Nitrate-Citrate Sol-gel Synthesis of Phase Pure Nd3+ doped Nanocrystalline Yttrium Aluminum Garnet

Phase pure nanopowders of undoped and neodymium (Nd3+)-doped yttrium-aluminum-garnet(YAG) was synthesised by sol-gel process using nitrate-citrate gel method. Complete crystallisation of YAG was studied using Fourier transform infra-red spectroscopy (FTIR) and x-ray diffraction (XRD). Complete phase formation took place at 900 OC for 2 h. The average primary particle size calculated was ~25 nm. Transmission electron microscopy (TEM) showed particles in the range of ~25 nm to 30 nm. Nd-dopant concentration levels of 2 and 4 atomic per cent were studied. Using XRD data the cell parameters of Nd (0, 2 and 4 atomic per cent):YAG were calculated and it was found to increase with increase in dopant concentration.Defence Science Journal, 2011, 61(3), pp.214-218, DOI:http://dx.doi.org/10.14429/dsj.61.43

Studies of Process Parameters on Scale up of Nd:YAG Nanopowder Synthesis by Sol-gel Process

Scale up of process from 6 g to 200 g batch for preparation of phase pure Neodymium doped Yttrium Aluminum Garnet (Nd:YAG) nanopowder by sol-gel process using nitrate-citrate route was carried out. Optimisation of process parameters was done to resolve problems associated with large batch such as evolution of large amount of acidic fumes, increased gelation and drying time and incomplete calcination. The problem of exhaust of excess acidic fumes with size scale up was handled by passing ammonia and optimized pH of the sol. Process of drying the sol was optimised for large batch size. On scaling up from 6 g to 200 g batch incomplete crystallization was observed  on calcination under conditions optimized for 6 g batch. The causes of incomplete calcination with size scale up was identified and resolved to achieve completely crystalline particles in the range of ~25 nm to 50 nm.Defence Science Journal, 2012, 62(1), pp.199-202, DOI:http://dx.doi.org/10.14429/dsj.62.83

Sol Freeze Dry Nd:YAG Nanopowder Synthesis and Sinterability Studies

Citrate nitrate sol freeze dry synthesis of 2 atomic % neodymium ion doped Yttrium Aluminium Oxide (Nd:YAG) nanopowders was explored for the first time. Sol was prepared by dissolving nitrates of Al3+, Y3+ and Nd3+ keeping molar ratio to be 5: 2.94: 0.06. Total metal ion to citric acid ratio was optimised at 1 is to 0.25. Sol was freeze dried at -80 °C for 48 h. Dried mass thus obtained was calcined at 1000 °C for 2 h to give phase pure Nd:YAG as characterised by FTIR and XRD. Particles were in the size range of 35 nm - 50 nm with close to spherical morphology as observed by TEM. Nanopowder was compacted and sintered at 1700 °C for 5 h under 10-6 mbar followed by hot isostatic press at 1750 °C for 4 h under 200 MPa, to give 71 per cent transmission at 1064 nm indicating synthesis of well sinterable Nd:YAG nanopowders

Narcotic Drug Detection and Identification through Synchronous Fluorescence Technique

Illegal production of potentially hazardous narcotics as well as various psychotropic drugs is being carried out in the neighbouring countries and international market which is causing narco-terrorism a global havoc. Compared with traditional/natural drugs the synthetic drugs are more smuggled nowadays. Because of the vulnerability of the borders to drug trafficking, India has increased surveillance at borders and coasts and thus has tackled the problem to some extent. Authors developing a Narcotic drug sensor (point sensor) for detection and identification of Narcotic drugs based on Laser Induced Fluorescence more specifically Synchronous Fluorescence Spectroscopy in an effort. Some narcotic samples viz. Caffeine, Quinine and Tramadol were considered for the study. The fluorescence spectrum was studied using our own laboratory-based sensor incorporating charge coupled device-based Spectrometer and Laser source (266 nm wavelength) and commercial system from ‘Horiba Scientific’ incorporating Photomultiplier tube and Xe lamp source

Nd:GGG Nanopowders by Microwave Gel Combustion Route and Sinterability Studies

Synthesis of Nd0.03Gd2.97Ga5O12 (Nd:GGG) nanopowder was carried out by microwave-assisted nitrate-citrate gel combustion technique. Various nitrate-to-citrate ratios from stoichiometric-to-fuel lean were explored. Gels were combusted by microwave heating and the combusted powders were calcined at 900 OC for 2 h. Fourier Transform Infra-red Spectroscopy (FTIR) and X-ray Diffraction (XRD) of calcined nanopowders showed phase pure Nd:GGG formation, from stoichiometric-to-fuel lean nitrate-to-citrate ratio of 1 to 0.416. Particles in the size range of 150 nm - 200 nm were obtained for stoichiometric ratio. Highly uniform, spherical morphology, with size range 90 nm - 100 nm, were obtained in fuel lean ratio of 1 to 0.416. Sintering of these nanopowders at 1550 °C for 2 h in air resulted in retention of phase purity as observed by XRD. Grain growth of less than 2 μm, for fuel lean ratio of 1 to 0.416, indicated formation of highly sinterable Nd:GGG nanopowders.Defence Science Journal, Vol. 64, No. 5, September 2014, pp.490-494, DOI:http://dx.doi.org/10.14429/dsj.64.540