High-temperature thermal and X-ray diffraction studies, and room-temperature spectroscopic investigation of some inorganic pigments

Inorganic Cr- and Mn-containing pigments of different structural types were investigated by high-temperature and spectroscopic methods. The differential scanning calorimetry in the temperature interval 298–1723 K was applied to measure temperatures of phase transition and melting of the studied compounds. High-temperature X-ray diffraction in the range 298–1173 K was used for the determination of the thermal expansion coefficients for the first time. Factor group analysis was used to predict general vibration modes of pigments and determine the activity of these vibrations in Raman and IR spectra, the Assignment of bands in Raman, IR and diffuse reflectance spectra was undertaken.

► Temperatures of phase transitions were measured for 7 Cr- and Mn-containing pigments.
► Thermal expansion coefficients of all studied compounds were determined.
► A detailed assignment of bands in Raman, IR and diffuse reflectance spectra was made.