CHEM01200604004 Shri Sanyasinaidu Boddu - Homi Bhabha ...

ions as next nearest neighbors around P in orthophosphate structural units. Significantly
different values of solubility product for Ga(OH) 3 (7.3 x 10 -36 ) and Eu(OH) (9.4 x 10 -27
3 )
further suggests that the ion exchange process is quite favorable in these system [177].
Intensity (arb.units)
600
300
(d)
0
3000 20 0 -20
2000
1000
(c)
0
20 0 -20
400
200 (b)
0
400
20 0 -20
200
(a)
0
20 0 -20
Chemical shift (ppm)
31
Fig.58. P MAS NMR patterns of GaPO 4 nanoparticles containing (a) 0 at %, (b) 2.5 at %,
(c) 5 at % and (d) 10 at % Eu 3+ ions. Samples were spun at 10000Hz.
To get insight regarding the electronic environment around P in these samples,
principal values of the 31 P chemical shift anisotropy tensor (δ 11 , δ 22 and δ 33 ) for GaPO 4
nanoparticles containing different amounts of Eu 3+
ions have been calculated from the
intensity of spinning sidebands observed in the 31 P MAS NMR patterns (recorded at a
spinning speed of 5000 Hz) (Table 6). The anisotropy parameter has been calculated from the
difference of δ 11 and δ 33 values and found to be around 20 ppm for GaPO 4 and 27 ppm for 2.5
at % Eu 3+ containing GaPO nanoparticles. For 5 and 10 at % Eu 3+ containing sample, the
4
110