Dielectric material based on barium-titanate for ceramic capacitors - consisting of additional metal-oxide(s) to give a high dielectric constant, low dielectric loss and small capacitance charge with voltage and temp.

摘要

Dielectric ceramic material consists of 100 pts. wt. BaTi03 within the following additives with less than 0.03 pts. wt. alkali-metal oxide present as a contamination: 0.6-2.0 pts. wt. Nb203, 0.1-0.8 pts.wt. CO2O3, 0.05-0.3 pts. wt. MnO2 and 0.02-4 pts.wt. of at least one of the following Rare Earth metal oxides : La2O3, CeO3, Nd2O3, Pr6O11, Dy2O3 and Sm2O3. Also claimed is the compsn. as above with the exception of 0.02-0.5 pts. wt. of a Rare Earth oxide and additionally 0.05-1.0 pts. wt. of a glass forming oxide containing BaO-SiO2-B2O3-Li20. USE/ADVANTAGE - The material shows a dielectric constant (epsilon) of more than 3,500, a low loss angle (tan(delta)) with a small dependence of less than 3% measured at an AC-field of 200V/mm, a grain size of less than 1 micron, a small change of dielectric constant with temp. in the range -50 to +125 deg.C. referred to 25 deg.C of less than +/- 15% and a low sinter temp., i.e. below 1280 deg.C. These parameters allow the material thickness between electrodes to be reduced and the use of AgPd 30/70 as inner electrode material in multilayer capacitors, resulting in small ceramic capacitors with a high capacitance value and low cost