粉砕された酸化亜鉛の欠陥構造について
1973 年 22 巻 238 号 p. 706-708
詳細
1973 年 22 巻 238 号 p. 706-708
It has been well-known that zinc oxide takes easily a nonstoichiometric form. Consequently, it is considered that the lattice distortion and defects appear easily in zinc oxide after mechanical treatments such as compression or grinding.
Such mechanochemical effects of oxides have been hitherto studied mainly by the X-ray diffraction measurements. However, the measurements of the physical properties, such as optical absorption spectra and electrical conductivity, seem to be more effective ways of studying the defects of zinc oxide produced after such mechanical treatments.
For these reasons, the defect structure of the ground zinc oxide was studied by measuring its absorption spectra, bulk current and photocurrent. Those results were compared with the result obtained by the X-ray diffraction analysis.
The results obtained are as follows:
Zinc oxide has a fundamental absorption band at the wavelength of 374mμ. As the grinding time of zinc oxide becomes longer, this absorption band becomes broader and shifts toward longer wave-lengths. Moreover, another broad absorption band in the visual range becomes distinctive with the grinding time. Such spectral changes may be due to the increase of interstitial zinc produced by grinding.
Photocurrent of zinc oxide decreases remarkably when ground for 50 hours, after that it decreases gradually with grinding time up to 200 hours. Such decrease of photocurrent may be due to the oxygen vacancies in the surface of crystallites, produced by grinding.
