Cubic structure types of rare-earth intermetallics and related compounds

Lu37Ru16.4In4 – coloring and vacancy formation in a new structure type closely related to a 8 × 8 × 8 bcc superstructure

The lutetium-rich intermetallic compound Lu37Ru16.4In4 was synthesized by induction melting of the elements in a sealed tantalum ampoule and subsequent annealing. The Lu37Ru16.4In4 structure was refined from single crystal X-ray diffractometer data: new type, I a 3 ‾ d $Ia\overline{3}d$ , a = 2756.21(11) pm, wR2 = 0.0579, 3056 F 2 values and 92 variables. The superstructure formation of Lu37Ru16.4In4 is discussed on the basis of a group–subgroup scheme starting from the bcc structure as the aristotype.

Scandium-rich ternary coloring variants of the cubic Ag7+xMg26–x type

Abstract

The scandium-rich intermetallic compounds Sc50T13In3(T = Ni, Ru, Pd) were synthesized from the elements in sealed tantalum crucibles in an induction furnace. The samples were studied through Guinier powder patterns and their structures were refined from single-crystal X-ray diffractometer data. The Sc50T13In3phases are site occupancy (coloring) variants of the aristotype Ag7+xMg26–x(Fm$$ \bar{3} $$3¯,cF264). Refinements of the occupancy parameters indicated one mixed occupied site for each crystal, leading to the refined compositions Sc50Ni13.16(1)In2.84(1), Sc49.59(1)Ru13In3.41(1), and Sc50Pd13.65(2)In2.35(2). The complex structures can be explained by a condensation of cubes (CN 8), sphenocorona (CN 10), and icosahedra (CN 12). The samples with nickel and palladium are Pauli paramagnets.

Graphic abstract

Enhancement of dielectric and electric-field-induced polarization of bismuth fluoride nanoparticles within the layered structure of carbon nitride

A single-pot, wet chemical method has been reported for the synthesis of bismuth fluoride nanoparticles (BF) and functionalized BF within the network of carbon nitride (BFCN). In BFCN, a structural transformation of BF, from cubic to pseudo-cubic (as evidenced by Rietveld refinement analysis), confirmed the contribution of carbon nitride (CN) on functionalization. The effect of functionalization of BF has been investigated through dielectric and field-induced polarization studies under different temperature and frequency conditions. Enhancement of dielectric constant values was noticed in BFCN as compared with BF system, in the order of 2.5 (30 °C) and 8.0 (100 °C) at 100 Hz. Fatigue-free maximum polarization values of 0.041 µC/cm2 and 0.054 µC/cm2, under the electric field of 5 kV/mm, were achieved for BF and BFCN samples, respectively, for 5 × 103 cycles.

The scandium-rich indide Sc50Pt13.47In2.53

The scandium-rich indide Sc50Pt13.47In2.53 was obtained by induction melting of the elements and subsequent annealing. The structure of Sc50Pt13.47In2.53 has been refined from single-crystal X-ray diffractometer data: Fm 3 ¯ $\overline{3}$ , a = 1774.61(3) pm, wR2 = 0.0443, 1047 F2 values and 35 variables. Sc50Pt13.47In2.53 is isopointal with the intermetallic phases Sc50Co12.5In3.5, Sc50Rh13.3In2.7, Sc50Ir13.6In2.4, Ag7+xMg26−x and Ga4.55Mg21.85Pd6.6 (Pearson code cF264 and Wyckoff sequence ih 2 fecba). Two of the eight crystallographic sites in the structure show mixed occupancies: M1 (≡Pt20.70In10.30) and M2 (≡Pt30.76In20.24). The structure contains four basic polyhedra: M2@Sc8 cubes, Pt1@Sc10 sphenocorona and slightly distorted M1@Sc12 and In3@Sc12 icosahedra. The polyhedra are condensed via common scandium corners and edges. The various Sc–Sc distances range from 302–334 pm and are indicative of substantial Sc–Sc bonding, stabilizing the Sc50Pt13.47In2.53 structure.