Synthesis and characterization of spherical and rod like nanocrystalline Nd2O3 phosphors

Spherical and rod like nanocrystalline Nd2O3 phosphors have been prepared by solution combustion and hydrothermal methods respectively. The Powder X-ray diffraction (PXRD) results confirm that hexagonal A-type Nd2O3 has been obtained with calcination at 900 °C for 3 h and the lattice parameters have been evaluated by Rietveld refinement. Surface morphology of Nd2O3 phosphors show the formation of nanorods in hydrothermal synthesis whereas spherical particles in combustion method. TEM results also confirm the same. Raman studies show major peaks, which are assigned, to Fg and combination of Ag + Eg modes. The PL spectrum shows a series of emission bands at ∼326–373 nm (UV), 421–485 nm (blue), 529–542 nm (green) and 622 nm (red). The UV, blue, green and red emission in the PL spectrum indicates that Nd2O3 nanocrystals are promising for high performance materials and white light emitting diodes (LEDs).

Research highlights▶ Neodymium oxide (Nd2O3) or rare earth sesquoxides is widely used in various applications such as photonic, luminescent materials, catalyst for automotive industry, UV absorbent, glass-polishing materials, and protective coatings. ▶ Literature survey reveals that most of the phosphor materials are produced by high temperature solid state synthesis, which is inhomogeneous, low surface area, large particle size, presence of large defects, which are harmful to luminescence. ▶ All the above mentioned problems could be mitigated by the use of wet chemical methods (combustion and hydrothermal). ▶ 4As a part of our programme on phosphor materials, here we report spherical and rod like nanocrystalline Nd2O3 phosphors and evaluate their structural and optical properties by using various spectroscopic techniques. ▶ 4Powder X-ray diffraction results (PXRD)confirm that hexagonal A-Nd2O3 phase can be obtained with calcination at 900 °C for 3 h. From PXRD the lattice parameters have been evaluated by Rietveld refinement. ▶ 4In combustion synthesized powders, the particles are spherical in shape and essentially consists of different sizes varying from 20–100 nm. ▶ In hydrothermal synthesized Nd2O3 the nano rods are dumbbell in shape having sharp tips with open ends. ▶ The particle size is found to be in the range 25–90 nm. ▶ 4Raman studies shows major peaks which are assigned to Fg and combination of Ag + Eg modes. ▶ 4UV-visible absorption spectrum shows a strong and broad absorption band at ∼250 nm for combustion and a sharp absorption peak at ∼235nm for hydrothermal method. ▶ This is attributed to particle size effect. ▶ 4The PL spectrum show a series of emission bands at ∼342–371 nm (UV), 423–485 nm (blue), 522–542 nm (green) and 622 nm (red). ▶ The UV, blue, green and red emission in the PL spectrum indicates that Nd2O3 nanocrystals are promising for high performance materials and white light emitting diodes (LEDs).