Variable-Temperature and High-Pressure Micro-Raman Spectra of Inorganic Artists' Pigments: Crystalline Wulfenite, Lead(II) Molybdate(VI), PbMoO_4

摘要

Variable-temperature (-150℃ to 600℃) and high-pressure (up to ~5 GPa) micro-Raman spectra have been obtained for the mineral wulfenite [lead(II) molybdate(VI), PbMoO_4], a main constituent of the artists' pigment, orange molybdate. The spectra were quite similar in both the temperature and the pressure studies, except for broadening and shifting of some peaks. No phase changes were detected, although there is possibly some amorphization beginning at ~600℃. The photoacoustic IR spectrum in the 1950–450 cm~(-1) region is reported for characterization purposes. The long-term stability of PbMoO_4 with respect to extreme changes in both temperature and pressure illustrates the importance of orange molybdate in artwork and protective coatings.