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Generation, properties, and order packing of monodispersed spherical colloid particles of yttrium hydroxy-carbonate: A colloidal route to minimizing voids in ceramics

Technical Report ·
OSTI ID:5354224
Yttrium hydroxy-carbonate particles were prepared by decomposition of urea in yttrium nitrate solutions. The nucleation and growth were studied in silica-seeded and unseeded systems. Precipitation took place only under neutral conditions. In unseeded systems, homogeneous nucleation yielded 3 x 10/sup 10/ nucleicm/sup 3/ while in seeded precipitation enough nuclei were produced to bring the total number of particles to 4 x 10/sup 10/cm/sup 3/. Systems containing at least 4 x 10/sup 10/ seedscm/sup 3/ underwent pure heterogeneous precipitation onto the existing seeds. Two diffusion-controlled growth models and the diffusion chronomal analysis were applied to the data of growth rate. Results confirmed the diffusion-controlled particle growth mechanism. Electron diffraction showed the particles to be crystalline. Electrophoresis showed a charge reversal from positive to negative with pH, with an isoelectric point of about 7.4. The chemical composition of the powders was determined to be Y(OH)CO/sub 3/ . H/sub 2/O. Stability of aqueous suspensions was studied as a function of pH. 74 refs., 27 figs., 3 tabs
Research Organization:
Ames Lab., IA (USA)
DOE Contract Number:
W-7405-ENG-82
OSTI ID:
5354224
Report Number(s):
IS-T-1302; ON: DE88007633
Country of Publication:
United States
Language:
English