12029-86-6Relevant articles and documents
Resolving composition and structure of RE-Sb-O-C natural superlattice phases (RE = La, Ho)
Wang, Peng,Forbes, Scott,Svitlyk, Volodymyr,Aushana, Ashur,Mozharivskyj, Yurij
, p. 3887 - 3895 (2011)
A family of rare earth antimonide oxycarbides have been prepared and structurally characterized. These superlattice phases are constructed from NaCl-type RESb slabs sandwiched between RE-O-C layers. Depending on the carbon content and synthetic conditions, three different RE-Sb-O-C structures can be obtained. At lower temperatures,RE9-δSb 5(O,C)5 phases are obtained for RE = La, Ho. These phases adopt a stuffed Sc2Sb-type structure with P4/nmm symmetry. An O/C mixture, in which the O/C ratio is larger than 4:1, is randomly distributed within the RE-O-C layers. The RE atoms are highly disordered within the oxide layer. At temperatures above the melting point of the samples, RE 9Sb5O4C phases with P4/n symmetry are produced. The RE-O-C layers in RE9Sb5O4 are fully ordered; the RE sites are well defined, and the O and C atoms occupy the tetrahedral and square-pyramidal voids, respectively. At high temperatures, a new ordered La14Sb8O7C structure with P4bm symmetry was discovered. The La14Sb8O7C phase is structurally similar to RE9Sb5O4C and features orderedarrangements of La and O/C atoms in the La-O-C layer. The RE9-δSb5(O,C)5, RE 9Sb5O4C and La14Sb8O 7C phases appear to be charge-balanced, and their compositions and structures are controlled by the O/C ratio. Parallel preparative experiments revealed the importance of carbon in the formation of these layered phases. In addition, it has been established that the purity of the rare earth metals influences the compositions and structures of the products.
Synthesis and Transport Properties of the Family of Zintl Phases Ca3RESb3(RE = La-Nd, Sm, Gd-Tm, Lu): Exploring the Roles of Crystallographic Disorder and Core 4f Electrons for Enhancing Thermoelectric Performance
Ogunbunmi, Michael O.,Baranets, Sviatoslav,Bobev, Svilen
, p. 9382 - 9392 (2021/12/13)
Zintl phases with complex crystal structures have been studied as promising candidate materials for thermoelectric (TE) applications. Here, we report the syntheses of the family of rare-earth metal Zintl phases with the general formula Ca4-xRExSb3 (x ≈ 1; RE = La-Nd, Sm, Gd-Tm, Lu). The structural elucidation is based on refinements of single-crystal X-ray diffraction data for 12 unique chemical compositions. The cubic structure is confirmed as belonging to the anti-Th3P4 structure type (space group I4ˉ 3d, no. 220, Z = 4), where the Ca and RE atoms share the same atomic site with ca. 75 and 25% occupancies, respectively. Such crystallographic disordering of divalent Ca and trivalent RE atoms in the structure provides a pathway to intricate bonding. The latter, together with the presence of heavy elements such as Sb and the lanthanides, are expected to enhance the scattering probability of phonons, thereby leading to low thermal conductivity κ comparable to that of the ordered RE4Sb3. The drive of the hypothetical parent compound Ca4Sb3 to be stabilized by alloying with rare-earth metals can be understood following the Zintl-Klemm concept, as the resultant formula may be rationalized as (Ca2+)3RE3+(Sb3-)3, indicating the realization of closed-shell electronic configurations for all elements. This notion is confirmed by electronic structure calculations, which reveal narrow bandgaps Eg = 0.77 and 0.53 eV for Ca3LaSb3 and Ca3LuSb3, respectively. In addition, the incorporation of RE atoms into the structure drives the phase into a state of a degenerate semiconductor with dominant hole charge carriers.
Synthesis, structure, magnetic and transport properties of LnFeSb 3 (Ln = Pr, Nd, Sm, Gd, and Tb) - Tuning of anisotropic long-range magnetic order as a function of Ln
Phelan, W. Adam,Nguyen, Giang V.,Karki, Amar B.,Young, David P.,Chan, Julia Y.
, p. 6403 - 6409 (2010/09/06)
Single crystals of LnFeSb3 (Ln = Pr, Nd, Sm, Gd, and Tb) have been grown from excess Sb flux. The crystal structure consists of ∞2[FeSb2] octahedra separated by layers of Ln atoms and nearly square planar nets of ∞ 2[Sb2]. These compounds are metallic and display anisotropic magnetic properties. Long-range antiferromagnetic order is observed in the Sm, Gd, and Tb samples when the magnetic field is applied along the crystallographic a-axis. Evidence of magnetic ordering in all the samples is observed for the field applied parallel to the layers. The magnetic properties are well-described by considering only the magnetic interactions between the Ln 4f moments, with no contribution from the Fe sublattice. Herein, we report the crystal growth, structure, magnetization, transport, and chemical stabilities of the title compounds. The Royal Society of Chemistry.
