Synchrotron Based Measurement of the Temperature Dependent Thermal Expansion Coefficient of Ammonium Perchlorate

Abstract

AbstractAmmonium perchlorate is commonly used as an oxidizer in solid rocket propellant. Having a knowledge of its thermal expansion properties is essential for its application in different environments. Knowledge of thermal expansion properties is also useful for the prediction of propellant mechanical properties and response of propellant slow cook off applications. X‐ray diffraction analysis was performed on ammonium perchlorate at temperatures ranging from 260 K to 500 K. From there, Bragg peaks were indexed by fitting theoretical values of 2θ to the 2θ values of peaks obtained from the experiment. The Miller indices along with the 2θ values were then used to solve for the lattice parameters at each temperature. The lattice parameters, in nanometers, range from 0.9201 to 0.9373, 0.5805 to 0.5865, and 0.7439 to 0.7535 for a, b, and c, respectively. The measurement of the lattice parameter expansion leads to the determination of the temperature dependent thermal expansion coefficients within the temperature range. The lattice parameter values also lead to the determination of strain and stress on the ammonium perchlorate crystal. Direct measurement of the strain within the crystal lattice provides a more accurate measurement method over traditional optical‐based techniques.