Molten Ga as a Solvent for Exploratory Synthesis. Preparation, Structure, and Properties of Two Ternary Silicides MNiSi₃ (M = Sm, Y)

Abstract

Two ternary silicides, MNiSi3 (M = Sm, Y), have been synthesized from Sm, Ni, and Si in molten Ga at 850 °C in sealed silica tubes. Both compounds form black shiny crystals and are stable even in aqua regia. The structures, determined by single-crystal X-ray diffraction, are orthorhombic, Cmmm (No. 65) with Z = 4, and have lattice parameters a = 3.965(2) Å, b = 21.144(2) Å, c = 4.007(1) Å for M = Sm and a = 3.930(2) Å, b = 21.021(2) Å, c = 3.960(1) Å for M = Y, respectively. Refinement based on F o 2 yielded R 1 = 0.0319 and wR 2 = 0.0712 [I > 2 σ(I)] for M = Sm and R 1 = 0.0267 and wR 2 = 0.0688 [I > 2σ(I)] for M = Y. The compounds adopt the SmNiGe3 structure type with zigzag Si chains and Si dimers and exhibit metallic p-type electrical conductivity. Variable temperature magnetic susceptibility data suggest that Sm is 3+ and Ni has no magnetic moment. SmNiSi3 has an antiferromagnetic transition at 12 K and follows the modified Curie−Weiss law above 12 K. Band structure calculations using density functional theory, generalized gradient approximation, full potential LAPW method, and also extended Hückel tight binding theory show that the materials are metallic and suggest that Ni is either neutral or in a reduced oxidation state. Additional insight into the bonding was obtained by extended Hückel calculations carried out on the [NiSi3]3- framework under the assumption that Y is mostly 3+. These results suggest that the Si zigzag chain contains single bonds with a partial double bond character.

Intermetallics as Zintl Phases: Yb2Ga4Ge6 and RE3Ga4Ge6 (RE=Yb, Eu): Structural Response of a [Ga4Ge6]4− Framework to Reduction by Two Electrons

“…Synthesis: Yb 2 Ga 4 Ge 6 (1) and Yb 3 Ga 4 Ge 6 (2) were first obtained from Yb/Ni/Ga/Ge reactions in liquid Ga, from which the hexagonal phase Yb 0.67 Ni 2 Ga 6Àx Ge x [30,4] (x % 0.67) was isolated in high yield, whereas 1 and 2 were present in only minor quantities. Nevertheless, the formation of 1 and 2 at reaction stoichiometries far from their ideal compositions suggested high stability of their crystal structures.…”

“…For the Ge(3) and Ge(6) atoms, the angles only slightly diverge from those of an ideal tetrahedron [108.07(5)±114.07(7)8 for Ge(3), and 103.31(5)±114.82(7)8 for Ge (6)]. The Ge(1)-and Ge(4)-centered tetrahedra are moderately distorted [90.59(6)±118.11(4)8 for Ge (1), and 100.60(5)±125.86(7)8 for Ge (4)]. The remaining two Ge atoms have grossly distorted environments with angles that range from 58.82(5) to 124.38(4)8 for Ge (2), and from 60.89(6) to 123.55(4)8 for Ge (5).…”

“…We have reported a number of intermetallics grown from Ga flux; these include RENiSi 3 , [1] Sm 2 NiGa 12 , [2] RE 4 FeGa 12Àx Ge x , [3] RE 0.67 M 2 Ga 5 + nÀx Ge x [4] (M = Ni, Co), RE 3 Ga 9 Ge, [5] REMGa 3 Ge (M = Ni, Co), and RE 3 Ni 3 -Ga 8 Ge 3 . [6,7] However, examples of Zintl compounds obtained from molten Ga are relatively scarce and include the clathrate compounds M 8 Ga 16 Tt 30 [8,9] (M = Ba, Sr; Tt = Si, Ge) and the Zintl phase Eu 4 Ga 8 Ge 16 .…”

Unraveling the Pathways to UVA‐Induced DNA Photodamage: (6–4) Photoproduct as a Potential “Trojan Horse”

“…The Ga‐flux synthetic technique has proven successful not only for the synthesis of novel intermetallics, but also for the discovery of new rare earth (RE) and Group 13/14 Zintl phases. We have reported a number of intermetallics grown from Ga flux; these include RENiSi 3 ,1 Sm 2 NiGa 12 ,2 RE 4 FeGa 12− x Ge x ,3 RE 0.67 M 2 Ga 5+ n − x Ge x 4 (M=Ni, Co), RE 3 Ga 9 Ge,5 REMGa 3 Ge (M=Ni, Co), and RE 3 Ni 3 Ga 8 Ge 3 6. 7 However, examples of Zintl compounds obtained from molten Ga are relatively scarce and include the clathrate compounds M 8 Ga 16 Tt 30 8, 9 (M=Ba, Sr; Tt=Si, Ge) and the Zintl phase Eu 4 Ga 8 Ge 16 10.…”

Solution chemistry synthesis, morphology studies, and optical properties of five distinct nanocrystalline Au–Zn intermetallic compounds

“…While intermetallic compounds of the late transition metals are typically synthesized using high-temperature metallurgical techniques, alternative low-temperature methods have opened the door to new phases [1][2][3][4][5][6][7][8][9][10][11][12][13], high-quality single crystals [5,7,9,11,12], thin films [2,14,15], and materials with a variety of nano-and micro-structures [16][17][18] that the traditional methods generally cannot access. Among these, low-temperature solution chemistry techniques have emerged as a useful platform for synthesizing intermetallic compounds as nanocrystals, often with the capability of controlling particle shape and size [19][20][21][22][23][24][25][26][27] and sometimes providing access to non-equilibrium phases [10,13,28].…”