Near‐Zero Thermal Expansion Ba_1−xSr_xZn₂Si₂O₇‐Based Microwave Dielectric Ceramics for 3D Printed Dielectric Resonator Antenna with Integrative Lens

Abstract

High‐gain, low‐weight, wide bandwidth, and miniaturized lens antennas with stable properties against temperature are intensely required in extreme environments such as aerospace field. However, high‐performance microwave dielectric ceramics with near‐zero thermal expansion and frequency shift with temperature are very rare; moreover, the requirement of 3D printing processes also restricts their developments. Ba0.4Sr0.6Zn2Si2O7 with negative coefficient of thermal expansion (CTE), which originates from the stretched [ZnO4] tetrahedral chain to the twisted one along b‐axis with temperature, and CaTiO3 with positive temperature coefficient of resonant frequency (τf) can effectively adjust both CTE and τf of Zn1.8SiO3.8 to near‐zero value in 0.95(0.9Zn1.8SiO3.8–0.1Ba0.4Sr0.6Zn2Si2O7)–0.05CaTiO3 ceramic. Then, a Ku‐band Luneburg lens integrative antenna fabricated by stereolithography 3D printing technology exhibits an average gain of 8.06 dBi at 10.45–11.39 GHz and 10.3 dBi at 12.27–13.45 GHz, which has potential applications in temperature‐stable satellite communication.

Nanostructured Silver Films with a Low Coefficient of Thermal Expansion as a Promising Material for Nanoelectronics

“…It should be noted that studies focused on the determination of CTE are mainly based on X‐ray diffraction (XRD) methods. [ 24–31 ] This method supposes placing the sample on a solid substrate. The violation of coherence at the film–substrate interface can lead to additional mechanical stresses that complicate the research conduction.…”

“…The obtaining of materials with a given CTE can be eased by the using of the size factor, which in the nanometer range often has a decisive influence on thermal expansion. For example, in works, [ 24–26 ] using the example of borides, it was shown that thermal expansion can both increase and decrease with the particle size of nanopowders. A similar situation is observed in continuous polycrystalline films.…”

A review on the ceramic additive manufacturing technologies and availability of equipment and materials

“…ZrO 2 [276][277][278][279][280][281][282][283][284][285][286][287] [296] Heat exchanger/dissipation Al 2 O 3 [170], AlN [297][298][299] Tool with optimized design (inner cooling structure) Al 2 O 3 [180], cemented carbide [300] Optical application (lens, armored/ sensor window, etc.) Al 2 O 3 [301], MgAl 2 O 4 spinel [302], SiC [303], Nd-doped YAG [304], Yb-doped YAG [305] Antenna Al 2 O 3 +glass [306], Ba 1-x Sr x Zn 2 Si 2 O 7 [307], MgTiO 3 +CaTiO 3 [308] Nuclear fusion Li 2 TiO 3 [309], Li 2 SiO 3 [310] Table VIII waste. Thus, machines that work with a small amount of material (60 mL) [316] and studies about recycling raw materials [286,354] have emerged.…”

Ultralow-Permittivity and Temperature-Stable Ba1–xCaxMg2Al6Si9O30 Dielectric Ceramics for C-Band Patch Antenna Applications

“…Nevertheless, the rare negative thermal expansion (NTE) was observed in the BaMg 2 Al 6 Si 9 O 30 ceramic. The drastic changes in CTE from positive to negative can cause a mismatch in CTE in solids, which may result in serious problems for devices, such as permanent damage and cracking . The NTE in the BaMg 2 Al 6 Si 9 O 30 ceramic does not meet the requirements for practical applications and must be inhibited.…”