Researchers from Lawrence Livermore National Laboratory, University of Nevada Las Vegas, Argonne National Laboratory, and University of Chicago have found a subtle phase transition in 1,3,5-Triamino-2,4,6- trinitrobenzene (TATB).  TATB is an important compound in the energetic materials community as it is a highly stable, insensitive explosive.  A more complete understanding of this and other energetic materials is crucial for practical use as well as the development of theoretical models.  Extensive single-crystal diffraction experiments were carried out at HPCAT—located at the Advanced Photon Source, Argonne National Lab—together with computational modelling at Livermore to explore the nature of the phase transition and the detailed atomic structure of the high pressure phase observed above 4 GPa.  The research is featured in the May 13 edition of Applied Physics Letters and additional details regarding the study can be found in Lawrence Livermore National Laboratory’s news.