Figure 4: Time- and temperature-dependent evolution of cation ordering.
From: Inferred time- and temperature-dependent cation ordering in natural titanomagnetites
Cation ordering evolution inferred from Curie temperature in natural titanomagnetites from four MSH sites (a,b) and four NV sites (c,d). Samples annealed for variable durations at 400 °C (black symbols) and 350 °C (grey symbols). (a,c) TC measured on heating (solid symbols/lines) and on cooling (open symbols/dashed lines) following each anneal. (b,d) Difference between TC measured on warming and on cooling (ΔTC) represents the relative change in order degree. The initial state before each annealing treatment is relatively disordered, resulting from a previous χ(T) run to 600 °C with a heating/cooling rate of 10 °C min−1. TC during heating increases systematically with anneal temperature and time, approximately as log(t) for the range studied. TC determined for the cooling leg of the χ(T) runs shows no systematic variation with anneal temperature or time, but does differ significantly for the different samples, showing a moderate correlation with Mg and Ti content.
