New rare earth metal-rich indides RE14Ni 3In 3 ( RE=Sc, Y, Gd–Tm, Lu)—synthesis and crystal chemistry

Abstract

The rare earth–nickel–indides RE 14Ni 3In 3 ( RE = Sc , Y, Gd–Tm, Lu) were synthesized from the elements by arc-melting and subsequent annealing. The compounds were investigated on the basis of X-ray powder and single crystal data: Lu 14Co 2In 3 type, P4 2/ nmc, Z = 4 , a = 888.1 ( 1 ) , c = 2134.7 ( 4 ) , w R 2 = 0.0653 , 1381 F 2 values, 63 variables for Sc 13.89Ni 3.66In 2.45; a = 961.2 ( 1 ) , c = 2316.2 ( 5 ) , w R 2 = 0.0633 , 1741 F 2 values, 64 variables for Y 13.84Ni 3.19In 2.97; a = 965.3 ( 1 ) , c = 2330.5 ( 5 ) , w R 2 = 0.0620 , 1765 F 2 values, 63 variables for Gd 14Ni 3.29In 2.71; a = 956.8 ( 1 ) , c = 2298.4 ( 5 ) , w R 2 = 0.0829 , 1707 F 2 values, 64 variables for Tb 13.82Ni 3.36In 2.82; a = 951.7 ( 1 ) , c = 2289.0 ( 5 ) , w R 2 = 0.0838 , 1794 F 2 values, 64 variables for Dy 13.60Ni 3.34In 3.06; a = 948.53 ( 7 ) , c = 2270.6 ( 1 ) , w R 2 = 0.1137 , 1191 F 2 values, 64 variables for Ho 13.35Ni 3.17In 3.48; a = 943.5 ( 1 ) , c = 2269.1 ( 5 ) , w R 2 = 0.0552 , 1646 F 2 values, 64 variables for Er 13.53Ni 3.14In 3.33; a = 938.42 ( 7 ) , c = 2250.8 ( 1 ) , w R 2 = 0.1051 , 1611 F 2 values, 64 variables for Tm 13.47Ni 3.28In 3.25; a = 937.3 ( 1 ) , c = 2249.6 ( 5 ) , w R 2 = 0.0692 , 1604 F 2 values, 64 variables for Tm 13.80Ni 3.49In 2.71; and a = 933.4 ( 1 ) , c = 2263.0 ( 5 ) , w R 2 = 0.0709 , 1603 F 2 values, 64 variables for Lu 13.94Ni 3.07In 2.99. The RE 14Ni 3In 3 indides show significant Ni/In mixing on the 4 c In1 site. Except the gadolinium compound, the RE 14Ni 3In 3 intermetallics also reveal RE/In mixing on the 4 c RE1 site, leading to the refined compositions. Due to the high rare earth metal content, the seven crystallographically independent RE sites have between 9 and 10 nearest RE neighbors. The RE 14Ni 3In 3 structures can be described as a complex intergrowth of rare earth-based polyhedra. Both nickel sites have a distorted trigonal-prismatic rare earth coordination. An interesting feature is the In2–In2 dumb-bell at an In2–In2 distance of 304 pm (for Gd 14Ni 3.29In 2.71). The crystal chemical peculiarities of the RE 14Ni 3In 3 indides are briefly discussed.