Thermal annealing rate

Figure 27.13 Effect of the heating rate of the thermal annealing on the heterostructure of the electroceramic thin film, (a) RBS spectra of two (Ca, PbiTiOs thin films prepared from the same precursor solutions but crystallized with different thermal annealing rates ...

At low conversions the diffraction efficiency of the holographic grating can be monitored to determine the rate of photodimerization. Kohler et al. have measured an upper limit on the activation energy for photodimerization of 3.6 kcal/mol, which is very close to a value of about 3.1 kcal/mol determined by Nakanishi et al. for the dimerization of distyrylpyrazine [96]. Rates of disappearance of the diffraction pattern can be used to measure the rate of reversion to starting monomer which occurs upon thermal annealing above 100°C. Kohler et al. have measured the activation energy for this process to be 23.7 kcal/mol. 

The exponent, n. is equal to 0.62 and is unchanged for all the radical concentrations examined. The rate constant, b, depends on the radiation dose and the thermal annealing after the irradiation. 

Fig. 8. The variation of the rate constant, b, of the longitudinal relaxation at 77 K of the alkyl radical in irradiated polyethylene with the change in the bulk radical concentration, (O) during the concentration increase caused by the increasing radiation dose and ( ) during the concentration decrease caused by the successive thermal annealing...

The exponent of tj, 0.62, is unchanged irrespective of the radiation dose and of the thermal annealing, and it is identical with the exponent determined for the alkyl radical in polyethylene. The rate constant, b, changes depending on the dose and the annealing treatment, as is shown in Fig. 13. 

When the concentration is decreased by successive thermal annealing at 360 K, the rate constant decreases more quickly to give a smaller intersect (closed circles). The difference between the two intersects divided by the slope of... 

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