New approach to improve the conductivity of apatite-type lanthanum germanate La_9.33Ge₆O₂₆ as electrolyte for IT-SOFCs

Abstract

La9.33Ge6O26 pellets synthesized by a molten-salt method exhibit higher conductivity owing to the high density and the avoidance of La2GeO5.

Low-temperature synthesis of apatite-type La 9.33 Ge 6 O 26 as electrolytes with high conductivity

“…[21][22][23][24] Therefore, in order to exhibit their best electrical properties using SSRM, dense ATLG ceramics with high purity are very difficult to obtain. In order to overcome this drawback, some synthesis methods were developed to optimize the precursor powders of ATLG, such as the ball-mill method, [25] sol-gel auto-combustion process, [26] hydrothermal synthesis method, [27] MSSM, [28] etc. Comparatively, the MSSM as a low-cost, low-temperature, few steps and versatile method can provide a melting-salt environment to form highquality ATLG powders, further to lay a solid foundation for gaining the highly dense and pure pellets at a lower sintering temperature.…”

“…Comparatively, the MSSM as a low-cost, low-temperature, few steps and versatile method can provide a melting-salt environment to form highquality ATLG powders, further to lay a solid foundation for gaining the highly dense and pure pellets at a lower sintering temperature. [28][29][30] In this paper, we successfully synthesize apatite-type La 9.33 Ge 6 O 26 powders by MSSM through using LiCl and LiCl/NaCl mixture (mass ratio 1:1) as molten salt, and the corresponding synthesis temperature reduces about 350 • C (LiCl), 500 • C (LiCl/NaCl) compared with by using the con-ventional SSRM, respectively, which can effectively avoid Ge volatility, agglomeration and crystallinity problems encountered in the conventional preparation process of precursor powders. Furthermore, on the basis of high-quality precursor powders obtained by the MSSM, highly dense and pure ceramic pellets are obtained at a lower temperature of 1100 • C, which exhibit higher conductivities and lower activation energies than those obtained by the conventional SSRM.…”

Pressure-induced structural evolution of apatite-type La 9.33 Si 6 O 26

“…Apatite-type lanthanum silicates (ATLSs) with the general formula La 9.33+x (SiO 4 ) 6 O 2+1.5x (0 ≤ x ≤ 0.67) have been gaining widespread attention owing to their potential applications in gas-sensing and fuel cell devices. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] ATLSs have an especially hexagonal apatite structure (Fig. 1), which is beneficial for conducting oxygen ions.…”