Inter-atomic potentials for radiation damage studies in CePO4 monazite

Highlights: • New interatomic potential for Monazite. • Fits structure and melting temperature. • Can be used in radiation damage studies. 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 $49\times {10}^{-6}$ 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.