On the Al/Fe substitution in iron doped monocalcium aluminate; the crystal structure of CaAl (sub 1.8) Fe (sub 0.2) O (sub 4)

A calcium ferro-aluminate with composition CaAl (sub 1.8) Fe (sub 0.2) O (sub 4) has been synthesized. The crystal structure of the phase was studied by X-ray single crystal diffraction and refined to an R1-index value of 0.033, for 1287 observed independent reflections, collected with graphite monochromatized MoKalpha -radiation. The compound crystallizes in the monoclinic space group P12 (sub 1) /n1 with Z = 12. Cell parameters were a = 8.758(1) Aa, b = 8.112(1) Aa, c = 15.311(1) Aa, beta = 90.21(1) degrees . The crystal structure is characterized by layers of six-membered tetrahedral rings of ditrigonal shape showing two different ring conformations of up (U) and down (D) pointing vertices: UUDUDD and UDUDUD, respectively. The stacking of layers comprises a three-dimensional framework containing channels that are occupied by the calcium cations. The structure is isotypic with CaAl (sub 2) O (sub 4) , the major compound of calcium aluminate cements.