Novel K2–2xAg2xMg2(MoO4)3 (x = 0–0.09) ceramics were synthesized by conventional solid-state sintering method. Based on the X-ray diffraction (XRD) patterns, all samples were identified to belong to ...an orthorhombic structure with a space group of P212121(19). The pure phase K2Mg2(MoO4)3 specimen when sintered at 590 °C revealed the favorable microwave dielectric properties: εr of 6.91, Q×f of 21,900 GHz and τf of −164 ppm/°C. The substitution of Ag+ for K+ in K2–2xAg2xMg2(MoO4)3 (x = 0.01–0.09) ceramics led to the more stable structure and dramatically enhanced the Q×f to a value of 54,900 GHz at 500 °C. The microwave dielectric properties were related to the relative density, microstructure, ionic polarization, lattice energy, packing fraction, and bond valence of the ceramics. It was suggested that for ultra-low temperature co-fired ceramic (ULTCC) applications, K1.86Ag0.14Mg2(MoO4)3 ceramic could be sintered at 500 °C, which revealed an excellent combination of microwave dielectric properties (εr =7.34, Q×f =54,900 GHz and τf =–156 ppm/°C) and good chemical compatibility with aluminum electrodes.
The position of a node in a social network, or node centrality, can be quantified in several ways. Traditionally, it can be defined by considering the local connectivity of a node (degree) and some ...non-local characteristics (distance). Here, we present an approach that can quantify the interaction structure of signed digraphs and we define a node centrality measure for these networks. The basic principle behind our approach is to determine the sign and strength of direct and indirect effects of one node on another along pathways. Such an approach allows us to elucidate how a node is structurally connected to other nodes in the social network, and partition its interaction structure into positive and negative components. Centrality here is quantified in two ways providing complementary information: total effect is the overall effect a node has on all nodes in the same social network; while net effect describes, whether predominately positive or negative, the manner in which a node can exert on the social network. We use Sampson’s like-dislike relation network to demonstrate our approach and compare our result to those derived from existing centrality indices. We further demonstrate our approach by using Hungarian school classroom social networks.
The MnTeMoO6 (MTMO) ceramics were prepared by the conventional solid-state ceramic method. It exhibits an orthorhombic structure, belongs to the space group P21212(18) and possesses a favorable ...combination of dielectric properties (εr =12.3, Q×f =36,000 GHz, and τf =–63 ppm/°C) at microwave frequency. The effects of A-site Mg-substitution on the sintering behavior, phase evolution, and microwave dielectric properties of MTMO ceramics were also investigated. XRD analysis showed that all samples reveal MTMO phase indicating the formation of solid solution in the experimental range. Upon substituting 5 mol. % Mg in the A-site, the relative density of the specimen can be raised from 95.1 % to 97.3 % along with the optimized properties of εr = 13, Q×f = 56,000 GHz and τf = –58.2 ppm/°C, which reveals a 55 % enhancement in the Q×f of the MTMO ceramic. It also renders an excellent chemical compatibility with aluminum metal electrode suggesting that it is a potential candidate for ULTCC applications.
•The novel MnTeMoO6 (MTMO) ceramics were prepared by the conventional solid-state ceramic method.•The Mn0.95Mg0.05TeMoO6 ceramic renders excellent dielectric properties with εr = 13, Q×f = 56,000 GHz and τf = –58.2 ppm/oC.•The Mn0.95Mg0.05TeMoO6 present excellent chemical stability with Al making it a potential candidate for ULTCC applications.•The designed a dual-polarized patch antenna for use in the 5G millimeter wave frequency band for the MMTMO ceramic.
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•The microwave dielectric properties of Na2Mg5-xZnx (MoO4)6 (x=0–0.09) ceramics have been investigated.•The highest Q×f of 46,000 GHz can be obtained for a specimen with x= 0.07 at ...570°C.•The TiO2-modified specimen combines the best microwave dielectric properties (εr ∼8.8, Q×f ∼31,100 GHz, τf ∼ –4.2 ppm/°C).•Na2Mg4.93Zn0.07(MoO4)6-0.01TiO2 ceramic has good Al-cofiring chemical compatibility.•The material is a promising candidate dielectric for ULTCC applications, particularly for the high-frequency 5G system.
Novel Na2Mg5-xZnx(MoO4)6 (x = 0–0.09) microwave dielectrics were synthesized for ULTCC (ultra-low temperature co-fired ceramics) applications while the effect of Zn substitution on the microwave dielectric properties of the ceramics was systematically investigated. The Raman spectrum of the specimen was also analyzed. All samples can be sintered at a temperature lower than 610 °C and formed a triclinic structured solid solution with a space group of P-1 (2). Microwave dielectric properties of the specimens can be dramatically enhanced with minutely substituting Mg with Zn. Specimen with x = 0.07 at 570 °C revealed the highest Q×f of 46,000 GHz along with εr of 7.62 and τf of –25.3 ppm/°C. With 1 mol% of TiO2 added, remarkable values combined an εr of 8.8, a Q×f of 31,100 GHz and a τf of –4.2 ppm/°C, can all be achieved for the ceramic sintered at 570 °C. Since the specimen is chemically compatible with the Al electrode, we anticipate that the ULTCC candidate material so investigated would be highly promising for today’s high-frequency 5 G applications.
A new strategy using silver nanoparticles (Ag NPs) to synthesize thiolated Au NCs is demonstrated. The quasi-spherical Ag NPs serve as a platform, functioning as a reducing agent for Au (III) and ...attracting capping ligands to the surface of the Ag NPs. Glutathione disulfide (GSSG) and dithiothreitol (DTT) were used as capping ligands to synthesize thiolated Au NCs (glutathione-Au NCs and DTT-Au NCs). The glutathione-Au NCs and DTT-Au NCs showed red color luminance with similar emission wavelengths (630 nm) at an excitation wavelength of 354 nm. The quantum yields of the glutathione-Au NCs and DTT-Au NCs were measured to be 7.3% and 7.0%, respectively. An electrophoretic mobility assay showed that the glutathione-Au NCs moved toward the anode, while the DTT-Au NCs were not mobile under the electric field, suggesting that the total net charge of the thiolated Au NCs is determined by the charges on the capping ligands. The detection of the KSV values, 26 M−1 and 0 M−1, respectively, revealed that glutathione-Au NCs are much more accessible to an aqueous environment than DTT-Au NCs.
Potassium secondary batteries are contenders of next-generation energy storage devices owing to the much higher abundance of potassium than lithium. However, safety issues and poor cycle life of K ...metal battery have been key bottlenecks. Here we report an ionic liquid electrolyte comprising 1-ethyl-3-methylimidazolium chloride/AlCl₃/KCl/potassium bis(fluorosulfonyl) imide for safe and high-performance batteries. The electrolyte is nonflammable and exhibits a high ionic conductivity of 13.1 mS cm−1 at room temperature. A 3.6-V battery with K anode and Prussian blue/reduced graphene oxide cathode delivers a high energy and power density of 381 and 1,350 W kg−1, respectively. The battery shows an excellent cycling stability over 820 cycles, retaining ∼89% of the original capacity with high Coulombic efficiencies of ∼99.9%. High cyclability is also achieved at elevated temperatures up to 60 °C. Uniquely, robust K, Al, F, and Cl-containing passivating interphases are afforded with this electrolyte, which is key to superior battery cycling performances.
TiO
2
ceramics synthesized from the rutile TiO
2
powders with a mean size of ~ 0.4 μm were sintered at temperatures ranging from 500 to 1300 °C. The diffraction peaks matched well with the pure ...rutile phase. Grain growth is an important factor of densification and it becomes significant at 800–1300 °C, suggesting that the sintering process likely moves into the intermediate stage. The density renders a value of 97.5% at 1300 °C and starts to bend suggesting that the sintering is reaching its final stage. A thermostable and wide process window can be achieved for TiO
2
specimen sintered at 500–800 °C, and it exhibits an
ε
r
of 21.7–28.18.8, a
Q
×
f
of 11,700–14,600 GHz, a
τ
f
of 383–390 ppm/°C, respectively. Not only did it provide a large positive
τ
f
, the rutile-TiO
2
also rendered a stable and wide process window, suggesting that the proposed TiO
2
ceramic can be a promising candidate for use as a
τ
f
compensator for ultra-low-temperature co-fired ceramics (ULTCC) materials and the microwave dielectric properties of ULTCC + TiO
2
ceramics may be predictable through the mixing rules.
The microwave dielectric properties and the microstructures of Nd(Co1/2Ti1/2)O3 (NCT) ceramics using starting powders of Nd2O3, CoO, and TiO2 prepared by the conventional solid‐state route have been ...researched. The dielectric constant values (ɛr) saturated at 24.8–27. Quality factor (Q×f) values of 37 900–140 000 (at 9 GHz) and the measured τf values ranging from −45 to −48 ppm/°C can be obtained when the sintering temperatures are in the range of 1410°–1500°C. The ɛr value of 27, the Q×f value of 140 000 (at 9 GHz) and the τf value of −46 ppm/°C were obtained for NCT ceramics sintered at 1440°C for 4 h. For applications of high selective microwave ceramic resonator, filter, and antenna, NCT is proposed as a suitable material candidate.
Li
2
Mg
2
(MoO
4
)
3
dielectric was prepared via the conventional solid-state method, and its dielectric properties were investigated in the microwave frequency region. The XRD patterns of the ...sintered samples revealed single-phase formation with an orthorhombic structure and a space group belonging to Pnma(62). Lattice parameters, bond length, and Raman spectra of the ceramics were also investigated. The dielectric properties exhibited significant dependence on the sintering conditions. The
values (resonant frequency temperature coefficient) remained in a range from - 60 to - 69 ppm/°C for all specimens because the changes in the unit cell volume were small. Excellent microwave dielectric properties (ε
r
~ 9.5, Q × f ~ 80,000 GHz and τ
f
~ - 69 ppm/°C) can be obtained for Li
2
Mg
2
(MoO
4
)
3
ceramics sintered at 880°C for 4 h. This constitutes a very promising material for LTCC applications.
In this study, amorphous Ce2Ti2O7 (CTO) thin films were prepared on an ITO/glass substrate using the sol-gel method. The effects of film thickness, annealing temperature, post-metal annealing, and ...the insertion of an additional AlOx layer in between the CTO film and ITO/glass on the resistance-switching characteristics of the device were studied. All samples exhibited bipolar resistive switching (BRS) behavior. The diffusion of Al and self-formed AlOx at the Al/CTO interface were observed in samples under post-metallization annealing (PMA) treatment. The diffused Al atoms can act as dopants to provide additional oxygen vacancies, while the self-formed AlOx prevents the outward diffusion of oxygen ions. A forming-free Al/CTO/ITO sample with a switching cycle of 1565, a Vset/Vreset ratio of −1.1 V/1.0 V, an on/off ratio of ∼102, and a retention time of 104 s can be obtained after a 300 °C PMA treatment. Insertion of an AlOx layer at the CTO/ITO interface can enhance the RS performance of the device. By varying the thickness of the AlOx layer, an optimal combination of RS properties (such as switching cycles of 1926, on/off ratio of ∼103) can be obtained, making it a promising candidate for RRAM applications.
•Amorphous CTO thin films were prepared on ITO/glass substrates using the sol-gel method.•The AlOx interfacial layer blocks oxygen ion diffusion during PMA treatment between the top electrode and CTO film.•The insertion of an additional AlOx layer prevented the excessive diffusion of In ions and increased oxygen vacancies.•The on/off ratio to ~103, along with 1926 switching cycles for the Al/CTO/AlOx/ITO sample under a 300ºC PMA treatment.•At 25 and 85 ºC, this device demonstrates a retention time exceeding 104 s.
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