The nonradiative transition rates follow the formulation WNR = W (0) exp(-alphap), where p is the number of phonons matching the Vitality gap. The nonradiative changeover rates of Er3+ exhibit temperature dependence in step with the multiphonon relaxation principle. In Tm3+ the temperature dependence of nonradiative peace rates is challenging https://er-yb-yab-crystal25678.tribunablog.com/er-yb-yab-crystal-an-overview-49169358