Structural and magnetic investigations of the pseudo-ternary RE ₂ TAl₃ series (RE=Sc, Y, La–Nd, Sm, Gd–Lu; T=Ru, Rh, Ir) – size dependent formation of two different structure types

Abstract

Several rare earth metal containing pseudo-ternary compounds in the RE2TAl3 series (RE=Sc, Y, La–Nd, Sm, Gd–Lu; T=Ru, Rh, Ir) have been synthesized from the elements by arc-melting or in tantalum capsules. Within the Rh series, the compounds with RE=La–Nd crystallize in the cubic MgCu2-type (Fd3̅m) structure. For Sm besides the cubic Laves phase also the hexagonal Laves phase (MgZn2 type, P63/mmc) is found. For the remaining compounds of both series, also the hexagonal MgZn2-type structure is observed. The structures of Ho2Ru0.96(1)Al3.04(1) (a=547.4(1), c=875.7(1) pm, wR=0.0397, 201 F2 values, 13 variables), Sc2Rh1.01(1)Al2.99(1) (a=528.0(1), c=852.8(1) pm, wR=0.0228, 184 F2 values, 13 variables), Ho2Rh1.00(1)Al3.00(1) (a=546.5(1), c=873.8(1) pm, wR=0.0590, 222 F2 values, 13 variables) and Tb2Ir1.06(1)Al2.94(1) (a=550.8(1), c=870.0(1) pm, wR=0.0743, 221 F2 values, 13 variables) have been refined from single-crystal data, indicating T/Al mixing on both crystallographic Zn sites of the aristotype. The Sc, Y, La and Lu containing compounds exhibit Pauli-paramagnetic behavior, while the other compounds show paramagnetism, in line with the rare earth atoms in the trivalent oxidation state. Ferro- and antiferromagnetic ordering up to TC=50.2(1) K for Gd2RhAl3 is observed, while Sm2RuAl3 shows van Vleck paramagnetism and Yb2RuAl3, finally, exhibits only partially trivalent Yb atoms, evident from a reduced magnetic moment and increased lattice parameters.

Intermetallic RE6T5Al7 Phases (RE = Sc, Y, Ce–Nd, Sm, Gd–Lu; T = Ru, Ir): Diversity in their Magnetic, Magnetocaloric, and Critical Properties

“…The Ru–Al distances are in line with e.g. binary RuAl (CsCl type, 262 pm) or ternary Ho 2 RuAl 3 (MgZn 2 type, 269–276 pm) but longer compared to RuAl 2 (MoSi 2 type, 241–254 pm). The Al–Al and Ru–Ru distances are in line with the ones found in the elements (fcc Al 286 pm; hcp Ru 264–270 pm) or in ternary Y 3 Ru 4 Al 12 (Gd 3 Ru 4 Al 12 type, Al−Al: 274–298 pm), or HoRu 2 Al 10 (YbFe 2 Al 10 type, Al−Al: 258–304 pm).…”

“…All annealed samples were analyzed by powder X-ray diffraction experiments in a first step: Guinier technique, imaging plate system (Fujifilm, BAS-READER 1800), Cu Kα 1 radiation, and α-SiO 2 ( a = 491.30 pm, c = 540.46 pm) as internal standard. The hexagonal lattice parameters (Table ) were refined by least-squares refinements: for the RE 6 T 5 Al 7 series, on the basis of the single-crystal data of Ho 6 Ru 5 Al 7 , and for the RERuAl series, on the basis of the structurally related RE 2 RuAl 3 compounds …”

“…Besides Yb 6 Ir 5 Ga 7 , also the isostructural RE 6 Ir 5 Ga 7 (RE = Sc, Y, Nd, Sm, Gd–Tm, Lu) series was recently prepared and investigated . During our endeavors in the ternary systems RE–T–Al (RE = rare earth element; T = transition metal), we were able to synthesize a number of MgCu 2 and MgZn 2 type representatives in the RE 2 TAl 3 series (RE = Sc, Y, La–Nd, Sm, Gd–Lu; T = Ru, Rh, Ir) . For the equiatomic compositions in these systems, the REIrAl series (RE = Y, Ce–Nd, Sm, Gd–Tm, Lu) was reported to crystallize in the TiNiSi type structure, while ScIrAl was reported to be of MgZn 2 type .…”

Magnetic Properties of theRE2Pt6X15(RE= Y, La–Nd, Sm, Gd–Lu;X= Al, Ga) Series

“…In comparison with other intermetallic compounds, e.g. SmPdGa 3 (Δ E = 1346 K) or HP‐SmPdSn (Δ E = 1366 K) exhibit higher values, however, also a number of compounds with significantly lower energy values [Δ E = 265 K for SmRu 2 Zn 20 , 412 K for SmCo 2 Zn 20 , 454 K for Sm 3 Pt 4 Ge 6 , 480 K for Sm 2 RuAl 3 , 703 K for Sm 2 Rh 3 Sn 5 , 714 K for Sm 2 CoIn 8 , 850 K for SmOs 4 Sb 12 or finally 942(2) K for SmPt 6 Al 3 ] have been observed and reported. The ZFC/FC curves for Sm 2 Pt 6 Ga 15 are finally depicted in Figure (bottom), exhibiting a splitting of the ZFC and FC curves, underlining the ferrimagnetic ground state, in analogy to Pr 2 Pt 6 Ga 15 and Nd 2 Pt 6 Ga 15 described before.…”

Extending the knowledge on the quaternary rare earth nickel aluminum germanides of the RENiAl4Ge2 series (RE=Y, Sm, Gd–Tm, Lu) – structural, magnetic and NMR-spectroscopic investigations

“…MAu 2 Al 2 with M = Ca, Sr [20]; MAuX with M = Ca-Ba and X = Al-In [21]; MPtAl 2 with M = Ca-Ba [22]) and the rare earth elements (e.g. RET 5 Al 2 with RE = Y, Gd-Tm, Lu and T = Pd, Pt [23], RE 2 TAl 3 with RE = Y, La-Nd, Sm, Gd-Lu and T = Ru, Rh, Ir [24], Eu 2 Pt 6 Al 15 [25], Eu 2 Ir 3 Al 9 [26] or YbPd 2 Al 3 [27]), the interest of extending the knowledge of quaternary aluminum containing compounds has sparked. Amongst the vast number of potential elemental combinations, the aluminum germanides of the rare earth elements were chosen due to the pronounced differences in the electron count of the respective elements, enabling single-crystal X-ray diffraction experiments.…”