A kind of ultra-low dielectric constant microwave dielectric ceramic with nearly zero resonant frequency temperature coefficient and preparation method thereof

Abstract

The invention discloses a low-temperature sintered ultralow dielectric constant microwave dielectric ceramic Li3Al5O9 with a near-zero temperature coefficient of resonance frequency and a preparation method of the microwave dielectric ceramic. The preparation method comprises the following steps: (1), weighing and dosing original powder of Li2CO3 and Al2O3 with the purity over 99.9% (percentage by weight); (2), wet ball-milling and mixing the raw material in the step (1), wherein the ball-milling medium is anhydrous ethanol, and pre-sintering for 6 hours in an atmosphere at 800 DEG C after drying; (3), adding a binder into the powder prepared in the step (2) and granulating, then pressing and molding, and finally sintering for 4 hours in an atmosphere at 850-900 DEG C, wherein the binder is a polyvinyl alcohol solution with mass concentration of 5% and the addition of polyvinyl alcohol is 3% of the total mass of the powder. The ceramic prepared by the invention is sintered well, the dielectric constant reaches 8.1-8.6, the quality factor value Qf reaches up to 134000-175000GHz, the temperature coefficient of resonance frequency is near-zero, and the microwave dielectric ceramic has an extremely huge application value industrially.

Description

technical field [0001] The invention relates to a dielectric ceramic material, in particular to a dielectric ceramic material for manufacturing microwave components such as ceramic substrates, resonators and filters used in microwave frequencies and a preparation method thereof. Background technique [0002] Microwave dielectric ceramics refer to ceramics that are used as dielectric materials in circuits in the microwave frequency band (mainly UHF and SHF bands) and perform one or more functions. They are widely used as resonators, filters, and dielectric substrates in modern communications. Components such as chips and dielectric waveguide circuits are the key basic materials of modern communication technology. They have been used in portable mobile phones, car phones, cordless phones, TV satellite receivers and military radars. They are used in modern communication tools. It is playing an increasingly important role in the process of miniaturization and integration. [00...

AI Technical Summary

Problems solved by technology

Li 3 Fe 5 o 9 Ceramic resonant frequency temperature coefficient τ ƒ Too large (+78 ppm / ℃ respectively) to be used as a practical microwave dielectric ceramic; while Li 3 Ga 5 o 9 with Li 3 Bi 5 o 9 As a semiconductor, its dielectric loss is too large to be used as a microwave dielectric ceramic

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