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Effect of Calcination Conditions and Excess Alkali Carbonate on the Phase Formation and Particle Morphology of Na 0.5 K 0.5 NbO 3 Powders
Author(s) -
Bomlai Pornsuda,
Wichianrat Pattraporn,
Muensit Supasarute,
Milne Steven J.
Publication year - 2007
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1551-2916.2007.01629.x
Subject(s) - calcination , alkali metal , orthorhombic crystal system , materials science , particle size , natural bond orbital , mineralogy , phase (matter) , inorganic chemistry , particle (ecology) , chemical engineering , analytical chemistry (journal) , crystallography , chemistry , crystal structure , geology , chromatography , organic chemistry , catalysis , oceanography , molecule , engineering
Sodium‐potassium niobate [Na 0.5 K 0.5 NbO 3 ] powders were prepared following the conventional mixed oxide method. An orthorhombic XRD pattern, consistent with single‐phase Na 0.5 K 0.5 NbO 3 , was obtained after calcination at 900°C for 6 h. Introducing 5 mol% excess Na 2 CO 3 and K 2 CO 3 into the starting mixture allowed milder calcination conditions to be used, for example 800°C for 2 h. Primary particles in 5 mol% excess samples were cuboid, with maximum sizes of ∼2.5 μm. Equiaxed 0.3–0.4‐μm particles were formed for non‐excess powders, and also for powders prepared with 1 and 3 mol% excess alkali carbonates. The results suggest liquid formation during calcination of the excess 5‐mol% starting powders.