EuAuGe Type Indides RAgIn (R = Ca, Sr, La, Eu).

The equiatomic intermetallic phases CaAgIn [a = 482.75(7), b = 750.0(1), c = 835.5(1) pm], SrAgIn [a = 495.86(5), b = 794.71(9), c = 851.89(9) pm], LaAgIn [a = 489.99(5), b = 767.93(9), c = 837.53(9) pm], and EuAgIn [a = 493.02(7), b = 781.6(1), c = 844.2(1) pm] were synthesized from the elements in sealed niobum containers. They crystallize with the EuAuGe type structure, space group Imm2. The four structures were refined from single-crystal Xray data. The silver and indium atoms build up orthorhombically dis torted, puckered Ag3In3 hexagons, which are stacked in AA' sequence, leading to direct Ag-Ag and In--In interlayer bonding (e.g. 303 and 304 pm in CaAgIn). Temperature dependent magnetic susceptibility measurements show a magnetic moment of 7.40(1) μ_B per europium atom. EuAgIn orders antiferromagnetically at 5.7(5) K. The divalent nature of europium is also evident from 151Eu Mössbauer spectra: δ = -10.50(1) mm·s^-1 at 78 K. [ABSTRACT FROM AUTHOR]