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

Abstract

Inorganic solid-state synthesis with phosphorus and tellurium requires a careful control of the reaction parameters because of the high volatility of the components. This initial disadvantage can be used as a benefit for the investigation of phase-formation mechanisms by analyzing the individual vapor pressure behavior. The high-temperature gas balance is introduced as a device for detection of heterogeneous solid-gas equilibria in closed reaction systems. The experimentally challenging synthesis of the phosphide telluride Zr 2 PTe 2 is exam-While many ternary inorganic compounds with combined pnictide and chalcogenide anions exist, [1][2][3][4] only three examples of ternary phosphide tellurides are known, and their direct solid-state synthesis seems to be extremely challenging. The strict control of the temperature program and, therefore, of the vapor pressure of the components was described as a prerequisite for a successful phase-pure synthesis. 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), [5] Ti/P/Te (Ti 2 PTe 2 ), [6,7] and Zr/P/Te (Zr 2 PTe 2, Zr 2+x PTe 2 , Zr 2 PTe). [8][9][10] 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 way, a general approach for syntheses of multinary compounds containing volatile components is aimed.In thermal analysis, several methods are established to investigate phase formations, phase transitions, and decomposition reactions. Unfortunately, conventional techniques reach their limit when analyzing chemical systems with volatile components since these are lost by vaporization in open environments. To overcome this issue, a different approach is used by the high-temperature gas balance (HTGB): The vapor phase is [a]

Crystal Growth by Chemical Vapor Transport: Process Screening by Complementary Modeling and Experiment

“…As a major advantage, the measurement is performed under similar experimental conditions such as the actual synthesis or transport attempt (closed systems). Recently, the concept of Hackert and Plies, called high temperature gas balance (HTGB), was pursued and enhanced to investigate phase formation processes in solid state reactions including volatile components, namely, elements of groups 15 and 16 of the periodic table. − …”