CHEM01200604004 Shri Sanyasinaidu Boddu - Homi Bhabha ...

strong emission characteristic of Eu 3+
ions, whereas on heating to 900°C the emission
intensity got significantly reduced as can be seen from Fig.53 (a). The 5 D 0 level of Eu 3+ ion in
all the samples has been found to decay bi-exponentially (Fig.53 (b)). The bi-exponential
nature indicates the presence of more than one type of Eu 3+ environment in the sample. The
lifetime is systematically reduced with increase in heat treatment temperature. For the as
prepared sample the values are found to be 143 µs (20%) and 258 µs (80%). These values are
comparable with that of bulk Sb 2 O 3 sample prepared in presence of Eu 3+ ions. The observed
weak luminescence and short lifetime for the 900°C heated samples have been attributed to
formation of Eu 2 O 3 phase.
(a)
Intensity(arb.units)
* = HSb 3
O 8
; # = Eu 2
O 3
; & = Sb 2
O 5
.xH 2
O
*
#
& &
* *
#
* * *
&
(b)
(c)
* *
&
30 40 50 60
2θ/°
Fig.52. XRD patterns for the product obtained by the reaction between Sb 3+ and Eu 3+ ions
taken in stoichiometric amounts and heated at different temperatures: (a) as prepared
(b) 500°C and (c) 900°C.
100