CHEM01200604004 Shri Sanyasinaidu Boddu - Homi Bhabha ...

pulse frequency) as excitation sources for steady state and for lifetime measurements. Red
sensitive PMT was used as the detector. Quantum yield was measured by using integrating
sphere which is coated inside with BaSO 4 as a reflector.
2.7.7. Thermal analysis: Thermal analysis methods are essential for understanding the
compositional and heat changes involved during reaction. They are useful for investigating
phase changes, decomposition, and loss of water or oxygen and for constructing phase
diagrams.
Thermo gravimetric analysis (TGA): In TGA, the weight of a sample is monitored as a
function of time as the temperature is increased at a controlled uniform rate. Loss of water of
crystallization or volatiles (such as oxygen, CO 2 , etc.) is revealed by a weight loss. Oxidation
or adsorption of gas shows up as a weight gain.
Differential thermal analysis (DTA): A phase change is generally associated with either
absorption or evolution of heat. In DTA experiments, the sample is placed in one cup, and a
standard sample (like Al 2 O 3 ) in the other cup. Both cups are heated at a controlled uniform
rate in a furnace, and the difference in temperature (ΔT) between the two is monitored and
recorded against time or temperature. Any reaction involving heat change in the sample will
be represented as a peak in the plot of ΔT vs T. Exothermic reactions give an increase in
temperature, and endothermic reaction leads to a decrease in temperature and the
corresponding peaks appear in opposite directions.
In the present study, thermo-gravimetric-differential thermal analysis (TG-DTA) of samples
was carried out in platinum crucibles using a Setaram, 92-16.18 make TG-DTA instrument.
The sample was heated under argon environment up to 1100°C at a heating rate of 10°C/min.
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