• K SAKTHIPANDI

Articles written in Bulletin of Materials Science

• Evaluation of anticorrosive behaviour of ZnO nanotetra-pods on a AZ91-grade Mg alloy

Highly cross-linked zinc oxide (ZnO) with the nanorod morphology of tetra-pods was successfully prepared using a microwave irradiation (MWI) technique. In comparison with the available conventional techniques, the MWI tech-nique has the advantage of producing different morphological structures with high purity and in a shorter reaction time. These tetra-pods consist of a ZnO core in the zinc blende from which four ZnO arms emerge in the wurtzite structure. In this investigation, the effects of irradiation times and the growth mechanism of ZnO nanotetra-pods were discussed. The structural, morphological and optical properties of ZnO nanorods were investigated by ﬁeld emission scanning electron microscopy, X-ray diffraction, an ultra violet visible spectrometry and energy-dispersive spectroscopy. The electrochemical corrosion behaviours of an AZ91-grade Mg alloy and a ZnO/PN nanotetra-pod-coated Mg alloy were investigated. The Tafel plot revealed that the corrosion of Mg drastically decreased on coating with a thin layer of ZnO nanotetra-pods and PN (Mg/PN/ZnO) compared to Mg in a KOH electrolyte.

• Turning of luminescence properties of Ba$_2$V$_2$O$_7$ phosphors by co-doping Eu$^{3+}$/Dy$^{3+}$ ions

A series of Ba$_{1.97–x}$Eu$_{0.03}$Dy$_x$V$_2$O$_7$ (x = 0.01, 0.02, 0.03, 0.04 and 0.05) phosphor materials were synthesized by hydrothermal method. Phase purity, structural, optical and luminescence characteristics of as-synthesized phosphorshave been studied using powder X-ray diffraction (PXRD), UV–visible spectroscopy and fluorescence spectrometry. The XRD patterns of as-synthesized phosphors were indexed and predicted as triclinic structure. The broad absorption in the UV region was originated from [VO$_4$]$^{3-}$ group charge transfer and the sharp peaks observed in the visible to near-infrared (NIR) region was originated from Eu$^{3+}$/Dy$^{3+}$ ions charge transfer. In photoluminescence (PL) spectra, the broad emission peak observed from 400 to 570 nm was due to the charge transfer band of [VO$_4$]$^{3-}$ group. A sharp peak observed from 570 to 710 nm were due to the charge transition of Eu$^{3+}$/Dy$^{3+}$ ions. The PL spectra recorded for different excitations at 268, 344, 335, 346, 346 and 339 nm, emitted bluish white colour with slight changes in its Commission International de l'Eclairage coordinate values. The white colour emission of Ba$_{1.97–x}$Eu$_{0.03}$Dy$_x$V$_2$O$_7$ phosphors was observed by the irradiation under the UV light 365 nm. Hence, the results have suggested that the as-prepared phosphor materials are the potential candidates in the fabrication of a UV or near-UV chip-excited white light-emitting diode.

• # Bulletin of Materials Science

Volume 46, 2023
All articles
Continuous Article Publishing mode

• # Dr Shanti Swarup Bhatnagar for Science and Technology

Posted on October 12, 2020

Prof. Subi Jacob George — Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bengaluru
Chemical Sciences 2020