Microwave-Assisted Synthesis of Nanocrystals and Nanostructures

A special issue of Crystals (ISSN 2073-4352).

Deadline for manuscript submissions: closed (31 October 2018) | Viewed by 27272

Special Issue Editors


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Guest Editor
Department of Engineering “Enzo Ferrari”, University of Modena and Reggio Emilia, 41125 Modena, Italy
Interests: materials science; inorganic solids; chemistry; silicates; glasses; microwave processing
Special Issues, Collections and Topics in MDPI journals

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Guest Editor
Laboratory of Nanostructures and Nanomedicine, Institute of High Pressure Physics, Polish Academy of Sciences, Sokolowska 29/37, 01-142 Warsaw, Poland
Interests: synthesis of nanoparticles; microwave technology; microwave solvothermal technology; ultrasonic technology; nanomedicine; application of nanoparticles for bone regrowth; antibacterial nanoparticles; physical properties of nanoparticles; phase transitions in nanoparticles

Special Issue Information

Dear Colleagues,

In this Special Issue, we aim to collect contributions dealing with studies on nucleation and growth in microwave-irradiated environments of nanoparticles (NPs), and various nanostructures: Nanoclusters, nanocomposites, core-shell NPs, decorated NPs, nanowires, etc., for different applications.

NPs exhibit an important state of condensed matter and cover the gap between atomic or molecular structure and bulk materials.

They find new applications in different fields, such as non-linear optics, battery cathodes and ionics, sensors, nano-wires, and other systems. Their special properties can be attributed to their morphology, crystallinity, purity, high surface area to volume ratio, outstanding driving force for diffusion, etc.

Since the properties of nanoparticles and nanostructures depend strongly on their size and morphology, as well as their chemical composition and crystalline structure, it is crucial to ensure precise control of these structural factors. Thus, it appears crucial to control their nucleation and growth from atomic/molecular to a distinctive nano-object, where at least one dimension is less than 100 nm.

Contributions on one-pot or multiple stage syntheses, as well as solvo-thermal or hydro-thermal preparations and gas phase deposition—all of these heated via microwave irradiation—are welcomed in this Special Issue.

Papers that demonstrate that microwave technology is advantageous in producing well reproducible and controlled nanostructures will be preferentially selected for publication. Thus, only papers where synthesis reactors, ensuring a controlled and reproducible synthesis processes, are used will be accepted. Examples of advantageous properties of the produced nano-objects are solicited.

We hope that this Special Issue will serve to promote microwave technology as an important tool for nanomaterial and nanostructure synthesis.

Prof. Dr. Cristina Leonelli
Prof. Dr. Witold Łojkowski
Guest Editors

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Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Crystals is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • microwave
  • nanocrystal
  • preparation method
  • growth
  • morphology
  • synthesis
  • nanowires
  • nanostructures
  • characterisation

Published Papers (4 papers)

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Research

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8 pages, 3711 KiB  
Article
Size Control of Ti4O7 Nanoparticles by Carbothermal Reduction Using a Multimode Microwave Furnace
by Jun Fukushima and Hirotsugu Takizawa
Crystals 2018, 8(12), 444; https://doi.org/10.3390/cryst8120444 - 27 Nov 2018
Cited by 6 | Viewed by 3122
Abstract
Utilization of Ti4O7 in applications such as catalyst support calls for control over the size of the Ti4O7 nanoparticles. This can be achieved using a simple process such as carbothermal reduction. In this study, various sizes of [...] Read more.
Utilization of Ti4O7 in applications such as catalyst support calls for control over the size of the Ti4O7 nanoparticles. This can be achieved using a simple process such as carbothermal reduction. In this study, various sizes of Ti4O7 nanoparticles (25, 60, and 125 nm) were synthesized by carbothermal reduction using a multimode microwave apparatus. It was possible to produce Ti4O7 nanoparticles as small as 25 nm by precisely controlling the temperature, heating process, and holding time of the sample while taking advantage of the characteristics of microwave heating such as rapid and volumetric heating. The results show that microwave carbothermal reduction is advantageous in controlling the size of the Ti4O7 nanoparticles. Full article
(This article belongs to the Special Issue Microwave-Assisted Synthesis of Nanocrystals and Nanostructures)
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28 pages, 8103 KiB  
Article
Structural and Magnetic Properties of Co‒Mn Codoped ZnO Nanoparticles Obtained by Microwave Solvothermal Synthesis
by Jacek Wojnarowicz, Myroslava Omelchenko, Jacek Szczytko, Tadeusz Chudoba, Stanisław Gierlotka, Andrzej Majhofer, Andrzej Twardowski and Witold Lojkowski
Crystals 2018, 8(11), 410; https://doi.org/10.3390/cryst8110410 - 31 Oct 2018
Cited by 24 | Viewed by 5542
Abstract
Zinc oxide nanoparticles codoped with Co2+ and Mn2+ ions (Zn(1−x−y)MnxCoyO NPs) were obtained for the first time by microwave solvothermal synthesis. The nominal content of Co2+ and Mn2+ in Zn(1−x−y)Mnx [...] Read more.
Zinc oxide nanoparticles codoped with Co2+ and Mn2+ ions (Zn(1−x−y)MnxCoyO NPs) were obtained for the first time by microwave solvothermal synthesis. The nominal content of Co2+ and Mn2+ in Zn(1−x−y)MnxCoyO NPs was x = y = 0, 1, 5, 10 and 15 mol % (the amount of both ions was equal). The precursors were obtained by dissolving zinc acetate dihydrate, manganese (II) acetate tetrahydrate and cobalt (II) acetate tetrahydrate in ethylene glycol. The morphology, phase purity, lattice parameters, dopants content, skeleton density, specific surface area, average particle size, average crystallite size, crystallite size distribution and magnetic properties of NPs were determined. The real content of dopants was up to 25.0% for Mn2+ and 80.5% for Co2+ of the nominal content. The colour of the samples changed from white to dark olive green in line with the increasing doping level. Uniform spherical NPs with wurtzite structure were obtained. The average size of NPs decreased from 29 nm to 21 nm in line with the increase in the dopant content. Brillouin type paramagnetism and an antiferromagnetic interaction between the magnetic ions was found for all samples, except for that with 15 mol % doping level, where a small ferromagnetic contribution was found. A review of the preparation methods of Co2+ and Mn2+ codoped ZnO is presented. Full article
(This article belongs to the Special Issue Microwave-Assisted Synthesis of Nanocrystals and Nanostructures)
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18 pages, 34687 KiB  
Article
Size Control of Cobalt-Doped ZnO Nanoparticles Obtained in Microwave Solvothermal Synthesis
by Jacek Wojnarowicz, Tadeusz Chudoba, Stanisław Gierlotka, Kamil Sobczak and Witold Lojkowski
Crystals 2018, 8(4), 179; https://doi.org/10.3390/cryst8040179 - 19 Apr 2018
Cited by 37 | Viewed by 7116
Abstract
This article presents the method of size control of cobalt-doped zinc oxide nanoparticles (Zn1−xCoxO NPs) obtained by means of the microwave solvothermal synthesis. Zinc acetate dihydrate and cobalt(II) acetate tetrahydrate dissolved in ethylene glycol were used as the precursor. [...] Read more.
This article presents the method of size control of cobalt-doped zinc oxide nanoparticles (Zn1−xCoxO NPs) obtained by means of the microwave solvothermal synthesis. Zinc acetate dihydrate and cobalt(II) acetate tetrahydrate dissolved in ethylene glycol were used as the precursor. It has been proved by the example of Zn0.9Co0.1O NPs (x = 10 mol %) that by controlling the water quantity in the precursor it is possible to precisely control the size of the obtained Zn1−xCoxO NPs. The following properties of the obtained Zn0.9Co0.1O NPs were tested: skeleton density (helium pycnometry), specific surface area (BET), dopant content (ICP-OES), morphology (SEM), phase purity (XRD), lattice parameter (Rietveld method), average crystallite size (FW1/5/4/5M method and Scherrer’s formula), crystallite size distribution (FW1/5/4/5M method), and average particle size (from TEM and SSA). An increase in the water content in the precursor between 1.5% and 5% resulted in the increase in Zn0.9Co0.1O NPs size between 28 nm and 53 nm. The X-ray diffraction revealed the presence of only one hexagonal phase of ZnO in all samples. Scanning electron microscope images indicated an impact of the increase in water content in the precursor on the change of size and shape of the obtained Zn0.9Co0.1O NPs. The developed method of NPs size control in the microwave solvothermal synthesis was used for the first time for controlling the size of Zn1−xCoxO NPs. Full article
(This article belongs to the Special Issue Microwave-Assisted Synthesis of Nanocrystals and Nanostructures)
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Review

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26 pages, 9865 KiB  
Review
Current Trends in the Development of Microwave Reactors for the Synthesis of Nanomaterials in Laboratories and Industries: A Review
by Sylwia Dąbrowska, Tadeusz Chudoba, Jacek Wojnarowicz and Witold Łojkowski
Crystals 2018, 8(10), 379; https://doi.org/10.3390/cryst8100379 - 27 Sep 2018
Cited by 120 | Viewed by 10839
Abstract
Microwave energy has been in use for many applications for more than 50 years, from communication, food processing, and wood drying to chemical reactions and medical therapy. The areas, where microwave technology is applied, include drying, calcination, decomposition, powder synthesis, sintering, and chemical [...] Read more.
Microwave energy has been in use for many applications for more than 50 years, from communication, food processing, and wood drying to chemical reactions and medical therapy. The areas, where microwave technology is applied, include drying, calcination, decomposition, powder synthesis, sintering, and chemical process control. Before the year 2000, microwaves were used to produce ceramics, semiconductors, polymers, and inorganic materials; in next years, some new attempts were made as well. Nowadays, it has been found that microwave sintering can also be applied to sintered powder and ceramics and is more effective than conventional sintering. Particularly interesting is its use for the synthesis of nanomaterials. This review identifies the main sources of microwave generation, the delivery mechanisms of microwave energy, and the typical designs and configurations of microwave devices, as well as the measurement and construction material problems related to microwave technology. We focus our attention on the configurations, materials, optimized geometries, and solvents used for microwave devices, providing examples of products, especially nanoparticles and other nanomaterials. The identified microwave devices are divided into four groups, depending on the scale, the maximum pressure developed, the highest temperature for sintering, or other special multi-functions. The challenges of using microwave energy for the synthesis of nanopowders have been identified as well. The desirable characteristics of microwave reactors in the synthesis of nanostructures, as well as their superiority over conventional synthetic methods, have been presented. We have also provided a review of the commercial and self-designed microwave reactors, digestors, and sintering furnaces for technology for synthesis of nanomaterials and other industries. Full article
(This article belongs to the Special Issue Microwave-Assisted Synthesis of Nanocrystals and Nanostructures)
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