Article
Chemistry, Physical
M. T. Candela, F. Aguado, J. A. Gonzalez, R. Valiente
Summary: The high-pressure behavior of (Eu1-xYbx)2O3 solid solution has been studied with Raman and photoluminescence spectroscopies. A reversible phase transition from monoclinic (B) to trigonal (A) phase has been observed, and the transition pressure increases linearly with Yb3+ content. The fraction of B and A phases as a function of pressure has been estimated and the effect of pressure on the spin-orbit coupling constant & xi;4f has been evaluated.
JOURNAL OF ALLOYS AND COMPOUNDS
(2023)
Article
Nanoscience & Nanotechnology
Sheng Jiang, Jichao Zhang, Lingrui Wang, Chuanlong Lin, Shuai Yan, Jing Liu, Aiguo Li, Renzhong Tai
Summary: The high pressure structural evolution of cubic Yb2O3 was studied using in situ synchrotron angle dispersive x-ray diffraction. The results showed an irreversible reconstructive phase transition from cubic to monoclinic phase at 11.2 GPa, followed by a reversible displacive transition from monoclinic to hexagonal phase at 22.7 GPa. The bulk modulus of each phase was determined, and the effects of hydrostatic pressure on the diffraction patterns and transition pressure of Yb2O3 were discussed. The enthalpies of the phase transitions were also calculated based on thermodynamic equations.
Article
Materials Science, Ceramics
Chuanlong Wang, Weihu Zhang, Qiang Li, Yu Xu, Anjiang Dong, Run Zhao, Shuibing Ge, Xiaodong Su, Rujun Tang
Summary: The growth, microstructure, and magnetic property of both bulk and thin film types of ScFeO3 were studied. It was found that a mono-phase bixbyite structure bulk ScFeO3 can be obtained with a sintering temperature above 1400 degrees C. The bulk ScFeO3 exhibits dominant antiferromagnetic property, while the epitaxial type of ScFeO3 thin film on SrTiO3(111) substrate shows notable room temperature ferromagnetism.
CERAMICS INTERNATIONAL
(2023)
Article
Chemistry, Physical
Julia Mari-Guaita, S. Gallego-Parra, J. A. Sans, M. Velazquez, Philippe Veber, P. Rodriguez-Hernandez, A. Munoz, F. J. Manjon
Summary: This study reports an experimental investigation of (Gd1-xYbx)(2)O-3 under high pressure using Raman scattering measurements and ab initio calculations, revealing a phase transition sequence different from that of pure Gd2O3. Theoretical calculations helped identify different polymorphs and assign the symmetry of Raman-active modes in the three phases. The pressure coefficients of Raman-active modes in the three phases were reported and compared to those of pure Gd2O3 and other rare-earth sesquioxides.
JOURNAL OF ALLOYS AND COMPOUNDS
(2021)
Article
Chemistry, Physical
Taesung Park, Hamid Reza Javadinejad, Young-Kuk Kim, Hye Jung Chang, Haneul Choi, Choo Woong, Andrews Nsiah Ashong, Youn Seoung Lee, Jeoung Han Kim
Summary: (Y-La-Ce-Nd-Gd)(2)O3 + β high-entropy rare earth oxides (HE-REOs) were synthesized using mechanochemical and chemical methods, with sol-gel process showing the best compositional uniformity. Although similar chemical uniformity and physical properties were obtained regardless of the synthesis method after heat treatment, sol-gel method required a lower annealing temperature. High phase stability of the synthesized HE-REOs was confirmed through thermodynamic calculations and comparisons.
JOURNAL OF ALLOYS AND COMPOUNDS
(2022)
Article
Chemistry, Physical
M. R. Sahoo, A. Barik, R. Ghosh, S. Kuila, Sweta Tiwary, P. D. Babu, S. D. Kaushik, P. N. Vishwakarma
Summary: In this study, manganese substituted strontium hexaferrite with different substitution levels were prepared, and the distribution of the substituted Mn was investigated. The change in crystal lattice and grain shape with the increase in Mn content was observed. The magnetic phase behavior and magnetic anisotropy of the samples were examined, and the x=5 composition was found to be a promising candidate for magnetoelectric applications.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2023)
Article
Crystallography
Elena Dobretsova, Olimkhon Alimov, Denis Guryev, Valery Voronov, Sergey Rusanov, Vitaly Kashin, Sergey Kutovoy, Viktor Vlasov, Lubov Badyanova, Ivan Novikov, Vladimir Tsvetkov
Summary: Yttrium scandate crystal fiber with a bixbyite crystal structure and high degree of disorder has been obtained through laser-heated pedestal growth. Spectral-kinetic investigation of the crystal fibers doped by rare-earth ions reveals the presence of two independent active optical centers, unaffected by the ionic radius size.
Article
Chemistry, Inorganic & Nuclear
Zhuanling Bai, Jacob Brannon, Cristian Celis-Barros, Nicholas Beck, Joseph M. Sperling, Brian M. Rotermund, Daniela Gomez Martinez, Hannah B. Wineinger, Thomas E. Albrecht-Schonzart
Summary: The synthesis, structure, and Raman spectrum of Ra-(NO3)(2) were investigated by experimentation and theory. Single crystal X-ray diffraction analysis showed that radium nitrate is isomorphous with Ba-(NO3)(2) and crystallizes in the cubic space group Pa 3 with a = 8.2268(1) angstrom at 100K. Ra-(NO3)(2) represents the first pure radium compound characterized by single crystal X-ray diffraction. The Raman spectrum of Ra-(NO3)(2) generally occurs at a lower frequency compared to Ba-(NO3)(2), as expected. Computational studies provided an estimation of bond orders and indicated weak Ra-O interactions.
INORGANIC CHEMISTRY
(2023)
Article
Chemistry, Applied
Binbin Jiang, Lihe Zheng, Dapeng Jiang, Handi Yin, Jiangang Zheng, Qiuhong Yang, Guofeng Cheng, Liangbi Su
Summary: Ytterbium and rare earth ions codoped CaF2-SrF2 single crystals were fabricated and their optical properties were analyzed, showing potential applications in high-power solid-state lasers. The study confirmed the effects of different rare earth ions on the crystal structure and optical performance.
JOURNAL OF RARE EARTHS
(2021)
Article
Chemistry, Inorganic & Nuclear
Artem B. Kuznetsov, Konstantin A. Kokh, Nursultan Sagatov, Pavel N. Gavryushkin, Maksim S. Molokeev, Valery A. Svetlichnyi, Ivan N. Lapin, Nadezda G. Kononova, Vyacheslav S. Shevchenko, Asset Bolatov, Bolat Uralbekov, Anastasia A. Goreiavcheva, Alexander E. Kokh
Summary: NaSrR(BO3)2 (R = Ho-Lu, Y, Sc) compounds with disordered positions of Sr2+ and Na+ atoms and interconnected RO6 polyhedra through BO3 groups were successfully synthesized. These compounds exhibit high transparency in the range of 250-900 nm, making them promising for phosphor applications.
INORGANIC CHEMISTRY
(2022)
Article
Chemistry, Physical
Shi-jie Song, Bai-Zhuo Li, Qin-Qing Zhu, Zhi Ren, Guang-Han Cao
Summary: We report the structural and physical properties of new nitridoborates RNiBN, which exhibit antiferromagnetic metal behavior and show magnetic transitions and giant magnetocaloric effects. Our results suggest that RNiBN may be promising candidates for low-temperature magnetic refrigeration.
JOURNAL OF ALLOYS AND COMPOUNDS
(2024)
Article
Biochemistry & Molecular Biology
Dmitrii Agarkov, Mikhail Borik, Galina Korableva, Alexey Kulebyakin, Irina Kuritsyna, Nataliya Larina, Elena Lomonova, Filipp Milovich, Valentina Myzina, Polina Ryabochkina, Nataliya Tabachkova, Tatyana Volkova, Denis Zakharov
Summary: The effect of long-term high-temperature annealing on the phase composition, local crystal structure, and oxygen-ion conductivity of SOFC membranes based on zirconium dioxide solid solutions was investigated. Crystals with different rare earth cations were obtained and their conductivity was analyzed. It was found that the conductivity of the crystals decreased with an increase in the ionic radius of the rare earth cation. The high-temperature degradation of conductivity was also discussed.
Article
Materials Science, Multidisciplinary
A. L. J. Pereira, J. A. Sans, O. Gomis, D. Santamaria-Perez, S. Ray, A. Godoy-Jr, A. S. da Silva-Sobrinho, P. Rodriguez-Hernandez, A. Munoz, C. Popescu, F. J. Manjon
Summary: In this study, the structural and vibrational properties of C-type Y2O3 under hydrostatic compression were investigated through a combination of high-pressure X-ray diffraction, Raman scattering experimental measurements, and ab initio theoretical calculations. The results confirmed the phase transition sequence of C-type to B-type to A-type on the upstroke and A-type to B-type on the downstroke. This finding is consistent with other rare-earth sesquioxides with similar ionic radii as Y. The good agreement between experimental and calculated results allowed for a more detailed understanding of the effect of pressure on rare-earth sesquioxides.
RESULTS IN PHYSICS
(2023)
Article
Chemistry, Physical
Dardan Ukaj, Hana Bunzen, Jan Berger, Gregor Kieslich, Roland A. Fischer
Summary: Electrically conductive metal-organic frameworks show potential for next-generation electronic devices. The incorporation of guest molecules in porous structures creates charge transport pathways. Vibrational spectroscopy is a powerful tool for understanding host-guest interactions and enhancing electrical conductivity in MOFs.
CHEMISTRY OF MATERIALS
(2021)
Article
Nanoscience & Nanotechnology
Sheng Jiang, Jichao Zhang, Shuai Yan
Summary: Pressure-induced phase transitions in cubic Eu2O3 were studied using in situ high-pressure synchrotron angle dispersive x-ray diffraction and Raman scattering measurements. The results showed that the phase transitions of cubic Eu2O3 depended on the nature of stress loading. Unlike the transformation into a hexagonal structure under hydrostatic pressure, the cubic Eu2O3 began to transform into a monoclinic phase at a non-hydrostatic pressure of about 4.3 GPa, with the monoclinic to hexagonal phase transition occurring at about 6.4 GPa. The study also provided evidence for the shear stress-induced cubic to monoclinic phase transition in cubic Eu2O3 and its corresponding mechanism.
Article
Biotechnology & Applied Microbiology
Irena Markovska, Dimitar Georgiev, Fila Yovkova, Miroslav Abrashev
Summary: This study proposed a technology for producing monolayer graphene through a combination of chemical and physical treatments, resulting in the formation of superfine graphene using ultrasound. The physicochemical properties of the graphene were characterized using various techniques, showing potential application prospects due to its lower electrical resistivity compared to pure graphite precursor.
CURRENT NANOSCIENCE
(2022)
Article
Materials Science, Multidisciplinary
Thuany Garcia Maraschin, Samuel Corvello Vilar, Dario Eberhardt, Adriano Friedrich Feil, Jose Antonio Malmonge, Julian Geshev, Griselda Barrera Galland, Nara Regina de Souza Basso
Summary: This work demonstrates an effective method for obtaining hybrid nanoparticles of Ni-Fe-Mo permalloy and reduced graphene oxide (rGO). The metallic nanoparticles were spread by the sputtering technique onto the rGO substrate powder. The resulting permalloy/rGO hybrid showed improved electrical conductivity and magnetization compared to the original rGO.
MATERIALS TODAY COMMUNICATIONS
(2021)
Article
Polymer Science
Benjamin Constant-Mandiola, Hector Aguilar-Bolados, Julian Geshev, Raul Quijada
Summary: A study has been reported regarding the development of new recyclable and/or biodegradable magnetic polymeric materials by adding magnetite supported on thermally reduced graphene oxide to polymeric matrices. The nanomaterials obtained at different ratios and temperatures showed varying coercivity, which can be used to prepare polylactic acid and polypropylene nanocomposites with different coercivity values. Theoretical models were used to analyze the mechanical and magnetic properties, providing a basis for further research.
Article
Physics, Multidisciplinary
Yoana Tavitian, Denitsa Y. Yancheva, Neno D. Todorov
Summary: Three Persian oil paintings from the Qajar era, depicting musicians and royalty, were studied for dating, conservation and technological evaluation. Analysis of samples and cross sections revealed similar composition and previous restorations, with the Royalty/Prince painting showing complex stratigraphy and overpaintings. The integrated materials reflect a blend of traditional techniques with minimal European influence, dating the paintings back to the early 19th century. These findings will guide the direction of their conservation and restoration.
EUROPEAN PHYSICAL JOURNAL PLUS
(2021)
Article
Engineering, Environmental
A. Dias, N. Bundaleska, E. Felizardo, D. Tsyganov, A. Almeida, A. M. Ferraria, A. M. Botelho do Rego, M. Abrashev, Th Strunskus, N. M. Santhosh, U. Cvelbar, J. Zavasnik, M. F. Montemor, M. M. Almeida, Patricia A. Carvalho, J. Kissovski, L. L. Alves, E. Tatarova
Summary: This paper proposes a novel approach using microwave plasma to synthesize high-yield and high-quality hybrid graphene-based nanostructures. The method can produce customizable electrode materials with well-structured metal-based nanostructures on graphene nanosheets.
CHEMICAL ENGINEERING JOURNAL
(2022)
Article
Materials Science, Multidisciplinary
C. H. Verbeno, V. Z. C. Paes, A. C. Krohling, T. E. P. Bueno, J. Geshev, J. van Lierop, E. C. Passamani
Summary: The morphological, structural, and magnetic properties of Co nanowire/IrMn film heterostructures are investigated in this study using atomic force microscopy, non-coplanar X-ray diffraction, and magnetization measurements. It is found that the thickness of the nanowires affects the magnetic phases, leading to changes in the exchange bias of the hysteresis loops. By considering dipolar interactions among the nanowires and using a modified polycrystalline model, the experimental hysteresis loops are successfully reproduced. The results highlight the importance of anisotropies and dipolar interactions in the coherent magnetization reversal processes observed.
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS
(2022)
Article
Energy & Fuels
Kush K. Upadhyay, N. Bundaleska, M. Abrashev, J. Kissovski, N. Bundaleski, O. M. N. D. Teodoro, Andre Mao de Ferro, Rui Pedro Silva, A. Dias, E. Felizardo, E. Tatarova, M. F. Montemor
Summary: Free-standing graphene synthesized using atmospheric pressure microwave plasma showed good supercapacitive properties and was used as an electrode. Electrodes made by mixing graphene with activated carbon demonstrated improved specific capacitance and rate capability compared to commercial activated carbon electrodes.
JOURNAL OF ENERGY STORAGE
(2022)
Article
Materials Science, Multidisciplinary
Marcelo Augusto Malagutti, Kelli de Fatima Ulbrich, Joao Paulo Winiarski, Vagner Zeizer Carvalho Paes, Julian Geshev, Cristiane Luisa Jost, Carlos Eduardo Maduro de Campos
Summary: In this study, gamma-CoTe2 nanocrystals were successfully synthesized using a ball mill within a short time. The nanocrystals exhibited excellent sensing abilities for ferulic acid, making them a promising alternative for quality control and real-time analysis in cosmetic industry.
MATERIALS TODAY COMMUNICATIONS
(2022)
Article
Materials Science, Multidisciplinary
J. Geshev, A. M. H. de Andrade
Summary: Recent research has found that the recoil magnetization curves of Fe, Co, and Ni films lie entirely outside the major hysteresis loop, which is known as a recoil-curve overshoot. A model of exchange-coupled grains with misaligned anisotropy axes can reproduce key features of these films, such as the collapse of the hard-magnetization axis, enhanced remanent magnetization and coercivity, the recoil-curve overshoot, and kinks in major loops near saturation. In this study, an interaction plot technique is used to investigate the interactions influencing magnetization reversal.
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS
(2022)
Article
Materials Science, Multidisciplinary
E. Valcheva, K. Kirilov, N. Bundaleska, A. Dias, E. Felizardo, M. Abrashev, N. Bundaleski, O. M. N. D. Teodoro, Th Strunskus, Zh Kiss'ovski, L. L. Alves, E. Tatarova
Summary: This paper investigates the electrical transport in free-standing graphene and N-graphene sheets fabricated by a microwave plasma-based method. Temperature-dependent resistivity/conductivity measurements are performed on the compressed graphene/N-graphene sheets, revealing directional dependence of current flow. SEM imaging confirms the preferential orientation of graphene sheets in the pellets. The observed charge transport mechanism is attributed to a partially disordered system with parallel placement and stacking of single graphene sheets.
MATERIALS RESEARCH EXPRESS
(2023)
Article
Chemistry, Multidisciplinary
Muhammad Nisar, Griselda Barrera Galland, Julian Geshev, Carlos Bergmann, Raul Quijada
Summary: Recent studies have shown that magnetically active polypropylene nanocomposites can be obtained by melt mixing and supporting metallic nanoparticles on thermally reduced graphene oxide. The addition of fillers improves the thermal stability and mechanical properties of the polymer, as well as changes the magnetic and hydrophilic properties of the materials.
Article
Electrochemistry
Aneliya Nakova, Miroslav Abrashev, Vessela Tsakova
Summary: Three types of carbon screen-printed electrodes (MC, CNF, SWCNT) were used as carbon supports for deposition of Ag. The electrodes were characterized by Raman spectroscopy and their structure showed significant differences. Metal deposition occurred in AgNO3 solution, resulting in the formation of homogenously distributed metal nanoparticles, with the type and amount depending on the potential used in the pre-treatment step and the structure of the carbon electrodes. Multiple pre-treatment/deposition cycles further influenced the characteristics of the metal deposit.
JOURNAL OF SOLID STATE ELECTROCHEMISTRY
(2023)
Article
Materials Science, Multidisciplinary
L. F. S. Azeredo, J. Geshev, P. L. Grande, A. M. H. de Andrade
Summary: Distinct sharp peaks in the angular variations of in-plane major-loop remanent magnetization and coercivity, known as hard-axis collapse, were observed in several polycrystalline films. Recent research also discovered recoil-curve overshoot (RCO), where recoil magnetization branches lie outside the major loop, resulting in a significantly larger loop area. In this study, polycrystalline magnetron-sputtered Co films were subjected to Ne+ bombardment at different ion fluences in the presence of a magnetic field, leading to hard-axis collapse and RCO phenomena. Data analysis suggests that these phenomena are primarily caused by domain splitting when the measurement magnetic field is nearly perpendicular to the grain's easy axis.
Article
Chemistry, Multidisciplinary
Marcelo Augusto Malagutti, Vagner Zeizer Carvalho Paes, Julian Geshev, Carlos Eduardo Maduro de Campos
Summary: The study demonstrates the mechanochemical synthesis of all cobalt tellurides' phases and characterizes their structural, microstructural, and magnetic properties. Different cobalt telluride phases with varying weight proportions were synthesized, with sizes in the range of tens of nanometers. The research also showed that the phases exhibit stable structural and microstructural properties over a two-year storage period.
Article
Materials Science, Multidisciplinary
J. Geshev, W. J. S. Garcia, V. Z. C. Paes, L. F. S. Azeredo, L. S. Dorneles, A. M. H. de Andrade
Summary: In this study, a peculiar magnetization reversal phenomenon, known as recoil-curve overshoot, was observed in magnetron-sputtered Co, Fe, and Ni films. The greatly enhanced recoil curve's remanence and coercivity led to a significant increase in loop's area. A model involving pairs of exchange-coupled grains with misaligned anisotropy axes successfully reproduced the key features of the recoil-curve overshoot and the kink in some major loops before saturation, providing further insights into the classical ferromagnetic hysteresis.
