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Investigation of Structural, Electron Transport, and
Microwave Absorption Properties of La0.4(Ca0.4Sr0.2)MnO3
Hyeyon Kim1, Christopher Schayer2, Dr. L.L Henry3 1Vanderbilt University
2Louisiana State University 3Southern University
!
Introduc)on
• LaMnO3 – Ceramic – Perovskite crystal
structure
• Doped LaMnO3 results in: – Colossal
magnetoresistance
La Mn
O
Synthesis
• Grind compounds • Calcina)on – Removes CO2 and excess O2
• Sintering – Pressure and heat to form a solid mass
Compound Rounded
La2O3 2.1 g
SrCO3 1 g
CaCO3 1.3 g
MnO2 2.8 g
Calcina)on
RT RT
12 hours
1300 ℃
Sintering
12 hrs
1250 ℃
1500 ℃
RT RT
1 hr
Sintered Pellets
• Hard, shiny, slightly magne)c
Making the thick film
+
= Glass slide
Clear nail polish
Sample
Silver paint
5.33mm X 2.54mm X 0.30 mm
Magnetoresistance
XRD on Calcined Sample
XRD on Sintered Sample
0
600
400
200
800
1000
1200
Intensity
(cou
nts)
20.000 60.000 40.000 80.000 2theta (deg.)
2theta (deg.) 20.000 40.000 60.000 80.000
0
200
400
600
800
1000
1200
Intensity
(cou
nts)
Microwave Absorp)on
Magnetoresistance (bulk)
0
0.2
0.4
0.6
0.8
1
0 1 2 3
Resistan
ce (Ω
)
Magne:c Field (T)
Trial 1
0
0.0002
0.0004
0.0006
0.0008
0.001
0 1 2 3
Resistan
ce (M
Ω)
Magne:c Field (T)
Trial 2
30.63% decrease
Magnetoresistance (powder)
0.053
0.054
0.055
0.056
0.057
0 1 2 3
Resistan
ce (M
Ω)
Magne:c Field (T)
Trial 1
0.0458
0.046
0.0462
0.0464
0.0466
0.0468
0 1 2 3
Resistan
ce (M
Ω)
Magne:c Field (T)
Trial 2
4.73% decrease 1.36% decrease
Conclusion
• Increased magne)c field caused a small decrease in electrical resistance
• Future work – Magnetoresistance of bulk and powder samples exposed to: • Varying temperatures • Ultraviolet rays
Acknowledgments
• This work was funded by the Louisiana Board of Regents, through LASIGMA [Award Nos. EPS-‐1003897, NSF (2010-‐15)-‐RII-‐SUBR, and HRD-‐1002541].
References • Kornfield, M.C.; Wicker, S.; Henry, L.L. “Synthesis and structural characteriza)on of La.5Ca.
25Sr.25MnO3.” • Wang, Zhou; Zhao, Guang-‐Lin. “Microwave Absorp)on Proper)es of Carbon Nanotubes-‐
Epoxy Composites in a Frequency Range of 2-‐20 GHz.” Open Journal of Composite Materials 3 (2013); 17-‐23.
• Ramirez, A.P. “Colossal magnetoresistance.” J. Phys.: Condens. Ma9er 9 (1997): 8171-‐8199. • Markovich, V.; Jung, G.; Fita, I.; Mogilyansky, D; et al. “Magnetotransport proper)es of
ferromagne)c LaMnO3+δ nano-‐sized crystals.” Journal of Magne<sm and Magne<c Materials 322 (2010): 1311-‐1314.
• Raziano, William; Franklin, Jermain; Henry, Larry. “Ultraviolet Radia)on effects on the electrical resis)vity of some La(Ca/Sr)MnO materials.” Proceedings of Louisiana EPSCoR RII La-‐SiGMA 2014 Symposium.
• Huang, Yun-‐Hui; Xu, Zhi-‐Gang; Yan, Chun-‐Hua; et al. “Sop chemical synthesis and transport proper)es of La0.7Sr0.3MnO3 granular perovskites.” Solid State Communica<ons 114 (2000): 43-‐47.
• Bristowe, N.C.; Varignon, J; et al. “Ferromagne)sm induced by entangled charge and orbital orderings in ferroelectric )tante perovskites.” Nat. Commun. 6 (2015): 6677
Ques)ons?