The crystal structure of Cs2I8(CsI4)

Abstract

The crystal structure of CsI a has been determined by X-ray analysis. Space group: P21/a; 4CsI 4 per unit cell. The signs of 60 out of the 71 observed hOl structure factors could be calculated directly from inequalities. Inequalities were not useful in the [001] projection, but a first approximation could be obtained from Buerger's minimum function. The coordinates were refined by Fourier syntheses of the three projections and corrected for the termination of the series. The final value of the disagreement factor R is 0.085, and the standard deviation in the atomic distances is 0-02-0.03 A. The structure consists of Cs + ions and flat [I~. 12. I~-] ions, the latter showing a weak interaction between their constituents.