Size and Morphology Control of Ultrafine Refractory Complex Oxide Crystals

Abstract

High-temperature complex oxides are of considerable interest as their applications cover a broad spectrum from catalytic to optical technology. Indeed, new exciting opportunities might emerge if these high-temperature complex oxides, in which structure crystallization is achieved at temperatures T > 1000°C, could be synthesized as nonaggregated, ultrafine building blocks. In general, such refractory complex oxide particles are difficult to synthesize as ultrafine crystals because of the strong driving force available for sintering and coarsening in this high-temperature range. This paper reports a new synthetic process for the preparation of nonaggregated, ultrafine barium hexaaluminate, BaO, 6Al 2 O 3 , (BHA), and Ba 0.9 Eu 0.1 MgAl 10 O 17 , (BAM) crystals in which structure crystallization occurs around 1300°C. Our process is based on the Ba 2þ and Al 3þ ions hightemperature controlled diffusion from carbon-inorganic hybrid compounds prepared from soft chemistry routes. Control of morphology of these refractory complex aluminates displaying nanoplatelets morphology was achieved via the tailoring of high-temperature diffusion lengths of the various cations involved in the formation of these ultrafine refractory crystals.

Highly Dense, Transparent α‐Al2O3 Ceramics From Ultrafine Nanoparticles Via a Standard SPS Sintering

“…With this objective, routine fabrication of transparent alumina ceramic requires availability of ultrafine Al 2 O 3 nanocrystals with controlled physicochemical properties. Various process routes were recently proposed for the fabrication of ultrafine refractory nanoparticles . Indeed, discrete, α‐Al 2 O 3 ultrafine nanoparticles were recently developed and commercialized.…”

“…Various process routes were recently proposed for the fabrication of ultrafine refractory nanoparticles. 8,9 Indeed, discrete, a-Al 2 O 3 ultrafine nanoparticles were recently developed and commercialized. Here, we show that using discrete, ultrafine highly pure a-Al 2 O 3 nanoparticles, careful control of feature characteristics such as surface chemistry, interparticle interactions during green body forming, and grain growth during sintering will allow the formation of highly dense a-Al 2 O 3 transparent ceramic through standard SPS sintering technique.…”

A gas-templating strategy to synthesize CZTS nanocrystals for environment-friendly solar inks

“…A strategy to synthesize highly homogeneous, crystalline complex building blocks is to design a high temperature synthetic route [18,19]. Indeed, high temperature facilitates both the achievement of crystallinity and defects annealing while repelling impurities to the outer surface of the nanocrystals.…”

Polyacrylamide modified mesoporous SBA-16 hybrids encapsulated with a lanthanide (Eu3+/Tb3+) complex

“…Considerable studies have been focused on the design and assembly of lanthanide complexes with organic ligands, such as aromatic carboxylic acids, b-diketones and heterocyclic derivatives, which show strong absorption of ultraviolet light and then facilitate an effective intramolecular energy-transfer process to the central lanthanide ions. [8][9][10][11][12] For applications in optical devices, it is advantageous to incorporate lanthanide complexes in an inert host matrix, such as silica-based materials, [13][14][15] polymers, 16,17 and liquid crystal, 18 to obtain the inorganic-organic hybrids. Recently, the luminescence properties of lanthanide complexes supported in a solid matrix were studied extensively because their photophysical properties could be modified by interaction with the host structure.…”