Thermo Gravimetric And Differential Thermal Analysis

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[53]. The direct band gap energy (Eg) of Tb3+: SA crystals grown by SEST and SR methods are found to be 4.20 eV, 4.10 eV respectively, which is in good accordance with the reported values [54]. The value of band gap of Sulfamic acid was found to decrease with increase in impurity concentration and it is found between 4 and 5 [54, 55]. Fig(7). Plot of α vs. photon energy.
3.6 Thermogravimetry (TG) and differential thermal analysis (DTA)

Thermogravimetry (TG) and differential thermal analysis (DTA) curves of the Tb3+ doped sulfamic acid single crystals were measured at a heating rate 10 0C/min between 25 and 800 0C in the nitrogen atmosphere. Using a PerkinElmer Diamond analyser. The thermo gravimetric and differential thermal analysis
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A graph is plotted between dielectric constant (εr) versus log frequency for different temperatures 30 0C, 60 0C, 90 0C and 120 0C for Tb3+: SA single crystals. From the Fig12(a) we can conclude that dielectric constant is high at low frequencies which is because of space charge polarization [61] which depends on purity and perfection of the sample. The maximum values of dielectric constant is 6.9, 6.8 for SR and SEST grown Tb3+: SA single crystals respectively, minimum values are 1.4, 1.2 for SR and SEST grown Tb3+: SA single crystals respectively. A graph is drawn between the dielectric loss and log frequency for different temperatures 30 0C, 60 0C, 90 0C and 120 0C. As seen in Fig. 12(b) it is observed that the dielectric loss decreases as frequency increases. The low dielectric loss at high frequency of the grown crystals shows that these materials possess better optical quality with lesser defects …show more content…
Emission spectrum of Tb3+: SA (SR) single crystal obtained at λex =265nm

Fig.13(b).Excitation spectrum of Tb3+: SA (SR) single crystal obtained at λEMI =543nm

Fig (13)c. Energy levels of Tb3+ ion with main transitions
3.13. Decay curve of Tb3+: SA single crystal
In Tb3+ doped SA single crystal luminescence decay is very long due to f-f transitions in Tb3+ are spin and parity forbidden. Decay curve of Tb3+ doped SA single crystal with λex = 263 nm and λem= 543 nm which is shown in Fig. 14. The decay curve of Tb3+ doped SA single crystal is corresponds to 5D4 level of Tb3+ and found to be single exponential with a lifetime value of 1. 37 ms. Fig (14). Decay curve corresponding to 5D0 level of Eu3+ from Tb3+: SA.

Conclusion
Bulk single crystals of semi organic Tb3+ co activated sulfamic acid single crystals are grown in unidirectional (100) from aqueous solution by a slow evaporation technique. Single crystal X-ray diffraction studies confirm that the grown crystal belongs to orthorhombic crystal system with space group Pbca. The grown crystals of single crystal XRD and

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