Thiophosphates Containing Ag+ and Lone-Pair Cations with Interchiral Double Helix Show Both Ionic Conductivity and Phase Transition
journal contributionposted on 2017-01-05, 17:04 authored by Yu-Hang Fan, Hui-Yi Zeng, Xiao-Ming Jiang, Ming-Jian Zhang, Bin-Wen Liu, Guo-Cong Guo, Jin-Shun Huang
Quaternary metal thiophosphates containing second-order Jahn–Teller distorted d10 Ag+ and lone-pair cations, Ag3Bi(PS4)2 (1), Ag7Sn(PS4)3 (2), and Ag7Pb(PS4)3 (3), were obtained by solid-state synthesis. The structural frameworks of 2 and 3 feature an infinite 1-D interchiral double helix ∞1(Ag3P2S11), which is rare in inorganic compounds. Compound 3 undergoes a significant first-order structural phase transition from monoclinic to hexagonal at ∼204 °C. This can be ascribed to the significant mismatch in the expansion coefficients between Pb–S (Ag–S) and P–S bonds evaluated by bond valence theory. The three compounds are Ag+ ionic conductors, and Ag+ ion migration pathways are proposed by calculating maps of low bond valence mismatch. Moreover, the optical properties of the three compounds were studied, and electronic structure calculations were performed. The combination of second-order Jahn–Teller distorted d10 cation and lone-pair cation provides a new strategy to explore new metal thiophosphates with interesting structures and promising properties.
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Interchiral Double Helix Showbond valence theory10 cationlone-pair cationexpansion coefficientsstructure calculationsIonic ConductivityPhase Transition Quaternary metal thiophosphates3 featurephase transitionCompound 31- D interchiralLone-Pair Cationsmetal thiophosphatesion migration pathways10 Agbond valence mismatchThiophosphates Containing Aglone-pair cations