Premium
Modeling of spray pyrolysis—why are the synthesized Y 2 O 3 microparticles hollow?
Author(s) -
Reuge N.,
Caussat B.,
Joffin N.,
Dexpertghys J.,
Verelst M.,
Dexpert H.
Publication year - 2008
Publication title -
aiche journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.958
H-Index - 167
eISSN - 1547-5905
pISSN - 0001-1541
DOI - 10.1002/aic.11375
Subject(s) - evaporation , yttrium , precipitation , pyrolysis , chemical engineering , materials science , particle (ecology) , thermal decomposition , spray pyrolysis , nanoparticle , spray drying , liquefaction , oxide , mineralogy , chemistry , nanotechnology , metallurgy , thermodynamics , thin film , geology , organic chemistry , meteorology , oceanography , physics , engineering
There are some major advantages to be gained in processing micronic europium doped yttrium oxide Y 2 O 3 particles for phosphor applications using spray pyrolysis. To better understand the influence of the operating conditions and also why hollow particles are formed, a complete one‐dimensional modeling of the pure evaporation then evaporation/precipitation steps of micronic water/Y(NO 3 ) 3 droplets has been performed. Among the main results, it appears that no concentration gradient exists inside droplets during the pure evaporation stage and that the evaporation/precipitation stage, occurring in less than 10 −3 s, leads to compact particles theoretically formed of a coherent porous medium of Y(NO 3 ) 3 ·5H 2 O. But the analysis of phenomena occurring during the thermolysis step between 95 and 300°C has revealed that a partial liquefaction of the hydrated yttrium nitrate occurs with concomitant release of gas. As a consequence, a crust of lightly hydrated yttrium nitrate probably appears, followed by particle inflation and leading to the formation of broken hollow particles. © 2007 American Institute of Chemical Engineers AIChE J, 2008