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Abstract <p>The phase transition in structure of the PdBi<sub>2</sub> compound has been studied using high-temperature in-situ methods (differential thermal analysis and high-temperature single-crystal X-ray diffraction). The structures of PdBi<sub>2</sub> polymorphic modifications are refined at temperatures of 300, 373, 473, 573, and 637 K based on high-temperature single-crystal X-ray diffraction data. A low-temperature modification of α-PdBi<sub>2</sub> corresponding to froodite occurs in a temperature range from 300K (27°C) to 573K (300°С) and is characterized by monoclinic syngony, space group C2/<i>m</i> (<i>a</i> = 12.726(1) Å, <i>b</i> = 4.2605(4) Å, <i>c</i> = 5.5668(5) Å, β = 102.51(1)°, <i>V</i> = 299.95(5) Å<sup>3</sup>, <i>Z</i> = 2). A high-temperature modification of β-PdBi<sub>2</sub>, which is registered at a temperature of 673K (400°C), has tetragonal syngony and space group I4/<i>mmm</i> (<i>a</i> = 3.3876(3) Å, <i>c</i> = 13.092(2) Å, <i>V</i> = 150.24(4) Å<sup>3</sup>, <i>Z</i> = 1) and is a structural analog of urvantsevite. The phase transition is referred to as type I and is a reconstructive polymorphic transformation with the rearrangement of the first coordination sphere.</p>

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Structural Transformations and Froodite (α-PdBi2)–Urvantsevite (β-PdBi2) Phase Transition at High Temperatures

  • 期刊论文

  • 发表日期：

    2025年4月1日

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  • O. V. Karimova,
  • N. N. Eremin,
  • A. A. Mezhueva,
  • N. S. Uporova,
  • A. A. Zolotarev,
  • D. A. Chareev

摘要

Abstract

The phase transition in structure of the PdBi2 compound has been studied using high-temperature in-situ methods (differential thermal analysis and high-temperature single-crystal X-ray diffraction). The structures of PdBi2 polymorphic modifications are refined at temperatures of 300, 373, 473, 573, and 637 K based on high-temperature single-crystal X-ray diffraction data. A low-temperature modification of α-PdBi2 corresponding to froodite occurs in a temperature range from 300K (27°C) to 573K (300°С) and is characterized by monoclinic syngony, space group C2/m (a = 12.726(1) Å, b = 4.2605(4) Å, c = 5.5668(5) Å, β = 102.51(1)°, V = 299.95(5) Å3, Z = 2). A high-temperature modification of β-PdBi2, which is registered at a temperature of 673K (400°C), has tetragonal syngony and space group I4/mmm (a = 3.3876(3) Å, c = 13.092(2) Å, V = 150.24(4) Å3, Z = 1) and is a structural analog of urvantsevite. The phase transition is referred to as type I and is a reconstructive polymorphic transformation with the rearrangement of the first coordination sphere.