CHEM01200604004 Shri Sanyasinaidu Boddu - Homi Bhabha ...

From the above studies, it is inferred that the host emission from ZnGa 2 O 4 can be
tuned by varying the particle size. It is interesting to know the variation in emission
maximum with iso-valent ions substitution at the Ga 3+ site in the ZnGa 2 O 4 lattice. Such
substitution can modify the levels due to GaO 6 octahedra in the band gap of ZnGa 2 O 4 .
Keeping this in mind ZnGa 2 O 4 nanoparticles have been doped with In 3+ and their emission
characteristics were measured as a function of In 3+ concentration and the results are described
below. In 3+ ion is chosen in the present study, as it is iso-valent with Ga 3+ ion and due its
heavier mass, it is expected to reduce the energy level corresponding to Ga/InO 6 units. This
can lead to the shifting of the emission maximum towards higher wavelength.
Normalised intensity
1.0
0.8
0.6
0.4
0.2
0.14 mmol Ga
1.44 mmol Ga
2.88 mmol Ga
14.36 mmol Ga
22.96 mmol Ga
Normalised intensity
1.5
1.2
0.9
0.6
0.3
0.14 mmol Ga
1.44 mmol Ga
2.88 mmol Ga
14.36 mmol Ga
22.96 mmol Ga
0.0
350 400 450 500 550 600
Wavelength (nm)
(a)
0.0
200 250 300 350
Wavelength (nm)
(b)
Fig.97. (a) Emission spectra of ZnGa 2 O 4 nanoparticles prepared by using different
concentrations Ga 3+ after exciting the samples in the range of 250-290 nm and (b)
corresponding excitation spectra.
5.4. Effect of Indium doping on crystallinity and photoluminescence of ZnGa 2 O 4 :
ZnGa 2-x In x O 4 (x = 0, 0.05, 0.1, 0.2, 0.3, 0.5) nanoparticles have been prepared in a mixture of
25 ml EG and 10 ml water with 0.716 mmol of Zn and 1.44 mmol of Ga and In together at
110°C. The corresponding XRD patterns for In 3+ doped ZnGa 2 O 4 nanoparticles are shown in
Fig.98. With increase in the In 3+ content, XRD peak becomes broader and shifts to lower 2θ
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