X-Ray characteristic temperature and thermal expansion coefficient of Mg2Ge

Anharmonic effects in Mg2X (X = Si, Ge, Sn) compounds studied by Raman spectroscopy

“…Temperature dependent data for the volume thermal expansion coefficient f3 can be found in references [14] and [15] for Mg2Si and Mg2Ge respectively, in the temperature range 300-530 K. For M92Sn only the room temperature value of fl could be found in the literature [16], while for higher temperatures provision has been taken so that the f3 ( T) curve has the same behaviour as those of Mg2Si and Mg2Ge. The values of f3 for lower temperatures were calculated using existing Debye temperatures [17] and the expression [6,18] where D ( n ) is the Debye integral…”

Order and disorder in the modulated phase hp‐Mg9Ge5.1

“…Thus, the observation is compatible with a monotropic (irreversible) phase transition. After the heating cycle, Xray powder diffraction data exhibit only diffraction lines of thermodynamically stable (anti-)CaF 2 -type Mg 2 Ge(cF12) [2][3][4][5]8] and Ge(cF8). [18][19][20] Thus, the experiments are consistent with a decomposition of Mg 9 Ge 5.1(2) at 496(5) K and atmospheric pressure confirming that the compound is a metastable highpressure phase at ambient pressure.…”

“…Differential scanning calorimetry measurement of the high-pressure phase Mg 9 Ge 5.1(2) at ambient pressure. The effect at 496(5) K is attributed to the exothermal decomposition into CaF 2type Mg 2 Ge [2][3][4][5]8] and diamond-type germanium. [18][19][20] .…”

“…Zintl phases Mg 2 Tt ( Tt =Si, Ge, Sn, Pb) form (anti‐)fluorite‐type crystal structures at ambient pressure [1–7] . The germanium variety Mg 2 Ge exhibits semiconducting electrical properties in accordance with its electron‐precise character.…”

“…Zintl phases Mg 2 Tt (Tt=Si, Ge, Sn, Pb) form (anti-)fluorite-type crystal structures at ambient pressure. [1][2][3][4][5][6][7] The germanium variety Mg 2 Ge exhibits semiconducting electrical properties in accordance with its electron-precise character. This has stimulated renewed recent interest in the compound as magnesiumbased thermoelectric material.…”