Sl. Morissette et al., Direct-write fabrication of Pb(Nb,Zr,Ti)O(3 d)evices: Influence of paste rheology on print morphology and component properties, J AM CERAM, 84(11), 2001, pp. 2462-2468
Lead niobium zirconate titanate (PNZT) pastes with tailored rheological pro
perties have been developed for direct-write fabrication of thick-film capa
citor elements in highly integrated, multifunctional electroceramic devices
. Such pastes exhibited pseudoplastic behavior with a low shear apparent vi
scosity of roughly 1 x 10(6) cP. On aging, the degree of shear thinning and
the low shear apparent viscosity decreased. Pastes prepared from as-receiv
ed powders attained printable, steady-state viscosities of similar to2 x 10
(5) cP after 50 days of aging. In contrast, pastes prepared from dispersant
-coated powders showed no measurable rheological changes after 1 day of agi
ng. Square elements were patterned on dense alumina substrates or Teflon sh
eets. Leveling behavior as a function of time for single line prints, and t
he resulting surface topographies of dried PNZT films were measured by lase
r profilometry. PNZT layers sintered at varying temperatures between 950 de
grees and 1050 degreesC for 5 h in either air or a lead-rich atmosphere yie
lded porous microstructures as revealed by scanning electron microscopy (SE
M). Such layers exhibited dielectric constants (K) of 1400-1570 at 1 kHz wi
th dissipation factors (D) of less than 4.1%.