Inter-atomic potentials for radiation damage studies in CePO4 monazite

An original empirical potential used for modelling phosphate glasses is adapted to be suitable for use with monazite (CePO4) so as to have a consistent formulation for radiation damage studies of phosphates. This is done by adding a parameterisation for the Ce-O interaction to the existing potential set. The thermal and structural properties of the resulting computer model are compared to experimental results. The parameter set gives a stable monazite structure where the volume of the unit cell is almost identical to that measured experimentally, but with some shrinkage in the a and b lengths and a small expansion in the c direction compared to experiment. The thermal expansion, specific heat capacity and estimates of the melting point are also determined. The estimate of the melting temperature of 2500 K is comparable to the experimental value of 2318 ± 20 K, but the simulated thermal expansion of 49×10-6 K−1 is larger than the usually reported value. The simulated specific heat capacity at constant pressure was found to be approximately constant at 657 J kg−1 K−1 in the range 300-1000 K, however, this is not observed experimentally or in more detailed ab initio calculations.