Lithuanian Journal of Physics最新文献_第4页

Solid-state NMR study of spin dynamics and local disorder in smart polymers: PDMAEMA 智能聚合物中自旋动力学和局部无序的固态核磁共振研究:PDMAEMA

IF 0.6 4区物理与天体物理

Lithuanian Journal of Physics Pub Date : 2022-12-10 DOI: 10.3952/physics.v62i4.4821

V. Klimavičius, V. Klimkevicius, L. Dagys, K. Aidas, R. Makuška, V. Balevičius

{"title":"Solid-state NMR study of spin dynamics and local disorder in smart polymers: PDMAEMA","authors":"V. Klimavičius, V. Klimkevicius, L. Dagys, K. Aidas, R. Makuška, V. Balevičius","doi":"10.3952/physics.v62i4.4821","DOIUrl":"https://doi.org/10.3952/physics.v62i4.4821","url":null,"abstract":"The solid-state 1H and 13C NMR spectra as well as the 1H–13C cross-polarization upon magic angle spinning (CP MAS) kinetics were studied for poly[2-(dimethylamino)ethyl methacrylate] (PDMAEMA), i.e. a smart pH- and thermo-responsive polymer. The stereochemical content of PDMAEMA was determined from the complex shaped 13C MAS signal of CH3 group. The kinetic data were processed using the Hirschinger and Raya spin dynamics model that includes the complete scheme of rotating frame spinlattice relaxation pathways. The general solution was adapted for the spin cluster treatment. The earlier studied experimental CP MAS kinetics data of poly [2-(methacryloyloxy)ethyl trimethylammonium chloride] (PMETAC), i.e. one of its quaternized form, were revisited and newly processed applying this model. The spin-lattice relaxation of protons in the rotating frame in PDMAEMA and PMETAC occurs in the same scale from one to tens of milliseconds. Very high anisotropy of spin-diffusion was found for both polymers. However, the local disorder of various spin sites in PDMAEMA is significantly higher than in PMETAC. It is characterized by the order parameters 0.71–0.77 and 0.87–0.91, respectively. The main chain in PDMAEMA is also more disordered and more flexible than in PMETAC.","PeriodicalId":18144,"journal":{"name":"Lithuanian Journal of Physics","volume":" ","pages":""},"PeriodicalIF":0.6,"publicationDate":"2022-12-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46629254","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 1

Improvement of terahertz images by adaptive discrete cosine transform (DCT)-based denoising 基于自适应离散余弦变换(DCT)去噪的太赫兹图像改进

IF 0.6 4区物理与天体物理

Lithuanian Journal of Physics Pub Date : 2022-12-10 DOI: 10.3952/physics.v62i4.4823

V. Abramova, S. Abramov, V. Lukin, I. Grigelionis, L. Minkevičius, G. Valušis

引用次数: 1

Phosphate bonded CoFe2O4–BaTiO3 layered structures: Dielectric relaxations and magnetoelectric coupling 磷酸键合CoFe2O4–BaTiO3层状结构：介电弛豫和磁电耦合

IF 0.6 4区物理与天体物理

Lithuanian Journal of Physics Pub Date : 2022-12-10 DOI: 10.3952/physics.v62i4.4817

A. Plyushch, D. Lewin, P. Ažubalis, V. Kalendra, A. Sokal, R. Grigalaitis, V. Shvartsman, S. Salamon, H. Wende, A. Selskis, K. Lapko, D. Lupascu, J. Banys

引用次数: 0

Dedication to Professor Jūras Banys 献给Marine Banys教授

IF 0.6 4区物理与天体物理

Lithuanian Journal of Physics Pub Date : 2022-12-10 DOI: 10.3952/physics.v62i4.4813

Lithuanian Journal of Physics,

{"title":"Dedication to Professor Jūras Banys","authors":"Lithuanian Journal of Physics,","doi":"10.3952/physics.v62i4.4813","DOIUrl":"https://doi.org/10.3952/physics.v62i4.4813","url":null,"abstract":"This year, on 30 December, is the 60th anniversary of the outstanding physicist, Vilnius University professor, academician, president of the Lithuanian Academy of Sciences Jūras Banys. J. Banys graduated with honours from the Faculty of Physics of Vilnius University in 1985, defended his doctoral thesis in 1990. In 1989–1990, he worked at a professor Mike Glazer’s laboratory at the University of Oxford (UK), studying the structural properties of ferroelectric crystals using X-ray diffraction methods. In 1993–1995, after receiving Alexander von Humboldt scholarship, he worked at the University of Leipzig, where he studied the local dynamics of phase transitions using electron paramagnetic spectroscopy. After returning to his Alma Mater, J. Banys took charge of the Laboratory of Microwave Spectroscopy, turning it into a modern centre for the study of the dielectric properties of ferroelectric materials. Over the years, he assembled here a group of highly qualified scientists who perform scientific experiments using unique materials developed in well-known foreign and Lithuanian laboratories. In 2000, J. Banys successfully defended his habilitation thesis, and in 2003 the title of Vilnius University professor was awarded to him.","PeriodicalId":18144,"journal":{"name":"Lithuanian Journal of Physics","volume":"1 1","pages":""},"PeriodicalIF":0.6,"publicationDate":"2022-12-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41657333","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Investigation of dielectric and magnetic properties of AL-800 ferrite AL-800铁氧体介电和磁性能的研究

IF 0.6 4区物理与天体物理

Lithuanian Journal of Physics Pub Date : 2022-12-10 DOI: 10.3952/physics.v62i4.4824

S. Rudys, S. Balčiu̅nas, C. Vollinger, J. Banys, V. Kalendra

{"title":"Investigation of dielectric and magnetic properties of AL-800 ferrite","authors":"S. Rudys, S. Balčiu̅nas, C. Vollinger, J. Banys, V. Kalendra","doi":"10.3952/physics.v62i4.4824","DOIUrl":"https://doi.org/10.3952/physics.v62i4.4824","url":null,"abstract":"Ferrites are usually used in accelerators for tuning radiofrequency (RF) cavities and in nonreciprocal devices controlling the power flow in RF accelerating systems. The conventional parallel‐biased Ni Zn ferrites employed for varying the frequency of accelerating cavities have the disadvantage of high saturation magnetization (4πMs). Application of the transversely biased yttrium iron garnet (YIG) material in RF tuners promises a significant reduction of power loss compared with systems that use the longitudinal bias. To inject the beam and extract the beam out of the CERN accelerator rings the fast kicker magnets made from ferrite materials must be used. Power deposition in the kicker magnets can be a limitation: if the temperature of the ferrite yoke exceeds the Curie temperature, the beam will not be properly deflected. Investigation of the ferrite electromagnetic properties of materials up to the GHz frequency range is essential for a correct impedance evaluation. This report summarizes an approach for deriving electromagnetic properties as a function of both frequency and temperature of the AL-800 garnet material. This information will be useful for simulating ferrite behaviour under realistic operating conditions.","PeriodicalId":18144,"journal":{"name":"Lithuanian Journal of Physics","volume":" ","pages":""},"PeriodicalIF":0.6,"publicationDate":"2022-12-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47219286","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Controversy on the ferroelectricity in metal–formate frameworks 金属甲酸框架中铁电性的争论

IF 0.6 4区物理与天体物理

Lithuanian Journal of Physics Pub Date : 2022-12-10 DOI: 10.3952/physics.v62i4.4814

P. Peksa, A. Sieradzki

引用次数: 1

Functional properties of PVDF-based NZF-BT flexible films PVDF基NZF-BT柔性薄膜的功能特性

IF 0.6 4区物理与天体物理

Lithuanian Journal of Physics Pub Date : 2022-12-10 DOI: 10.3952/physics.v62i4.4825

R. Grigalaitis, R. Šalaševičius, J. Banys, M. V. Vijatović Petrović, A. Dzunuzovic, M. Zaghete, G. F. Teixeira, B. Stojanović

引用次数: 0

Electrical properties of LLTO thick films LLTO厚膜的电学性能

IF 0.6 4区物理与天体物理

Lithuanian Journal of Physics Pub Date : 2022-12-10 DOI: 10.3952/physics.v62i4.4826

E. Kazakevičius, A. Žalga, V. Kavaliukė, S. Daugėla, T. Šalkus, A. Kežionis

引用次数: 0

Dielectric and piezoelectric properties of 0.8Na0.5Bi0.5TiO3-0.2BaTiO3 modified with sodium niobate 铌酸钠改性0.8Na0.5Bi0.5TiO3-0.2BaTiO3的介电和压电性能

IF 0.6 4区物理与天体物理

Lithuanian Journal of Physics Pub Date : 2022-12-10 DOI: 10.3952/physics.v62i4.4816

S. Svirskas, T. Kudrevičius, E. Birks, M. Dunce, A. Sternbergs, C. Huang, J. Banys

{"title":"Dielectric and piezoelectric properties of 0.8Na0.5Bi0.5TiO3-0.2BaTiO3 modified with sodium niobate","authors":"S. Svirskas, T. Kudrevičius, E. Birks, M. Dunce, A. Sternbergs, C. Huang, J. Banys","doi":"10.3952/physics.v62i4.4816","DOIUrl":"https://doi.org/10.3952/physics.v62i4.4816","url":null,"abstract":"In this paper, we present the dielectric and piezoelectric properties of tetragonal 0.8Na0.5Bi0.5TiO3-0.2BaTiO3 modified with NaNbO3 ((1-x)[0.8Na0.5Bi0.5TiO3-0.2BaTiO3]-xNaNbO3). Our experimental study has revealed that the ferroelectric phase in these compositions is suppressed with the increase of sodium niobate concentration. A broad anomaly, resembling relaxor ferroelectrics, appears in the 325–450 K temperature interval. The investigation of the electric field dependence of polarization has indicated that the double hysteresis loop behaviour is characteristic of the modified compositions, which is associated with the 1st order phase transition under the applied electric field. The experiments below room temperature have revealed that the range of stability of the ferroelectric phase is shifted to lower temperatures upon the increase of sodium niobate concentration. The electromechanical displacement in the modified compositions shows a similar maximum displacement in the whole concentration range. The electromechanical response in 0.8Na0.5B0.5TiO3-0.2BaTiO3 solid solutions is due to the piezoelectric effect, while, in the mixed compositions, it is related to the jump-like change of the lattice constants in the vicinity of electric fieldinduced 1st order phase transition.","PeriodicalId":18144,"journal":{"name":"Lithuanian Journal of Physics","volume":" ","pages":""},"PeriodicalIF":0.6,"publicationDate":"2022-12-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42763842","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Optimization of terahertz detectors based on graphene field effect transistors by high impedance antennae 基于高阻抗天线的石墨烯场效应晶体管太赫兹探测器的优化

IF 0.6 4区物理与天体物理

Lithuanian Journal of Physics Pub Date : 2022-12-10 DOI: 10.3952/physics.v62i4.4822

D. Vizbaras, K. Ikamas, S. Pralgauskaitė, J. Matukas, A. Generalov, A. Lisauskas

{"title":"Optimization of terahertz detectors based on graphene field effect transistors by high impedance antennae","authors":"D. Vizbaras, K. Ikamas, S. Pralgauskaitė, J. Matukas, A. Generalov, A. Lisauskas","doi":"10.3952/physics.v62i4.4822","DOIUrl":"https://doi.org/10.3952/physics.v62i4.4822","url":null,"abstract":"This contribution presents the results of investigations performed on monolayer graphene field effect transistor- based (GFET-based) terahertz detectors. We have implemented three different types of planar antennae: a bowtie, a bow-tie with transmission lines and a slot-disc, allowing us to realize different conditions for high-frequency impedance matching. We present a semi-empirical model which uses physical parameters derived from electrical characterization results of devices and electrodynamic characteristics of antennae, allowing us to predict THz responsivity. Model predictions have been compared with the responsivity measurements performed at room temperature in a frequency range from 50 to 1250 GHz. Good agreement between the model predictions and experimental results implies the eligibility of a distributed resistive mixing approximation for GFET. In addition, the device stability, the temperature dependence and the origin of noise in the transistor channel have been investigated. Finally, to the best of our knowledge, we demonstrate the record performance values for room temperature graphene-based terahertz detectors: 80V/W optical responsivity without the normalization to the antenna effective area and a noise equivalent power of 111 pW/√ — Hz at 336 GHz.","PeriodicalId":18144,"journal":{"name":"Lithuanian Journal of Physics","volume":" ","pages":""},"PeriodicalIF":0.6,"publicationDate":"2022-12-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49160862","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0