= Snoek effect
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= Snoek relaxation
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The Snoek effect is <anelasticity> caused by stress-induced redistribution of mobile <interstitial defects> among differently oriented sites in a crystal. An applied <stress> favors orientations whose local distortion best accommodates it. At low frequency the atoms can track that bias and provide additional relaxed compliance; at high frequency their populations are nearly frozen. Dissipation is largest between these regimes. For a weak single relaxation, the <loss tangent> has the approximate shape $\Delta\omega\tau/[1+(\omega\tau)^2]$, with $\tau=\tau_0e^{E_a/(k_BT)}$ for thermally activated hopping. The peak is near $\omega\tau=1$. This describes a standard mechanism for interstitial impurities in body-centred cubic metals, not every damping mechanism in every alloy. https://www.jstage.jst.go.jp/article/isijinternational1989/37/6/37_6_610/_pdf[ISIJ International 37 (1997), 610: stress-induced interstitial diffusion, Eq. (2) for the Debye-shaped damping peak and its activated relaxation time]{ref}
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