Article
Chemistry, Physical
Jesus Gonzalez-Cobos, Brice Mylonoyannis, Guangtao Chai, Weidong Zhang, Chengcheng Tian, Akim Kaddouri, Sonia Gil
Summary: Un-supported spinel-type cobalt chromite catalysts were synthesized by propionic acid-mediated sol-gel method and evaluated for toluene oxidation. The Co and Cr content and the preparation conditions were found to significantly affect the physico-chemical, surface and catalytic properties. Co-rich CoCr2O4 catalyst showed the highest activity due to the formation of a single CoCr2O4 spinel phase, favorable surface composition, and higher low-temperature reducibility. Surface Cr6+ ions and adsorbed oxygens were found to play an important role in toluene oxidation reaction.
APPLIED CATALYSIS A-GENERAL
(2023)
Article
Materials Science, Multidisciplinary
Semiramis Gulkesen, Kutluhan Utku Tumen, Mustafa Akyol, Ahmet Ekicibil
Summary: In this study, a series of Co(Cr1-xFex)(2)O-4 compounds were synthesized by sol-gel method, and it was found that magnetic and magnetocaloric properties were significantly altered when Fe ions partially replaced Cr ions in CoCr2O4. After 50% Fe substitution, the material exhibited higher magnetic transition temperature and magnetic entropy change values, making it a potential candidate for magnetic refrigerant applications.
APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING
(2021)
Article
Materials Science, Ceramics
Cheng Liu, Wenhao Xu, Hongyang Zhang, Liang Shi, Wenwen Wang, Xiaolei Shi, Huaiwu Zhang
Summary: The novel magnetic-dielectric ceramics based on LZTF ferrites and LZT dielectrics, fabricated through a traditional solid-state reaction method, exhibited pure spinel structure and dense morphology within a wide sintering temperature range. The introduction of LZT dielectrics into LZTF magnetic phase resulted in reduced magnetic properties while significantly decreasing the FMR line width values. This ceramic system shows potential for high frequency applications with acceptable microwave dielectric properties.
JOURNAL OF ELECTROCERAMICS
(2021)
Article
Materials Science, Ceramics
Kazuki Kanehara, Shingo Urata, Sou Yasuhara, Takaaki Tsurumi, Takuya Hoshina
Summary: In this study, the dielectric properties of oxide glasses were investigated for potential applications in high-frequency communications. The results showed that silica glass exhibited low dielectric dispersion, while alkali silicate glasses exhibited high dielectric dispersion. The shape of the dispersion profile depended on the alkali-metal ions, with lighter ions resulting in broader curves and heavier ions resulting in sharper curves. Molecular dynamics simulations and ion dynamics analysis confirmed the experimental data and revealed that alkali-metal ions significantly affect the dielectric properties of alkali-silicate glasses. Therefore, when fabricating filter devices, a minimal amount of light alkali metals should be used to minimize dielectric loss while maintaining productivity.
JOURNAL OF THE AMERICAN CERAMIC SOCIETY
(2023)
Article
Engineering, Electrical & Electronic
Benedikt Leander Krause, Amlan Kusum Mukherjee, Sascha Preu
Summary: In this paper, a photonic spectrum analyzer is presented for measuring spectral power, linewidth, and harmonics of signals in the terahertz range. By using a photonically generated local oscillator frequency and a photoconductor, the signal under test can be downconverted and measured. The measurement results demonstrate that this method is suitable for measuring signals transported via a dielectric waveguide and characterizing on-chip sources.
IEEE JOURNAL OF SELECTED TOPICS IN QUANTUM ELECTRONICS
(2023)
Article
Physics, Multidisciplinary
Peng Zhang, Kaibo He, Zheng Wang, Shile Zhang, Jianming Dai, Fuhai Su
Summary: In this study, THz-TDS was used to investigate polycrystalline MnCr2O4 at low temperatures and <9 T. It was observed that there is a linear blueshift in the sub-THz range as the magnetic field is increased from 4 T to 9 T. These magnetism-driven absorptions are attributed to ferromagnetic resonance, which is consistent with low-field electron spin resonance measurements and ferromagnetic resonance theory. The low-temperature g-factors of MnCr2O4 were also determined using THz-TDS. This study provides new insights into the spin dynamics of chromite spinel compounds in the THz region.
Article
Chemistry, Physical
Thomas Dippong, Mihaela Diana Lazar, Iosif Grigore Deac, Petru Palade, Ioan Petean, Gheorghe Borodi, Oana Cadar
Summary: This study investigates the effect of Mn2+ substitution for Co2+ in CoFe2O4 embedded in a SiO2 matrix on the structural, surface, morphological, and magnetic properties. With an increase in Mn content, particle size increases and magnetic properties change accordingly. The mesoporous structure facilitates the release of fine nanoparticles in aqueous environment.
JOURNAL OF ALLOYS AND COMPOUNDS
(2022)
Article
Engineering, Electrical & Electronic
Alejandro Rivera-Lavado, Muhsin Ali, Daniel Gallego-Cabo, Luis-Enrique Garcia-Munoz, Dmitri V. Lioubtchenko, Guillermo Carpintero
Summary: RF probes based on 50-omega planar transmission lines are crucial for RF device development, but current technology lacks precision and repeatability. Here, we propose a novel RF probe technology based on near-field coupling of dielectric waveguides, offering an extremely broad frequency range up to 340 GHz, the largest continuous bandwidth reported to date. A concept demonstrator using this approach enables contactless RF probing across the microwave, millimeter-wave, and Terahertz range.
IEEE TRANSACTIONS ON TERAHERTZ SCIENCE AND TECHNOLOGY
(2023)
Article
Materials Science, Ceramics
Lianting Nong, Xuefeng Cao, Chunchun Li, Laijun Liu, Liang Fang, Jibran Khaliq
Summary: The critical order/disorder transition in spinel ceramics significantly affects the variation in microwave dielectric properties.
Maximum degree of order at x = 0.75 results in the highest quality factor and near-zero stability.
Cation ordering/disordering plays a critical role in determining the optimal microwave dielectric properties in spinel ceramics.
JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
(2021)
Article
Chemistry, Physical
Tetiana Tatarchuk, Alexander Shyichuk, Zbigniew Sojka, Joanna Grybos, Mu Naushad, Volodymyr Kotsyubynsky, Maria Kowalska, Sylwia Kwiatkowska-Marks, Nazarii Danyliuk
Summary: A simple green method for the synthesis of cobalt-zinc ferrites nanoparticles was proposed in this study, with detailed structural and morphological analysis conducted using various techniques. The samples exhibited high adsorption capacity and magnetic hyperthermia performance, making them promising for potential applications in these fields.
JOURNAL OF MOLECULAR LIQUIDS
(2021)
Article
Nanoscience & Nanotechnology
Bin Wang, Hao Wang, Bowen Chen, Pengyu Xu, Qiangguo Chen, Bingtian Tu, Weimin Wang, Zhengyi Fu
Summary: The novel ZnGa2O4 transparent ceramic has excellent optical properties and mechanical properties, as well as high thermal conductivity, with a wide transmission range and high transmittance.
SCRIPTA MATERIALIA
(2021)
Article
Chemistry, Physical
Elisa Zanchi, Justyna Ignaczak, Bartosz Kamecki, Piotr Jasinski, Sebastian Molin, Aldo R. Boccaccini, Federico Smeacetto
Summary: This paper investigates how the microstructure of Mn-Co spinel interconnect coating influences Cr contamination in intermediate temperature solid oxide cells. Different densification levels were achieved through one-step and two-step sintering. The performance of the coatings with different microstructures in retaining Cr was evaluated through electrochemical characterization, aging, and post-mortem analysis.
Article
Materials Science, Multidisciplinary
Shojiro Kimura, Shusaku Imajo, Masaki Gen, Tsutomu Momoi, Masayuki Hagiwara, Hiroaki Ueda, Yoshimitsu Kohama
Summary: In this study, the magnetocaloric effect and specific heat measurements of chromium spinel oxide HgCr2O4 were conducted. It was found that besides the known magnetic-field-induced phases, a quantum phase was detected just before the saturation of the magnetization, which cannot be explained by classical theories. Based on recent theoretical model calculations, it is suggested that this quantum phase may be related to a spin nematic state.
Article
Materials Science, Multidisciplinary
Hossein Nikmanesh, Elnaz Jaberolansar, Parviz Kameli, Ali Ghotbi Varzaneh, Mohsen Mehrabi, Mohsen Shamsodini, Mohammad Rostami, Inaki Orue, Volodymyr Chernenko
Summary: A series of samarium-doped cobalt ferrite nanoparticles were successfully synthesized using sol-gel auto-combustion method. The saturation magnetization decreased with increasing samarium content, but showed an improvement at lower temperatures. Samarium-doped cobalt ferrite is a suitable candidate for moderate permanent magnets and high density information storage, especially at low temperatures.
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS
(2022)
Article
Chemistry, Physical
Xiaochi Lu, Bin Quan, Kailai Zheng, Peng Chu, Jian Wang, Guangxu Shen, Qitu Zhang, Feng Xu
Summary: The Sc3+ modified ZnGa2O4 ceramics show stable epsilon(r) around 10, while the tau(f) values have a linear correlation with Sc3+ concentration. Additionally, the Qxf values increase to a maximum value and then decrease with increasing Sc3+ concentration.
JOURNAL OF ALLOYS AND COMPOUNDS
(2021)
Article
Optics
Sergey Kudryashov, Alena Nastulyavichus, George Krasin, Kamil Khamidullin, Kirill Boldyrev, Demid Kirilenko, Alexander Yachmenev, Dmitry Ponomarev, Gennady Komandin, Sergey Lebedev, Dmitry Prikhod'ko, Michael Kovalev
Summary: Direct laser writing/ultra-hyperdoping technology was used to fabricate a Si-based broadband n-p junction detector with its spectral response controlled by external cooling. Temperature-dependent photoconductivity was observed in a biased n-p junction made of sulfur-ultrahyperdoped Si. The observed broadband photoconductivity is due to the presence of sulfur impurity donor states near the conduction band bottom, supporting the migration of PC maximum with increasing temperature. The high concentration of electrically-active donor sulfur centers in the uh-Si sample enables the fabrication of universal Si detectors with broad spectral response.
OPTICS AND LASER TECHNOLOGY
(2023)
Article
Physics, Condensed Matter
Boris Gorshunov, Veniamin Abalmasov, Vladimir Uskov, Yuk Tai Chan, Ece Uykur, Pavel Abramov, Martin Dressel, Victor Thomas, Maxim Savinov
Summary: The quasistatic dielectric permittivity of D2O type I molecules in hydrothermally grown beryl crystals was measured under different internal pressures and D2O type II molecule contents. It was found that all crystals exhibited quantum paraelectric behavior, with permittivity increasing and then saturating below a certain temperature. The data analysis showed that excess internal pressure and excess content of D2O-II molecules led to increased quantum temperature and decreased Curie constant, while the Curie temperature remained unchanged. The enhanced quantum effects in the dipole-dipole-coupled D2O-I molecules were attributed to the enhanced azimuthal tunneling within the hexagonal localizing potential. The study suggests the potential of using crystal growth conditions to control the strength of quantum effects in polar water molecule networks.
PHYSICA STATUS SOLIDI B-BASIC SOLID STATE PHYSICS
(2023)
Article
Engineering, Electrical & Electronic
Samuel W. Pinnock, Seulki Roh, Tobias Biesner, Artem V. Pronin, Martin Dressel
Summary: In this article, we demonstrated the effective generation of vortex terahertz (THz) beams with angular momenta P = +/- 1 and P = +/- 2 using 3-D printed spiral phase plates (SPPs). The generation of vortex beams was confirmed through frequency-domain transmission spectroscopy. The topological charge P of the vortex beams was determined using phase-sensitive Mach-Zehnder interferometry, and the resulting interference patterns supported the expected intensity distributions for the given P, providing strong evidence for the spatial phase structure of the generated THz vortex beams.
IEEE TRANSACTIONS ON TERAHERTZ SCIENCE AND TECHNOLOGY
(2023)
Article
Crystallography
Vladimir Sirotinkin, Alexandr Bush, Vladislav Kozlov
Summary: The xBa(Ti(1-y)Zry)O-3-(1-x)PbTiO3 ceramic samples with various compositions were successfully synthesized by solid state reaction. XRD and Rietveld method were used to analyze their crystallographic data, and it was found that all the samples were solid solutions with tetragonal perovskite structure. The degree of tetragonal distortion decreased with increasing Zr content. Microstructure analysis revealed that the broadening of diffraction peaks on the XRD patterns was caused by both strains and small crystallite sizes.
ZEITSCHRIFT FUR KRISTALLOGRAPHIE-CRYSTALLINE MATERIALS
(2023)
Article
Optics
Gennady A. Komandin, Sergey P. Lebedev, Stella L. Korableva, Oleg A. Morozov, Vladimir M. Kyashkin, Vadim V. Semashko, Pavel P. Fedorov
Summary: The basic mechanisms of absorption of THz range radiation in optically perfect LiGdF4 single crystals were studied using experimental data and dielectric response function analysis within the harmonic oscillator model. Polarized IR reflection spectra were used to determine phonon contribution, while transmission spectra provided information on birefringence and the effects of various multiparticle processes. Additionally, the optical and electrodynamic parameters of the LiGdF4 single crystal were established for the design of nonlinear optical devices.
Article
Physics, Applied
Gennadiy A. Komandin, Artem M. Kuzmenko, Igor E. Spektor, Alexander A. Mukhin
Summary: The absorption mechanisms in orthoferrite TbFeO3 were studied using various spectroscopy techniques. The spectra were analyzed using the oscillator model and four-parameter model, and the parameters were determined. The main absorption processes were identified, including contributions from phonons, multi-phonon processes, electron transitions, and antiferromagnetic resonance modes. The electrodynamic response in TbFeO3 showed significant absorption in the THz range due to multi-phonon processes, surpassing optical phonon contribution by an order of magnitude at room temperature.
JOURNAL OF APPLIED PHYSICS
(2023)
Article
Instruments & Instrumentation
Yuk Tai Chan, Ece Uykur, Martin Dressel
Summary: In this study, we present the modifications, performance, and test of a diamond anvil cell for radio frequency dielectric spectroscopy studies of single crystals. The modified pressure cell can be used from room temperature down to 4 K and up to pressures of 5-6 GPa, allowing continuous frequency-dependent measurements between 5 Hz and 1 MHz. With an excellent performance and a stray capacitance of around 2 pF that is temperature-, frequency-, and pressure-independent, this cell enables the use of relatively small samples with a weak dielectric response.
REVIEW OF SCIENTIFIC INSTRUMENTS
(2023)
Article
Chemistry, Analytical
Gennady A. Komandin, Vadim S. Nozdrin, Sergey Chuchupal
Summary: The physical and chemical properties of saccharides are influenced by their isomerism and hydrogen bond parameters. Pulsed terahertz spectroscopy was used to study the vibrational spectra of mono- and disaccharides, revealing the stability ranges and resonance parameters. Differences in the vibrational modes of hydroxyl groups in different saccharides show correlation with hydrogen bond parameters. Anharmonicity of vibrational modes appears as coupling between resonances and the formation of wide asymmetric bands. The temperature square dependence of resonance eigenfrequencies in disaccharides has been observed.
VIBRATIONAL SPECTROSCOPY
(2023)
Article
Physics, Condensed Matter
Alexander Bush, Anton Matasov, Victor Andrianov, Vladislav Kozlov
Summary: Ceramic samples of CuCrO2 phase with a delafossite structure were synthesized and characterized. The threshold electric field switching effect from a high-resistivity to a low-resistivity state was observed under specific temperature and electric field conditions, which can be explained by the polaron conduction mechanism.
PHYSICA B-CONDENSED MATTER
(2023)
Article
Chemistry, Multidisciplinary
T. A. Ageeva, A. A. Bush, D. V. Golubev, A. S. Gorshkova, R. N. Mozhchil, O. I. Koifman, V. S. Kozlov, M. E. Matis, V. D. Rumyantseva, A. S. Sigov, V. V. Fomichev
Summary: This paper presents the results of a systematic study on the search for organometallic molecules with a large dipole moment, and their application in the creation of new film electret materials. The compounds were synthesized and identified, and their properties were evaluated using physicochemical methods and quantum chemical calculations. The inclusion of these compounds in polyvinyl acetate films and the deposition of copper layers resulted in pronounced electret effects.
RUSSIAN CHEMICAL BULLETIN
(2023)
Article
Nanoscience & Nanotechnology
Cenk Beydeda, Konstantin Nikolaou, Marius Tochtermann, Nikolaj G. Ebensperger, Gabriele Untereiner, Ahmed Farag, Philipp Karl, Monika Ubl, Harald Giessen, Martin Dressel, Marc Scheffler
Summary: This paper discusses various experimental strategies to distinguish designed and spurious modes in coplanar superconducting resonators that are operated in a broad frequency range. These strategies include tracking resonance evolution with temperature, magnetic field, and microwave power. It is also found that local modification of the resonator can lead to characteristic signatures in different resonance modes depending on the local strength of the electric or magnetic microwave fields.
Article
Materials Science, Multidisciplinary
Alexander A. Tsirlin, Brenden R. Ortiz, Martin Dressel, Stephen D. Wilson, Stephan Winnerl, Ece Uykur
Summary: High-pressure single-crystal x-ray diffraction experiments show that the superconducting kagome metal CsV3Sb5 undergoes a transformation from hexagonal to monoclinic symmetry above 10 GPa under nonhydrostatic pressure conditions. This is different from its behavior under quasihydrostatic conditions in neon where it retains hexagonal symmetry up to at least 20 GPa. The monoclinic distortion mainly affects the honeycomb nets of Sb atoms, while the kagome planes remain almost unchanged. Ab initio density-functional calculations reveal that there are only minor changes in the electronic structure between the quasihydrostatic and nonhydrostatic cases. The reentrant behavior is likely caused by Fermi surface reconstruction driven by the formation of interlayer Sb-Sb bonds in both monoclinic and hexagonal CsV3Sb5 structures at high pressures.
Article
Materials Science, Multidisciplinary
R. Roesslhuber, R. Huebner, M. Dressel, A. Pustogow
Summary: We investigate the dielectric properties of the molecular quantum-spin-liquid candidate K-(BEDT-TTF)2 Ag2(CN)3 under varying frequency, pressure, and temperature. The transition from incoherent semiconducting to Mott-insulating state leads to a decrease in the low-frequency dielectric constant to small positive values (~10). The characteristic relaxor-type peak shifts to lower temperatures with increased pressure, and an additional feature appears near the percolative first-order transition. The pressure-dependent dielectric response is similar to the sister compound K-(BEDT-TTF)2Cu2(CN)3.
Article
Optics
G. A. Komandin, V. S. Nozdrin, S. Chuchupal, A. A. Gavdush, G. R. Musina, I. E. Spektor
Summary: This study measures the reflection spectra of single-phase pressed samples of saccharides using coherent submillimeter, pulsed terahertz, and broadband Fourier-transform infrared spectroscopy. The parameters of the absorption bands are estimated using the additive classical oscillator model. The possibility of analyzing the vibrational spectrum with correction for scattering using calibration data for the visible and terahertz ranges is shown. However, the sensitivity and accuracy of this approach are limited by low reflection coefficients, resulting in a low signal-to-noise ratio, as well as asymmetric broadening of bands due to anharmonicity of vibrations and overlap of absorption bands.
OPTICS AND SPECTROSCOPY
(2022)
