Hydrogenation Reaction Pathways and Crystal Structures of La2H2Se, La2H3Se and La2H4Se. Issue 10 (8th February 2022)

• Record Type: Journal Article
• Authors: Pflug, Christian; Rudolph, Daniel; Schleid, Thomas; Kohlmann, Holger
• Is Part Of: European journal of inorganic chemistry. Volume 2022:Issue 10(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-02-08
• Subjects: In situ neutron diffraction -- Metal hydride -- Rare-earth metal -- Rietveld refinement -- Selenide; Chemistry, Inorganic -- Periodicals; Organometallic chemistry -- Periodicals; Bioinorganic chemistry -- Periodicals; Solid state chemistry -- Periodicals; 546
• DOI: 10.1002/ejic.202101095
• Languages: English
• ISSNs: 1434-1948

Abstract

Abstract: The crystal structures and formation reactions of lanthanum hydride selenides were studied by neutron diffraction on the deuterides. The reaction of La2 D2− x Se with deuterium gas (298 K≤ T ≤567 K, 0.1 MPa≤ p (D2 )≤9.0 MPa) was followed in situ by neutron diffraction in a sapphire single‐crystal gas‐pressure cell with a time resolution of two minutes. The crystal structures and phase fractions of La2 D2− x Se, La2 D3 Se and La2 D4 Se were determined by Rietveld refinement. With stepwise increasing deuterium pressure at 498 K up to 3.0 MPa La2 D2− x Se is deuterated to La2 D4 Se. La2 D3 Se remains present, even when further increasing the pressure up to 9.0 MPa and heating up to 567 K. The previously suggested structural models were confirmed by Rietveld refinement (La2 D1.6 Se: Ce2 O2 S type, P 3 ‾ m 1, a =4.1268(1) Å, c =6.8733(3) Å at 298 K; La2 D3 Se: Ba2 H3 Cl type, P 3 ‾ m 1, a =4.139(2) Å, c =6.960(5) Å at 298 K; La2 D4 Se: Ce2 F4 Se type, R 3 ‾ m, a =4.0542(2) Å, c =22.609(2) Å at 310 K). La2 D2− x Se exhibits a considerable hydrogen gas pressure dependent phase width (0≤ x <0.40). Abstract : The crystal structures of La2 D1.6 Se (Ce2 O2 S type, P 3 ‾ m 1), La2 D3 Se (Ba2 H3 Cl type, P 3 ‾ m 1), and La2 D4 Se (Ce2 F4 Se type, R 3 ‾ m ) were determined by in situ neutron diffraction. By increasing hydrogen pressure interstitials in La2 H2− x Se are successively filled by hydrogen atoms followed by the formation of La2 H4 Se as a stoichiometric compound.