Nano‐Blast Synthesis of Nano‐size CeO₂–Gd₂O₃ Powders

Abstract

CeCl 3 . 7H 2 O and GdCl 3 . 6H 2 O that were dissolved in water were precipitated with urea (NH 2 CONH 2 ) to produce matrix agglomerates for three-component nano-reactors. Mixing hexamethylenetetramine with dilute nitric acid resulted in the formation of well-dispersed nano-particles of cyclotrimetilene trinitramine (C 3 H 6 N 6 O 6 ) (RDX) in the solvent. Nano-reactors were produced by impregnating the nano-C 3 H 6 N 6 O 6 into the matrix agglomerates of an intermediate complex of cerium and gadolinium compounds. Blast initiation of the C 3 H 6 N 6 O 6 resulted in extremely rapid detonation and gaseous products formation at temperatures of 20001-50001C, which were compressed into a volume nearly equal to the initial volume of each RDX nano-particle. Multiple ''nano-blasts'' occurred in the volume of each nano-reactor. The impact of the blast waves led to fragmentation of the surrounding matter. The evolution of a large volume of gaseous products dissipated the heat of the process and limited temperature increase, thus reducing the possibility of local sintering among the primary particles. The shortterm high temperature generated during the blasts enhanced the solid solubility of the metal oxides. Uniform aggregates of 22B74 nm consisting of 6B14 nm crystallites of gadolinia in ceria solid solution were synthesized.

Nanoblast synthesis and SPS of nanostructured oxides for SOFC

“…Mixing urotropin with nitric acid causes the formation and precipitation of cyclotrimethylene trinitramine (C 3 H 6 N 6 O 6 ) [18][19][20]. Mixing the dissolved hexamethylenetetramine with diluted nitric acid causes the formation of well-dispersed nanoparticles of the C 3 H 6 N 6 O 6 in the solvent.…”

“…At room temperature, it is extremely stable, non-soluble in water but partially soluble in ethanol. Its thermal decomposition starts at about 170°C, melting at 204°C, and it become explosive at 233°C [18,19].…”

“…For the thermal decomposition of preliminary engineered nanoreactors in this study, we employed the recently developed nanoblast technique [18,19]. Explosions involve a rapid and violent oxidation reaction with a sudden release of mechanical and chemical energy in a violent manner, accompanied with the generation of a high temperature and the release of extremely hot gases.…”

“…Ceramic nanopowders are usually synthesized by several aqueous-solution-based precipitation techniques [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] which have included approaches based on sol-gel processing , a reverse-micellar nanoreactor [3,4], hydrothermal synthesis [13][14][15], sonochemically and/or microwave-assisted decomposition of various aqueous (or non-aqueous) precursor solutions [15], salt-assisted aerosol decomposition and combustion synthesis [16][17]. However, due to the differences in the synthesis kinetic, high surface energy of the nanoparticles, and its chemical activity, hard agglomeration and the compositional inhomogeneity are the main problems encountered in nanosynthesis [1,[6][7][8][9][10][11][12][13][14][15][18][19][20][21][22][23][24][25]…”

“…However, due to the differences in the synthesis kinetic, high surface energy of the nanoparticles, and its chemical activity, hard agglomeration and the compositional inhomogeneity are the main problems encountered in nanosynthesis [1,[6][7][8][9][10][11][12][13][14][15][18][19][20][21][22][23][24][25][26].…”