Preparation and characterization of La9.33Si6O26 powders by molten salt method for solid electrolyte application

New approach to improve the conductivity of apatite-type lanthanum germanate La9.33Ge6O26 as electrolyte for IT-SOFCs

“…The crystal parameters of P-MS are almost same with that of P-SS, which indirectly indicates the inexistence of Na in the samples prepared by MSS method. 30 To more distinctly clarify the effect of melting environment, a schematic illustration of reaction process is shown in Fig. 3.…”

“…This mass ratio is determined through a large number of experiments, and the same mass ratio has been adopted by Li and his co-workers in the fabrication of apatite-type lanthanum silicates. 29,30 The intimately mixed powders (La 2 O 3 , GeO 2 and NaCl) were rst ball-milled in ethanol medium at a speed of 400 rpm for 8 h, dried, ground and sied to avoid agglomerated powders. The sied powders were calcined at 750 C, 800 C and 900 C for 4 h, respectively.…”

“…Therefore, it is the aim of the present paper to demonstrate a novel route for preparing ATLG as electrolyte materials for IT-SOFCs by using molten-salt synthesis (MSS) method. This method has been adopted by Li and his co-workers to fabricate ATLS, 29,30 by which the use of NaCl as eutectic salt has been typically involved at the synthesis temperatures as low as 900 C. This synthesis temperature is signicantly lower than the generally reported temperatures for preparing ATLG, hence it is expected to effectively solve the Ge volatility problem when employing MSS method. In addition, as compared to the traditional SSS method, MSS method exhibits advantages of simple process, clean, repeatability of the salt and also better crystal morphology and homogeneity of the obtained powder product, which is more applicable from the industrial point of view.…”

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

“…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.…”

Infrared photoluminescence of sol–gel spin-coated films of rare-earth activated lanthanum silicate

“…Nevertheless, preparing single phase RE-silicate complexes with high photoluminescence (PL) efficiency remains difficult. Preparation methods to avoid and/or overcome multi-phase formation include hydrothermal, precipitation and co-precipitation, molten flux, sol-gel, and physical and chemical vapor deposition techniques [5][6][7][8]. Er 3 þ -activated phosphors have been of interest as up-converters [9], as mid-infrared lasers [10,11] but most recently in fiber-optic and other communications applications because of the emission peak at 1.53 mm [12].…”