Infrared spectroscopic studies on spinel-type chromium indium sulfide solid solutions

Evolution of the optical properties of chromium spinels CdCr2O4, HgCr2SRabia1, Baldassarre2, Tsurkan3 et al. 2014Phys. Rev. B10240View full textAdd to dashboardCite

“…On the other hand, Lutz and coworkers [41][42][43][44][45][46] that almost all atoms contribute to the four IR-active phonon modes. They proposed that the contribution of A-site atoms to the higher-frequency phonon modes (mode (1) and ( 2)) is smaller compared to that to the two lower-frequency phonon modes.…”

The effect of annealing temperature on the structure and optical properties of sol–gel derived nanocrystalline cobalt aluminate spinel

“…A breakdown of the IR selection rules can occur due to various factors which can subsequently lead to an increase in the number of IR modes [26,27] According to Wang et al [28], for normal CoAl 2 O 4 spinel these vibrations occur at 666 cm À1 , 554 cm À1 , and 504 cm À1 spectral regions. In the case of the spinel having Co 3þ in octahedral coordination, such as Co 3 O 4 , the characteristic bands occur at 670, 655 and 588 cm À1 [29].…”

“…Bands at w550 cm À1 also tend to be assigned to AleO stretching vibrations of the AlO 6 octahedral groups [26,31], but also to the CoeO stretching vibration of the CoO 4 tetrahedra [30,32] The lowfrequency band at w500 cm À1 is attributed to the CoeO stretching vibration of the CoO 4 tetrahedra [31,32], or to combined vibrations of both cations in tetrahedral and octahedral sites [26,27,33,34].…”

Raman scattering study of pressure-induced phase transitions in MIn2S4 spinels

“…Inverse spinels have in common M-ion radii lower than that of In (0.80), while normal spinels show M-ion radii similar to that of In. If this tendency is correct and taking into account the similar electronegativities of Cr and In, one possible reason for the normal spinel structure of chromium sulphides and for the inverse spinel structure of indium sulphides [36] is the smaller ion radius of Cr (0.61) as compared to In (0.80). In this way, the low ionic radius of Cr prevents the formation of inverse spinels in chromium compounds, because M ions usually have larger ion radii.…”