Luminescence properties of NiWO4 powders and films prepared with novel methods

摘要

The NiWO4 powders have been synthesised by reaction between NiCl2 and Na2WO4 aqueous solutions and following calcinations at different temperatures. XRD and SEM analyses were used to characterise the powders. Single phase NiWO4 powders were formed above calcining temperature of 600°C. XRD analysis indicated that the NiWO4 powders had a monoclinic structure and particle sizes of 26˙8 and 30˙3 nm for calcining temperatures of 600 and 700°C respectively. A little increase in intensity of the XRD peaks was observed when calcining temperature was increased from 600 to 700°C. SEM image indicated that powders had uniform and very small particle size. The powders showed a broad blue-green emission band. The broad band of NiWO4 powders calcined at 600°C consisted of two bands at 423˙2 nm (2˙93 eV) and 487˙3 nm (2˙54 eV) and two weak bands at 447˙0 nm (2˙77 eV) and 532˙0 nm (2˙33 eV). Little shift in the peaks of excitation and luminescence and its little increase in intensity were observed when calcining temperature was increased to 700°C. The films were deposited with sol-gel method using the precipitation as starting materials. The deposited films showed a similar blue-green emission with the powders.