Solids in Europe

A special issue of Solids (ISSN 2673-6497).

Deadline for manuscript submissions: closed (31 January 2023) | Viewed by 39291

Special Issue Editors


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Guest Editor
Wlodzimierz Trzebiatowski Institute of Low Temperature and Structure Research of the Polish Academy of Sciences, Wroclaw, Poland
Interests: organic–inorganic hybrid materials; metal–organic frameworks; coordination polymers; ferroelectrics; multiferroics; optoelectronic materials; IR; Raman; optical properties
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Guest Editor
Department of Inorganic and Organic Chemistry, University Jaume I-Castellón, 12071 Castelló de la Plana, Castelló, Spain
Interests: ceramic and glass ceramic materials; development of new properties in ceramic materials; study of synthesis methods and processing of ceramic materials; improvements in ceramic tiles industry; development of photovoltaic tiles for their architectural integration (BIPV)
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Solids has made significant progress in its several-decades-long existence as a scientific field. The need for the field has never been more clear than it is today. Many European research groups are working on solid-state sciences.

This Special Issue is dedicated to the new achievements from European laboratories in research areas of all areas of solid-state sciences, including theoretical, fundamental, and applied research topics. Original research articles, reviews, or communications within the scope of Solids and from researchers based at any European university or scientific institution are welcome. 

Prof. Dr. Mirosław Mączka
Prof. Dr. Juan B. Carda Castelló
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

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. Solids is an international peer-reviewed open access quarterly 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 1000 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

  • solid materials
  • biomaterials
  • solid-state physics
  • solids in pharmacy
  • computational aspects of solids

Published Papers (16 papers)

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Research

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19 pages, 639 KiB  
Article
A Theory of Dynamical Responses for Metal Films: Surface Roughness Effects
by Sam Praill, Charlotte Lawton, Hasan Balable and Hai-Yao Deng
Solids 2023, 4(3), 268-286; https://doi.org/10.3390/solids4030017 - 18 Sep 2023
Viewed by 918
Abstract
A generic expression is derived for the dynamical response function of metal films, with conductivity tensors as the only input. The semi-classical model is then used to provide an analytical expression for the conductivity tensor, thus establishing a kinetic theory for the response [...] Read more.
A generic expression is derived for the dynamical response function of metal films, with conductivity tensors as the only input. The semi-classical model is then used to provide an analytical expression for the conductivity tensor, thus establishing a kinetic theory for the response function. A major advantage of the theory is its ability to handle surface roughness effects through the use of the so-called specularity parameter. We applied the theory to study the properties of surface plasma waves. It is found that surface roughness does not affect the dispersion, but rather the decay rate of these waves. Furthermore, it significantly affects the spectral weight carried by the SPW resonances, which diminishes toward zero as the specularity parameter approaches unity. Full article
(This article belongs to the Special Issue Solids in Europe)
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7 pages, 1720 KiB  
Communication
Combined X-ray and Neutron Powder Diffraction Study on B-Site Cation Ordering in Complex Perovskite La2(Al1/2MgTa1/2)O6
by Yoo Jung Sohn, Volodymyr Baran, Ralph Gilles, Georg Roth and Robert Vaßen
Solids 2023, 4(1), 87-93; https://doi.org/10.3390/solids4010006 - 01 Mar 2023
Viewed by 1472
Abstract
Complex perovskite La2(Al1/2MgTa1/2)O6 (LAMT) crystallizes in a monoclinic unit cell with space group P21/n at room temperature. Its B-site cations are ordered in a rock-salt-type arrangement. Previously, the full occupancy of Mg [...] Read more.
Complex perovskite La2(Al1/2MgTa1/2)O6 (LAMT) crystallizes in a monoclinic unit cell with space group P21/n at room temperature. Its B-site cations are ordered in a rock-salt-type arrangement. Previously, the full occupancy of Mg on the 2c-Wyckoff position was deduced from powder X-ray diffraction (PXRD). However, conventional X-rays could not properly resolve the mixed occupation on the B-site, since there is little scattering contrast between the neighbouring elements Mg and Al of the periodic table. Hence, complementary neutron diffraction studies were carried out to verify the exact B-site cation ordering in the unit cell. In this specific configuration of the B-cations, with its occupancy ratio and the presence of a heavy element Ta as well as neighbouring elements Mg and Al, only the strategy of a combined Rietveld analysis using both the X-ray and neutron diffraction data simultaneously succeeded in elucidating an accurate B-site cation ordering in this complex perovskite system. A full occupancy of Mg on the 2c-Wyckoff position and each a half occupancy of Al and Ta on the 2d-Wyckoff position could be resolved for the rock-salt-type ordering of the B-site cations in the monoclinic unit cell of LAMT. Full article
(This article belongs to the Special Issue Solids in Europe)
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21 pages, 13287 KiB  
Article
Chemical and Structural Comparison of Different Commercial Food Supplements for Silicon Uptake
by Yannic Curto, Marcus Koch and Guido Kickelbick
Solids 2023, 4(1), 1-21; https://doi.org/10.3390/solids4010001 - 03 Jan 2023
Cited by 1 | Viewed by 2667
Abstract
Various food supplements for silicon uptake were compared in terms of their structures and chemical compositions. In particular, we analyzed the silanol group content, which can be an indicator of the uptake of the siliceous species in the human body. We analyzed the [...] Read more.
Various food supplements for silicon uptake were compared in terms of their structures and chemical compositions. In particular, we analyzed the silanol group content, which can be an indicator of the uptake of the siliceous species in the human body. We analyzed the commercial products Original Silicea Balsam®, Flügge Siliceous Earth Powder, Pure Colloidal Silicon, and BioSil® by applying various methods such as FTIR, 29Si NMR, and TGA. The Si-OH group content of the samples containing pure silica was the highest for the Original Silicea Balsam followed by the Pure Colloidal Silicon. The siliceous earth powder revealed the lowest content of such groups and the densest structure. BioSil® contained a considerable concentration of organic molecules that stabilized orthosilicic acid. The study may help to understand the silicon uptake behavior of different food supplements depending on their chemical structure. Full article
(This article belongs to the Special Issue Solids in Europe)
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8 pages, 1536 KiB  
Article
Thickness-Dependent Sign Change of the Magnetoresistance in VTe2 Thin Films
by Omar Concepción, Liesbeth Mulder, Daan H. Wielens and Alexander Brinkman
Solids 2022, 3(3), 500-507; https://doi.org/10.3390/solids3030033 - 02 Sep 2022
Cited by 2 | Viewed by 1941
Abstract
Transition metal dichalcogenides of type VX2 (X = S, Se, Te) have recently attracted great interest as it has been predicted that they host ferromagnetism at room temperature. Whether ferromagnetism is indeed present is an open experimental question. An in-depth study of [...] Read more.
Transition metal dichalcogenides of type VX2 (X = S, Se, Te) have recently attracted great interest as it has been predicted that they host ferromagnetism at room temperature. Whether ferromagnetism is indeed present is an open experimental question. An in-depth study of the structural and magnetoelectric properties of VTe2 thin films is presented in this work. The VTe2 thin films were grown through molecular beam epitaxy, which allows for precise control of thicknesses, ranging from several nanometers down to monolayers. The low-temperature magnetoelectric transport studies reveal no sign of intrinsic ferromagnetism. However, a transition from positive to negative magnetoresistance is present upon decreasing film thickness. Full article
(This article belongs to the Special Issue Solids in Europe)
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17 pages, 4356 KiB  
Article
Numerical Investigation of the Influence of Fatigue Testing Frequency on the Fracture and Crack Propagation Rate of Additive-Manufactured AlSi10Mg and Ti-6Al-4V Alloys
by Mustafa Awd and Frank Walther
Solids 2022, 3(3), 430-446; https://doi.org/10.3390/solids3030030 - 22 Jul 2022
Cited by 1 | Viewed by 2039
Abstract
Advances in machine systems and scanning technologies have increased the use of selective laser melted materials in industrial applications, resulting in almost full-density products. Inconsistent mechanical behavior of components under cyclic stress is caused by microstructure and porosity created during powder melting. The [...] Read more.
Advances in machine systems and scanning technologies have increased the use of selective laser melted materials in industrial applications, resulting in almost full-density products. Inconsistent mechanical behavior of components under cyclic stress is caused by microstructure and porosity created during powder melting. The extended finite element method, XFEM, was used to imitate crack propagation utilizing an arbitrary fracture route to study fatigue crack growth in additively produced fatigue specimens. The influence of loading level and testing frequency on fatigue life was studied using fracture energy rate curves. Micro-computed tomography (µ-CT) scans offer 2D images in angular increments. There are several ways to reduce the number of faces and vertices. Opensource software was used to isolate the cylindrical shell from interior pores and create finite element models from µ-CT projections. All simulations were on supposedly cylindrical fatigue specimens made by selective laser melting (SLM) based on previous experimental results of the authors. Crack propagation rate curves were utilized to evaluate the effects of loading level and testing frequency. At larger loads, the fracture area increases abruptly at 3E3 cycles, then stabilizes at 4E4 cycles in Al alloys in comparison to Ti-6Al-4V alloys. Crack propagation rate curves may be used to determine Paris constants based on the applied stresses. Full article
(This article belongs to the Special Issue Solids in Europe)
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16 pages, 4429 KiB  
Article
Effect of Vanadium Catalysts on Hydrogen Evolution from NaBH4
by Piotr Antoni Orłowski and Wojciech Grochala
Solids 2022, 3(2), 295-310; https://doi.org/10.3390/solids3020021 - 18 May 2022
Cited by 2 | Viewed by 1749
Abstract
NaBH4 is a very cheap and hydrogen-rich material, as well as a potential hydrogen store. However, the high temperature of its thermal decomposition (above 530 °C) renders it inapplicable in practical use. Here, we studied the effect of addition of diverse V-containing [...] Read more.
NaBH4 is a very cheap and hydrogen-rich material, as well as a potential hydrogen store. However, the high temperature of its thermal decomposition (above 530 °C) renders it inapplicable in practical use. Here, we studied the effect of addition of diverse V-containing catalysts on thermal hydrogen desorption. It turns out that mechanochemical doping of NaBH4 with vanadium metal, its oxides, or nanoparticles lowers the temperature of pyrolysis significantly. Notably, NaBH4 milled for 3 h with 25 wt.% V2O5 or VO2 releases ca. 70% of stored hydrogen in the temperature range of ca. 370–450 °C. On the other hand, precursors and solvents used to prepare rather uniform vanadium nanoparticles (~4 nm) suspended in THF or less uniform and larger ones (~15 nm) in o- difluorobenzene have adverse effect on the purity of hydrogen evolved. Full article
(This article belongs to the Special Issue Solids in Europe)
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13 pages, 8844 KiB  
Article
Investigation of the Tetrakis(dimethylamino)hafnium and H2S ALD Process: Effects of Deposition Temperature and Annealing
by Zsófia Baji, Zsolt Fogarassy, Attila Sulyok and Péter Petrik
Solids 2022, 3(2), 258-270; https://doi.org/10.3390/solids3020018 - 05 May 2022
Viewed by 1863
Abstract
HfS2 has recently emerged as a promising 2D semiconductor, but the lack of a reliable method to produce continuous films on a large scale has hindered its spreading. The atomic layer deposition of the material with the precursor tetrakis-dimethylamino-hafnium with H2 [...] Read more.
HfS2 has recently emerged as a promising 2D semiconductor, but the lack of a reliable method to produce continuous films on a large scale has hindered its spreading. The atomic layer deposition of the material with the precursor tetrakis-dimethylamino-hafnium with H2S is a relatively novel solution to this problem. This paper shows that it is a facile approach to synthesizing homogeneous and smooth HfS2 layers in a controlled and reproducible manner. The deposition is examined at different temperatures and layer thicknesses, exploring the ALD window of the deposition and the chemical, morphological and electronic properties of the films. The method yielded films with wafer-sized uniformity and controlled properties and is, thus, a promising way to prepare this important transition metal dichalcogenide material. Full article
(This article belongs to the Special Issue Solids in Europe)
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16 pages, 538 KiB  
Article
An Electron Waveguide Model for FDSOI Transistors
by Ulrich Wulf
Solids 2022, 3(2), 203-218; https://doi.org/10.3390/solids3020014 - 15 Apr 2022
Viewed by 1843
Abstract
We extend our previous semi-empirical model for quantum transport in a conventional nano-MOSFET to FDSOI transistors. In ultra-thin-body and -BOX (UTBB) FDSOI transistors, the electron channel can be treated as an electron waveguide. In the abrupt transition approximation, it is possible to derive [...] Read more.
We extend our previous semi-empirical model for quantum transport in a conventional nano-MOSFET to FDSOI transistors. In ultra-thin-body and -BOX (UTBB) FDSOI transistors, the electron channel can be treated as an electron waveguide. In the abrupt transition approximation, it is possible to derive an analytical approximation for the potential seen by the charge carriers. With these approximations we calculate the threshold voltage and the transfer characteristics, finding remarkably good agreement with experiments in the OFF-state given the relative simplicity of our model. In the ON-state, our theory fails because Coulomb interaction between the free charge carriers and the device heating is neglected in our approach. Full article
(This article belongs to the Special Issue Solids in Europe)
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11 pages, 4323 KiB  
Article
Temperature-Dependent Raman Studies of FAPbBr3 and MAPbBr3 Perovskites: Effect of Phase Transitions on Molecular Dynamics and Lattice Distortion
by Mirosław Mączka and Maciej Ptak
Solids 2022, 3(1), 111-121; https://doi.org/10.3390/solids3010008 - 19 Feb 2022
Cited by 17 | Viewed by 3759
Abstract
Three-dimensional hybrid organic–inorganic lead halide perovskites are promising photovoltaic and light-emitting materials. A key phenomenon relevant for their optoelectronic applications is electron–phonon coupling. Since it can be strongly modified by structural deformation and changes in the dynamics of molecular cations, it is of [...] Read more.
Three-dimensional hybrid organic–inorganic lead halide perovskites are promising photovoltaic and light-emitting materials. A key phenomenon relevant for their optoelectronic applications is electron–phonon coupling. Since it can be strongly modified by structural deformation and changes in the dynamics of molecular cations, it is of great importance to study the temperature dependence of phonon properties of hybrid perovskites. In this work, temperature-dependent Raman scattering studies of FAPbBr3 and MAPbBr3 single crystals are reported in the 1800–22 cm−1 and 300–90 K ranges. The Raman data of MAPbBr3 showed clear anomalies near 236, 155 and 148 K, which were attributed to Pm3¯mI4/mcmP4/mmm (or Imma)→Pnma phase transitions. They also provided strong evidence that crystal structure of the phase stable in the 155–148 K range is very similar to structure of the I4/mcm phase, not structure of the lowest-temperature Pmna phase, as suggested in some reports. Therefore, the symmetry of this phase seems to be more likely P4/mmm rather than Imma. An analysis of the temperature evolution of MAPbBr3 Raman modes revealed that the phase transitions near 236 and 155 K are associated with weak distortion of the inorganic subnetwork and changes in the dynamics of MA+ ions. Very pronounced changes in the lattice modes region and a narrowing of bands below 148 K indicated that the phase transition to the Pnma phase is triggered by a freezing of MA+ motions, which in turn leads to strong distortion of the inorganic subnetwork. Raman studies of FAPbBr3 showed that this material behaves in a very different way than MAPbBr3. First of all, the molecular dynamics of FA+ cations are not frozen even in the lowest-temperature Pnma phase. Moreover, the distortion of the inorganic subnetwork is small in the Pnma phase. The observation of weak anomalies in the lattice modes region confirmed, however, that the two crystallographically resolved phase transitions (Pm3¯mP4/mbm near 260 K and P4/mbmPnma near 150 K) lead to weak distortion of the inorganic subnetwork. On the other hand, an analysis of FA+ internal modes indicated that these transitions, as well as two other crystallographically unresolved transitions near 120 and 180 K, are triggered by a change of FA+ dynamics. Full article
(This article belongs to the Special Issue Solids in Europe)
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21 pages, 6996 KiB  
Article
Effect of Stoichiometry on Shape Memory Properties of Ti-Ni-Hf-Cu-Nb Shape Memory Alloys Manufactured by Suspended Droplet Alloying
by Sheng Li, Minshi Wang, Khamis Essa, Chunlei Gan, Chunyan Liu and Moataz Attallah
Solids 2022, 3(1), 1-21; https://doi.org/10.3390/solids3010001 - 05 Jan 2022
Viewed by 2260
Abstract
A novel Ti-Ni-Hf-Cu-Nb shape memory alloy has been developed by a new combinatorial alloy synthesis method, the Suspended Droplet Alloying. The influence of alloying elements on the transformation temperature, the microstructure and the shape memory effect of this alloy have also been studied. [...] Read more.
A novel Ti-Ni-Hf-Cu-Nb shape memory alloy has been developed by a new combinatorial alloy synthesis method, the Suspended Droplet Alloying. The influence of alloying elements on the transformation temperature, the microstructure and the shape memory effect of this alloy have also been studied. It was found that Cu has a greater negative influence on the transformation temperature of Ti-Ni-Hf-CuX alloys (about −5 K/at.%) than on the Ti-Ni-CuX alloys (−0.67 K/at.%). In addition, the negative effect intensifies with increasing Hf content. The transformation temperature rapidly decreases with increasing Nb composition in the Ti-Ni-Cu-Nb and Ti-Ni-Hf-Cu-Nb alloys, with the solid solution of Nb in the matrix being 1 at.%. A Ti-Ni-Cu-Hf-Nb alloy with high thermal cycle stability has been developed, where the alloying elements affect the transformation behaviour via altering the slipping energy and forming different types of precipitations. Full article
(This article belongs to the Special Issue Solids in Europe)
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17 pages, 5987 KiB  
Article
Experimental Investigations of Effective Thermal Conductivity of the Selected Examples of Steel Porous Charge
by Rafał Wyczółkowski
Solids 2021, 2(4), 420-436; https://doi.org/10.3390/solids2040027 - 16 Dec 2021
Cited by 3 | Viewed by 2178
Abstract
In many cases of heat treatment of steel products, the heated charge has a porous structure. The examples of such charges include bundles of long steel components e.g., bars. The basic thermal property of the charge in this form is effective thermal conductivity [...] Read more.
In many cases of heat treatment of steel products, the heated charge has a porous structure. The examples of such charges include bundles of long steel components e.g., bars. The basic thermal property of the charge in this form is effective thermal conductivity kef. This paper presents the results of experimental examinations of effective thermal conductivity of the porous charge, which is composed from various types of steel long components. Due to the specific nature of the samples, a special measurement stand was constructed based on the design of a guarded hot plate apparatus. The measurements were performed for sixteen different samples across a temperature range of 70–640 °C. The porosity of the samples, depending on the type of components used, ranged from 0.03 to 0.85. Depending on these factors, the effective thermal conductivity ranged from 1.75 to 8.19 W·m−1·K−1. This accounts for 0.03 to 0.25 of the value of thermal conductivity of the solid phase of the charge, which in the described cases was low-carbon steel. It was found that the effective thermal conductivity rises linearly with temperature. The intensity of this increase and the value of coefficient kef depend on the transverse dimension of the components that form the charge. The results may represent the basis for the validation of various models of effective thermal conductivity with respect to the evaluation of thermal properties of the porous charge. Full article
(This article belongs to the Special Issue Solids in Europe)
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13 pages, 3078 KiB  
Article
Development of SnO2 Composites as Electron Transport Layer in Unencapsulated CH3NH3PbI3 Solar Cells
by Gennaro V. Sannino, Antonella De Maria, Vera La Ferrara, Gabriella Rametta, Lucia V. Mercaldo, Maria Luisa Addonizio, Laura Lancellotti, Adriana Pecoraro, Ana B. Muñoz-García, Michele Pavone and Paola Delli Veneri
Solids 2021, 2(4), 407-419; https://doi.org/10.3390/solids2040026 - 16 Dec 2021
Cited by 3 | Viewed by 2861
Abstract
Improving morphological and electronic properties of the electron transport layer (ETL) is a critical issue to fabricate highly efficient perovskite solar cells. Tin dioxide is used as an ETL for its peculiarities such as low-temperature solution-process and high electron mobility and several handlings [...] Read more.
Improving morphological and electronic properties of the electron transport layer (ETL) is a critical issue to fabricate highly efficient perovskite solar cells. Tin dioxide is used as an ETL for its peculiarities such as low-temperature solution-process and high electron mobility and several handlings have been tested to increase its performances. Herein, SnO2:ZnO and SnO2:In2O3 composites are studied as ETL in planar n-i-p CH3NH3PbI3 solar cells fabricated in ambient air, starting from glass/ITO substrates. Morphological, electrical and optical properties of zinc- and indium-oxide nanoparticles (NPs) are investigated. First-principle calculations are also reported and help to further explain the experimental evidences. Photovoltaic performances of full devices show an improvement in efficiency for SnO2:In2O3–based solar cells with respect to pristine SnO2, probably due to a suppression of interfacial charge recombination between ITO/ETL and ETL/perovskite. Moreover, a better homogeneity of SnO2:In2O3 deposition with respect to SnO2:ZnO composites, conducts an increase in perovskite grain size and, consequently, the device performances. Full article
(This article belongs to the Special Issue Solids in Europe)
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12 pages, 6109 KiB  
Article
Development of Ti PVD Films to Limit the Carburization of Metal Powders during SPS Process
by Maria-Rosa Ardigo-Besnard, Aurélien Besnard, Mathias Moser and Florian Bussière
Solids 2021, 2(4), 395-406; https://doi.org/10.3390/solids2040025 - 03 Dec 2021
Cited by 3 | Viewed by 2449
Abstract
Spark plasma sintering technique is used for the fabrication of dense materials with a fine-grained microstructure. In this process, a powder is placed into a graphite mold and a uniaxial pressure is applied by two graphite punches. A graphite foil is inserted between [...] Read more.
Spark plasma sintering technique is used for the fabrication of dense materials with a fine-grained microstructure. In this process, a powder is placed into a graphite mold and a uniaxial pressure is applied by two graphite punches. A graphite foil is inserted between the punches and the powder and between the mold and the powder to ensure good electrical, physical and thermal contact. One of the major drawbacks during sintering of metal powders is the carburization of the powder in contact with the graphite foils. In this study, a PVD coating of titanium was applied on the graphite foils in contact with the metal powder (pure iron). The results are promising, as the investigations show that the application of a Ti PVD film of 1.5 and 1.1 µm thickness is effective to completely avoid the carburization of iron powder. Carbon diffuses inside the PVD film during sintering. In parallel, iron diffusion was revealed inside the Ti coating of 1.5 µm thickness. On the other hand, a Ti PVD film of 0.5 µm thickness provides a protection against carbon diffusion just on the sides in contact with the mold, proving that the coating thickness represents an important parameter to consider. Full article
(This article belongs to the Special Issue Solids in Europe)
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30 pages, 6991 KiB  
Article
Effects on Microstructure and Ionic Conductivity of the Co-Doping with Strontium and Samarium of Ceria with Constant Oxygen Vacancy Concentration
by Toby Sherwood and Richard T. Baker
Solids 2021, 2(4), 341-370; https://doi.org/10.3390/solids2040022 - 04 Nov 2021
Viewed by 2335
Abstract
Partially substituted cerias are attractive materials for use as electrolytes in intermediate-temperature solid oxide fuel cells (SOFCs). Ceria doped with Sm or Gd has been found to have high ionic conductivities. However, there is interest in whether doping with multiple elements could lead [...] Read more.
Partially substituted cerias are attractive materials for use as electrolytes in intermediate-temperature solid oxide fuel cells (SOFCs). Ceria doped with Sm or Gd has been found to have high ionic conductivities. However, there is interest in whether doping with multiple elements could lead to materials with higher ionic conductivities. The present study looks at the effects of co-doping Sr and Sm in ceria. A compositional series, Ce0.8+xSm0.2−2xSrxO2−δ (with x = 0–0.08), designed to have a constant oxygen vacancy concentration, was successfully prepared using the citrate–nitrate complexation method. A solubility limit of ~5 cation% Sr was found to impact material structure and conductivity. For phase-pure materials, with increasing Sr content, sinterability increased slightly and intrinsic conductivity decreased roughly linearly. The grain boundaries of phase-pure materials showed only a very small blocking effect, linked to the high-purity synthesis method employed, while at high %Sr, they became more blocking due to the presence of a SrCeO3 impurity. Grain capacitances were found to be 50–60 pF and grain boundary capacitances, 5–50 nF. The variation in the bulk capacitance with Sr content was small, and the variation in grain boundary capacitance could be explained by the variation in grain size. Slight deviations at high %Sr were attributed to the SrCeO3 impurity. In summary, in the absence of deleterious effects due to poor microstructure or impurities, such as Si, there is no improvement in conductivity on co-doping with Sr and Sm. Full article
(This article belongs to the Special Issue Solids in Europe)
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Review

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41 pages, 2393 KiB  
Review
Natural and Synthetic Polymer Fillers for Applications in 3D Printing—FDM Technology Area
by Bogna Sztorch, Dariusz Brząkalski, Daria Pakuła, Miłosz Frydrych, Zdeno Špitalský and Robert E. Przekop
Solids 2022, 3(3), 508-548; https://doi.org/10.3390/solids3030034 - 16 Sep 2022
Cited by 22 | Viewed by 5728
Abstract
This publication summarises the current state of knowledge and technology on the possibilities and limitations of using mineral and synthetic fillers in the field of 3D printing of thermoplastics. FDM technology can be perceived as a miniaturised variation of conventional extrusion processing (a [...] Read more.
This publication summarises the current state of knowledge and technology on the possibilities and limitations of using mineral and synthetic fillers in the field of 3D printing of thermoplastics. FDM technology can be perceived as a miniaturised variation of conventional extrusion processing (a microextrusion process). However, scaling the process down has an undoubtful drawback of significantly reducing the extrudate diameter (often by a factor of ≈20–30). Therefore, the results produced under conventional extrusion processing cannot be simply translated to processes run with the application of FDM technology. With that in mind, discussing the latest findings in composite materials preparation and application in FDM 3D printing was necessary. Full article
(This article belongs to the Special Issue Solids in Europe)
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25 pages, 4358 KiB  
Review
Surface Plasmons Excited by X-rays in the Surface Layers of Solids
by Valery M. Stozharov
Solids 2022, 3(1), 122-146; https://doi.org/10.3390/solids3010009 - 01 Mar 2022
Viewed by 1811
Abstract
The phenomenon of total external reflection of X-rays at a sliding angle of incidence of a beam of incident X-rays is investigated. For metals, a quantitative law of direct dependence of the refractive index decrement on the interplane distance is obtained. The excitation [...] Read more.
The phenomenon of total external reflection of X-rays at a sliding angle of incidence of a beam of incident X-rays is investigated. For metals, a quantitative law of direct dependence of the refractive index decrement on the interplane distance is obtained. The excitation of surface plasmons by X-rays that have experienced complete external reflection is detected. For surface plasmons, a dimensional effect was observed, expressed in an increase in the energy of plasmons and the concentration of conduction electrons with an increase in the depth of the output of surface plasmons. By the method of dispersion of surface plasmons, internal mechanical micro-stresses and spontaneous polarization of the surface layers of glassy dielectrics and in thin layers of vanadium dioxide were determined. The absence of micro-stresses in the lithium fluoride ionic single crystal was found out, and the polarization observed in it is due to the large dipole moment of the molecules of this crystal. In thin films of vanadium dioxide, the dependence of micro-stresses on the stresses in the substrates was found. Full article
(This article belongs to the Special Issue Solids in Europe)
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