. = 4); Z = 8. . 12, . , 1,542 Ǻ (2%). , 10928/ ( L3 ).

(Ehrenberg, 1926; Tu, 1932; Renninger, 1937; Trzewatowski, 1937; Riley, 1944; Lonsdale, 1947; Straumanis, Aku, 1951; Skinner, 1957 .). (Skinner, 1957) 25 = 1 : =3,566880,00009 Ǻ. . 13. . 2.

, . 堠 , 堠  .