Publication Date:
2012-04-15
Description:
This article reports single-step molten salt synthesis to prepare single-crystal, platelike NaNbO 3 particles without the Bi 2 O 3 byproduct. In the previous method of two-step molten salt synthesis, platelike Bi 2.5 Na 3.5 Nb 5 O 18 particles have been prepared by heating a mixture of Bi 2 O 3 , Na 2 CO 3 , and Nb 2 O 5 in molten NaCl ; the particles are then converted to platelike NaNbO 3 particles by reaction with Na 2 CO 3 in molten NaCl . The obtained NaNbO 3 particles are polycrystalline, and Bi 2 O 3 particles form as a byproduct. In the present method, single-crystal, platelike NaNbO 3 particles without the Bi 2 O 3 byproduct are obtained by heating mixtures of Bi 2 O 3 , Na 2 CO 3 , and Nb 2 O 5 with molar ratios of 5:7:10 (the composition of Bi 2.5 Na 3.5 Nb 5 O 18 ) and 5:5:8 (the composition of Bi 2.5 Na 2.5 Nb 4 O 15 ) in molten NaCl at 1225°C for 12 h. During heating, platelike Aurivillius ( Bi 2.5 Na 3.5 Nb 5 O 18 and Bi 2.5 Na 2.5 Nb 4 O 15 ) particles are formed first and these then react with NaCl to form platelike NaNbO 3 particles, BiCl 3 , and Na 2 O . BiCl 3 evaporates from the system and Na 2 O is washed out after heating. Thus, single-phase NaNbO 3 is obtained. Sluggish conversion from the Aurivillius phases to NaNbO 3 is responsible for the formation of single-crystal particles.
Print ISSN:
0002-7820
Electronic ISSN:
1551-2916
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
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