In situ neutron powder diffraction measurements were also collected for the other two compositions, L1P3N3 and L3P1N3 at the POWGEN beamline (0.0008 < ∆d/d < 0.025), SNS, Oak Ridge National Laboratory, USA. Powder samples were placed in a quartz sample holder with a 0.5 cm radius and 4 cm length. A fused silica quartz tube furnace, with vanadium foil elements operating under vacuum conditions, was used to heat the sample. A quartz line was used as a vertical hanger for holding the quartz sample holder, which was then lowered into the quartz tube until the sample was in the path of the beam and the furnace hot zone . The furnace temperature was calibrated using a ZnO reference sample . Powder samples were equilibrated under a continuous flow of simulated air (20% O2) for at least one hour before measurement at each temperature. Diffraction patterns were also collected every 100˚C from room temperature to 800˚C in the d-spacing range of 0.45 -5.35Å. Several patterns with shortened collection times were collected and examined prior to the 2 hour-long measurements to ensure that the sample had reached equilibrium, monitored by means of observing any shifts in lattice parameters.