Solid Solution Nanocrystals in the CeO₂‐Y₃NbO₇ System: Hydrothermal Formation and Control of Crystallite Growth of Ceria

Abstract

New solid solution nanocrystals with fluorite-type cubic structure in the ceria (CeO 2 )-yttrium niobate (1/4Y 3 NbO 7 ) system were directly formed at 120°C-240°C from the precursor solution mixtures of (NH 4 )Ce(NO 3 ) 6 , YCl 3 Á6H 2 O, and NbCl 5 under mild hydrothermal conditions in the presence of aqueous ammonia. The hydrothermal formation of cubic solid solution nanocrystals in the wide composition range of CeO 2 (mol%) = 10-100 in the CeO 2 -1/4Y 3 NbO 7 system was effectively achieved via the assistance of the presence of CeO 2 component more than 10 mol% as a promoter with the same fluorite-type structure. The optical band gap of the solid solutions gradually decreased with increased CeO 2 component. The high phase stability of the solid solutions in the CeO 2 -1/4Y 3 NbO 7 system was confirmed, i.e., the single cubic phase of the solid solutions was maintained after heat treatment at 600°C-1500°C for 1 h in air. The presence of Y 3 NbO 7 as an inhibitor and the substitutional incorporation of Y 3 NbO 7 into the lattice, CeO 2 effectively controlled the crystallite growth of CeO 2 , and nano-sized cubic solid solutions with high specific surface areas were maintained after heat treatment up to 800°C-1000°C for 1 h air.

Direct Formation and Luminescence of Nanocrystals in the System Eu2Sn2O7–Gd2Sn2O7 Complete Solid Solutions

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Direct Formation of Luminescent Fine Crystals Based on (Y,Eu)TiNbO6 Complete Solid Solution with High Crystallinity

“…Recently, considerable attention has been focused on the formation of fine crystals of inorganic materials via wet chemical synthesis routes because their characteristics and performances are closely linked to their synthesis routes. The aqueous solution routes including hydrothermal synthesis method are advantageous to the formation of fine inorganic materials, e.g., new compounds, solid solutions, metastable phases, and composite particles, especially fine crystals based on metal oxides and complex oxides . Now, rare‐earth ions‐activated phosphor materials have received considerable attention due to their unique properties and potential applications in a variety of fields including luminescent devices, optical transmission, biochemical probes, medical diagnosis, biological fluorescence labels, and so on .…”

Nanocrystalline BaTi2O5 dielectric ceramic prepared by full crystallization from containerless solidified glass

“…[1][2][3][4][5][6]. A number of nanocrystalline ceramics have been fabricated by using spark plasma sintering (SPS) [7,8], two-step sintering [9,10], microwave sintering [11], ultra-high pressure sintering [12], and so on [13,14]. SPS is used as a good method of preparing ceramics with pure phase because of short duration within sintering process [15].…”