Marta B. Vassallo

IR spectra of VO2 and V2O3

Abstract IR spectra of the tetragonal modification of VO 2 and of the trigonal form of V 2 O 3 are recorded at room temperature and compared with that of V 2 O 5 . The investigated samples of the two lower-valent vanadium oxides, obtained on temperature-programmed reduction treatment, were also characterized with diffuse reflectance and electron-paramagnetic resonance spectra. The effect of atmospheric oxygen on these materials was revealed with XPS measurements and also studied with IR spectra.

The vibrational spectrum of the NaZnPO4 ferroelectric phase

We report the infrared and Raman spectra of the NaZnPO 4 crystalline phase and assign the observed bands

Thermal behaviour and vibrational characterization of MH2(IO3)3 phases (M=K, Rb and NH4)

The thermal behaviour of the MH2(IO3)3 (M=K, Rb and NH4) isomorphous compounds, as well as the IR and Raman spectra have been investigated as part of a study of the properties of solid protonic conductors. Detailed stoichiometries, sustained by TG, DTA, XRD and IR analysis, have been developed into the three phases. There were also evidences of the formation of the [I3O8]− polymeric phases. Their stabilities were associated to the different polarizing power of the H, K and Rb cations.ZusammenfassungAls Teil einer Studie der Eigenschaften von Feststoff-Protonenleitern wurde neben den IR- und Raman-Spektren auch das thermische Verhalten der isomorphen Verbindungen MH2(IO3)3 (M=K, Rb, NH4) untersucht. In den drei Phasen wurden mit Hilfe von TG, DTA, IR und Röntgendiffraktionsuntersuchungen detaillierte Stöchiometrien entwickelt. Es gab auch Beweise für die Bildung von polymeren [I3O8]− Phasen. Ihre Stabilität steht in Verbindung mit der unterschiedlichen Polarisationsfähigkeit der H-, K- und Rb-Kationen.

Vibrational spectrum of RbVOPO4

Abstract The infrared and Raman laser spectra of RbVOPO4 were recorded and briefly discussed with the aid of factor group analysis. Some comparisons with the spectra of related materials were also made.

Mössbauer and susceptibility studies of FeMoVO7

The oxidic phase FeMoVO7 of the Fe2O3-V2O5-MoO3 system has been synthesized. Susceptibility measurements from 4.2 K to room temperature display an antiferromagnetic behaviour with an effective magnetic moment of 5.80ώb. This value, and the measured Mössbauer isomer shift of 0.40±0.02 mm/s, are characteristic of high-spin Fe(III). The lowTn value of 15 K suggests a weak interaction among the Fe-O polyhedra. The relative small QS=0.28±0.02 mm/s found in this compound shows that the Fe-O polyhedra symmetry is close to octahedral and almost undistorted.