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Co-precipitation of low-agglomerated Y<inf>2</inf>W<inf>3</inf>O<inf>12</inf> nanoparticles: The effects of aging time, calcination temperature and surfactant addition

Abstract:

Current methods for the synthesis of ceramic powders from the A2M3O12 family of thermomiotics cause, inconveniently, agglomeration between nanoparticles being an obstacle to be overcome. Y2W3O12, a highly negative thermal expansion material, was synthesized by modified reverse strike co-precipitation at pH = 10 and the combined effects of the aging time, calcination temperature and surfactant addition on the agglomerate sizes of the as-prepared powders were investigated. The aging decreased by 50% the agglomerate size of Y2W3O12 amorphous precursor when compared to the non-aged sample. The applied calcination conditions (700, 715 and 730 °C, during 20 min) demonstrated that an increment of 15 °C in calcination temperature increased by 20% the average sizes of Y2W3O12 agglomerates. The addition of cetyltrimethylammonium bromide (CTAB) surfactant to the suspension of Y2W3O12 amorphous aged precursor at 0.5 mM and 0.9 mM concentrations improved the deagglomeration during calcination process. The CTAB provides steric stabilization, however, the major contribution to deagglomeration is due to its volatilization during calcination. This synthesis route decreased the agglomeration of Y2W3O12 nanopowders to levels as low as 0.5 μm, being significantly reduced over those previously reported in literature.