<i>RE</i> ₃ Co ₉ In ₂ ( <i>RE</i> = Pr, Nd, Sm) compounds – new members of the homologous series based on CaCu ₅ - and CsCl-type slabs. Electronic structure of Pr ₃ Co ₉ In <sub>2</sub

Abstract The intermetallic phases RE 3 Co 9 In 2 ( RE = Pr, Nd, Sm) were obtained by arc-melting of the elements in an argon atmosphere followed by annealing at T = 600 °C for 1,500 h in evacuated and sealed quartz ampoules. All samples were characterized through their powder X-ray diffraction patterns and metallographic and quantitative phase analyses. The crystal structure of Pr 3 Co 9 In 2 was refined from powder X-ray diffraction data using the Fullprof program package. The compound crystallizes in a Sm 2 Co 9 In 3 -related structure type (orthorhombic space group Cmmm , Z = 2; a = 23.123(4); b = 5.1003(7); c = 4.0423(5) Å) and is a two-layer structure with layers perpendicular to the z direction. The crystal structure of Pr 3 Co 9 In 2 is based on the intergrowth of CaCu 5 - and CsCl-type related slabs and is a member of the homologous series RE 2 m +2 n +2 p T 2 m +2 n X 2 n +2 p , where m and n are the numbers of RET 5 and RET 4 X (CaCu 5 type) slabs and p is the number of REX (CsCl type) slabs ( T = Co, X = In), respectively. For Pr 3 Co 9 In 2 the values are m = n = p = 2. Isostructural compounds were obtained with Nd and Sm.