CHEM01200604004 Shri Sanyasinaidu Boddu - Homi Bhabha ...

Similar studies were also carried out for other lanthanide ions like Tb 3+ and the
results are discussed below. Tb 3+ is chosen in the present study for doping because unlike
BiPO 4 and LaPO 4 which have got monoclinic structure, TbPO4 exists in the tetragonal form.
Hence solid solution formation between BiPO 4 and TbPO 4 will be quite interesting both with
respect to fundamental aspect as well as with respect to light emitting applications. Figure 84
3+
shows the XRD patterns of BiPO4 nanomaterials containing different amounts of Tb . With
increase in Tb 3+ to Bi 3+ ratio, the peaks maxima are shifted to higher 2θ values. This is
explained based on the lattice contraction brought about by the replacement of the larger
ionic radius Bi 3+ (1.11 Å) with the smaller ionic radius Tb 3+ (1.04 Å) ions. In pure TbPO 4
case, it is an entirely different crystalline phase with tetragonal structure (Fig.84). Hence,
based on XRD, FT-IR and 31 P MAS NMR studies of BiPO :Ln 3+
4 nanomaterials, it is
confirmed that extensive solid solution formation occurs with BiPO 4 and LnPO4. In the
following section, luminescence properties of Ln 3+ doped BiPO nanorods are discussed.
4
TbPO 4
Intensity (arb.units)
Bi 0.5
Tb 0.5
PO 4
Bi 0.75
Tb 0.25
PO 4
Bi 0.9
Tb 0.1
PO 4
BiPO 4
26 28 30 32 34
2θ /°
Fig.84. XRD patterns of Bi 1-x TbxPO4 (x = 0, 0.1, 0.25, 0.5, 1) nanomaterials prepared at
185°C
141