TY - JOUR
T1 - Novel ultra-sonic boron refinement in distilled water for cost-efficient fabrication of MgB2 bulk ceramic superconductors
AU - Arvapalli, Sai Srikanth
AU - Miryala, Muralidhar
AU - Sakai, Naomichi
AU - Murakami, Masato
AU - Jirsa, Milos
N1 - Funding Information:
This work was partly supported by Shibaura Institute of Technology (SIT) International Research Center for Green Electronics and Grant-in-Aid FD research budget code: 721MA56383 . One of the authors (SSA) acknowledges support from SIT for his post-doctoral fellowship. Participation of M. Jirsa was supported from the Strategy AV21 of the Czech Academy of Sciences , the research program AV21-VP3 “Energy storage in flywheels”.
Publisher Copyright:
© 2022 The Authors
PY - 2022/10/1
Y1 - 2022/10/1
N2 - Cheap commercial boron was refined ultra-sonically in distilled water medium for various durations. X-ray diffraction pattern (XRD) indicated impurity-free nature of ultra-sonically refined boron. Field emission scanning electron microscope (FE-SEM) showed refinement of coarse boron to nanoscale. Rietveld phase fraction analysis on XRD pattern of sintered bulk prepared from ultra-sonically refined boron and Mg powder revealed a complete MgB2 phase formation, with a few impurities of MgO. FWHM (Full width at half maximum) is used to estimate crystallite size and microstrain. Tc,onset was around 38.5 K, with a sharp transition (ΔTc ∼ 0.5 K). Critical current density (Jc) of bulks prepared with B ultra-sonicated in distilled water for 15 and 30 min reached 295 and 305 kAcm−2 at 20 K/self-field, respectively. This is 35% increase in Jc showing the cost efficiency of this novel technique. Transmission electron microscopy of bulk MgB2 revealed a high density of nano-sized grains in the bulk prepared of B ultra-sonicated for 30 min. Flux pining diagrams with peak position at b = 0.2 points to a strong grain boundary pinning. The results prove that ultra-sonic treatment in distilled water results in boron refinement and Jc increase. The role of ultra-sonication medium viscosity in the process of MgB2 grain size refinement and Jc enhancement is elucidated.
AB - Cheap commercial boron was refined ultra-sonically in distilled water medium for various durations. X-ray diffraction pattern (XRD) indicated impurity-free nature of ultra-sonically refined boron. Field emission scanning electron microscope (FE-SEM) showed refinement of coarse boron to nanoscale. Rietveld phase fraction analysis on XRD pattern of sintered bulk prepared from ultra-sonically refined boron and Mg powder revealed a complete MgB2 phase formation, with a few impurities of MgO. FWHM (Full width at half maximum) is used to estimate crystallite size and microstrain. Tc,onset was around 38.5 K, with a sharp transition (ΔTc ∼ 0.5 K). Critical current density (Jc) of bulks prepared with B ultra-sonicated in distilled water for 15 and 30 min reached 295 and 305 kAcm−2 at 20 K/self-field, respectively. This is 35% increase in Jc showing the cost efficiency of this novel technique. Transmission electron microscopy of bulk MgB2 revealed a high density of nano-sized grains in the bulk prepared of B ultra-sonicated for 30 min. Flux pining diagrams with peak position at b = 0.2 points to a strong grain boundary pinning. The results prove that ultra-sonic treatment in distilled water results in boron refinement and Jc increase. The role of ultra-sonication medium viscosity in the process of MgB2 grain size refinement and Jc enhancement is elucidated.
KW - Boron ultra-sonication
KW - Bulk MgB ceramics
KW - Distilled water medium
KW - J enhancement
UR - http://www.scopus.com/inward/record.url?scp=85132857278&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85132857278&partnerID=8YFLogxK
U2 - 10.1016/j.ceramint.2022.06.115
DO - 10.1016/j.ceramint.2022.06.115
M3 - Article
AN - SCOPUS:85132857278
SN - 0272-8842
VL - 48
SP - 28102
EP - 28111
JO - Ceramics International
JF - Ceramics International
IS - 19
ER -