Study of microwave surface resistance of type-II superconductors carrying transport current

We investigate the microwave surface resistance of an infinitely long type-II superconductor in the critical state carrying transport DC current, in the absence and in the presence of external magnetic fields. Calculations include both different cooling processes and various current and field arrangements. Theoretical results in field-cooled sample show that the microwave surface resistance exhibits an initial slow variation followed by a faster one above a threshold current value. This occurs when the current induced magnetic field generates fluxons of opposite directions on the two sample edges. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Effects of Meissner surface current on the microwave surface resistance of type-II superconductors

Influence of the Meissner current on the field-induced variations of the microwave (mw) surface resistance in type-II superconductors is demonstrated to be well reproduced by exploiting different critical state models. Rs(B)/Rn versus Ba curves have been obtained using Kim and exponential type Jc(B) considering Meissner current circulating at the surface of the superconducting specimen. © 2010 Elsevier B.V. All rights reserved.2009/10This study has been supported by Scientific Research Projects Commission of Gaziosmanpasa University (Project No: 2009/10)

Enerji Metodu ile Sertlik Hesaplamaları Üzerine Matematiksel Bir Model

Bu  çalışmada, kuvvet-yerdegiştirme  grafiklerinin altındaki alandan hareketle sertlik hesaplamasını yapabilmek üzere, matematiksel bir model geliştirilmiştir. Bu metod, özellikle, yumuşak numunelerde kuvvet-yüzey etkileşmesinde ortaya çıkan ve hesaplamaları ciddi şekilde etkileyen yüzey egilmeleri sıkıntısını ortadan kaldırmakta ve gerçeğe daha yakın sertlik degerleri vermektedir. </p

Mechanical Characterization of Ruthenocuprates by Nanoindentation Technique

The nanomechanical properties of RuSr 2 RECu 2O8 (RE = Eu, Gd and Ho) prepared by ammonium nitrate melt technique (ANMT) were investigated using nanoindentation technique. The indentation load–displacement curves of the samples were obtained at different peak loads ranging from 10 to 400 mN. Reduced elastic modulus and hardness of the superconductors calculated from loading–unloading curves were peak load dependent, i.e., indentation size effect (ISE). We observed that Ho substitution led to a substantial improvement in mechanical properties of the RuSr2RECu2O8, which was attributed to the strong grain connectivity and dense and less porous structure of RE = Ho sample. © 2014, Springer Science+Business Media New York

Mechanical properties of BSCCO superconductor by oliver-pharr method and work of indentation approach

Polycrystalline superconducting Bi-Pb-Gd-Sr-Ca-Cu-O bulk samples with nominal composition Bi1.7Pb0.3-x Gd x Sr 2Ca3Cu4O12+y (x=0.00,0.01,0.05) were produced by the melt quenching method. The mechanical properties of the samples were characterized by depth sensing indentation technique under different peak loads ranging from 200 to 1800 mN. The experimental data were comparatively analyzed by the Oliver-Pharr method and a work of indentation approach. It was found that the work of indentation approach gave more reliable results because of the reducing pile-up effect. The results implied that both microhardness and reduced elastic modulus increased with increasing Gd substitution. © 2013 Springer Science+Business Media New York.Devlet Planlama ÖrgütüAcknowledgements The authors would like to acknowledge the financial support (Project No.: 2003K120510) by Turkish State Planning Organization (DPT)