Article
Materials Science, Multidisciplinary
Zhuorui Lu, Natalia Vakula, Michele Ude, Martiane Cabie, Thomas Neisius, Francois Orange, Franck Pigeonneau, Laeticia Petit, Wilfried Blanc
Summary: For the first time, MCVD germanosilica glass embedded with YbPO4 crystals were drawn into optical fibers. The YbPO4 crystals were successfully embedded in the silica soot using solution doping prior to the collapsing step. Through analysis with scanning/transmission electron microscopes and confocal Raman microscope, it was demonstrated that the YbPO4 crystals survived both the MCVD process and the drawing process, despite the high temperature (up to 2100 degrees C) involved. The fiber contained 100 nm-crystals with the same composition and structure as the as-prepared crystals, and during the drawing process, these crystals showed a preferential orientation along the c-axis.
Article
Chemistry, Physical
Lianping Chen, Yuanhong Gao, Yibin Chen, Jun Cao
Summary: The influence of europium on the structure and luminescent properties of CaWO4 thin films was investigated, and the sputtering yields of different compounds were studied. The results showed that the compositions of the deposits matched those of the targets, and the lattice constants increased under certain conditions. The preferential growth along a specific crystal plane also increased due to the substitution of Ca2+ with Eu2+. Doping of Eu led to improved photoluminescence performance of the films.
JOURNAL OF ALLOYS AND COMPOUNDS
(2022)
Article
Materials Science, Multidisciplinary
Christian Saringer, Michael Tkadletz, Josef Thurner, Christoph Czettl, Nina Schalk
Summary: Using thermally activated chemical vapor deposition (CVD), Ti1-xAlxN coatings with Al contents up to x > 0.8 can be synthesized due to their high global Al content and self organized nanolamellar microstructure. However, the formation mechanism of the microstructure and the resulting coating properties are not fully understood. The study investigates the effects of deposition temperature, pressure, and gas feed rotation speed on the microstructure and mechanical properties.
INTERNATIONAL JOURNAL OF REFRACTORY METALS & HARD MATERIALS
(2023)
Article
Materials Science, Multidisciplinary
Bhaskar Bhaduri
Summary: In this study, copper nanoparticles grown carbon nanofibers (Cu-CNFs) were synthesized on graphite powder using catalytic chemical vapor deposition (CVD) method with acetylene as the carbon source. The CNFs were heat treated under inert atmosphere, and the analysis showed that the synthesis followed tip growth mechanism, with the material being of high purity confirmed by EDS and XPS analysis.
Article
Chemistry, Physical
C. Calvo-Mola, V Torres-Costa, Y. Gonzalez, A. Ruediger, M. Sanchez, G. Santana, G. Contreras-Puente, C. de Melo, J. Ghanbaja, D. Horwat, O. de Melo
Summary: In this study, a novel system for hot wall evaporation of MoO3 was developed and characterized in a horizontal furnace under low vacuum atmosphere. Pure MoO3 material with a strong preferential orientation was obtained, and its properties were analyzed using electron microscopy, micro-Raman spectroscopy, and x-ray diffraction. The relationship between photoluminescence and Raman spectra with temperature was investigated. The temperature coefficients of the vibrational modes were reported and compared, and their relation with the thermal expansion coefficient was discussed. Additionally, the temperature dependence of photoluminescent contributions for MoO3 was studied, revealing an anomalous increase in intensity followed by normal quenching at high temperatures. The Shibata model was used to explain this anomalous effect.
JOURNAL OF ALLOYS AND COMPOUNDS
(2022)
Article
Chemistry, Multidisciplinary
Debaditya Chatterjee, Shuoyuan Huang, Kaichen Gu, Jianzhu Ju, Junguang Yu, Harald Bock, Lian Yu, M. D. Ediger, Paul M. Voyles
Summary: Physical vapor deposition is used to create stable organic glass systems with nanoscale orientational and translational ordering of molecules. Using low-dose 4D STEM and a 2 nm probe, we have mapped columnar order in glassy samples of a discotic mesogen. Both vapor-deposited and liquid-cooled glassy films show similar domains of orientation, with size variations depending on processing. These results demonstrate the potential of low-dose 4D STEM for characterizing mesoscale structures in molecular glass systems relevant to organic electronics.
Article
Chemistry, Physical
M. R. Butaev, V. I. Kozlovsky, V. P. Martovitsky, Y. K. Skasyrsky, D. E. Sviridov
Summary: An investigation was conducted on the growth of CdS/ZnSe multi quantum well (MQW) heterostructures by metalorganic vapor-phase epitaxy (MOVPE), revealing changes in QW design during growth and observing a blueshift in emission line. Simulation of experimental X-ray diffraction curves showed changes in the average composition of QWs and the formation of type II band offsets.
JOURNAL OF ALLOYS AND COMPOUNDS
(2021)
Article
Chemistry, Multidisciplinary
Hao-Chin Huang, Kai-Yuan Hsiao, Yu-Han Tseng, Yan-De Chen, Ming-Yen Lu
Summary: In this study, an in situ transmission electron microscopy (TEM) heating system was used to investigate the morphological changes of cubic Ag nanoparticles (NPs) and Ag-based core-shell structures induced by sublimation, as well as the influence of shell coverage on thermal stability. It was found that large Ag NPs (>50 nm) showed a three-stage sublimation-induced morphological change, while small Ag NPs (<30 nm) showed a uniform sublimation. The sublimation process of core-shell NPs started at stage II, and the thermal stability was enhanced by carbon shell passivation.
Article
Materials Science, Multidisciplinary
Aagam Shah, Joshua A. Schiller, Isiah Ramos, James Serrano, Darren K. Adams, Sameh Tawfick, Elif Ertekin
Summary: In this work, we demonstrate a neural network that automatically distinguishes between pixels in SEM images corresponding to regions with and without graphene. The trained model shows an accuracy of over 90% and an F1 score over 80%. The network also exhibits reasonable performance when applied to other 2D materials, suggesting the potential for transfer learning.
MATERIALS TODAY COMMUNICATIONS
(2023)
Article
Materials Science, Multidisciplinary
Jia Lin, Hua Jin, Xiaohong Ge, Yihang Yang, Guimei Huang, Jinhuo Wang, Fenqiang Li, Hui Li, Shuai Wang
Summary: The study investigated the effects of synthesis temperature, time, and catalyst amount on the quality and quantity of grown CNTs. The optimal conditions for obtaining uniform size CNTs with high graphitization degree on ZrB2 were determined.
DIAMOND AND RELATED MATERIALS
(2021)
Article
Crystallography
Philip Chan, Caroline E. Reilly, Stacia Keller, Steven P. DenBaars, Shuji Nakamura
Summary: Semipolar InN quantum dash growth on GaN by metalorganic chemical vapor deposition was studied regarding growth time and temperature. Room temperature photoluminescence was observed with peak emission wavelengths ranging from 1350 to 1500 nm. The emission intensity and wavelength were found to be sensitive to the growth temperature and time of the GaN capping layer.
JOURNAL OF CRYSTAL GROWTH
(2021)
Article
Chemistry, Multidisciplinary
Yao Chen, Bingchu Mei, Huiling Liu, Zaichun Sun, Huijuan Zhang
Summary: A novel deposition technique was developed to synthesize highly crystalline and controllable morphological Bi2S3 thin films. The films showed continuous surface and superior photoelectrochemical performance at a moderate synthesis temperature.
CRYSTAL GROWTH & DESIGN
(2022)
Article
Chemistry, Multidisciplinary
Steven Rhodes, Warner Cribb, Valentin Taufour, Dwight Patterson, Dereje Seifu, Saeed Kamali, Suman Neupane
Summary: Alumina is an essential ceramic insulator, while carbon nanotubes (CNTs) have intriguing mechanical, thermal, electrical, and magnetic properties. We report the successful synthesis of CNTs/Al2O3 nanocomposites using the CVD process with iron as a catalyst. Experimental results show that the composites contain CNTs with an average diameter of 40 nm distributed homogenously within the alumina matrix, resulting in a dramatic enhancement of ferromagnetic properties.
JOURNAL OF PHYSICS AND CHEMISTRY OF SOLIDS
(2022)
Article
Materials Science, Ceramics
H. Plaisantin, J. Danet, I. Berdoyes, G. Laduye, A. Desenfant, G. Chollon
Summary: Chemical vapor deposited SiC coatings were examined using X-ray diffraction, Raman microspectroscopy, and transmission electron microscopy. Different (micro)structures were observed based on specific preparation conditions, showing varying levels of disorder. The coatings exhibited a columnar morphology with a preferred orientation and a faulted cubic structure.
JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
(2023)
Article
Nanoscience & Nanotechnology
John Lasseter, Philip D. Rack, Steven J. Randolph
Summary: In this study, a method for selectively depositing 3D nanostructures using photothermal transport is reported. The ability to initiate the process on sub-diffraction-limit nanoscale features is demonstrated. Thermal simulations show that the geometric shape and optical and thermal properties of the nanostructures are crucial for controlling the CVD reaction.
ACS APPLIED NANO MATERIALS
(2022)
Article
Materials Science, Ceramics
Jong-Chan Lim, Changhyun Jin, Myung Sik Choi, Min Young Kim, Sang-il Kim, Soon-Mok Choi, Seung-Hyub Baek, Kyu Hyoung Lee, Hyun-Sik Kim
Summary: The research found that the response of Co-doped three-dimensional flower-like tungsten oxide nanoplates to ethanol gas sensing changes gradually according to the process temperature and Co doping concentration, influenced by a variety of complex factors. Therefore, in the field of ethanol gas sensing, analyzing various factors and predicting the results may be more important.
CERAMICS INTERNATIONAL
(2021)
Article
Chemistry, Analytical
Myung Sik Choi, Ali Mirzaei, Han Gil Na, Sangwoo Kim, Dong Eung Kim, Kyu Hyoung Lee, Changhyun Jin, Sun-Woo Choi
Summary: This study proposed a method to enhance the gas sensing properties of metal oxide nanowires by preparing Pd metal catalyst surrounded by SnO2-x with structural defects on the surface of SnO2 nanowires. Gas sensing studies demonstrated the promising effects of this approach, showing the usefulness of significantly enhancing the gas sensing properties.
SENSORS AND ACTUATORS B-CHEMICAL
(2021)
Article
Chemistry, Physical
Myung Sik Choi, Jihye Ahn, Min Young Kim, Ali Mirzaei, Soon-Mok Choi, Dong Won Chun, Changhyun Jin, Kyu Hyoung Lee
Summary: The crystal structural change of Al-doped SnO2 nanoparticles affects the gas response of the sensor significantly. By optimizing the bonding characteristics and surface area, the sensor shows a greatly improved response to H2S gas. This technique has the potential for application in other semiconducting metal oxides.
APPLIED SURFACE SCIENCE
(2021)
Article
Chemistry, Physical
Myung Sik Choi, Min Young Kim, Ali Mirzaei, Hyun-Sik Kim, Sang-il Kim, Seung-Hyub Baek, Dong Won Chun, Changhyun Jin, Kyu Hyoung Lee
Summary: Porous ZnO nanosheets were synthesized using a solvothermal method for high sensitivity detection of NO2 gas, showing high selectivity and stability. Enhanced response was attributed to the synergetic effects of high surface area, ZnO/ZnO homojunctions, and structural defects.
APPLIED SURFACE SCIENCE
(2021)
Article
Nanoscience & Nanotechnology
Yu-Hyung Lee, Suyoung Park, Changhyun Jin
Summary: The study proposed testing of household ozone sterilizer and ORP, revealing bubbles in tap water after passing through nine meshes. It was observed that smaller matter size from bulk to nano-scale results in rapid energy increase, leading to changes in water group system size and energy. As the scale and number of meshes increased, ozone, chlorine, and oxygen constituents were generated, altering the basic water composition and potentially revolutionizing future applications in fluids.
Article
Chemistry, Analytical
Changhyun Jin, Myung Sik Choi, Kyu Hyoung Lee, Sun-Woo Choi
Summary: Gas sensors based on p-type NiO/n-type ZnO composite nanofibers were fabricated in this work, showing selective detection of oxidizing and reducing gas molecules. By adjusting the composition ratio of NiO/ZnO, the composite nanofibers demonstrated different sensing performances for oxidizing and reducing gases, with 0.5NiO-0.5ZnO NFs exhibiting strong response to oxidizing gases and 0.8NiO-0.2ZnO NFs showing good selectivity for reducing gases.
SENSORS AND ACTUATORS B-CHEMICAL
(2021)
Article
Materials Science, Ceramics
Changhyun Jin, Jong-Chan Lim, Min Young Kim, Myung Sik Choi, Sang-Il Kim, Seung-Hyub Baek, Sun-Jae Kim, Seung Yong Lee, Hyun-Sik Kim, Kyu Hyoung Lee
Summary: WO3 nanostructures with different morphologies and dimensions were fabricated via solvothermal synthesis. By adjusting the stirring time of the precursor solution, the growth behavior of the nanostructures was significantly changed, resulting in the production of nanostructures with tunable surface reactivity and varying NO2 sensing performances.
JOURNAL OF ASIAN CERAMIC SOCIETIES
(2022)
Article
Chemistry, Applied
Min Young Kim, Jeong Yun Hwang, Ali Mirzaei, Sun-Woo Choi, Sang-il Kim, Hyun-Sik Kim, Sun-Jae Kim, Jong Wook Roh, Myung Sik Choi, Kyu Hyoung Lee, Seung Yong Lee, Changhyun Jin
Summary: In this study, a simple and scalable synthesis route was developed to prepare Ag-functionalized porous ZnO sheets, which exhibited enhanced NO2 gas sensing properties. The porous ZnO sheets were functionalized with well-dispersed submicron Ag particles using a hydrothermal method-based one-pot synthesis route. The gas sensor fabricated with 3 at% Ag-functionalized porous ZnO sheets showed optimized NO2 gas sensing performance at 200 degrees C, with a high response of 17.18 to 10 ppm NO2 gas and a response of 14.05 even at 60% relative humidity, attributed to the synergistic effect of improved NO2 gas adsorption and increased resistance at Ag-ZnO heterojunctions.
ADSORPTION SCIENCE & TECHNOLOGY
(2023)
Article
Engineering, Multidisciplinary
Myung Sik Choi, Han Gil Na, Sun-Woo Choi, Kyu Hyoung Lee, Changhyun Jin
Summary: SnO2 and Au were deposited using flame chemical vapor deposition (FCVD) to form a double layer. A compound of Sn and O with multiple band gaps was formed in a short time, with Sn moving to the Au side and leaving O behind. Sn's capillarity allowed it to form a unique structure with Au-Sn-O nanoparticles and amorphous Sn-O nanotubes.
ALEXANDRIA ENGINEERING JOURNAL
(2023)
Article
Materials Science, Multidisciplinary
Changhyun Jin
Summary: A mass formation hypothesis is proposed based on the behaviour of electromagnetic waves, which exhibit both particle and wave properties. This model unifies MKS-based units (meter, kilogram, second) and A-based units (Ampere) into one. The hypothesis suggests that when mass is expressed as 'm kg', considering the range of 'm', classical mechanics and quantum mechanics can be perfectly matched. This concept is supported by a comparison with Maxwell's and Planck's dimensional analyses.
MRS COMMUNICATIONS
(2023)
Article
Nanoscience & Nanotechnology
Jeong Yun Hwang, Yerin Lee, Gyu Ho Lee, Seung Yong Lee, Hyun-Sik Kim, Sang-il Kim, Hee Jung Park, Sun-Jae Kim, Beom Zoo Lee, Myung Sik Choi, Changhyun Jin, Kyu Hyoung Lee
Summary: A high-performance ammonia gas sensor operating at room temperature was fabricated by decorating Au nanoparticles onto TiO2 nanosheets. The sensor exhibited temperature- and concentration-dependent properties, and achieved a high response under low concentration NH3 gas.
Article
Materials Science, Multidisciplinary
Changhyun Jin
Summary: All matter exists in space with different density, and its energy must be balanced between the interior and exterior. An atom is the result of stored energy and material split, which corresponds to the maximum spatial energy and minimum mass energy. This relation is demonstrated through thermodynamic examples.
MRS COMMUNICATIONS
(2023)
Article
Nanoscience & Nanotechnology
Changhyun Jin
Summary: This study proposes a new classification of energy, suggesting that it can be broadly classified into mass-based and non-mass-based categories. It also recommends revising the definition of total energy based on the product of temperature and entropy. The findings validate the concept of energy in space and indicate that the current concept of temperature corresponds to spatial density.
SCIENCE OF ADVANCED MATERIALS
(2022)
Article
Engineering, Electrical & Electronic
Han Gil Na, Changhyun Jin
Summary: Mass-energy equivalence states that energy and mass can be converted into each other. However, the underlying motives of each constituent are still not fully understood, as the current definitions and analyses of mass-energy equivalence are mostly restricted to the phenomenological theory of results. Our research defines a series of relationships between energy maximum, energy quantity, and energy level in E = mc(2) based on invariant space energy using physical units such as electron, mass, and velocity.
JOURNAL OF NANOELECTRONICS AND OPTOELECTRONICS
(2022)
Article
Nanoscience & Nanotechnology
Suyoung Park, Sangwoo Kim, Han Gil Na, Changhyun Jin
Summary: The study reported the improvement of mechanical properties by physicochemical changes of Ni coating layer after irradiation of high energy beam (HEB). The irradiation method resulted in a change in the energy amplitude of the dipole formed in the material, leading to oxidation of the Ni coating layer to NiO and improvement of mechanical properties.Experimental and theoretical predictions were performed simultaneously to understand the diffusion effect of the irradiation.
SCIENCE OF ADVANCED MATERIALS
(2021)