Application of calorimetry and thermodynamics to critical problems in materials science

New phases Bi 12.5 Ln 1.5 ReO 24.5 : Thermodynamics and influence of dopant size on lattice energy (Ln – lanthanide)

“…Compounds on the basis of bismuth oxides possess a wide set of unique properties and they can be quite perspective in various areas [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19]. So, they can be used as ecological inorganic pigments applied in paints, plastics, ceramics and etc.…”

“…After that Bi 12.5 Yb 1.5 ReO 24.5 thermodynamic stability will be examined with respect to its decomposition to Bi 14 ReO 24.5 . The following reaction can be written:‫݅ܤ398.0‬ ଵସ ܴܱ݁ ଶସ.ହ + 0.75ܻܾ ଶ ܱ ଷ + 0.054ܴ݁ ଶ ܱ = ‫݅ܤ‬ ଵଶ.ହ ܻܾ ଵ.ହ ܴܱ݁ ଶସ.ହ The Gibbs free energy was calculated as:∆ ‫ܩ‬ = +8.2 ± 6.2 kJ mol -1This value is positive, which signifies that Bi 12 5. Yb 1.5 ReO 24.5 is thermodynamically unstable with respect to decomposition into mixtures including Bi 14 ReO 24.5 , Yb 2 O 3 , and Re 2 O 7 at room temperature.…”