Structural and luminescent properties of terbium doped strontium titanate xerogel
We report on synthesis and photoluminescence of sol-gel derived terbium doped strontium titanate on monocrystalline silicon and in the porous anodic alumina matrix. The microstructure and morphology of the samples are analyzed by X-ray diffraction and scanning electron microscope analyses. The thickness of the spin-on films deposited on silicon is about 115 and 170 nm due to the annealing temperature 750 and 1000 °C respectively. The samples reveal terbium luminescence in the visible range.
CHARACTERIZATION OF POLYCRYSTALS OF STO DOPED WITH EUROPIUM: Sr1 − XEuxTiO3
ABSTRACT The crystalline structure, microstructure, luminescence and dielectric properties of SrTiO3 polycrystals doped with Eu3 + at different compositional ratios were studied by XRD, XPS and SEM analyses. Rietveld refinement of the XRD data shows a slight decrease of the cell volume indicating the incorporation of Eu3 + in the crystalline structure. The structure remains cubic (Pm3m) at room temperature in the analyzed range of Eu doping. XPS studies revealed the characteristic signal of the Eu3 + ion in the solid solution. From the dielectric behavior it was possible to identify that Eu doping produces changes with respect to pure STO. Photoluminescence spectra taken at room temperature showed that Eu3 + doping of SrTiO3 causes emission peaks at 590 and 616 nm.
Analysis of molecular interactions in solid dosage forms; challenge to molecular pharmaceutics.
The molecular states of active pharmaceutical ingredients (APIs) in pharmaceutical dosage forms strongly affect the properties and quality of a drug. Various important fundamental physicochemical studies were reviewed from the standpoint of molecular pharmaceutics. Mechanochemical effects were evaluated in mixtures of APIs and pharmaceutical additives. Amorphization, complex formation and nanoparticle formation are observed after grinding process depending on the combination of APIs and pharmaceutical additives. Sealed-heating method and mesoporous materials have been used to investigate drug molecular interactions in dosage forms. Molecular states have been investigated using powder X-ray diffraction, thermal analysis, IR, solid state fluorometry, and NMR.