Currently, research on A 3+ B 3+ O 3 - type microwave dielectric ceramics is scarce. To address these challenges, a novel perovskite - type LaTmO 3 ceramic with a single phase orthorhombic structure (space group Pnma (62)) was synthesized via the solid state reaction method at 1450–1575 °C. Furthermore, SEM was employed to observe the microstructure of the sample, and Raman spectroscopy was utilized to analyze the impact of lattice vibrations on dielectric loss. Additionally, calculations based on the complex chemical bond theory revealed that the values of the εᵣ , Q×f , and τ f were influenced by bond ionicity, lattice energy, and bond energy, respectively. The LaTmO 3 ceramic sintered at 1525 °C demonstrated optimal microwave dielectric properties: Q×f = 179,601 ± 9579 GHz (at 8.4 GHz), εᵣ = 27.8 ± 0.18, and τ f = +9.8 ± 1.5 ppm/°C. Moreover, HFSS simulations demonstrated the applicability of LaTmO 3 in dielectric resonator antennas, achieving >90 % radiation efficiency, about 5.5 dBi gain, and 130 MHz bandwidth at 4.7 GHz, highlighting its potential for 5G oriented components.
P(VDF-HFP) is widely used in transistors, electret and artificial skin due to its excellent dielectric properties . In order to dramatically improve its dielectric constant, conductive fillers are used for doping, but the compatibility is not optimistic between the fillers and the PVDF . In this paper, PEDOT:PSS/P(VDF-HFP) all-organic films with interpenetrating network structure were prepared by the addition of H 2 O. The dielectric constant of the film with 0.5 wt % PEDOT:PSS reached up to 323 and the tanδ was only 0.48 (1 k Hz, 18 °C). The addition of the H 2 O made the small amount of PEDOT:PSS evenly distribute in the P(VDF-HFP), as a result, the percolation threshold decreased. Besides, molecular chains of PEDOT:PSS were overlapped to form a uniform network. This paper provided a novel preparation method for a uniform film with two kinds of matters with different compatibility.
Wenzheng Chen,Sijia Li,Mingyu Lu,Yiping Guo,Hao Yin,Yujie Chen,Qunfu Fan,Hezhou Liu,Hua Li
The “Brick-and-Mortar” structure endows the nacre outstanding abilities of dissipating kinetic energy, attenuating stress wave and keeping high mechanical strength. However, current artificial bio-inspired materials, such as the materials with unit structure arranged in an ordered hierarchy at merely one dimension, have yet to achieve desirable damping and mechanical behavior under monotonous damping mechanisms. Herein, the nacre-like structure, conductive network, and nano piezoelectric thin film are synergistically combined in multidimension to enhance the damping and vibration attenuating behavior by different mechanisms. The continuous piezoelectric composites with nacre-like lamellar structure demonstrates superior damping property. By introducing a conductive network, piezoelectric damping is enabled, and the damping behavior is further promoted, achieving a maximum loss factor of 1.19 and tanδ area value of 34.28. The nacre-like structure in macro dimension offers the framework of PZT thin film in nano dimension, and the conductive network in micro dimension stimulates the continuous piezoelectric damping, in which the contribution of each dimension is decoupled. Based on this finding, the vibration attenuating behavior is evaluated by cantilever beam vibration test where the composites lower 26.2 dB and damping ratio increase by 95%, which are greatly demanded for many damping applications including watercraft structures and aerospace scaffold.
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