Temperature dependence anomalous dielectric relaxation in Co doped ZnO nanoparticles

Journal Article · Sat Dec 15 04:00:00 EST 2012 · Materials Research Bulletin

DOI:https://doi.org/10.1016/J.MATERRESBULL.2012.08.079· OSTI ID:22215664

Ansari, Sajid Ali; Nisar, Ambreen; Fatma, Bushara ^[1]; Khan, Wasi ^[1]; Chaman, M. ^[1]; Azam, Ameer ^[1]; Naqvi, A. H. ^[1]

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1. Centre of Excellence in Materials Science (Nanomaterials), Department of Applied Physics, Z.H. College of Engg. and Tech., Aligarh Muslim University, Aligarh 202 002 (India)

Graphical abstract: Display Omitted Highlights: ► We prepared Co doped ZnO by facile gel-combustion method. ► Studied temperature dependent dielectric properties in detail. ► Relaxation time shifts toward the higher temperature as increase in Co content. ► SEM analysis shows formation and agglomeration of nanoparticles. ► Dielectric constants, loss and ac conductivity increases with rise in temperature. ► The dielectric constant, loss and ac conductivity decreases as Co ion increases. -- Abstract: We have reported temperature and frequency dependence of dielectric behavior of nanocrystalline Zn{sub 1−x}Co{sub x}O (x = 0.0, 0.01, 0.05 and 0.1) samples prepared by gel-combustion method. The synthesized samples were examined by X-ray diffraction (XRD), scanning electron microscopy (SEM) and LCR-meter, respectively. The XRD analysis reveals that ZnO has a hexagonal (wurtzite) crystal structure. The morphology and size of the nanoparticles (∼10–25 nm) were observed by SEM for 5% Co doped ZnO sample. In dielectric properties, complex permittivity (ε{sup *} = ε′ − jε″), loss tangent (tan δ) and ac conductivity (σ{sub ac}) in the frequency range 75 kHz to 5 MHz were analyzed with temperature range 150–400 °C. The experimental results indicate that ε′, ε″, tan δ and σ{sub ac} decreases with increase in frequency and temperature. The transition temperature as obtained in dispersion curve of dielectric constant shifts toward higher temperature with increase Co content.

• OSTI ID: 22215664
• Journal Information: Materials Research Bulletin, Journal Name: Materials Research Bulletin Journal Issue: 12 Vol. 47; ISSN MRBUAC; ISSN 0025-5408
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
77 NANOSCIENCE AND NANOTECHNOLOGY
CRYSTAL STRUCTURE
CRYSTALS
DIELECTRIC MATERIALS
DOPED MATERIALS
FREQUENCY DEPENDENCE
GELS
NANOSTRUCTURES
PERMITTIVITY
RELAXATION TIME
SCANNING ELECTRON MICROSCOPY
SYNTHESIS
TEMPERATURE DEPENDENCE
TRANSITION TEMPERATURE
X-RAY DIFFRACTION
ZINC OXIDES