The 13th Global Conference on
Materials Science and Engineering (CMSE 2024)

Abstract: We propose the materials design of smart oxide films with thicknesses ranging from 2 to 2000 nm for wide applications. We have succeeded in the 100-nm-thick high Hall mobility (µH) Ce-doped hydrogenated In₂O₃ films for use as electrodes in photovoltaic solar cells, that have been commercial. In order to develop new type of 2D materials, we very recently reported high µH W-doped In₂O₃ polycrystalline films with thicknesses ranging from 5 to 10 nm. For Ga-doped ZnO (GZO) films, we have found that a decrease in thicknesses of 50 nm or less causes a reduction of Young modulus, i.e., such thin films show the flexibility. This research produces polymer substrates with GZO films. On the other hand, thick some micron meter-thick GZO films show magnetic shielding characteristics. We have been developing the unique deposition apparatus; reactive plasma deposition with dc arc discharge (RPD) through the academic-industrial collaboration that has been already commercial. The typically film-deposition rates is 200 nm/min. The RPD provides smart oxide films deposited on the substrates with a large size of 1m×1m. In this presentation, we show smart materials design together with the above business.

Keywords: Highly transparent conductive oxides, 2D, flexibility, carrier transport, reactive plasma deposition.

References:
Eiji Kobayashi, Yoshimi Watabe, Tetsuya Yamamoto, Yoichi Yamada,Sol. Energy Mater. Sol. Cells 149 (2016) 85–90;
Yutaka Furubayashi, Makoto Maehara, Tetsuya Yamamoto, Nanoscale Res. Lett. 14 (2019) 20;
Tetsuya Yamamoto, Rajasekaran Palani, Hisashi Kitami, Hisao Makino, JSAP Rev. (2024) 240404-1-240404-5.

Acknowledgements: We have been continuing a joint research and development with Sumitomo Heavy Industries, Ltd. We would like to express our deepest gratitude to all involved.

Abstract: Nb-Si based ultrahigh temperature alloys possess low densities, high melting point and good high temperature mechanical properties, which are expected to be employed as the promising high-temperature structural materials to replace nickel-based superalloy at 1200-1400 ℃ for aviation turbine engine blades. In the present presentations, the Nb-Si based alloys adding element carbon were prepared by vacuum non-consumable arc melting. The microstructure, nanoindentation microhardness, room temperature fracture toughness, compressive strength at 1250℃ and oxidation resistance of the alloy were evaluated. The results show that adding carbon in multi-elemental Nb-Si based alloys can make the eutectic point of the alloy move to the direction of lower silicon content, and increase the degree of hypereutectic alloy. Alloying with carbon inhibit the formation of (Nb,X)₃Si phase and promote the formation of γ(Nb,X)₅Si₃ phase, and precipitate (Ti,X)C in the alloys. The dissolved carbon (mainly in γ(Nb,X)₅Si₃) has the effect of solid solution strengthening and improve the nanoindentation hardness of phases. Alloying with carbon increase the compressive strength at 1250 ℃ of the alloys. The high temperature compressive strength of 4C alloy is 31.8% higher than that of 0C alloy due to the solid solution strengthening, the increase of primary silicide contents and (Ti,X)C precipitation. The addition of carbon can improve the fracture toughness at room temperature, the KQ value of 3C alloy was 13.5 MPa·m^1/2, which is the highest value among the six alloys. Alloying with carbon reduces the oxidation resistance of the alloy at 1250 ℃, and the oxide film thickness and porosity of the alloy increase.

Keywords: Nb-Si based ultrahigh temperature alloy, carbon alloying, phase constituents, room-temperature fracture toughness, high-temperature compressive strength, high-temperature oxidation resistance, nanoindentation hardness.

Abstract: [2.2]Paracyclophane is a common cyclophane compound consisting of face-to-face benzene rings fixed by ethylene chains at the para-positions. Two eclipsed benzene rings are closely stacked, causing suppression of their rotatory motion. [2.2]Paracyclophane compounds with one or more substituents are planar chiral compounds depending on the substitution position(s). Enantiopure [2.2]paracyclophane compounds have been employed mainly as chiral ligands and chiral auxiliaries in organometallic and organic chemistry, respectively. However, there are only a few examples of their applications in the fields of polymer and materials chemistry [1]. Recently, we achieved optical resolutions of six kinds of di- and tetrasubstituted [2.2]paracyclophanes by the diastereomer method using appropriate chiral auxiliaries [2]. Subsequently, we synthesized various optically active molecules [3] containing planar chiral [2.2]paracyclophane units; the obtained chiral molecules exhibited excellent circularly polarized luminescence (CPL) properties.

We introduce syntheses of optically active cyclic oligomers [4] and macromolecules [5] based on the planar chiral [2.2]paracyclophanes as chiral building blocks. Their synthetic procedures and chiroptical properties, in particular good CPL profiles, are disclosed.

Keywords: Circularly polarized luminescence (CPL), cyclic oligomer, macrocycle, [2.2]Paracyclophane, planar chirality.

References:
[1] Bull. Chem. Soc. Jpn. 2019, 92, 265-274.
[2] For example: (a) J. Am. Chem. Soc. 2014, 136, 3350-3353. (b) Chem. Commun. 2021, 57, 9256-9259. (c) J. Mater. Chem. C 2023, 11, 986-993.
[3] For recent examples: (a) Chem. Asian J. 2022, 17, e202200418. (b) Bull. Chem. Soc. Jpn. 2022, 95, 1353-1359e. (c) Science 2022, 377, 673-678.
[4] (a) Chem. Asian J. 2022, 17, e202101267. (b) Chem. Eur. J. 2023, 29, e202203533.
[5] (a) Bull. Chem. Soc. Jpn. 2022, 95, 110-115. (b) Adv. Funct. Mater. in press (DOI: 10.1002/adfm.202310566).

Abstract: VAW was founded in 1917. Focus of research was on Alumina and Smelter Technologies. Focus on Alumina was Digestion Technology. Autoclaves for the Dsigestion of Bauxite have natural limitations. The reaction area cannot be extended ultimately. In addition to this, the availability of easy processible trihydratic bauxites is diminishing. With increasing amounts of monohydratic bauxites the digestion temperature has to be 250 to 300 °C to achieve reasonable yields.

Tube digestors are a solution.

VAW has developed this technology since 1956 to production stage. In the last 20 years most of the newly built alumina plants use tube digestors.

In parallel efficient drum disc filter technologies have been developed.

Another development is the calcination technique for Hydroxide. In order to replace the energy intensive rotary kilns, VAW has developed the energy-efficient fluid bed calciners.

All of these technologies contribute to a successful production of 120 Mio tons/a of Alumina in the world.

Keywords: Tube digestion, filter system, calcing

Abstract: A series of Pr³⁺ doped boro tellurite glass samples are synthesized using melt quenching technique and investigated for their potential in gamma ray shielding applications. The amorphous nature of prepared samples is confirmed through X-Ray diffraction technique. The shielding characteristics of prepared glass samples were assessed by determining various parameters, including the linear attenuation coefficient (LAC), half-value layer (HVL), mean free path (MFP), effective atomic number (Z_eff), and mass attenuation coefficient (MAC) across the energy range of 15 keV to 15 MeV. The significant decrease in the linear attenuation coefficient (LAC) for all the prepared samples indicates their enhanced radiation attenuation capabilities. Furthermore, it was observed that LAC values are nearly consistent in the energy range from 60 keV<E<15 MeV, for all the prepared samples, demonstrating its independence from the atomic number of the sample. Additionally, HVL values decreases in the energy range from 8 MeV -15 MeV for all the prepared samples which underscores its exceptional efficacy in radiation shielding. This significant reduction in HVL indicates that the Pr³⁺-doped glass provides superior attenuation of gamma radiation, making it an excellent choice for applications where effective radiation protection is critical. A sharp peak at 40KeV is observed in Z_eff graph showing the dominance of Te absorption edge. The higher values of Z_eff at 0.6 MeV for all the prepared samples in this study are evident compared to those reported for lead borate, lead silicate, and lead phosphate in the literature. The current study highlights the effectiveness of the prepared samples as gamma radiation shielding materials.

Keywords: Boro-tellurite glasses, melt quenching technique, X-Ray diffraction technique, gamma radiation shielding.

Abstract: Superhydrophobic materials have been drawing increasing attention in medical fields. Interfacial interactions between cells and surfaces correlate quite well with many important phenomena in biological systems and have been considered for developing of several biomaterials and applications. In this work, surfaces were modified with environmentally friendly superhydrophobic coatings and were used to test their applications. Superhydrophobicity controls the interactions of cells with the surfaces and facilitates the flow of blood or plasma without damaging blood cells in the design of blood-containing devices. Spheroids, 3D multicellular aggregates, have recently emerged as a model that mimics an in vivo environment with more representative cell-to-cell interactions and better intercellular communication. Nevertheless, cost-effective and lab-friendly fabrication and effective recovery are challenges that restrict the broad application of spheroids [1]. The proposed SHS were used for the 3D spheroid preparation from tumoral and non-tumoral cell lines [2]. The effectiveness of the spheroid recovery and the cell viability of the derived entities was demonstrated by 2D culture conditions. Using representative skin cell lines, improved adhesion and proliferation in the migrated cells were demonstrated, both advanced properties for regenerative applications [3]. From macrophage-derived spheroids, changes in polarization and activation of migrated cells suggested promising differentiated immune responses [4]. Insights into the interaction of SHS with bacteria demonstrated promising control on bacterial adhesion under biofilm conditions for which microorganisms adopt a multicellular behavior protecting them against drugs.

Keywords: Biocompatibility, cell-based therapies, medical devices, polarization, spheroids, superhydrophobicity, surfaces.

References:
[1] Ferrari, M.; Cirisano, F.; Morán, M.C. Front. Biosci. 2022, 27, 144.
[2] Ferrari, M.; Cirisano, F.; Morán, M.C. Molecules 2022, 27, 1247.
[3] Morán, M.C.; Cirisano, F.; Ferrari, M. Pharmaceutics 2023, 15, 2226.
[4] Morán, M.C.; Cirisano, F.; Ferrari, M. Pharmaceuticals 2024, 17, 1042.

Abstract: Biofouling is the term used to describe the accumulation and growth of a diverse array of organisms, including bacteria, algae, fungi, and larger organisms, on surfaces in the ocean. The naval industry faces significant issues with surface deterioration, as higher roughness levels result in greater fuel consumption and ultimately, increased material corrosion. Such constraints can be surpassed by superhydrophobic surfaces (SHS) as these surfaces possess both low surface energy and a specific surface morphology (micro-nano roughness), resulting in surfaces that are significantly less wettable with water contact angles (CA) greater than 150° and hysteresis lower than 5°. Protection and reducing friction in marine environments and underwater applications are crucial because interactions with water are typically best avoided. Underwater robots can effectively take advantage of these highly water-repellent coatings. The goal of incorporating smart materials in research is to enhance various characteristics, focusing on the longevity of the surface exposed to the surroundings and the effectiveness of movement. Mixed organic-inorganic materials have been created to have self-cleaning properties, and their durability against aging was studied based on the characteristics of the coating. Surface analysis and field-based investigations were carried out to evaluate how effectively metals are protected from fouling and deterioration in underwater environments.

Keywords: Superhydrophobicity, wettability, fouling, corrosion.