| Due to the possibility of combining the merits of both organic and inorganic components, organic/inorganic hybrid materials have attracted much attention. Researchers have carried out intensive and extensive investigations on the preparation and properties of organic/inorganic hybrid materials, in order to prepare materials with excellent properties. From the view of practical applications, the thermal stability is a key factor to the hybrid semiconductors, because it determines the reliability and durability of the electronic devices. In this thesis, we investigated the thermal stability of a new layerd perovskite-like organic/inorganic hybrid semiconducting crystals ((4-X-C6H4-NH3)3CdBr5, X=Cl, Br) by an in-situ FTIR technique, and the effect of pressure on the thermal decomposition of these crystals were also studied.For clearly explaining the experimental results, we calculated the IR absorption spectra of (4-X-C6H4-NH2, X=Cl, Br) and (4-Cl-C6H4-NH3+) using the Gaussian software (DFT/B3LYP/6-31G(d)). The result indicates that, the computational spectra agreed quite well with that collected in the experiments.The thermal analysis results revealed that, the decomposition temperature of ((4-X-C6H4-NH3)3CdBr5, X=Cl, Br) was 178-210℃, and the remaining solid after complete decomposition was CdBr2. Furthermore, the results of FTIR in-situ monitoring experiments indicated that, the IR peaks of-NH3 which related to the hydrogen bonds red-shifted or weakened before the decomposition process started. With the temperature exceeding the decomposition point, gaseous products 4-X-C6H4-NH2 and HBr escaped from the crystals, and they recombined into organic ammonia salt at the place with lower temperature. On the other hand, the decomposition temperature of the crystals increased to a rather large extent when a pressure of-4MPa was applied on them. This phenomenon proved that, the thermal stability of the hybrid crystals can be improved by applying a high pressure.
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