Far-Infrared Investigation on Structure of Amorphous Selenium

The structural ordering in various forms of amorphous selenium has been studied by means of far-infrared measurements on the two types of spectrum, corresponding to the Se^8-ring component and the polymeric chain. The chemical extraction method of the Se^8-ring component by CS_2 is re-examined in terms of the spectroscopic analysis which shows that the ring component can not be extracted entirely from the mixture of the ring and the chain. A polycrystalline trigonal selenium is obtained from the component extracted from the vitreous selenium quenched at a high temperature above 700℃. Black amorphous selenium is obtained by heat treatment of red one. The spectra for both of the amorphous states show that they consist of similar mixtures of the ring and the chain components, so that the transition from red to black does not correspond to the structural change from the ring to the chain nor vice versa

The Structure and Crystallization of Amorphous Se

application/pdfThe far-infrared transmission spectrum of amorphous selenium has been measured for different temperatures of quenching. The spectrum shows that the weight fraction of Se^8-ring decreases and that of the polymeric chain increases if the temperature just before quenching, T_, increases above the melting point of 217℃. The thermal crystallization process of selenium samples with different values of T_ has been studied by differential scanning calorimetery (DSC) . The result may be explained by a phenomenological model that the crystallization of amorphous selenium develops from nuclei with the Maxwellian velocity of the crystallization front with the activation energy, E=0.8 5eV for T_<620℃.紀要類(bulletin)39702 bytesdepartmental bulletin pape

The Structure and Crystallization of Amorphous Selenium Film(Physics)

The far-infrared transmission spectrum of vacuum evaporated amorphous film of seleuium has been measured with samples made at different deposition rates. The spectrum shows that ordering of evaporated particles develops, if the deposition rate becomes smaller. The crystallization has been identified and analyzed by differential scanning calorimetry in the temperature range from 70℃ to 160℃, and also by optical microscope measurement. The result indicates that the activation energy for the crystallization is closely related to the deposition rate

The Crystallization of Vitreous Selenium (Physics)

Crystallization of vitreous selenium has been investigated under an optical microscope with particular attention to the density of the nucleus for crystallization as a function of the quenching temperature. Nucleation of crystallization is found to be heterogeneous on account of the fact that the distribution of crystallization nuclei hardly changes with the heating time at a given temperature above ～60℃. The curve of nucleus density vs. quenching temperature shows a minimum near the quenching temperature of 500℃. The activation energy for the crystallization has been found in good agreement with that deduced from differential scanning calorimetry