Lead free piezoelectric single crystals of sodium potassium niobate (K 0.5 Na 0.5 )NbO 3 (KNN) were grown by high-temperature solution method using two different fluxes; one with a mixture of NaF and KF and other with addition of B 2 O 3 along with the mixture. In the present study, the growth of KNN crystals without B 2 O 3 flux and the same with B 2 O 3 flux were compared. It was found that additions of small amounts of B 2 O 3 lowered the melting temperature of the solid solution and enabled better dielectric properties. Phase analysis showed that all samples were crystallized in pure orthorhombic perovskite phase. AFM morphological studies showed that the addition of B 2 O 3 flux increased the roughness of the grown crystal. Further, addition of B 2 O 3 flux slightly decreased the orthorhombic to tetragonal phase transition temperature T (O-T) and the Curie temperature T C . The ferroelectric behaviour of KNN single crystal has been investigated at room temperature. The crystal grown using B 2 O 3 flux exhibited a remanent polarization (P r ) ∼ 32 μC/cm 2 and coercive field (Ec) of ∼11.8 kV/cm whereas the crystal grown without the use of B 2 O 3 flux had a remanent polarization (P r ) ∼ 36 μC/cm 2 and coercive field (Ec) of ∼14.6 kV/cm.

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Zinc–tin–vanadium oxide (ZTV) nanocomposite room temperature ethanol sensor (98.96% for 300 ppm) with fast adsorption (32 s) and desorption (6 s) rate is reported for first time and the mechanism is elucidated based on its structure and morphology.

Abstract-Lead free piezoelectric single crystals of (K 0.5 Na 0.5 )NbO 3 and 0.5 wt%, 1.0 wt% and 1.5 wt% MnO 2 doped (K 0.5 Na 0.5 )NbO 3 (KNN) were grown by high-temperature solution method using K 2 CO 3 -Na 2 CO 3 eutectic composition as flux with addition of small amounts of boron oxide for lowering the melting temperature. The effect of the manganese dopant on the dielectric properties, surface morphology and the domain structure were investigated. The MnO 2 -doped KNN crystals were found to exhibit higher dielectric permittivity when compared with pure KNN single crystal. Mn doping increases the dielectric constant and decreases the dielectric loss. A slight decrease in the orthorhombic to tetragonal phase transition temperature T (O-T) and Curie temperature T C has been observed in manganese-doped KNN single crystals. From SEM and AFM analysis, the domain size of KNN-Mn crystal was found to be of the order of 5-13 µm at room temperature which is smaller than that of the pure KNN crystal (20-30 µm).

Abstract-Lead free piezoelectric single crystals of sodium potassium niobate (K0.5Na0.5)NbO3 and 0.5wt%, 1wt%, 1.5wt% of copper oxide CuO doped sodium potassium niobate (K0.5Na0.5)NbO3 (KNN) single crystals were grown by hightemperature solution method and the dielectric properties, morphology and domain pattern were investigated. The flux used during crystal growth is eutectic mixture of potassium carbonate K2CO3 and sodium carbonate Na2CO3. Additions of small amounts of boron oxide B2O3 further lower the melting temperature of the eutectic mixture. It was found that 1.5wt% CuO doped single crystals of sodium potassium niobate exhibits excellent dielectric properties. XRD results showed sharp peaks indicating good crystalline behavior of both pure and CuO doped KNN crystals. Phase analysis showed that all samples crystallized in pure orthorhombic perovskite phase. A slight decrease in the diffraction angles has been observed with increase in doping concentration. This is due to the replacement of Nb5+ ions by Cu2+ ions, leading to the formation of higher oxygen vacancies with the doping concentrations.

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The dielectric behaviour of polar liquids such as propan-1-ol, propionaldehyde and their equimolar binary mixture in non-polar solvent benzene is studied in the microwave frequency range using the cavity perturbation technique at 6.218 GHz (J band), 9.880 GHz (X band), 16.331 GHz (P band) and 24.951 GHz (K band). Ab initio geometry optimization is performed in the 6-31G (d) basis set using the Gaussian 94W program for both pure and binary systems of propan-1-ol and propionaldehyde. Dipole moments of the binary mixtures are calculated from the dielectric data using Higasi's method and compared with the ab initio results. Conformational analysis of the formation of hydrogen bond between the propan-1-ol and propionaldehyde is supported by the FT-IR spectra. The average relaxation times are calculated from their respective Cole-Cole plots.