| Studies on Sintering of Barium Titanate Derived
from BaTiO(Cz04)z. 4Hz0: Correlation between
Powder Characteristics, Sintering and
Dielectric Properties |
K. THIAGARAJAN AND V. K. MOORTHY
Pages : 39-45
DOI : 10.1080/0371750X.1978.10840668 |
| Abstract |
| Polycrystalline barium titanate capacitors derived from the
mechanical mixture of BaC03 and Ti02 showed changes
in the molar ratio between BaO and Ti02, phases other
than tetragonal BaTi03, lack of homogeneity, etc. The
extent of such variations depends on the fabrication technology
and these undesirable changes were ignored while
studying the end properties. Hence, in the pesent study,
highly pure (>99.9% pure), homogeneous and stoichiometric
barium titanate was prepared by thermal decomposition
of barium titanyl oxalate tetrahydrate. The activity
required for subsequent sintering of the compacts was
suitably varied by calcination temperature in the range
of 600°-l100°C. It was seen that when the powders were
calcined in the temperature range of 800° -900°C, compacts
having more than 95% of theoretical density with zero open
porosity could be prepared by sintering at 1200°C. For the
powders calcined at 600°-700°C or 1000°-l100°C, compacts
with these physical properties were not obtained at
such a low temperature of sintering. The dielectric properties
were measured on the discs having more than 95%
of theoretical density with zero open porosity so that the
exclusive influence of calcination and sintering on the end
properties could be clearly established. By judicious choice
of method of powder preparation and sintering schedule,
dielectric constant of the order of 14,000 could be achieved
on pure barium titanate which is almost seven times the
single crystal average value ( ~ 2000). |
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