The phrase "crystalline structure" refers to the arrangement of particles or atoms in a material that is very organized, like the pattern you see in a crystal. Full definition
A team led by Jonathan Poplawsky of the Center for Nanophase Materials Sciences used advanced microscopy techniques to discover efficiency differences of crystalline structures of various mixtures of cadmium, tellurium and selenium. (sciencedaily.com)
Reynolds: He collected rocks and crystals from an early age, and later on his interest in crystalline structures led to a desire to distinguish between an anthropomorphic - centered worldview and an abstract one. (brooklynrail.org)
The 1930 account of William H. Bragg, for instance, describes how x-rays can provide a window into crystalline structure. (scientificamerican.com)