Infrared and EPR studies of the red potassium molybdenum bronze K0.33MoO3

Infrared reflectance and electron-paramagnetic-resonance (EPR) of the red b ronze K0.33MoO3 are presented. The infrared measurements at 300 K indicated that red bronze K0.33MoO3 is a semiconductor with very strong anisotropy i n the range. The presence of three sharp lines at bout 900 cm(-1) for P per pendicular tob is in fact due to the intramolecular oscillations of oxygen inside one octahedron. The phonon oscillators near 500 cm(-1) for P perpend icular tob and P parallel tob associate with the modification of the effect ive charge. The EPR signals can be attributed to electrons localized in the isolated Mo5+ paramagnetic center. The difference of relative intensities of the EPR lines in 300 K and 100 K is due to the electronic excitation. Th e inhomogeneous broadening of the resonance lines is due to a g-factor dist ribution arising from crystalline field and spin-orbit coupling. (C) 2001 K luwer Academic Publishers.