 2H₂O in aqueous solutions with and without anionic surfactant (sodium dodecyl sulphate or sodium lauryl sulphate). The product morphologies were influenced by the pH values and the surfactant. Micro-crystalline PbWO₄ composing of Pb, W and O, and W-O stretching vibration band of WO₄ tetrahedrons were detected using XRD, SEM, EDX, TEM, SAED and FTIR. Photoluminescent intensities, caused by the electronic transition from ¹T₂ to ¹A₁ states, shown to increase with the increase in the pH values of the solutions.     

Microwave-assisted hydrothermal synthesis of BiOBr/BiOCl flowerlike composites used for photocatalysis

Research on Chemical Intermediates - BiOBr/BiOCl flowerlike composites were successfully synthesized in different solutions containing 0.00–1.50 g polyvinylpyrrolidone (PVP) by...     

Influence of Calcination Temperature on Particle Size and Photocatalytic Activity of Nanosized NiO Powder

Russian Journal of Physical Chemistry A - Nanosized NiO particles were synthesized by a combined solvothermal-calcination process using Ni(NO3)2 · 6H2O as a starting reagent in the presence of...     

Influence of cetyltrimethylammonium bromide on the morphology of AWO4 (A = Ca, Sr) prepared by cyclic microwave irradiation

AWO₄ (A = Ca, Sr) was prepared from metal salts [Ca(NO₃)₂·4H₂O or Sr(NO₃)₂], Na₂WO₄·2H₂O and different moles of cetyltrimethylammonium bromide (CTAB) in water by cyclic microwave irradiation. The structure of AWO₄ was characterized by X-ray diffraction (XRD) and selected area electron diffraction (SAED). Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) revealed the presence of nanoparticles in clusters with different morphologies; spheres, peaches with notches, dumb-bells and bundles, influenced by CTAB. Six Raman vibrational peaks of scheelite structure were detected at 908, 835, 793, 399, 332 and 210 cm⁻¹ for CaWO₄ and 917, 833, 795, 372, 336 and 192 cm⁻¹ for SrWO₄, which are assigned as ν₁(A_g), ν₃(B_g), ν₃(E_g), ν₄(B_g), ν₂(A_g) and ν_f.r.(A_g), respectively. Fourier transform infrared (FTIR) spectra provided the evidence of W-O stretching vibration in [WO₄]²⁻ tetrahedrons at 793 cm⁻¹ for CaWO₄ and 807 cm⁻¹ for SrWO₄. The peaks of photoluminescence (PL) spectra were at 428-434 nm for CaWO₄, and 447-451 nm for SrWO₄.