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1. (WO1998049120) SOLUTION COATED HYDROTHERMAL BaTiO3 FOR LOW-TEMPERATURE FIRING

Pub. No.:    WO/1998/049120    International Application No.:    PCT/US1998/008504
Publication Date: Fri Nov 06 00:59:59 CET 1998 International Filing Date: Wed Apr 29 01:59:59 CEST 1998
IPC: C04B 35/468
C04B 35/622
Applicants: THE PENN STATE RESEARCH FOUNDATION
Inventors: WITHAM, John, P.
RANDALL, Clive, A.
KUMAR, Umesh
SELVARAJ, Ulagaraj
WANG, Sea-Fue
DOUGHERTY, Joseph, P.
Title: SOLUTION COATED HYDROTHERMAL BaTiO3 FOR LOW-TEMPERATURE FIRING
Abstract:
Hydrothermal BaTiO3 crystallites were coated with Bismuth solutions prepared from Bismuth metal-organics and anhydrous solvents. The Bismuth metal-organics were Bi 2-ethylhexanoate and Bi-neodecanoate. Bismuth oxide was also used as a comparison to the Bismuth solutions. BaTiO3 ceramics with either 3.0 wt.% equivalent Bismuth oxide or 5.0 wt.% equivalent Bismuth oxide were made by sintering the compacts between 700 °C and 1000 °C. BaTiO3 ceramics that were coated by Bi-neodecanoate densified > 90 % theoretical as low as 800 °C for 3.0 wt.% equivalent Bi2O3. Average grain sizes of 0.2-0.4 νm were observed for Bi-coated BaTiO3 ceramics, for sintering temperatures below 950 °C. Dielectric K versus temperature measurements of Bismuth-coated BaTiO3 ceramics, sintered in the lower temperature ranges, showed consistently superior dielectric characteristics.