Chemistry; Materials Science and Engineering; Ames Laboratory
Chemistry, Materials Science and Engineering, Ames Laboratory
Although the Pt–Pr phase diagram has been explored well, recent work on rare-earth metal cluster halides with endohedral transition metal atoms has provided a new binary intermetallic that is nonexistent in the known phase diagram: The binary Pt3Pr4 (1) crystallizes in a new structure type (mP56, P21/c, a = 12.353(2) Å, b = 7.4837(9) Å, c = 17.279(2) Å, β = 118.003(7)°, Z = 8) with six crystallographically independent Pt as well as eight Pr positions. The subsequent detailed investigation has led to another previously unreported, binary phase with the Ga2Gd3 structure type, Pt2–xPr3 (2, tI80, I4/mcm, a = 11.931(9) Å, c = 14.45(1) Å, Z = 16), that is practically overlapping with the rhombohedral Pt2Pr3 existing in the phase diagram. Application of different tin containing fluxes to reproduce the newly detected phases brought about two almost iso-compositional ternary compounds with Sn, Pt4Sn6Pr2.91 (3), and Pt4Sn6Pr3 (4), as well as Pt12Sn24Pr4.84 (5). 3 is a representative of the Pt4Ge6Ce3 type (oP52, Pnma, a = 7.2863(3) Å, b = 4.4909(2) Å, c = 35.114(2) Å), while 4 represents a new variant of the prolific T4E6R3 family (T = transition metal, E = main group (semi)metal, R = rare-earth metal; Pt4Sn6Pr3: oP52, Pnma, a = 27.623(1) Å, b = 4.5958(2) Å, c = 9.3499(5) Å). Pt12Sn24Pr5–x (5) crystallizes as a variant of the Ni8Sn16Gd3 type (cI82, Im3̅, a = 12.274(1) Å, Z = 2). Electronic structure calculations provide hints on the origin of the structural changes (pseudo-polymorphism) for PtxPr3 with x = 1.97 and 2.00, respectively, and reveal that heteroatomic Pt–Pr bonding strongly dominates in both binaries while the addition of the reactive metal tin leads to dominating Pt–Sn bonding interactions in the ternaries; Pt–Pt bonding interactions are strong but represent a minority in the binaries and are not present at all in the ternaries.
DOE Contract Number(s)
Department of Energy Subject Categories
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; 36 MATERIALS SCIENCE
Iowa State University Digital Repository, Ames IA (United States)