First Effect in TDA

FIGURE 4.43 (a) Block diagram of the dielectric differential thermal analyzer. 

The Physical Chemistry of Materials Energy and Environmental Applications 

The effect has the form of a peak because at the origin of the peak, the increase in temperature is linked with the increasing mobility of water molecules adsorbed in the cavities and the channels of the zeolite. This event is followed by an increment of the permittivity of the zeolite sample, and this increase of the sample permittivity is detected by the thermodielectric analyzer as an increase in V0 (see Equation 4.34). 

The further increase in temperature and the time elapsed during temperature scanning is the reason for a decrease in the water content of the zeolite and, consequently, a decrease in the permittivity. Both the growth of the permittivity with temperature and the following permittivity decrement with the subsequent increase in temperature justify the form of peak exhibited by the first thermodielectric effect. 

---