Article
Chemistry, Multidisciplinary
Jincheng Ji, Kun Wang, Simin Zhu, Weihua Zhu
Summary: The study shows that as the impurity concentration in the crystal increases, the stability decreases and impurity molecules tend to form aggregates, leading to a significant decrease in the band gap of the NTO crystal with increasing impurity content.
Article
Materials Science, Multidisciplinary
Nikoletta Laczai, Laszlo Kovacs, Laura Kocsor, Laszlo Bencs
Summary: The synthesis and characterization of polycrystalline cerium-doped Y2SiO5 and lutetium yttrium oxyorthosilicate scintillator materials were studied. The concentration of LiF flux and cerium content affect particle size and photoluminescence intensity of the host crystal, with increasing Ce content leading to a redshift in PL emission spectra.
MATERIALS RESEARCH BULLETIN
(2021)
Article
Chemistry, Multidisciplinary
Oleg Sidletskiy, Iaroslav Gerasymov, Yanina Boyaryntseva, Pavlo Arhipov, Serhii Tkachenko, Olga Zelenskaya, Kateryna Bryleva, Konstantin Belikov, Kheirreddine Lebbou, Christophe Dujardin, Bernd Buechner, Borys Grynyov
Summary: This study investigates the effect of carbon co-doping on Ce-doped garnets and found that tuning the cerium and carbon concentrations can enhance the light yield significantly, extending the application range of garnet-type materials.
CRYSTAL GROWTH & DESIGN
(2021)
Article
Chemistry, Physical
Yu Hizhnyi, V Borysyuk, V Chornii, S. Nedilko, P. O. Tesel'ko, O. Dubovik, P. Maksymchuk, I Tupitsyna, A. Yakubovskaya, M. Androulidaki, N. Klyui
Summary: Li2MoO4 crystals are considered as promising cryogenic scintillation materials for use in elementary particle physics experiments. This study presents experimental and computational investigations into the electronic structure and optical properties of the crystals, analyzing the spectral characteristics and the impact of defects on their scintillation properties.
JOURNAL OF ALLOYS AND COMPOUNDS
(2021)
Article
Chemistry, Physical
Rocio Ariza, Ana Urbieta, Javier Solis, Paloma Fernandez
Summary: ZnO nano- and microstructures doped with K were successfully grown by the Vapor-Solid method. The morphology of the structures varied, including wires, needles, ribbons, triangular plates, and ball-shaped structures. The different lattice positions occupied by K ions depending on its concentration in the structures result in variations in morphology, crystalline quality, and luminescence emissions. The elongated structures were found to have the potential to act as waveguides and optical resonators.
Article
Materials Science, Multidisciplinary
Shashi Pandey, Alok Shukla, Anurag Tripathi
Summary: Defect engineering plays a significant role in optoelectronic devices, enhancing their optoelectronic properties such as light absorption, electrical switching, and photocurrent.
COMPUTATIONAL MATERIALS SCIENCE
(2022)
Article
Chemistry, Physical
Radoslaw Lisiecki, Jaroslaw Komar, Boguslaw Macalik, Michal Glowacki, Marek Berkowski, Witold Ryba-Romanowski
Summary: Optical absorption and luminescence spectra of different crystal samples were studied at different temperatures, revealing higher relative thermal sensitivities for YAl3(BO3)(4):Dy3+ and Lu2SiO5:Dy(3+). Analysis of the crystal structure characteristics showed that the observed differences in thermosensitive features were not directly attributed to structural factors, but were related to the rates of radiative transitions of Dy3+.
Article
Chemistry, Multidisciplinary
Xiaodan Huang, Xiaojun Wei, Yan Zeng, Lihong Jing, Haoran Ning, Xiaodan Sun, Yingying Li, Di Li, Yuanping Yi, Mingyuan Gao
Summary: Spinel oxide nanocrystals are promising hosts for Cr3+ in the creation of persistent luminescent nanomaterials due to their suitable fundamental bandgaps. A wet-chemical synthetic route for preparing Cr3+-doped ZnAl2O4 nanoparticles with long NIR persistent luminescence is reported here, with methanol playing a critical role in tailoring the morphology of the resulting nanocrystals.
Article
Physics, Multidisciplinary
Ali Moghaddam, Dmitry Chernyavsky, Corentin Morice, Jasper van Wezel, Jeroen van den Brink
Summary: The study focuses on the spectral properties of one-dimensional lattices with position-dependent hopping amplitudes and smooth bounded on-site potentials. An exact integral form for the density of states (DOS) in the limit of an infinite number of sites is found using a mixed Bloch-Wannier basis. The research also provides an exact solution for constructing the position-dependence of hopping in a lattice model yielding a given DOS, with results confirmed through numerical comparisons. The DOS integral form is further generalized to multi-orbital tight-binding models with longer-range hoppings and higher dimensions.
Article
Materials Science, Multidisciplinary
Jianyong Guo, Wen Chen, Ziqing Ye, Li Liu, Junnian Chen, Yunbin He
Summary: Butylammonium lead chloride and butylammonium lead cadmium chloride thin films were prepared through a solution method, showing good crystallinity and white-light emission characteristics. The emission properties of the lead cadmium chloride films can be effectively regulated by varying Cd content, with optimal performance achieved at Cd content of 0.4. This work demonstrates the potential of these 2D perovskites for developing white-light emission devices.
Article
Chemistry, Multidisciplinary
Marcos F. Sousa, Bruno Ribeiro de Mesquita, Joeslei L. Oliveira, Ricardo D. S. Santos, Marcos V. dos S. Rezende
Summary: The effects of Eu incorporation in the RbBaPO4 structure were explored through atomistic simulation and crystal field models. The preferred intrinsic defect type was found to be the anti-site defect. It was observed that Eu3+ tends to enter the Ba site as charge compensation in the presence of RbBa' anti-sites. Crystal field theory revealed that substitution of Eu3+ for Ba2+ in the anti-site defect induces a local symmetry distortion of the slightly distorted C4 type. The 7F1 and 7F2 energy sublevels as well as the 7F1 manifold were successfully reproduced using phenomenological charge factors and non-null crystal field parameters.
JOURNAL OF PHYSICS AND CHEMISTRY OF SOLIDS
(2023)
Article
Materials Science, Multidisciplinary
Claudia M. S. Calado, Isis F. Manali, Isabela M. S. Diogenis, Sergio F. N. Coelho, Veronica C. Texeira, Bruno R. de Mesquita, Joeslei L. Oliveira, Fernando A. Sigoli, Marcos V. dos S. Rezende
Summary: Optical spectroscopy and defect disorder of Eu-doped NaYF4 and NaY(1-x)GdxF(4) structures were studied through computational and experimental methods. Atomistic modeling was used to predict intrinsic disorder and Eu doping sites, and calculate crystal field parameters. The experimental emission spectrum of Eu-doped structures was obtained, showing agreement with theoretical predictions of local symmetry.
Article
Materials Science, Multidisciplinary
Joeslei L. Oliveira, Marcos F. Sousa, Ricardo D. S. Santos, Andre M. Otsuka, Marcos A. Couto dos Santos, Marcos V. dos S. Rezende
Summary: Atomistic simulation was used to study the defect process caused by europium in the NaCdPO4 structure. The calculations showed that the most favorable intrinsic defect type is cation anti-site defect, and doping by Eu3+ on the Cd site is energetically favorable. Charge compensation by Na-Cd anti-site defect is also probable. Crystal field parameters were calculated to discuss the local symmetry of Eu3+.
Article
Materials Science, Multidisciplinary
S. Zazubovich, V Laguta, K. Kamada, A. Yoshikawa, K. Jurek, M. Nikl
Summary: The co-doping of Gd3(Ga,Al)5O12:Ce single crystals with W and Mo impurity ions significantly affects the photoluminescence and thermally stimulated luminescence characteristics, influencing various aspects such as spectra and intensity. The presence of W and Mo related electron traps in the crystals enhances the intrinsic emission contribution to the luminescence spectrum.
Article
Optics
S. Zazubovich, V. V. Laguta, P. Machek, K. Karnada, A. Yoshikawa, M. Nikl
Summary: Characteristics of photo- and thermally stimulated luminescence, as well as defect creation processes, were investigated in the Li+ co-doped single crystal of GAGG:Ce in the temperature range of 85-510K. Results compared with other single crystals of similar composition revealed the influence of Li+ and Mg2+ ions on various luminescence characteristics, including the conversion of Ce3+ to Ce4+ and the formation of intrinsic lattice defects in GAGG:Ce,Li crystals. Discussed were the origin of these defects and trapping centers in the crystal.
JOURNAL OF LUMINESCENCE
(2022)
Article
Physics, Condensed Matter
A. Schulman, H. Palonen, V Lahteenlahti, A. Beiranvand, H. Huhtinen, P. Paturi
Summary: The study investigates the relationship between the properties of Gd0.1Ca0.9MnO3 thin films and their thickness, revealing a sudden change in electrical transport properties and an insulator-to-metal transition when film thickness exceeds 80 nanometers. This transition coincides with the appearance of a ferromagnetic phase in thicker samples.
JOURNAL OF PHYSICS-CONDENSED MATTER
(2021)
Article
Physics, Applied
I Nevinskas, R. Norkus, A. Geizutis, L. Kulyuk, A. Miku, K. Sushkevich, A. Krotkus
Summary: Research found that transition metal dichalcogenides of different dopant type emit THz pulses of opposite polarity, indicating the role of surface field in THz emission. Contradictions exist between optical pump-THz probe experiments and THz emission observations, with a decrease in photoconductivity at higher energy quanta. The proposed THz pulse generation mechanism assumes the accumulation of excitonic electric dipoles during optical pulse absorption and a rapid build-up of the internal electric field.
JOURNAL OF PHYSICS D-APPLIED PHYSICS
(2021)
Article
Physics, Condensed Matter
K. Sushkevich, E. Goncearenco, N. Nedeoglo, D. Nedeoglo
Summary: A study on ZnSe samples doped with Sb and I revealed the presence of a specific PL band, suggesting the involvement of the (Sb-Se-I-Se) radiative center.
PHYSICA B-CONDENSED MATTER
(2021)
Article
Physics, Condensed Matter
E. Rivasto, H. Huhtinen, T. Hynninen, P. Paturi
Summary: We introduce a molecular dynamics based simulation model that enables efficient optimization of complex pinning structures in a wide range of magnetic field and angular conditions. The model allows modeling of critical current and anisotropy in the presence of various defects, such as nanorods and stacking faults. By comparing the results with previous experimental and computational observations, the validation of the proposed simulation model is provided, making it a valuable tool for pushing the limits of ampacity in the coated conductor industry.
JOURNAL OF PHYSICS-CONDENSED MATTER
(2022)
Article
Physics, Applied
Moe Moe Aye, Elmeri Rivasto, Hannes Rijckaert, Heikki Palonen, Hannu Huhtinen, Isabel Van Driessche, Petriina Paturi
Summary: Experimental study on the effect of BaZrO3 (BZO) nanorod density within the YBa2Cu3O6+x (YBCO) lattice reveals that the maximum flux pinning can be achieved by controlling the BZO content. The best pinning performance is observed at a BZO concentration of 10%, where the distance between nanorod edges is approximately equal to the nanorod diameter.
SUPERCONDUCTOR SCIENCE & TECHNOLOGY
(2022)
Article
Physics, Applied
P. Paturi, H. Huhtinen
Summary: We present a method to achieve the maximum critical current density, J(c), for YBa2Cu3O6+x (YBCO) thin films. By optimizing both the mean free path and the flux pinning structure, the maximum values can be reached.
SUPERCONDUCTOR SCIENCE & TECHNOLOGY
(2022)
Article
Physics, Applied
H. Rijckaert, M. Malmivirta, S. Banerjee, S. J. L. Billinge, H. Huhtinen, P. Paturi, K. De Buysser, I Van Driessche
Summary: Two different types of HfO2 nanocrystals were studied to investigate their effect on the structural defects in the YBCO matrix. The results showed that the crystallinity, lattice parameters, nanocrystal structures, and core diameter of the nanocrystals played a significant role in the formation of structural defects around the particles in the YBCO matrix, leading to different pinning performances.
SUPERCONDUCTOR SCIENCE & TECHNOLOGY
(2022)
Article
Physics, Condensed Matter
E. Rivasto, T. Hynninen, H. Huhtinen, P. Paturi
Summary: We propose that the current carrying properties of high-temperature superconducting thin films can be enhanced by introducing multilayer structures that balance zero field critical current and vortex pinning performance. In this study, we investigate a simple bilayer structure composed of pure YBCO and BZO doped YBCO under a mid-field range magnetic field. Our computational model reveals that the optimized bilayer structure can have up to 50% higher current carrying capability compared to single layer films. The results provide a foundation for future experimental realization of the proposed bilayer structures and further study of vortex interactions.
JOURNAL OF PHYSICS-CONDENSED MATTER
(2023)
Article
Materials Science, Multidisciplinary
Naman A. Naushahi, I. Angervo, M. Saloaro, A. Schulman, H. Huhtinen, P. Paturi
Summary: The effect of deposition distance on SFMO thin films was investigated, and it was found that optimal properties can be achieved at longer deposition distances than previously expected. The films deposited at longer distances showed increased metallicity and magnetoresistive response, with an onset Curie temperature of about 400 K and a middle transition value of 372 K.
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS
(2022)
Article
Education & Educational Research
Teemu Hynninen, Henna Pesonen, Olli Lintu, Petriina Paturi
Summary: We examine the changes in attitudes towards physics among Finnish first-year physics majors as a result of mandatory remote learning during the coronavirus pandemic. Our findings suggest that the extended period of remote learning had a negative impact on students' expertlike thinking, and those who experienced remote learning in high school also displayed a lower level of expertlike thinking upon entering university. However, moderate positive gains were observed as contact teaching resumed, although it did not fully bridge the gap in student attitudes caused by the pandemic.
PHYSICAL REVIEW PHYSICS EDUCATION RESEARCH
(2023)
Article
Physics, Condensed Matter
A. Tuomola, E. Rivasto, M. M. Aye, Y. Zhao, H. Huhtinen, P. Paturi
Summary: The effect of multilayering YBCO thin films with sequentially deposited CeO2 layers on self-field critical current density J(c)(0) is investigated. The improvement in J(c)(0) depends on YBCO layer thickness and temperature, with a potential increase of 50% at high temperature compared to single layer films. A critical thickness for YBCO layer is determined based on experimental results and theoretical analysis of the growth mechanism, where the maximum self-field J(c)(0) is strongly influenced by the competing issues of strain relaxation and defect formation during film growth. These findings can be applied in future coated conductor technology to maximize overall in-field J(c)(B).
JOURNAL OF PHYSICS-CONDENSED MATTER
(2023)
Article
Physics, Multidisciplinary
Elmeri Rivasto, Milica Todorovic, Hannu Huhtinen, Petriina Paturi
Summary: This study investigates the possibility of using artificial intelligence (AI) models to optimize high-temperature superconducting (HTS) multilayer structures for specific field and temperature ranges. A new vortex dynamics simulation method is proposed to improve the efficiency of training data sampling required for AI models. The performance of different AI models, including kernel ridge regression (KRR), gradient-boosted decision tree (GBDT), and neural network, is compared, and the GBDT model is found to be the best fitted for the problem. The use of GBDT in finding optimal multilayer structures at 10K temperature under 1T field is demonstrated, and the results align well with previous studies, further validating the use of AI in this problem. The AI models are considered highly efficient tools for optimizing HTS multilayer structures and are suggested as the primary method for pushing the limits of HTS films for specific applications.
NEW JOURNAL OF PHYSICS
(2023)
Article
Physics, Condensed Matter
K. Sushkevich, N. Siminel, V. Sirkeli, N. Nedeoglo, A. Siminel, S. Vatavu, Gh. Ghiletchii, T. Iurieva, L. Kulyuk, D. Nedeoglo
Summary: The photoluminescence (PL) spectra of ZnSe single crystals grown by the chemical vapor transport (CVT) method with iodine as a transport agent and doped with group V elements (P, As, Sb, Bi) were investigated. It was found that co-doping with iodine and group V elements resulted in the formation of acceptor-type associative centers of activator luminescence (ISeASe), which were responsible for new wide bands of long-wavelength emission. A photoluminescence mechanism explaining the behavior of the observed PL bands with temperature variation was proposed.
PHYSICA B-CONDENSED MATTER
(2023)
Article
Engineering, Electrical & Electronic
Enrique Miranda, Ville Lahteenlahti, Hannu Huhtinen, Alejandro Schulman, Petriina Paturi
Summary: This article presents a compact behavioral model for SPICE simulations of Al/Gd0.1Ca0.9MnO3 (GCMO)/Au resistive switching devices. The model takes into account electron transport and vacancy displacement, and explains the reversible movement of micro-filaments. It also introduces a novel approach for solving the internal state of the device, which can be applied to other structures and dynamics.
IEEE TRANSACTIONS ON NANOTECHNOLOGY
(2022)
Proceedings Paper
Engineering, Electrical & Electronic
Hans L. Hartnagel, Vadim P. Sirkeli, Pablo Acedo
Summary: THz waves have low photon energy, are not harmful to biological tissues, but are sensitive to water. Therefore, the application of terahertz imaging and spectroscopy techniques in the field of biomedicine is gaining interest.
2021 INTERNATIONAL SEMICONDUCTOR CONFERENCE (CAS)
(2021)
