CHEM01200604004 Shri Sanyasinaidu Boddu - Homi Bhabha ...

CHAPTER 7: Summary and Conclusions
The work presented in this thesis deals with the synthesis and characterization of a
variety of inorganic luminescent nanomaterials based on oxides, phosphates, gallates and
tungstates. Luminescent and structural properties of these materials before and after doping
with lanthanide ions have been investigated by using
XRD, TEM, SEM, FT-IR, Raman,
TG-DTA, 31 P MAS NMR and photoluminescence techniques. A brief introduction about
nanomaterials, their luminescence properties and different types of luminescent materials are
described in chapter 1. Basic principles of different experimental techniques used for the
characterization of the prepared nanomaterials are discussed in chapter 2. Subsequent
chapters (chapters 3-6) deal with the synthesis of lanthanide doped nanomaterials and
investigation of their structural and luminescent properties. The last chapter summarizes the
work of the present investigation.
GaOOH nanorods with different aspect ratios were prepared by changing the urea
concentration in the reaction medium. Lanthanide doping (~ 1 at %) in GaOOH nanorods
causes significant structural and morphological changes leading to amorphisation of
crystalline GaOOH. Based on XRD, SEM and vibrational studies it is concluded that the
lanthanide ions interact with hydroxyl groups present at the inter-layers of GaOOH to form
europium hydroxide, thereby disrupting the OH groups, which stabilizes the layered structure
of GaOOH. This leads to the formation of finely mixed europium and gallium hydroxides.
Existence of energy transfer between GaOOH and dopant lanthanide ions confirms the fine
dispersion of lanthanide hydroxides with GaOOH. On heating, the nanorods maintain their
morphology and lanthanide ions diffuses into the Ga 2 O 3 lattice as revealed by the existence of
strong energy transfer between the Ga 2 O 3 and lanthanide ions. Strong NIR emission (~ 1535
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