Neighbors rarely begin random arguments over boundaries. More often, boundary issues arise when a property owner makes improvements or changes —erects a new fence or wall, for example. A dispute against a neighbor might soon become ripe for a lawsuit if the neighbor: constructs an improvement that clearly crosses a property line. A grain boundary (GB) is the interface between two grains, or crystallites, in a polycrystalline material. Grain boundaries are defects in the crystal structure, and tend to decrease the electrical and thermal conductivity of the material. A grain boundary is a general planar defect that separates regions of different crystalline orientation.