http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Radheshyam Rai,Indrani Coondoo,Rashmi Rani,Igor Bdikin,Seema Sharma,Andrei L. Kholkin 한국물리학회 2013 Current Applied Physics Vol.13 No.2
(1 -x) K0.5Na0.5NbO3 -xLiNbO3 (where x = 0.0, 5.0, 5.5, 6.0, and 6.5 wt.%) (KNLN) perovskite structured ferroelectric ceramics were prepared by the solid-state reaction method. X-ray diffraction patterns indicate that single phase was formed for pure KNN while a small amount of second phase (K6Li4Nb10O30, w3%) was present in LN doped KNN ceramics. Phase analysis indicated the change in the crystal structure from orthorhombic to tetragonal with increase in LN content. The electrical behavior of the ceramics was studied by impedance spectroscopy technique in the high temperature range. Impedance analysis was performed using an equivalent circuit model. The impedance response in pure KNN and KNLN ceramics could be deconvoluted into two contributions, associated with the bulk (grains) and the grain boundaries. Activation energies for conductivity were found to be strongly frequency dependent. The activation energy obtained from dielectric relaxation data was attributed to oxygen vacancies. From PFM we found that the composition with 6.5 wt.% LN displays stronger piezocontrast as compared to pure KNN implying an evidence of a pronounced piezoelectric coefficient.
Radheshyam Rai,Sunil Kumar Mishra,N.K. Singh,Seema Sharma,Andrei L. Kholkin 한국물리학회 2011 Current Applied Physics Vol.11 No.3
A simple and effective method of solid state reaction followed by quenching process is used to prepare multiferroic Er^3+ and La^3+ doped BiFeO_3 ceramics. X-ray diffraction patterns indicated that these ceramics were of single-phase perovskite structure. Doping with La enhanced the dielectric, ferroelectric and ferromagnetic properties of BiFeO_3. A-site substitution with the La and Er ions has been found to suppress the spiral spin structure of BiFeO_3 giving rise to the appearance of room-temperature weak ferromagnetism. The enhanced multiferroic properties are attributed to the enhanced magnetoelectric interaction, which results from the La and Er substitution-induced destruction of the spin cycloid.
Graphene-based materials and structures for energy harvesting with fluids – A review
Tarelho, Joã,o P.G.,Soares dos Santos, Marco P.,Ferreira, Jorge A.F.,Ramos, A.,Kopyl, Svitlana,Kim, Sang Ouk,Hong, Seungbum,Kholkin, Andrei Elsevier 2018 Materials today Vol.21 No.10
<P><B>Abstract</B></P> <P>Graphene and graphene-based systems have recently been recognized as promising platforms for energy harvesting, microelectronic components and energy storage owing to their excellent electrical and thermal conductivity, outstanding mechanical properties, good chemical stability, area adaptability, among other significant properties. Integration of energy harvesting systems relying on the graphene/graphene-based materials in contact with fluids has been emphasized in recent years, as well as their potential impact on electric energy generation for a wide range of applications (e.g. innovative medical devices, advanced electronic systems and highly-efficient transduction systems for renewable energy). This review summarizes, for the first time, major breakthroughs carried out in the scope of energy harvesting exploiting graphene-based material systems (comprising graphene films, graphene grids, graphene membranes, 3D graphene composites and tribological structures) in contact with ionic and non-ionic fluids. Several transduction mechanisms for energy harvesting have been thoroughly analyzed. Energy outputs, materials and structures, substrates, types of fluid, manufacture methodologies, and experimental test methodologies are systematically highlighted in this review. Finally, future research directions and innovative applications of these harvesters are proposed.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>