Synthesis and Characterization of K and Eu Binary Phosphides

Abstract

The synthesis, structural characterization, and optical properties of the binary Zintl phases of α-EuP3, β-EuP3, EuP2, and α-K4P6 are reported in this study. These crystal structures demonstrate the versatility of P fragments with dimensionality varying from 0D (P6 rings in α-K4P6) to 1D chains (EuP2) to 2D layers (both EuP3). EuP2 is isostructural to previously reported SrP2 and BaP2 compounds. The thermal stabilities of the EuP2 and both EuP3 phases were determined using differential scanning calorimetry (DSC), with melting temperatures of 1086 K for the diphosphide and 1143 K for the triphosphides. Diffuse reflectance spectroscopy indicated that EuP2 is an indirect semiconductor with a direct bandgap of 1.12(5) eV and a smaller indirect one, less than 1 eV. Both EuP3 compounds had bandgaps smaller than 1 eV.

High-efficiency thermoelectric Ba8Cu14Ge6P26: bridging the gap between tetrel-based and tetrel-free clathrates

“… 17 Until now, only a dozen tetrel-free clathrates have been reported, which include phosphides, Ba 8 M 16 P 30 ( ref. 15 and 24 ) and AeM 2 P 4 (Ae = Sr, Ba; M = Ni, Cu), 18 arsenides and antimonides, A 8 E 18 Pn 28 , A = Rb, Cs; E = Zn, Cd; Pn = As, Sb. 44 , 45 Prior to our work, there was an insurmountable gap between these two clathrate groups, despite the reported attempts to dope Sb into tetrel clathrates.…”

“…16 , 17 In turn, tetrel-free clathrates show full segregation of transition metal and phosphorus atoms over different framework positions, which result in the formation of either long-range ordered structures, as in the case of Ba 8 M 16 P 30 , BaM 2 P 4 , and Ba 8 Zn 11 Cu 13 P 28+ δ (M = Cu, Au, Ni), or short-range ordering, as in the case of Ba 8 (Cu/Zn) 16+ y P 30– y . 15 , 18 , 24 – 26 …”

EuNi2P4, the first magnetic unconventional clathrate preparedviaa mechanochemically assisted route

“…Eu2Ni7P4 [36], EuNi5P3 [37], Eu2Ni12P5 [38], Eu2Ni12P7 [39] and two modifications of EuNi10P6 [40]) and some recent synthetic attempts [41], our new compound, EuNi2P4, expands the P-rich region of the Eu-Ni-P system.…”

Special Issue: Advances in Zintl Phases

“…The thermochemistry was analyzed and thermoelectric properties measured. It is a p-type narrow gap semiconductor with thermal stability up to 700 K. The synthesis of four new phosphide-containing compounds is described by Kovnir et al [5]. This work demonstrates the richness of Zintl crystal chemistry with a variety of structures varying from zero dimensional (0D), 1D to 2D.…”