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Studies on fluorination of Y(2)O(3) by NH(4)HF(2)

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Title Studies on fluorination of Y(2)O(3) by NH(4)HF(2)
 
Creator MUKHERJEE, A
AWASTHI, A
MISHRA, S
KRISHNAMURTHY, N
 
Subject RARE-EARTH-OXIDES
AMMONIUM BIFLUORIDE
FLUOROLANTHANATES
REDUCTION
FLUORIDES
METAL
Ammonium yttrium fluorides
Rare earth fluoride
Fluorination
 
Description Fluorination of Y(2)O(3) by NH(4)HF(2) to obtain pure YF(3) is studied in this work by observing the mass changes at room temperature and by employing TGA and DTA at higher temperatures, and observing the subsequent phase changes by X-ray diffraction. Fluorination begins at room temperature with the formation of (NH(4))(3)Y(2)F(9) and NH(4)F, and continues with the later further fluorinating any leftover Y(2)O(3) to ammonium yttrium fluorides with the evolution of NH(3). Similarly, on heating a mixture of Y(2)O(3) and NH(4)HF(2), the reaction proceeds sequentially through the formation of (NH(4))(3)Y(2)F(9), NH(4)Y(2)F(7) and finally YF(3). Any Y(2)O(3) still remaining reacts with YF(3) to form yttrium oxyfluorides, which continue as impurity. Substantial evaporation of NH(4)HF(2) is possible even before it could participate in the reaction. This disturbs the stoichiometry of the charge causing oxygen to remain in final YF(3). The compound reported in literature as YF(3)center dot 1.5NH(3) appears to be NH(4)Y(2)F(7). (C) 2011 Elsevier B.V. All rights reserved.
 
Publisher ELSEVIER SCIENCE BV
 
Date 2012-06-26T08:36:39Z
2012-06-26T08:36:39Z
2011
 
Type Article
 
Identifier THERMOCHIMICA ACTA,520(1-2)145-152
0040-6031
http://dx.doi.org/10.1016/j.tca.2011.03.032
http://dspace.library.iitb.ac.in/jspui/handle/100/14198
 
Language English