| Summary: | Class II ceramics are a material with high permittivity but low reliability of their capacitance and bias voltage due to high the temperature sensitivity of their dielectric permittivity. In this work, a BST-based (Ba<sub>0.9−x</sub>Sr<sub>x</sub>Ca<sub>0.1</sub>)TiO<sub>3</sub>·0.03(Bi<sub>2</sub>O<sub>3</sub>·3TiO<sub>2</sub>) (x = 0.2, 0.25, 0.3, 0.35, 0.4) composition with Y5U characteristics was investigated through compositional control to develop high-permittivity and voltage-stable ceramic compositions. Sr doping can increase the breakdown strength (<i>E<sub>b</sub></i>) but decreases the Curie temperature (<i>T<sub>c</sub></i>). The composition at x = 0.3 can obtain optimal comprehensive electrical properties, with high permittivity of 4206, low dielectric loss of ~0.009, and moderate breakdown strength (<i>E<sub>b</sub></i>) of 77.6 kV/cm, which meets Y5U specifications. Typically, a low bias-voltage dependence of capacitance is confirmed with a variation rate of 7.64% under 20 kV/cm. This strategy provides a promising candidate for high-permittivity Class II ceramic dielectrics that can be used in this field.
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