D. Houde

High resolution infrared spectroscopy of hydrogen impurities in potassium tantalate

Abstract The high resolution infrared absorption related to the OH stretching mode (around 3500 cm−1) in KTaO3 is studied as a function of temperature. In two samples, we observed a splitting of each of the three high temperature peaks into up to four peaks at low temperature. The spectrum obtained is essentially the same for both samples, the small differences resulting from the different thickness of the two samples. The evolution of the absorption frequency as a function of temperature is followed for the three samples. The absorption frequency decreases with increasing temperature and a simple model, involving thermal expansion, is presented and successfully confronted to our datas. The multiplicity of the peaks is related to the presence of three inequivalent positions for the OH dipole giving rise to the three high temperature peaks. The low temperature splitting is related to the fluctuations of the ferroelectric soft modes as it was found in SrTiO3.

Infrared spectra of CdSb

Abstract We present new measurements of infrared reflectivity of CdSb crystals. Phonons were detected for the three crystallographic axes and fitted with the factorized oscillator model. Fourteen out of the fifteen predicted phonons were detected.

The temperature dependence of the OH stretching mode in the incipient feroelectrics SrTiO3 and KTaO3

Abstract The OH infrared strectching mode near 3500 cm−1 has been observed in high resolution as a function of temperature in the perovskytes SrTiO3 and KTaO3. In SrTiO3 above the phase transition temperature of 110 K and in KTaO3 over the whole range of temperature studied, we have observed a principal absorption peak accopanied by three satellites. Additional peaks appear in the case of SrTiO3 below 110 K. We interpret their presence and their temperature dependence as being relate to the combined effect of fluctuations of the ferroelectric soft mode and the antiferrodistorsive phase transition which interact with the OH bond.

The infrared spectrum of Cd3As2

Abstract We present new measurements of infrared reflectivity of Cd 3 As 2 at 15 K. One plasmon and eleven phonon characteristics are determined by the fitting process that reveals weak dipolar moments in the structure.

The infrared absorption and the raman spectra of β-LiIO3 at low temperature

Abstract The low temperature infrared absorptions and the Raman spectra of β-LiIO3 are presented with a brief group analysis. 23 out of the 28 infrared active modes and 35 of the 45 allowed Raman active modes are detected.

Study of the CO2-3 impurity in KTa1−xNbxO3

Abstract Infrared transmission and Raman scattering permitted the detection of CO2-3 impurities in KTaO3 and KTa1−xNbxO3 materials. These impurities could generate the observed anomalies in the physical properties of such compounds.

Infrared active phonons of β-LiIO3 crystal

Infrared reflectivity and absorption spectra at room and low temperature of β-LiIO3 crystal are studied and 28 infrared active modes are detected.