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0.05AlPO 4 -0.05BPO 4 -0.90SiO 2 glass-ceramic and glass-free 0.45AlPO 4 -0.45BPO 4 -0.10SiO 2 ceramic have been prepared by a solid-state reaction process and their terahertz (THz) dielectric responses were characterized by time-domain spectroscopy (TDS) techniques in the frequency range from 0.2 to 1.6 THz. Both samples demonstrate little dielectric dispersions in the (sub) THz frequency range, having dielectric permittivities (ε r) of ∼3.35(7) and ∼4.06(8), respectively. The dielectric responses are dominated by the phonons and electronic polarizations in the (sub) THz frequency range. The contributions to the relative permittivities from electronic polarization ε r ∞ are 1.85(4) and 1.99(4), which are ∼55% and ∼49% of the total ε r at THz frequencies, respectively. The dielectric losses of both samples continuously increase with increasing frequency in the THz band, while the loss factor of glass-ceramic is one order of magnitude higher than that of glass-free ceramic. The glass-free sample exhibits extremely high Q×f values of 100,000–190,000 GHz in the THz band, being much higher than that of the glass-ceramic (∼7000–25,000 GHz). [ABSTRACT FROM AUTHOR]

Sixth generation (6G) wireless networks operating in terahertz frequency region are significant solutions to the increasing number of telecommunication devices and the demand for faster data transmission. However, few dielectric materials exhibiting an ultralow relative dielectric constant (εr), loss tangent (tanδ), and high mechanical strength are found suited for 6G telecommunication. In this study, we developed lightweight ceramic foams by directly sintering glass hollow spheres. The effects of sintering temperatures on their mechanical performance, and terahertz optical and dielectric properties were systematically investigated. The final compositions of ceramic foams contain glass, cristobalite, quartz, and wollastonite. The crystalline content increases with increasing sintering temperature. The ceramic foams sintered at low temperatures of 700–850°C exhibit a high porosity ranging from 74.6% to 87.3%, ultralow εr ranging from 1.41 to 1.83, and tanδ of ∼0.011 at 0.5 THz, as well as high compressive strength ranging from 10.1 to 27.4 MPa, which could be promising materials for 6G telecommunication. [ABSTRACT FROM AUTHOR]

Despite predictions of the paperless office, global demand for printing and writing paper remains strong, and paper appears to be here to stay for some time. Not only firms, but also governments, libraries, and archives are in possession of large collections of legacy documents that still must be sorted and scanned. In this study, terahertz-based techniques are demonstrated to address several routine tasks related to the automated paper handling of unsorted legacy documents. Specifically, we demonstrate terahertz-based counting of the number of sheets in unconsolidated paper stacks, as well as locating stapled documents buried in paper stacks.

Despite predictions of the paperless office, global demand for printing and writing paper remains strong, and paper appears to be here to stay for some time. Not only firms, but also governments, libraries, and archives are in possession of large collections of legacy documents that still must be sorted and scanned. In this study, terahertz-based techniques are demonstrated to address several routine tasks related to the automated paper handling of unsorted legacy documents. Specifically, we demonstrate terahertz-based counting of the number of sheets in unconsolidated paper stacks, as well as locating stapled documents buried in paper stacks. [ABSTRACT FROM AUTHOR]