Table 2.

Average lifetime τ of the ⁵D₀ level for the different samples before and after thermal treatment at 900 °C.

Samples		τ (ms)
		25° C	900 °C
$\mathit{S}\mathit{i}\mathit{E}{\mathit{u}}_{\mathit{C}\mathit{l}}^{\mathit{y}}$	y = 0.2 mol%	0.11	1.03
	y = 0.5 mol%	0.12	1.42
	y = 1.0 mol%	0.13	1.22
$\mathit{S}\mathit{i}\mathit{E}{\mathit{u}}_{\mathit{N}}^{\mathit{y}}$	y = 0.2 mol%	0.16	0.87
	y = 0.5 mol%	0.16	0.98
	y = 1.0 mol%	0.15	0.96
$\mathit{S}\mathit{i}\mathit{M}{\mathit{g}}_{\mathit{N}}^{\mathbf{10}}\mathit{E}{\mathit{u}}_{\mathit{N}}^{\mathit{y}}$	y = 0.2 mol%	0.40	1.80
	y = 0.5 mol%	0.42	1.80
	y = 1.0 mol%	0.34	1.78