[en] Flavonoids are widespread groups of natural constituents and present in the drugs in the form of mono or diglycosides. Being physiologically active, flavonoids are important in the field of pharmacological and clinical applications. Not many physical properties of flavonoids have been studied so far excepting UV and NMR studies. This paper deals with the evaluation of electron ionization cross section through λ sub max, a parameter available from UV studies. Electron ionization cross section was primarily conceived to be of use in radiation chemical data, mass spectroscopic and thermodynamic studies. But later attempts to correlate electron ionization cross-section with structural and related parameters prompted the authors to derive an explicit expression relating λ sub max and electron ionization cross-section (Q). The application of this method to correlate Q through λ sub max and interpret the results in terms of chemical activity are discussed

[en] Cr³⁺ metal ion doped Zinc-Lead-Lithium-Phosphate glass samples are made by melt quenching technique, by varying 0.2% mol (20-x) Li₂CO_3−x Cr₂O₃ in glass mixture composition. To identify basic structural units in these glasses, to investigate structural changes with the change in glass composition and to relate structural changes with the difference in properties of glasses, the samples subjected to spectral studies of XRD, UV–vis, EPR and FTIR. The physical properties of the glass samples like average molecular weight, Cr³⁺ ion concentration, density, refractive index etc, were calculated. Spin–Hamiltonian parameters are evaluated from EPR spectra which exhibit two resonance intense signals representing coupled pair and free state of Cr³⁺ ions. The breakage of Phosphorous—Oxygen—Phosphorous (P–O–P) link and the development of cross ionic bonding among the chains of phosphate are identified in FTIR spectra. From optical absorption spectra, crystal field parameters and optical band gap values have been calculated. The optical band gap value of the prepared phosphate glasses is found to lie in the range 1.60–1.63 eV, which fined immediate applications in the fabrication of ultra high speed Integrated circuits, IR photon detectors and thin films. (paper)

[en] In the present work, structural, magnetic, and dielectric properties of conventional- and microwave-sintered Ni_0.6Zn_0.4-xCu_xFe₂O₄ (x = 0.0 to 0.4 in steps of 0.1) are studied. X-ray diffraction measurements confirm the formation of a single spinel phase. Crystallite size estimated from Scherrer’s method found between 30–41 nm and 36–28.5 nm in conventional- and microwave-sintered samples respectively. The lattice constant decreases with Cu substitution, suggesting the incorporation of Cu into the spinel lattice. SEM images reveal that microwave sintering results in larger grains with intragranular pores. Saturation magnetization was found to decrease with Cu content. Cation distribution estimated from the magnetization data supports the observed changes in magnetic parameters. A significant influence on microstructure and cation redistribution on dielectric properties are observed for microwave-sintered samples.

[en] A series of diamagnetic aluminum (Al³⁺) substituted Ni-Zn Nanoferrites have been synthesized using sol-gel auto combustion route. Structural, magnetic, and dielectric properties were systematically studied and reported with respect to Al³⁺ substitution in host Fe³⁺ ions. X-ray diffraction (XRD) and infrared spectroscopy (IR) measurements confirm the presence of Al³⁺ ions at both A and B sites. Cation distribution proposed from XRD and IR correlates with magnetic and dielectric results. It is observed that Al³⁺ ions are distributed in to tetrahedral and octahedral sub-lattices. The saturation magnetization varies between 58.5 and 44.2 emu/g with increasing Al³⁺ substitution. This decrease in magnetization is ascribed to presence of the non-collinear spin (canted spin) structure in octahedral sub-lattice. Dielectric constant decreased and a significant improvement in AC resistivity is observed with Al³⁺ substitution. The observed variations are accounted on the basis of cation distribution in spinel ferrite.

[en] Highlights: • NaBiSrP glasses with Dy³⁺ ions were prepared by using melt quench technique. • Under 350 nm excitation the NaBiSrP glasses give white emission. • Energy transfer through dipole-dipole interaction leads to concentration quenching. • Calculated CIE coordinates are fall in white region and close to commercial pc-LED. • 1.0 mol% of Dy3+ ions in these glasses exhibits 89.17% quantum efficiency. -- Abstract: This paper focus on spectroscopic analysis of Sodium Bismuth Strontium Phosphate (NaBiSrP) glasses doped with dysprosium (Dy³⁺) ions using X-ray Diffraction (XRD), Raman Spectroscopy, Fourier Transform-Infrared (FT-IR) Spectroscopy, Photoluminescence (PL) Spectroscopy and decay spectral measurements. Excitation spectra of the glasses under 575 nm emission possess a sharp band corresponding to ⁶H_15/2 → ⁶P_7/2 transition (350 nm). Subsequently, emission spectra recorded under 350 nm excitation exhibit sharp bands at 480 and 575 nm. The Judd-Ofelt (J-O) theory has been applied to the measured energies of the absorption bands/oscillator strengths to study various radiative parameters such as radiative and total transition probabilities (A_R &A_T), branching ratios (β_R) and radiative lifetimes (τ_R) for the prominent fluorescent levels of Dy³⁺ doped NaBiSrP glasses. It was observed that glass D has got highest value of Ω₂ signalling high symmetry of crystal field of Dy³⁺ ions and a maximum intensity for hypersensitive transition. PL decay analysis reveal experimental lifetimes of ⁴F_9/2 energy level under 350 nm excitation decreases with increase in Dy³⁺ ion concentration indicating the energy transfer between Dy³⁺ ions. The Inokuti-Hirayama (I–H) curve fitting was also done for the glass with the highest Dy³⁺ ion concentration showing dipole-dipole interaction. From the above-mentioned results, it is apt to say that the as synthesized phosphate glasses doped with Dy³⁺ ions are quite suitable for designing the white light emitting diodes (wLEDs) and other optoelectronic devices.