Structural Stability Diagram of ALnP₂S₆ Compounds (A = Na, K, Rb, Cs; Ln = Lanthanide)

Abstract

Thiophosphate compounds have been studied extensively in the past for their rich structural variations and for a large variety of interesting properties. Here, we report 11 new phases with the composition ALnPS (A = Na, K, Rb, Cs; Ln = lanthanide). These new thiophosphates crystallize in four different structure types, with the space groups Fdd2, P1̅, P2, and P2/c, respectively. All phases are insulating and the calculated band gaps range between 3 eV and 3.5 eV. Magnetic measurements on the compounds with open f-shells show paramagnetic behavior and magnetic moments that match the expected free ion values of the respective lanthanide cations. We present a structural stability phase diagram for the ALnPS family of compounds, which reveals a clear relationship between ionic radii and the preferred crystal structure, as well as stability regions to form ALnPS-type phases.

The First Quinary Rare Earth Thiophosphates: Cs5Ln3X3(P2S6)2(PS4) (Ln = La, Ce, X = Br, Cl) and the Quasi‐Quaternary Cs10Y4Cl10(P2S6)3

“…The polyhedra form layers in the ab plane and the Cs ions are located in the voids. The P–S bond lengths are in the range of 2.01–2.08 Å for both anions and the P–P bond length in the [P 2 S 6 ] 4– anion is on the order of 2.19 Å, which is in good agreement with commonly observed bond lengths for a P–P dumbbell , …”

New Light on an Old Story: The Crystal Structure of Boron Tetrathiophosphate Revisited

“…As part of our systematic studies on ternary thiophosphates and our investigations of the Al‐P‐S system, we here revisit and clarify the structure of boron tetrathiophosphate. To this end, we resynthesized BPS 4 to obtain single crystals suitable for structure solution and performed Raman spectroscopy supported by quantum chemical calculations.…”

Synthesis and Characterization of Three New Lithium‐Scandium Hexathiohypodiphosphates: Li4–3xScxP2S6 (x = 0.358), m‐LiScP2S6, and t‐LiScP2S6

“…The compounds exist in three different structure types (see Table S4, Supporting Information). They complete the structural stability diagram of ALn P 2 S 6 compounds ( A = Na, K, Rb, Cs; Ln = lanthanide) . All three contain isolated ethane‐like [P 2 S 6 ] 4– hexathiohypodiphosphate(IV) building blocks.…”

“…The compounds exist in three different structure types with either two or three dimensional topologies. They complete the structural stability diagram of ALn P 2 S 6 compounds ( A = Na, K, Rb, Cs; Ln = lanthanide) that we published recently …”

“…Lithium thiophosphates are potential candidates for high lithium ion conductivities, but the number of known thiophosphate compounds that are lithium superionic conductors is relatively small. Inspired by the lack of lithium compounds in our systematic studies on quaternary rare earth metal thiophosphates, we extensively investigated the Li‐Sc‐P‐S system and found three new lithium‐scandium hexathiohypodiphosphates(IV). The compounds exist in three different structure types with either two or three dimensional topologies.…”