Phase Diagram Studies in the Systems La₂O₃–SrO–Ga₂O₃, La₂O₃–MgO–Ga₂O₃, and SrO–MgO–Ga₂O₃ at 1400°C in Air

Abstract

The ternary systems La2O3–SrO–Ga2O3, La2O3–MgO–Ga2O3, and SrO–MgO–Ga2O3 were studied at 1400°C in air, with emphasis on LaGaO3. The compound exhibited a small solid solubility of strontium substituting for lanthanum and also of magnesium substituting for gallium. In the system La2O3–SrO–Ga2O3, LaGaO3 existed only within a very narrow concentration region, whereas in the system La2O3–MgO–Ga2O3, LaGaO3 was in equilibrium with most of the phases of the system. The system SrO–MgO–Ga2O3 at 1400°C in air was characterized by an extended liquid phase at ∼1185°C.

Improved sintering and electrical properties of La-doped CeO2 buffer layer for intermediate temperature solid oxide fuel cells using doped LaGaO3 film prepared by screen printing process

“…Majewski et al reported that a liquid phase in a ternary system of SrO-MgO-Ga 2 O 3 was observed during DTA measurement. An extended and complete melting was occurred at~1,260°C and~1380°C, respectively [36]. Thus, the presence of a liquid phase can be also expected during calcination of the LSGM powder.…”

Thermodynamic assessment of the ternary systems Ga–Mg–O, Ga–Ni–O, Mg–Ni–O and extrapolation to the Ga–Mg–Ni–O phase diagram

“…The solid solubility of Ga in MgO was found to increase from 4.7 at 1673 K to 12.7 mol% Ga 2 O 3 at 1873 K The column 'Use' indicates whether the values were used (+) or not used (−) in the optimisation. [18][19][20]. A surprisingly large solubility of Mg in ␤-Ga 2 O 3 at 1673 K (11.3 mol% MgO) has been reported by Majewski and co-workers [18,19].…”

“…At 1300 K, the spinel phase exists between 47.4 and 50.3 mol% MgO [17]. Majewski and co-workers reported that the compound MgGa 2 O 4 exhibited a variable Mg:Ga ratio between 35:65 and 40:60 at 1673 K [18,19]. Both compositions are, however, on the MgO-rich side and, since the uncertainty of such measurements is unknown, a systematic error may be suspected.…”

“…[18][19][20]. A surprisingly large solubility of Mg in ␤-Ga 2 O 3 at 1673 K (11.3 mol% MgO) has been reported by Majewski and co-workers [18,19]. Using optical pyrometry, Scott et al [21] determined the congruent melting point of MgGa 2 O 4 as 2223 ± 75 K. The distribution of cations over the tetrahedral and octahedral sites in MgGa 2 O 4 has been studied on powder samples, which have been annealed at various temperatures (1191-1673 K) and then quenched in water or liquid nitrogen [17,22,23].…”

Vaporization and Diffusion Studies on the Stability of Doped Lanthanum Gallates

“…For example, at 1,673 K it takes about 250 h to equilibrate LSGM within a distance of 1 lm, i.e., a grain of 2 lm diameter or a surface layer of 1 lm thickness. In the phase diagram [ 17,18] and diffusion studies the current authors have explicitly taken care of this fact by equilibrating the samples at 1,673 K for 10 days, in contrast to previous phase diagram studies with fairly short equilibration times [46][47][48].…”