CHEM01200604004 Shri Sanyasinaidu Boddu - Homi Bhabha ...

Rhabdophane) and the other is monoclinic CePO 4 [108, 109]. CePO 4 / LaPO 4 nanorods as
well as CePO 4 :Tb 3+ -LaPO 4 core-shell nanorods were synthesised and characterised by Cao, et
al. [110] and Zhu, et al. [111] under hydrothermal condition in presence of surfactants and
ultra-sonication respectively. Li and Yam [112] have prepared CePO 4 :Tb 3+ nanowires in
aqueous medium at room temperature by the reaction between Ce 3+ / Tb 3+
ions and
NH 4 H 2 PO 4 in presence of cyclodextrin. Kompe, et al.[113] employing co-precipitation in
presence of coordinating ligands like tributyl phosphate (TBP) and trihexyl amine, prepared
CePO 4 :Tb 3+
core and CePO 4 :Tb 3+ -LaPO 4 core – shell nanoparticles in water free
environments at 200°C. These studies revealed that luminescence property of CePO 4 :Tb 3+
nanorods/ nanoparticles get significantly improved when covered by a shell of LaPO 4 .
Improved dispersability of nanoparticles/ wires in alcohols and water is extremely important
for making good quality silica sols and xero-gels incorporated with nanoparticles. Such sols
and xero-gels, when immobilized with proteins and enzymes, combines the advantages of
biological inertness, biodegradability and compatibility with bio-molecules at the same time,
can also act as efficient luminescence based biosensors for monitoring the protein and
enzyme activities in biological systems. Gulnar, et al. [114] have prepared crystalline CePO 4 ,
CePO 4 :Tb 3+ and CePO 4 :Dy 3+ nanoleaves with monoclinic structure. These nanomaterials are
dispersible in solvents like water and methanol and can be incorporated in silica sols based on
sol-gel method. Such nanoleaves incorporated silica sols have improved luminescence
properties compared to silica sols directly doped with lanthanide ions.
1.7 Scope of present work: In the present investigation, a variety of inorganic matrices
varying from oxides (Ga 2 O 3 , Sb 2 O 3 ), phosphates (SbPO 4 , BiPO 4 , GaPO 4 ), gallate (ZnGa 2 O 4 )
to tungstates (CaWO 4 , SrWO 4 , BaWO 4 ) both undoped and doped with lanthanide ions have
been synthesised and their luminescent properties are investigated. Even though number of
reports are available on the luminescence properties of both undoped and lanthanide ions
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