We present measurements of the absorption and emission cross-sections for Yb:YAG, Yb:LuAG and Yb:CaF sub(2) as a function of temperature between 80 and 340 K. The cross-sections are determined by the combination of the McCumber relation and the Fuchtbauer-Ladenburg (FL) equation to achieve reliable results in spectral regions of high and low absorption. The experimental setup used for the fluorescence measurements minimizes re-absorption effects due to the measurement from small sample volume, providing nearly undisturbed raw data for the FL approach. The retrieved cross-sections together with the spectral characteristics of the tested materials provide important information for the design of energy efficient, high-power laser amplifiers.