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This paper addresses the effect of Mn (2%, fixed) and Co (2, 4, and 6%, varied) substitution on the structural, optical, dielectric and magnetic responses of ZnO nanoparticles synthesized by the co-precipitation chemical route.

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In this study, the frequency and temperature dependent dielectric relaxation and electrical conduction mechanisms in NiAl2O4 spinel oxide ceramic have been explored in a frequency range of 50-10x106 Hz over a measured temperature from 163-283 K. The polycrystalline NiAl2O4 was synthesized via solid state reaction route and sintered at 1000 °C. The room temperature X-ray powder diffraction pattern confirmed the formation of NiAl2O4 spinel phase with Fd3m space group. The surface morphology of the sample was investigated by scanning electron microscopy and chemical properties by Fourier transform infrared spectroscopic analysis. Complex impedance studies revealed the presence of relaxation time distribution and charge carriers were found to be thermally activated. The Nyquist plots exhibited depressed semicircles and their fitting by an equivalent circuit model with configuration (RGCG)(RGBCGB) resolved the contributions of grains and grain boundaries to the electrical transport properties of the material. Electrical conductivity analysis followed the Jonscher’s power law behavior and the frequency exponent suggested small polaron hopping as the governing transport mechanism in NiAl2O4 spinel oxide. Non-Debye type nature of dielectric relaxation was confirmed by the complex modulus analysis whereas dielectric constant and tangent loss analysis verified that the hopping mechanism was thermally activated.

The fresh plant material of stem, leaves and seeds of Zanthoxylum alatum Roxb (Rutaceae) collected at high altitude of District Kotli, the State of Azad Jammu & Kashmir and subjected to Clevenger type hydro distillation for the extraction of essential oils. The essential oils were characterized by using gas chromatography-mass spectrometry (GC-MS) technique. Twenty five components have been identified from the stem yielded about 95.8% of the total essential oils, the major constituents were Terpinen-4-ol (30.47%), β-Terpenene (16.16%), eighteen components identified from the leaves which yields about 89.08% of the oil, Tridecanone (25%), Isohexane (21.4%), Eucalyptol (8.5%) and Linalool (7.21%) were the major constituents. From the seeds of Z. alatum twenty components have been identified which yielded about 98.5 % of the oil; major components were Linalool (45%), Isohexnae (38%), Methyl-10-octadecanoate (6.25%). The essential oils show significant antioxidant, antimicrobial activities. The essential oils of Z. alatum are expected to be used as traditional herbal system of medicine.