CHEM01200604004 Shri Sanyasinaidu Boddu - Homi Bhabha ...

Based on these results, it can be inferred that the Eu 3+ ions are not replacing Ga 3+
ions in the lattice of GaOOH. It is also in accordance with the significantly different ionic
radii of Ga 3+ and Eu 3+ ions (0.62Å and 0.95Å respectively) [172] under a coordination
number of six. However, broadening of the peaks and conversion of crystalline GaOOH to an
amorphous phase with increase in Eu 3+ concentration suggest that the GaOOH lattice is
influenced by the presence of Eu 3+ in the reaction medium. Similar results are also observed
with Dy 3+ and Tb 3+ doped samples and corresponding XRD patterns are shown in Fig.21.
Table 1. Variation in the lattice parameters of GaOOH samples prepared in the presence of
Eu 3+ ions.
Eu 3+
GaOOH
concentration
(at %) a (Å) b (Å) c (Å) Cell volume (Å 3 )
0 4.546(2) 9.797(2) 2.972(3) 132.35(2)
0.5 4.544(3) 9.786(2) 2.976(3) 132.32(2)
0.75 4.541(3) 9.787(3) 2.975(2) 132.23(3)
1 4.527(4) 9.805(3) 2.975(2) 132.05(4)
(a)
Intensity(arb.units)
(b)
10 20 30 40 50 60 70
2θ/°
Fig.21. XRD patterns of GaOOH samples prepared in presence of (a) 2 at % Tb 3+ and (b) 2 at
% Dy 3+ .
From the above studies, it is inferred that even the presence of around 2 at % Eu 3+ /
Tb 3+ / Dy 3+
during the precipitation process of GaOOH can significantly affect its
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