Investigation on the Thermal Expansion and Theoretical Density of 1,3,5‐Trinitro‐1,3,5‐Triazacyclohexane

The CTE and the theoretical density are important properties for energetic materials. To obtain the CTE and the theoretical density of 1,3,5‐trinitro‐1,3,5‐triazacyclohexane (RDX), XRD, and Rietveld refinement are employed to estimate the dimensional changes, within the temperature range from 30 to 170 °C. The CTE of a, b, c axis and volume are obtained as 3.07×10⁻⁵ K⁻¹, 8.28×10⁻⁵ K⁻¹, 9.19×10⁻⁵ K⁻¹, and 20.7×10⁻⁵ K⁻¹, respectively. Calculated from the refined cell parameters, the theoretical density at the given temperature can be obtained. The theoretical density at 20 °C (1.7994 g cm⁻³) is in close match with the RDX single‐crystal density (1.7990 g cm⁻³) measured by density gradient method. It is suggested that the CTE measured by XRD could perfectly meet with the thermal expansion of RDX.