Dimorphic ErAgSn and TmAgSn – High‐Pressure and High‐Temperature Driven Phase Transitions |
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Authors: | C Peter Sebastian Gunter Heymann Birgit Heying Ute Ch Rodewald Hubert Huppertz PD Dr Rainer Pöttgen Prof Dr |
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Institution: | 1. Münster, Institut für Anorganische und Analytische Chemie der Universit?t and NRW Graduate School of Chemistry;2. München, Department Chemie und Biochemie der Ludwig‐Maximilians‐Universit?t;3. Hubert Huppertz, Department Chemie und Biochemie, Ludwig‐Maximilians‐Universit?t München, Butenandtstrasse 5–13 (Haus D), 81377 München, Germany;4. Rainer P?ttgen, Institut für Anorganische und Analytische Chemie, Universit?t Münster, Corrensstrasse 30, D‐48149 Münster, Germany |
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Abstract: | The stannides ErAgSn and TmAgSn have been investigated under high‐temperature (HT) and high‐pressure (HP) conditions in order to investigate their structural chemistry. ErAgSn and TmAgSn are dimorphic: normal‐pressure (NP) ErAgSn and HT‐TmAgSn crystallize into the NdPtSb type structure, P63mc, a = 466.3(1), c = 729.0(2) pm for NP‐ErAgSn and a = 465.4(1), c = 726.6(2) pm for HT‐TmAgSn. NP‐ErAgSn was obtained via arc‐melting of the elements and subsequent annealing at 970 K, while HT‐TmAgSn crystallized directly from the melt by rapidly quenching the arc‐melted sample. HT‐TmAgSn transforms to the ZrNiAl type low‐temperature modification upon annealing at 970 K. The high‐pressure (HP) modification of ErAgSn was synthesized under multianvil high‐pressure (11.5 GPa) high‐temperature (1420 K) conditions from NP‐ErAgSn: ZrNiAl type, , a = 728.7(2), c = 445.6(1) pm. The silver and tin atoms in NP‐ErAgSn and HT‐TmAgSn build up two‐dimensional, puckered Ag3Sn3] networks (277 pm intralayer Ag–Sn distance in NP‐ErAgSn) that are charge‐balanced and separated by the erbium and thulium atoms. The fourth neighbor in the adjacent layer has a longer Ag–Sn distance of 298 pm. The AgSn] network in HP‐ErAgSn is three‐dimensional. Each silver atom has four tin neighbors (281–285 pm Ag–Sn). The AgSn] network leaves distorted hexagonal channels, which are filled with the erbium atoms. The crystal chemistry of the three phases is discussed. |
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Keywords: | Rare earth compounds Crystal chemistry High pressure |
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