Temperature dependence of the derivative d ln (μ / G) / dT for the initial (red squares) and relaxed states (blue triangles). Positive and negative values of this derivative correspond to an increase and decrease of the defect concentration, respectively, as implied by Eq. (4). This is directly seen when compared with the inset, which shows temperature dependences of the defect concentration in the initial and relaxed states calculated using Eq. (5), see the text for more details.