Even a microscopic crystallite is millions of unit cells long. This minimizes the overall bond-valence distortions of the crystallite. The X-ray results showed the shapes and thickness of the crystallite. The Tomes' processes are angled, which introduces differences in crystallite orientation, and hence structure. Urea perchlorate is a sheet-shaped crystallite with good chemical stability and strong hygroscopicity. The term "crystallite boundary" is sometimes, though rarely, used. This way a photovoltage parallel to the surface is developed in each crystallite. The higher water content compared to boehmite can be explained by a smaller crystallite size. The crystallite size can be measured directly using transmission electron microscopy. The crystallite size can vary from a few nanometers to several millimeters. The crystallite are typically not at equilibrium and they may contain different polymorphs. The crystallite size can be thought of as a lower limit of particle size.