SCHEDULED MAINTENANCE
Ultra-low temperature co-fired ceramics with adjustable microwave dielectric properties in the Na2O–Bi2O3–MoO3 ternary system: a comprehensive study†
Abstract
Herein, a series of microwave dielectric materials in the Na2O–Bi2O3–MoO3 ternary system, such as Na2MoO4, Na6Mo10O33, Na2Mo2O7, Bi2Mo3O12, Bi2Mo2O9, and Bi2MoO6, were studied via phase identification, microstructure characterization, spectral analysis and microwave dielectric property tests; all the samples of each component could be sintered below 750 °C. Three different kinds of bulk ceramics, x(NaBi)0.5MoO4–(1−x)Na2MoO4 (x = 0.2–0.6), x(NaBi)0.5MoO4–(1−x)Bi2MoO6 (x = 0.6, 0.8) and 0.5(NaBi)0.5MoO4–0.5Bi2Mo2O9, were considered as the main research objects in this work. The sintering temperature of the x(NaBi)0.5MoO4–(1−x)Na2MoO4 (x = 0.2–0.6) composite ceramics ranged from 600 °C to 640 °C; high-performance microwave dielectric properties with relative permittivities in the range of 8.9–16.2, Qf (quality factor) values in the range of 11 050 GHz–8,900 GHz, and τf values ranging from −27–11 ppm °C−1 could be obtained in these ceramics. For the x(NaBi)0.5MoO4–(1−x)Bi2MoO6 (x = 0.6, 0.8) composite ceramics, a near-zero τf value (−2.6 ppm °C−1) was achieved with the 0.8(NaBi)0.5MoO4–0.2Bi2MoO6 ceramic sintered at 720 °C with a middle-permittivity of 32.6 and a Qf value of 14570 GHz. The multiphase ceramic 0.5(NaBi)0.5MoO4–0.5Bi2Mo2O9 could be sintered at 680 °C; the dense sample had a relative permittivity of 35.7, a Qf value of 9780 GHz and a small positive τf value of 17 ppm °C−1. As this study shows, the Na2O–Bi2O3–MoO3 ternary system had a lot of new composite ceramics with low sintering temperatures and great microwave dielectric properties. All these materials could be regarded as candidates applicable to LTCC/ULTCC technology.
- This article is part of the themed collection: Journal of Materials Chemistry C HOT Papers
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