Research on the thermal shifts and electron-phonon coupling parameters of R-line for Cr3+ and Mn4+ ions in YAlO3 crystals

► Thermal shifts of R-line for 3d3 ions Cr3+ and Mn4+ in YAlO3 crystal are studied. ► Both the static and vibrational contributions are included in the studies. ► True electron-phonon coupling parameters α′ for both 3d3 ions in YAlO3 are obtained. ► Reason of the larger parameter α′ of Mn4+ than that of Cr3+ in YAlO3 is given.