Low-loss dielectric ceramic materials and their properties

Abstract

In addition to the constant demand of low-loss dielectric materials for wireless telecommunication, the recent progress in the Internet of Things (IoT), the Tactile Internet (fifth generation wireless systems), the Industrial Internet, satellite broadcasting and intelligent transport systems (ITS) has put more pressure on their development with modern component fabrication techniques. Oxide ceramics are critical for these applications, and a full understanding of their crystal chemistry is fundamental for future development. Properties of microwave ceramics depend on several parameters including their composition, the purity of starting materials, processing conditions and their ultimate densification/porosity. In this review the data for all reported low-loss microwave dielectric ceramic materials are collected and tabulated. The table of these materials gives the relative permittivity, quality factor, temperature variation of the resonant frequency, crystal structure, sintering temperature, measurement frequency and references. In addition, the methods commonly employed for measuring the microwave dielectric properties, important from the applications point of view, factors affecting the dielectric loss, methods to tailor the dielectric properties and materials for future applications, are briefly described. The data will be very useful for scientists, industrialists, engineers and students working on current and emerging applications of wireless communications.

Novel thermally stable, high quality factor Ba4(Pr0.4Sm0.6)28/3Ti18−yGa4y/3O54 microwave dielectric ceramics

“…In decades, due to the rapid development of wireless technology, the microwave components play an important role in the field of the fifth‐generation (5G) mobile communication, global positioning system, wireless fidelity, and so on . As the key materials, the microwave ceramics should possess high microwave dielectric constant ( ε r ), high quality factor (Qf) ( Q = ), and near‐zero TCF (temperature coefficient of resonant frequency) …”

3D printed dielectric ceramic without a sintering stage

“…These factors determine the feasibility of the material in different electrical applications 35,36 . The measured densities and dielectric properties are reported in Table 1 in comparison with those reported for Li 2 MoO 4 parts manufactured with RTF and post-processing at 120 °C 22 , and sintering at 540 °C 20,37 .…”

Controllable τf value of barium silicate microwave dielectric ceramics with different Ba/Si ratios

“…However, low‐permittivity microwave dielectric ceramics exhibit generally high‐magnitude negative τ f values according to the ε r ‐τ f relationship . In general, temperature compensated dopants with a large positive τ f value, such as TiO 2 , CaTiO 3 , and SrTiO 3 , are used in conventional processes in air to control the τ f value of low‐permittivity microwave dielectric ceramics .…”