A Universal Relation between Electron Density Minima and Ionic Radii in Ceramics

A universal relation between electron density minima and ionic radii, was discovered from the first principles calculations of electronic structures in ceramics over 60 species, including oxides, borides, carbides, nitride and fluorides. Every ceramic falls on a curve of log(ρ m i n Z - 3 ) vs. 2(Z/n)r m i n , where ρ m i n is the minimum electron density in the line linking the first-nearest-neighbor nuclei, r m i n is the distance r at ρ m i n , Z is the atomic number, and n is the principal quantum number.