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Title: Effect of Cu substitution on the magnetic and dielectric properties of La{sub 2}NiMnO{sub 6}

In the continuation of our previous work [Biswal et al., J. Appl. Phys. 115, 194106 (2014)] of biphasic La{sub 2}NiMnO{sub 6} (LNM) prepared via sol-gel technique, here we are reporting the effect of Cu substitution at Ni site of LNM. The powder x-ray diffraction results of La{sub 2}Ni{sub 1−x}Cu{sub x}MnO{sub 6} (x = 0, 0.05, 0.1) confirm the biphasic nature (Pbnm + R-3c) for all samples along with increasing R-3c phase with Cu content in the sample. The temperature variation of magnetization (M) plot shows sharp ferromagnetic transitions of R-3c phase at 285 K, 278 K, and 270 K (obtained from dM/dT plot) and that of Pbnm phase at 165 K, 145 K, and 145 K for x = 0, 0.05, and 0.1, respectively. Weak antiferromagnetic type feature at 25 K (x = 0), is getting pronounced with Cu content in the sample and is now seen at 32 K and 266 K (for x = 0.05) and 32K and 257 K (for x = 0.1). Fitting of Curie-Weiss law in the paramagnetic region of χ{sup −1} vs T plot results slightly lower values of corresponding T{sub c}'s of R-3 c phase (277 K, 270 K, and 260 K), thus manifesting possibility of Griffiths like singularity. The onset temperature of Griffiths singularity occurs at 295 K (x = 0) and 281 K (x = 0.05 and 0.1), such that 295–277 Kmore » in x = 0, 281–270 K in x = 0.05, and 281–260 K in x = 0.1 sample is in Griffith's phase. Temperature dependent dielectric constant (ε{sub r}) shows usual step-like transitions with corresponding relaxation peaks in the dielectric loss (D) part. Cu substitution in LNM makes the entire dielectric plot shifts towards lower temperature such that high temperature plateau of step transition becomes evident. The peaks in dielectric loss for all compositions are found to obey Arrhenius law with activation energies 237 meV, 207 meV, and 180 meV for x = 0, 0.05, and 0.1, respectively.« less
Authors:
; ;  [1] ; ;  [2]
  1. Department of Physics and Astronomy, National Institute of Technology, Rourkela, Odisha 769008 (India)
  2. UGC DAE Consortium for Scientific Research, Mumbai Centre, BARC, Mumbai 400085 (India)
Publication Date:
OSTI Identifier:
22409980
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 117; Journal Issue: 17; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; ACTIVATION ENERGY; ANTIFERROMAGNETISM; COPPER COMPOUNDS; CURIE-WEISS LAW; DIELECTRIC MATERIALS; LANTHANUM COMPOUNDS; MAGNETIC PROPERTIES; MAGNETIZATION; MANGANATES; NICKEL COMPOUNDS; ORTHORHOMBIC LATTICES; PARAMAGNETISM; PERMITTIVITY; POWDERS; RELAXATION; RELAXATION LOSSES; SOL-GEL PROCESS; TEMPERATURE DEPENDENCE; X-RAY DIFFRACTION