Grain growth kinetics of Li3PO4-doped calcium carbonate

Grain growth mechanisms of calcium carbonate doped with lithium phosphate were determined. With small lithium phosphate addition, an abnormal needle-like grain growth was observed. Addition of the dopant as solid solution in calcite follows the equation: Li3PO4-(CaCO3)-->3(Li-i(+))(+)+V-Ca2+(2-)+(PO4CO32+3--). In slightly higher quantities (2 wt.%) above the solubility limit of Li3PO4, a second phase segregated at the grain boundaries. Whatever the thermal treatment (temperature, CO2 partial pressure), the grain distribution was self-similar (G(t)/(G) over bar(r))=time independent) and followed a single log normal law. The grain growth kinetics can be described by the equation: d (G) over bar/dt=k((G) over bar(-1)-G(c)(-1)). The grain growth was controlled by the mobility of the second phase.