The spectral widths, positions, and shifts of the sharp emission lines for the R1→X5 and R2→Y3 inter-Stark transitions within the respective intermanifold transitions of 4F3/2→4I9/2 and 4F3/2→4I11/2 of Nd3+ ions in Ba0.25Mg2.75Y2Ge3O12 laser host have been investigated as a function of temperature. The linewidths of these transitions increased as the temperature of the host crystal was increased. The emission line for the R1→X5 transition shifted toward the shorter wavelength (blue shift), while the emission line for the R2→Y3 transition shifted toward the longer wavelength (red shift) with increasing temperature. The experimental results of the temperature-dependent linewidths and line shifts of these transitions are explained in light of the existing theory of the phonon-ion interaction in crystalline solids. © 1998 American Institute of Physics.