Homogeneity Range of the Zirconium Phosphide Telluride Zr_2+xPTe₂ and the High‐Temperature Phase Transformation to Zr₂PTe

Abstract

The synthesis of the phosphide telluride Zr2+xPTe2 was accomplished by a solid‐state reaction from the elements. Le Bail refinements of the data from the as‐synthesized crystalline powders as well as the thermal decomposition of Zr2PTe2 along the homogeneity range Zr2+xPTe2 with the release of P4(g) and Te2(g) evidence a maximum zirconium content corresponding to the composition Zr2.5PTe2. The thermal decomposition product of Zr2.5PTe2 undergoes a phase transformation to “Zr2PTe”, which adopts the structural motif of the binary phases ZrTe and ZrTe2. The new phase “Zr2PTe” has a wide homogeneity range Zr2–xP1–yTe1+y and tolerates a deficit in the cation position and a mixed occupation of the anions. The composition of the crystalline decomposition product was determined to be Zr1.95P0.84Te1.16 by Rietveld refinement and by analysis of the elemental composition by inductively coupled plasma optical emission spectroscopy (ICP‐OES). Zr1.95P0.84Te1.16 crystallizes in the hexagonal space group P63/mmc (no. 194) with lattice constants a = 3.8726(1) Å and c = 13.008(1) Å.

Understanding Solid‐State Phase‐Formation Processes by Using the High‐Temperature Gas Balance: The Example of Zr2PTe2

“…Small temperature ranges are mostly used to achieve the kinetic conditions for the phase formation and to avoid thermal decomposition of the targeted phase. The only ternary systems that contain isolated phosphide and telluride anions are U/P/Te (UPTe), Ti/P/Te (Ti 2 PTe 2 ),, and Zr/P/Te (Zr 2 PTe 2, Zr 2+ x PTe 2 , Zr 2 PTe) . With this in mind, their phase formations should be investigated by analyzing the temperature as well as the temperature dependent vapor pressure while synthesis.…”

“…In this project, we have picked the compound Zr 2 PTe 2 as a chemical system with multiple volatile compounds , . Already the starting materials, elemental phosphorus and tellurium, sublime at temperatures of about 500 °C with p (i) > 10 –3 bar.…”