OPTICAL-ABSORPTION STUDIES OF PYRITE-TYPE RUS2 RUSE2 AND RUTE2 SINGLE-CRYSTALS

Far-Infrared optical characterization of pyrite - type RuS2 . RuSe2 an d RuTe2 have been studied by absorption measurements. We measured thes e three types of pyrite single crystals in spectra ranging from 100 - 700 cm(-1) at temperature among 80 - 300 K. Those vibration modes of t hese crystals are clearly shown temperature dependent behavior in far- infrared range. The main peaks of phonon modes of RuS2 are near around 244 . 341 . 366 . 401 and 416 cm(-1) at 80 K that is shown in its ref lectance spectra There are three main phonon peaks clearly showed 207 . 257 and 297 cm(-1) for RuSe2 single crystal. However RuTe2 crystal h as only clearly shown a main phonon peak near around 247 cm(-1) at 80 K in the reflectance spectra for its highly metallic behavior. This me tallic behavior of RuTe2 is also shown in photo reflectance measuremen ts. All of these phonon modes have 2 - 4 cm(-1) shift in among 80 - 30 0 K. The phonon modes, carrier concentration, mobility, effective mass as well as their dielectric behavior of these pyrite-type crystals wi ll go further study.