Patent ID: 8367205

Claim:
A self-supporting flat polycrystalline particle comprising a plurality of crystal grains that, when viewed in cross-section taken along a plane perpendicular to the particle thickness, have a wavy structure composed of wavy grain boundaries, the wavy grain boundaries including arcuate concave portions and arcuate convex portions, the arcuate concave portions and the arcuate convex portions mating with arcuate convex portions and arcuate concave portions of adjacent crystal grains, respectively, wherein every crystal grain in the particle has at least one wavy grain boundary, the curvature of crystal grains, defined by the length of a first straight line between adjacent triple points of grain boundaries divided into the maximum length of a perpendicular line drawn from the first straight line to the grain boundary between the adjacent triple points, is at least 0.1, the number of crystal grains in the thickness direction is substantially one, the self-supporting flat polycrystalline particle has a degree of orientation of at least 15% as determined by the Lotgering method, the grain boundaries of the crystal grains, when viewed in cross-section taken along a plane parallel to the particle thickness, are substantially straight, and the self-supporting flat polycrystalline particle has a size that will pass through a mesh opening of 1.0 mm or less.