Effect of strontium on Nd doped Ba1-x Sr x Ce0.65Zr0.25Nd0.1O3-δ proton conductor as an electrolyte for solid oxide fuel cells.

This paper investigated the Sr doping effect on the microstructure, chemical stability, and conductivity of Ba1-x Sr x Ce0.65Zr0.25Nd0.1O3-δ (0 â©½ x â©½ 0.2) electrolyte prepared by sol-gel method. The lattice constants and unit cell volumes were found to decrease as Sr atomic percentage increased in accordance with the Vegard law, confirming the formation of solid solution. Incorporation of Sr into the composition resulted in smaller grains besides suppressing the formation of secondary phases of SrCeO3. Among the synthesized samples BaCe0.65Zr0.25Nd0.1O3-δ pellet with orthorhombic structure showed highest conductivity with a value of 2.08 × 10-3 S/cm(dry air) and 2.12 × 10-3 S/cm (wet air with 3% relative humidity) at 500 °C due to its smaller lattice volume, larger grain size, and lower activation energy that led to excessive increase in conductivity. Ba0.8Sr0.2Ce0.65Zr0.25Nd0.1O3-δ recorded lower conductivity with a value of 4.62 × 10-4 S/cm (dry air) and 4.83 × 10-4 S/cm (wet air with 3% relative humidity) at 500 °C than Sr undoped but exhibited better chemical stability when exposed to air and H2O atmospheres. Comparisons with the literature showed the importance of the synthesis method on the properties of the powders. Hence this composition can be a promising electrolyte if all the values such as sintering temperature, Sr dopant concentration, and time are proportionally controlled.

A combined experimental and theoretical studies on FT-IR, FT-Raman and UV-vis spectra of 2-chloro-3-quinolinecarboxaldehyde.

In the present study, the FT-IR and FT-Raman spectra of 2-chloro-3-quinolinecarboxaldehyde (2Cl3QC) have been recorded in the region 4000-400 and 3500-50 cm(-1), respectively. The fundamental modes of vibrational frequencies of 2Cl3QC are assigned. Theoretical information on the optimized geometry, harmonic vibrational frequencies, infrared and Raman intensities were obtained by means of density functional theory (DFT) gradient calculations with complete relaxation in the potential energy surface using 6-31G(d,p) basis set. The vibrational frequencies which were determined experimentally from the spectral data are compared with those obtained theoretically from DFT calculations. A close agreement was achieved between the observed and calculated frequencies by refinement of the scale factors. The infrared and Raman spectra were also predicted from the calculated intensities. Thermodynamic properties like entropy, heat capacity, zero point energy, have been calculated for the molecule. The predicted first hyperpolarizability also shows that the molecule might have a reasonably good non-linear optical (NLO) behavior. The calculated HOMO-LUMO energy gap reveals that charge transfer occurs within the molecule. Stability of the molecule arising from hyper conjugative interactions, charge delocalization have been analyzed using natural bond orbitals (NBO) analysis. The results show that charge in electron density (ED) in the π(∗) antibonding orbitals and E((2)) energies confirms the occurrence of ICT (intra-molecular charge transfer) within the molecule. UV-visible spectrum of the title molecule has also been calculated using TD-DFT/CAM-B3LYP/6-31G(d,p) method. The calculated energy and oscillator strength almost exactly reproduces reported experimental data.

Vibrational and electronic spectra of N-aryl ring substituted (Z)-N-(4-amino-5-(4-chlorophenyl)-3-phenylthiazol-2(3H)-ylidene)benzamide compounds.

In the present paper the vibrational, electronic and nonlinear optical properties of three N-aryl ring substituted (Z)-N-(4-amino-5-(4-chlorophenyl)-3-phenylthiazol-2(3H)-ylidene)benzamide compounds have been investigated by UV-vis, FT-IR and FT-Raman spectroscopic measurements. The electrochemical properties of the compounds were measured by cyclic voltammetry. Density functional theory calculations with B3LYP/6-31+G(d,p) basis set was used to determine the ground state molecular geometries (bond lengths and bond angles), harmonic vibrational frequencies, infrared intensities and Raman activities of title compounds. Potential energy distributions (PEDs) and normal modes, for the spectral data computed at B3LYP/6-31+G(d,p) level, have also been obtained from force-field calculations. A comparison of the theoretical spectra and experimental FT-IR and FT-Raman spectra of the title molecule has been made and full vibrational assignments of the observed spectra have been proposed. The substituent effect on the electronic properties of the title compounds were investigated by time-dependent density functional theory calculations.

Vibrational and electronic absorption spectral studies of 5-amino-1-(4-bromophenyl)-3-phenyl-1-H-pyrazole.

The FT-IR and FT-Raman spectra of 5-amino-1-(4-bromophenyl)-3-phenyl-1-H-pyrazole have been measured in the regions 4000-400 cm(-1) and 3500-100 cm(-1), respectively. The equilibrium geometry, bonding features and harmonic vibrational frequencies have been carried out with the help of DFT method. The assignments of the vibrational spectra have been carried out with the normal coordinate analysis (NCA) following the scaled quantum mechanical force field methodology (SQMFF). The first-order hyperpolarizability (ß(0)) and related properties (µ, α(0), and Δα) of 5A4BP3PP are calculated by using HF/6-31G(d,p) method on the finite field approach. Stability of the molecule arising from hyperconjugative interactions, charge delocalization have been analyzed using natural bonding orbital (NBO) analysis. The results show that electron density (ED) in the σ(*) and π(*) antibonding orbitals and second order delocalization energies E(2) confirms the occurrence of the intramolecular charge transfer (ICT) within the molecule. UV-vis spectrum of the compound was recorded and the electronic properties, such as HOMO and LUMO energies, were performed by TDDFT using 6-31G(d,p). The HOMO-LUMO calculations indicating the charge transfer takes place within the molecule.

FT-IR, FT-Raman and UV-Vis spectra and DFT calculations of 3-cyano-4-methylcoumarin.

The vibrational and electronic spectra of 3-cyano-4-methylcoumarin (3C4MC) are reported and discussed. In this work the structural properties, vibrational frequencies and electronic spectra of 3C4MC have been investigated extensively using density functional theory (DFT) employing B3LYP exchange correlation with the normal basis level 6-31G(d,p). NBO and HOMO, LUMO analysis has been carried out. The geometries and normal modes of vibrations obtained from B3LYP calculations are in good agreement with the experimentally observed data.

Vibrational and electronic spectra of 5-Acetyluracil - an experimental and theoretical study.

The vibrational and electronic properties of 5-Acetyluracil have been investigated in the ground state using experimental techniques (FT-IR, FT-Raman and UV spectra) and density functional theory (DFT) employing B3LYP exchange correlation with the 6-31G(d,p) basis set. The theoretically calculated optimized parameters, vibrational frequencies, etc., were compared with the experimental values, which yield good agreement between the observed and calculated values. The complete assignments of fundamental modes were performed on the basis of the potential energy distribution (PED). UV-vis spectrum of the compound was recorded in the region of 300-700 nm and compared with the theoretical spectrum obtained from time-dependent DFT(TD-DFT). Fluorescence microscopic imaging studies proved that the compound can be used as one of the potential light sources in the green region.