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A systematic study of orthorhombic phase formation at ambient conditions beyond a critical concentration of dopant Tantalum (Ta) in HfO 2 is reported. The effect on the path of structural evolution...

We have prepared the composites of a room temperature nematic liquid crystalline material namely 4-(trans-4′-n-hexylcyclohexyl) isothiocyanatobenzoate (6CHBT) and gold nanoparticles (GNPs). Thermodynamic, electro-optical and dielectric properties have been investigated. Effect of dispersion of GNPs on various electro-optical and display parameters of host liquid crystalline material have been studied. Physical parameters such as threshold voltage, dielectric anisotropy and splay elastic constant have altered for composite systems. Due to the dispersion of GNPs, nematic to isotropic transition temperature is significantly increased. Relaxation frequency corresponding to flip-flop motion of the 6CHBT molecules about their short axes has increased due to the presence of GNPs.

Boron was determined in ThO2 employing spectrophotometry using curcumin as complexing agent after dissolution with 85 % ortho phosphoric acid and separation of boron with 10 % 2-ethyl hexane 1,3 diol in CHCl3. The methodology was validated by employing ThO2 standards made from inter laboratory comparison experiments DAE, India. Absolute detection limit of the methodology was found to be 30 ng. Precision and accuracy of the methodology were found to be 4.2 and 2 % respectively. The expanded uncertainty in measurement of boron (at coverage factor 2) was estimated as per ISO guidelines employing bottom-up approach and it was found to be 9.2 %.

Electric field induced dichroism of the UV absorption and dipole relaxation behavior of OH - in CsBr at low temperature is unlike its behavior in other alkali halides. Single-multiplet tunneling model, quite successful in explaining the behavior of OH - in most of the alkali halides, fails in the case of CsBr. It is shown that the two-multiplet tunneling model, introduced in previous work to explain some of the anomalous results in other systems, successfully accounts for the anomalous behavior of OH - in CsBr.

A microscopic model for the substitutional ${\mathrm{NO}}_{2}^{\mathrm{\ensuremath{-}}}$ impurity ion in NaCl-structure alkali halide crystals is developed on the basis of a specific theoretical potential. Coulomb, induction, and short-range interactions are included to obtain expressions for the barriers hindering the rotational motion of the impurity in the matrix cage. Preferred orientations, off-center displacements, and barrier parameters for this impurity are calculated in KCl, KBr, and KI host crystals. The results are used to explain most of the features of the infrared spectra in these impurity systems.