15^th Annual Congress on Materials Research and Technology February 19-20, 2018 Paris, France

Rawdha Dekhili is currently pursuing his PhD in Chemistry at Universite de Lorraine, France and is affiliated to Centrale Supelec, France, Universite de Tunis El Manar, Tunisia and Universite de Tunis, Tunisia

Many studies are devoted to the family of compounds of formula MX2RO4 (M=K, Rb, NH4, Cs, Tl, X=H, D, R=P, As). Among these compounds, KDP is the most known material owing to many physical and chemical properties used for applications in non-linear optics, ferro-electricity piezoelectricity and electro-optics. Here our interest concerns new materials of this family: LiH2PO4 (LDP) and KLi(H2PO4)2 (KLDP). A few data were only reported on these materials. We more deeply investigate their structural, vibrational and optical properties. The KLDP and LDP compounds were synthetized by slow evaporation method and their crystal structure was determined at room temperature by X-ray diffraction. KLDP crystal belongs to the P21/c (C2h) space group of the monoclinic system whereas LDP crystal has the orthorhombic structure with the space group Pna21-C29v. The structures constitute on PO4 and LiO4 tetrahedra interconnected by oxygen atoms, to form a tridimensional network. Furthermore, the hydrogen bonds types consolidate the structure. The vibrational properties of LDP and KLDP crystals have been investigated at room temperature by means of Raman spectroscopy. The analysis of spectra revealed tetrahedrons PO4 and LiO4 vibration internal modes, stretching and bending OH modes. The results were confirmed by the DFT calculations. Raman measurements as a function of temperature and differential scanning calorimetry evidenced phase transition temperatures.

Fumio Narita is currently a Professor in the Department of Materials Processing at Tohoku University in Japan. From 1998 until 1999 he has worked as an Engineer at Tokin Corporation. He is engaged in research to design and develop piezoelectric/magnetostrictive materials and structures for energy harvesting for the IoT, wearable devices and smart sensors. He is making extensive use of state-of-the-art electro-magneto-mechanical characterization techniques in combination with computational multi-scale modeling to gain insights into fundamental structure-property relationships of complex multifunctional composite materials.

This paper presents the numerical and experimental study on the energy harvesting characteristics of piezoelectric laminated composite consisting of barium titanate (BaTiO3) and copper (Cu) due to temperature changes. First, the output voltages of the piezoelectric BaTiO3/Cu laminated composite were evaluated from room temperature to a liquid nitrogen temperature (77 K). The output power was also obtained for various values of load resistance. The output voltages of the BaTiO3/Cu laminated composite were then measured from room temperature to a higher temperature (333 K). Next, linking phase field and finite element simulations were performed to discuss the output voltages of the BaTiO3/Cu laminated composite due to temperature changes. A phase field model for grain growth was employing to generate grain structures and the phase field model was employed for BaTiO3 polycrystals, coupled with the time-dependent Ginzburg-Landau theory and the oxygen vacancies diffusion, to calculate the temperature-dependent piezoelectric coefficient and permittivity. The output voltages of the BaTiO3/Cu laminated composite from room temperature to both 77 K and 333 K were predicted by three-dimensional finite element methods, using these properties and the results are presented for several grain sizes and oxygen vacancy densities. The effects of grain sizes and oxygen vacancy densities on the relationship between the output voltage and the thermally induced bending stress were examined in detail.

Pinar Sengun is currently pursuing MSc in Materials Science and Engineering at Anadolu University. She has expertise on the synthesis of inorganic powders by using different solution-based synthesis methods. She is working on syntheses of un-doped and/or doped zinc oxide (ZnO) powders with tailored morphologies and investigation of the effect of the dopant elements on electrical and optical properties of zinc oxide materials

Nowadays, the development of technology and economy, electricity might cause some economical and vital risks via formation of static charges and electrostatic discharge (ESD) events. ESD events can cause firing, explosions, arc formation, breakdown of electronic circuits and devices. Moreover, electrical shocks, which may even end human lives. Therefore, should prevent these events. Antistatic products are currently used as an effective method for preventing ESD events. To avoid ESD events static charges should be grounded slowly. Through moderate resistivity of antistatic materials (104<ρ<1011 ohm), they provide slow decay of the static charges. A recent promising approach is using conductive polymer composites (CPCs) which consist of polymer matrices and conductive filler materials. Generally, carbon based materials and metal nanoparticles used as conductive filler in CPCs. In addition, conductive oxides (COs) are utilized for electronic applications such as solar cells, optical coatings, sensors, photovoltaic cells. Furthermore, one of the other application areas for these materials is antistatic coatings. Zinc oxide (ZnO) is one example of the conductive oxides and it can be used for this purpose due to its wide direct band gap energy (3.37 eV). Pure ZnO has relatively high electrical resistivity (≈104 ohm). Doping is one of the widely applied methods to enhance the electrical conductivity of ZnO. To date Al doped ZnO (AZO) nanoparticles have been used in CPCs as conductive fillers, because of its low electrical resistivity. Although nanoparticles can be considered as good fillers, unfortunately, they exhibit uncontrolled agglomeration problems due to their high surface energy. Since increasing conductive filler can result in filler aggregation and decreasing antistatic performance. Accordingly, we developed micron sized platelets of Al-doped ZnO particles (called MicNo®-AZO) which are composed of 30-40 nm primary particles. In this presentation, we will discuss electrical, optical and antistatic performance of MicNo®-AZO particles.

Inga Ermanova is a master-student who combined studies in National University of Science and Technology (NUST MISIS) in the Electronics and Nanoelectronics direction with working in Laboratory of Energy Efficiency. Her scientific employment is devoted to research optoelectrical characteristics and morphology of organometal halide perovskite solar cells.

Perovskite solar cell with semitransparent top electrode composed of layers of SWCNT+MWCNT (single-wall carbon nanotubes and multi-wall carbon nanotubes) soaked with transport layer (PCBM or Spiro-MeOTAD) is found to be more stable than the standard aluminum (Al) or gold (Au) electrodes. The improved performance was observed both for a cathode, made by the combination of both types of CNTs and through the PC61BM added, attributed to the enhanced contact between CNTs and the perovskite solar cell films. Similarly the anode, (made of MWCNT soaked by spiro-MeOTAD) shows good performance, as compared to traditional Au anode. An improvement in the stability under illumination was studied for both cathode and anode with the semitransparent CNT/transport layer composite electrode and improved stability is related with the chemically inactive nature of carbon material, which is non-reactive with iodine of the MAPbI3 perovskite. Carbon nanotubes (CNT) both single-wall (SWCNT) and multi-wall (MWCNT) have been used in the past as transparent flexible electrodes in OPV and in organic light-emitting diodes (OLEDs) as substitute for brittle indium tin oxide (ITO). We have shown that dry drawn CNT sheets can be easily obtained in free standing films state and can be laminated either on glass as usual as anodes of OPV and OLED or if laminated on top, as cathodes collecting electrons. For cathodes in OPV, the CNT should be properly doped in order to lower the work function or raise the Fermi level. Recently, fast progress of hybrid perovskite solar cells in planar configuration is available. Although several approaches to solve task of top transparent electrode have been reported by using graphene or these carbon nanosheets, the top laminated perovskite solar cells with a CNT cathode has not been demonstrated. In present paper we show that using a combination of SWCNT and MWCNT both laminated on top of the ETL (electron transport layer) of the perovskite solar cells can solve a problem of top cathode and can be used instead of Al or Ag in perovskite.

Chunyan Song is a Lecturer of College of Metallurgy and Energy, North China University of Science and Technology. She has been working in the fields of special metallurgy and novel materials preparation. Her research on nitriding of alloys with crystal and amorphous phase provides new technologies for improving nitrogen absorption of Fe-based alloys. She has 16 invention patents and research publications in materials and metallurgy engineering journals. She is currently the major investigator of National Natural Science Foundation of China (51574104) and Natural Science Foundation-Steel and Iron Foundation of Hebei Province (E2014209213).

Rapid solidification technology is used widely to fabricate micro-crystalline and amorphous alloys. In traditional nitriding process of coarse-grained Sm-Fe alloys, it is hard to further increase the nitrogen content and improve the uniform of nitrogen distribution. Therefore, the nitriding behaviors and microstructure evolution of rapidly-solidified Sm-Fe alloy ribbons fabricated in a rotating-quenching furnace were investigated in this work. Results indicate that with the rotating velocity of wheel increases, the cooling rate increases, the thickness of Sm-Fe alloy ribbon decreases and microstructural characteristics transform from coarse dendrites to cellular crystal, microcrystal, mixture of crystal and amorphous phase. Moreover, Sm and Fe elements in alloy ribbons tends to uniform compare with the as-cast alloys according to the laser ablation inductively coupled plasma mass spectrometry map. The size of all grains is still less than 10 μm although the crystalline grains grew during nitriding process of rapidly solidified Sm-Fe alloy at 420 °C. The smaller grain size and more grain boundaries in Sm-Fe alloy ribbons provide more locations for atomic nitrogen absorption in the nitriding process and improve the diffusion of nitrogen atoms. However, most penetrated nitrogen in Sm-Fe alloys are distributed on the boundaries of cellular grains in the forms of nitrogenous compounds. A quickly quenched Sm-Fe alloy ribbon with a stable near-stoichiometric Sm2Fe17 phase and amorphous matrix in microstructure was fabricated successfully when the rotating velocity of wheel was greater than 34 m/s. After nitridation of quickly quenched Sm-Fe alloy ribbons, the constitutional phases are crystalline Sm2Fe17Nx and α-Fe and amorphous nitrides. This phenomenon indicates that nitrogen atoms are distributed not only in crystalline phase but also in amorphous matrix. The nitrogen content in Sm-Fe alloy ribbons is up to 4.155%, which indicated the microstructure characteristics of quickly quenched Sm-Fe alloy is helpful for the improvement of nitrogen absorption.

Kyoung Duck Seo is currently an Assistant Professor in the Department of Mechanical Engineering at Wonkwang University, Jeonbuk, South Korea. He has received his BS, MS and PhD degrees (Mechanical Engineering) from POSTECH, Pohang, South Korea, in 2008, 2010 and 2016, respectively.

Complex-shaped micro-particles (MPs) with multi-compartments have been attempted to be produced for utilizing MPs in cell/drug delivery, multiplexing assays, actuators, as self-assembly building blocks, as well as photonic devices. Several methods have been suggested to synthesize the microparticles such as emulsification, micromolding, photolithography and microfluidics. Among these methods, microfluidic devices have been introduced to synthesized MPs having distinct characteristics, such as well-tailored sizes with narrow distribution and various morphologies. Although the microfluidic devices successfully increased the shape complexity of the MPs, they still required the integration of intricate microfluidic devices. Hence, in this work, several phase separation approaches including phase separation of: (1) Highly concentrated N-isopropylacrylamide, (2) Poly (ethylene glycol) diacrylate (PEGDA)-coacervate and 3) high molecular weight (PEGDA)-low molecular weight(PEGDA) are introduced for simplicity in synthesizing complex-shaped MPs with no need for intricate microfluidic devices. In microfluidic device, phase separated two aqueous phase solutions are dispersed in continuous oil phase and create micro-droplets having complex morphology (Janus and core-shell) while compartmentalizing their internals. After formation of the micro-droplets, MPs were synthesized with help of a UV-light source. These present phase separation methods based on microfluidic device may lead us to a simple and helpful direction in synthesizing various functional MPs with tailored morphology; Janus and core-shell. The suggested functional MPs will have implications on both the fundamental research and broad applications such as biomedicine and biochemical.

Mi-Ra Shin has attendant Korea National University of Transportation and majored in rechargeable batteries and manufactures nanofibers of various compositions using electro-spinning. In addition, she has published more than two papers in a reupted journal.

Although the attainable specific energy density and cycle stability of LiFePO4 is only higher than that of LiCoO2, LiFePO4 has the low electronic and ionic conductivity. The common strategy to solve this problem was to downsize LiFePO4 and to coating the nano-crystal with conductive carbon film. This study was prepared nano-sized LiFePO4/C cathode material by electrospinning method and surface of manufactured cathode material was fabricated by a facile and cost-effective dip-coating method to improve the interfacial hydrophilic, electrical conductivity and electrochemical performance of electrode. Due to the PDA coating, it makes the nano-fiber surface hydrophilic and thus increases the electrolyte uptake and ionic conductivity, resulting in the enhanced performance of Li-ion batteries. PDA-LiFePO4 and uncoated cathode material were evaluated by contact angle test and uptake volume of liquid electrolyte, AFM, FE-SEM (field emission scanning electron microscope) and electrochemical measurements. The results improved electrochemical performance and hydrophilic property of PDA coated cathode material compared to bare cathode material.

Hajar Ghanbari has her expertise in carbonaceous and 2D materials, ceramic composites and laser-assisted synthesis of nanomaterials. She has proposed her explosion model on the laser-assisted synthesis of graphene in organic solvents in 2014. She has joined Iran University of Science and Technology, Faculty of Metallurgy and Materials Engineering, Ceramics Division since September 2016 and established a research group focusing on modern ceramics.

Aluminum Nitride (AlN) as a stoichiometric ceramic structure is best known for their thermal conductivities, insulation performance and high range optical transparency from UV to IR, low thermal expansion and thus thermal shock resistance. High mechanical properties alongside with their corrosion resistance up to 1200 ºC also nominate this material as one of the functional options in different engineering fields. One of the challenging issues in these industrial applications is the high cost of powder preparation and sintering process. For the improvement of physical, mechanical and oxidation behavior of final piece, the purification of grain boundaries, also cost reduction, the presence of different additional phases is proposed and examined. In this work, the relatively low-cost method of carbothermal nitridation is used for the in situ preparation of AlN/Al2O3 powder. Urea, aluminum nitrate nonahydrate and dextrose are used as the starting materials. One-pot reaction in less than 10 minutes, following by carbothermal nitridation in tube furnace is used for complete crystallization of as- prepared mixture. AlN crystals are formed after nitridation at 1400 ºC-1500 ºC. The phase percentage of Alpha and gamma will increase by decarburization temperature rising from 700 ºC to 1000 ºC. In fact, by the post-decarburization process, alumina phase percentage is selective. On the other side, by nitridation of the center core of combustion process, the gamma alumina is eliminated, and high temperature stable C3N4 phase was formed instead. Phase and morphology characterization of the mixed powders were investigated by TEM and SEM. Also, the wettability of the powder is studied as well. TG/DTA and FT-IR Spectroscopy are used for the mechanism studies of the synthesis process.