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Didde S, Dubey RS, Panda SK, Babu GS. Experimental Investigation of Calcium-Doped Zinc Aluminate Nanoparticles as a Promising Material for Microwave Applications. ACS OMEGA 2023; 8:38064-38071. [PMID: 37867709 PMCID: PMC10586277 DOI: 10.1021/acsomega.3c03983] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/06/2023] [Accepted: 09/21/2023] [Indexed: 10/24/2023]
Abstract
Miniaturization of microstrip patch antennas (MPAs) is vital in applications such as wireless networks, mobile devices, global positioning satellites, and upcoming wireless terminals. This miniaturization has led to a demand for new materials with higher permittivity compared to the existing ones. Zinc aluminate (ZnAl2O4) ceramic is an exceptional and versatile material in this context, thanks to its high dielectric permittivity and low tangent loss, making it suitable for microwave applications. This article explores the feasibility of sol-gel-prepared Ca-doped ZnAl2O4 ceramic nanoparticles to be useful in fabricating a MPA. These nanoparticles were examined using X-ray diffraction, which confirmed their polycrystalline structure, and the morphological investigation evidenced the spherical grains having a mean diameter of 16 nm. The dielectric permittivity of the ZnAl2O4Ca nanoparticles is 21.11, with a tangential loss of 0.0247. A prototype MPA made by using Ca-doped ZnAl2O4 nanoparticles showed a return loss of -20.92 dB at a resonance frequency of 6.8 GHz with a bandwidth of 600 MHz. These results indicate that Ca-doped ZnAl2O4 ceramic nanoparticles possess exceptional dielectric characteristics, which make them a promising candidate for MPA applications.
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Affiliation(s)
- Sekhar Didde
- Department of ECE, Koneru Lakshmaiah Education Foundation, Greenfields, Vaddeswaram, Guntur, Andhra Pradesh 520002, India
- Department of Electronics & Communication Engineering, Swarnandhra College of Engineering and Technology, Seetharamapuram, Narsapur, Andhra Pradesh 534280, India
| | - Raghvendra Sarvjeet Dubey
- University Institute of Engineering & Technology, Guru Nanak University, Ibrahimpatnam, R. R. District, Hyderabad, Telangana State 501506, India
- Department of Electronics & Communication Engineering, Guru Nanak Institutions Technical Campus, Ibrahimpatnam, R. R. District, Hyderabad, Telangana State 501506, India
| | - Sampad Kumar Panda
- Department of ECE, Koneru Lakshmaiah Education Foundation, Greenfields, Vaddeswaram, Guntur, Andhra Pradesh 520002, India
| | - Gandla Satheesh Babu
- Interdisciplinary Research Center, RV College of Engineering, Mysore Road, Bangalore, Karnataka 560059, India
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Li L, Andrews J, Mitchell R, Button D, Sinclair DC, Reaney IM. Aqueous Cold Sintering of Li-Based Compounds. ACS APPLIED MATERIALS & INTERFACES 2023; 15:20228-20239. [PMID: 37052205 PMCID: PMC10141261 DOI: 10.1021/acsami.3c00392] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/10/2023] [Accepted: 03/30/2023] [Indexed: 06/19/2023]
Abstract
Aqueous cold sintering of two lithium-based compounds, the electrolyte Li6.25La3Zr2Al0.25O12 (LLZAO) and cathode material LiCoO2 (LCO), is reported. For LLZAO, a relative density of ∼87% was achieved, whereas LCO was sintered to ∼95% with 20 wt % LLZAO as a flux/binder. As-cold sintered LLZAO exhibited a low total conductivity (10-8 S/cm) attributed to an insulating grain boundary blocking layer of Li2CO3. The blocking layer was reduced with a post-annealing process or, more effectively, by replacing deionized water with 5 M LiCl during cold sintering to achieve a total conductivity of ∼3 × 10-5 S/cm (similar to the bulk conductivity). For LCO-LLZAO composites, scanning electron microscopy and X-ray computer tomography indicated a continuous LCO matrix with the LLZAO phase evenly distributed but isolated throughout the ceramics. [001] texturing during cold sintering resulted in an order of magnitude difference in electronic conductivity between directions perpendicular and parallel to the c-axis at room temperature. The electronic conductivity (∼10-2 S/cm) of cold sintered LCO-LLZAO ceramics at room temperature was comparable to that of single crystals and higher than those synthesized via either conventional sintering or hot pressing.
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Affiliation(s)
- Linhao Li
- College
of Mathematics and Physics, Beijing University
of Chemical Technology, Beijing 100029, China
- Department
of Materials Science and Engineering, University
of Sheffield, Mappin Street, Sheffield S1 3JD, U.K.
| | - Jessica Andrews
- Department
of Materials Science and Engineering, University
of Sheffield, Mappin Street, Sheffield S1 3JD, U.K.
| | - Ria Mitchell
- Department
of Materials Science and Engineering, University
of Sheffield, Mappin Street, Sheffield S1 3JD, U.K.
| | - Daniel Button
- Department
of Materials Science and Engineering, University
of Sheffield, Mappin Street, Sheffield S1 3JD, U.K.
| | - Derek C. Sinclair
- Department
of Materials Science and Engineering, University
of Sheffield, Mappin Street, Sheffield S1 3JD, U.K.
| | - Ian M. Reaney
- Department
of Materials Science and Engineering, University
of Sheffield, Mappin Street, Sheffield S1 3JD, U.K.
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Microwave dielectric properties of Mg1.8R0.2Al4Si5O18 (R = Mg, Ca, Sr, Ba, Mn, Co, Ni, Cu, Zn) cordierite ceramics and their application for 5G microstrip patch antenna. Ann Ital Chir 2022. [DOI: 10.1016/j.jeurceramsoc.2021.12.050] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022]
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Ndayishimiye A, Fan Z, Funahashi S, Randall CA. Assessment of the Role of Speciation during Cold Sintering of ZnO Using Chelates. Inorg Chem 2021; 60:13453-13460. [PMID: 34403579 DOI: 10.1021/acs.inorgchem.1c01806] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Cold sintering (CS) is a chemically driven densification technique enabling a substantial decrease in the sintering temperature of oxides, by several hundreds of degrees Celsius. Although the densification process in CS is known to be mainly driven by pressure solution creep, additional fundamental aspects driving the interfacial chemistry reactions are still a subject of debate. Herein, we focus on the aspect of speciation in the densification process. The densification of zinc oxide (ZnO) by CS using zinc acetylacetonate hydrate (Zn(acac)2·xH2O), a versatile ligand often used as a precursor for ZnO synthesis in wet chemistry, is reported. The successful densification of ZnO using H2O and Zn(acac)2·xH2O confirms the importance of speciation in CS, as ZnO has a very low solubility in pure H2O. The evolution of the system at different stages of sintering and the role of the Zn(acac)2·xH2O species were evaluated.
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Affiliation(s)
- Arnaud Ndayishimiye
- Materials Research Institute, The Pennsylvania State University, University Park, Pennsylvania 16802, United States.,Department of Materials Science and Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Zhongming Fan
- Materials Research Institute, The Pennsylvania State University, University Park, Pennsylvania 16802, United States.,Department of Materials Science and Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Shuichi Funahashi
- Murata Manufacturing Co., Ltd., 1-10-1 Higashikotari, Nagaokakyo, Kyoto 617-8555, Japan
| | - Clive A Randall
- Materials Research Institute, The Pennsylvania State University, University Park, Pennsylvania 16802, United States.,Department of Materials Science and Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
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