Carbon Ownby P D, Yang X, Liu J Journal of the American Ceramic Society 75 (1992) 1876-1883 Calculated X-ray diffraction data for diamond polytypes Note: hexagonal, 4H structure Note: theoretically calculated structure values _database_code_amcsd 0014067 2.5221 2.5221 8.2371 90 90 120 P6_3/mmc atom x y z C1 0 0 .09375 C2 1/3 2/3 .15625