Junaid, Bushiri M; Vinod, R; Sajan, P; Sreekumar, Rajappan Achary; Vicente, Muñoz-Sanjosé(Wiley, February 11, 2014)
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Abstract:
The magnetic properties of Mn-doped ZnO (ZnO:Mn) nanorods
grown by hydrothermal process at a temperature of 200 8C
and a growth time of 3 h have been studied. The samples were
characterized by using powder X-ray diffraction with Rietveld
refinement, scanning electron microscopy, energy-dispersive
X-ray analysis and SQUID magnetometry. Mn (3 wt%) and
(5 wt%)-doped ZnO samples exhibit paramagnetic and
ferromagnetic behavior, respectively, at room temperature.
The spin-glass behavior is observed from the samples with
respect to the decrease of temperature. At 10 K, both samples
exhibit a hysteresis loop with relatively low coercivity. The
room-temperature ferromagnetism in 5 wt% Mn-doped ZnO
nanorods is attributed to the increase in the specific area of grain
boundaries, interaction between dopant Mn2þ ions substituted
at Zn2þ site and the interaction between Mn2þ ions and Zn2þ
ions from the ZnO host lattice
Description:
Phys. Status Solidi A 211, No. 5, 1155–1161 (2014)
ZnO micro particles in the range 0.4-0.6 μm were synthesized by microwave irradiation
method. The XRD analysis reveals that the sample is in the wurtzite phase with orientation
along the (101) plane. SAED pattern of the sample reveals the single crystalline nature of
the micro grains. TEM images show the formation of cylindrical shaped ZnO micro
structures with hexagonal faces. The optical phonon modes were slightly shifted in the
Raman spectrum,attributed to the presence of various crystalline defects and laser induced
local heating at the grain boundaries. A broad transmission profile was observed in the
FTIR spectrum from 1550-3400 cm-1 which falls in the atmospheric transparency window
region. PL spectrum centered at 500 nm with a broad band in the region 420-570 nm
comprised of different emission peaks attributed to transition between defect levels.
Various emission levels in the sample were expliained with a band diagram
Description:
Journal of Optoelectronics and Biomedical Materials Vol. 4, Issue 1, January-March 2012, p. 1 - 7
Junaid, Bushiri M; Gopakumar, V; Vaidyan, V K(January 17, 2013)
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Abstract:
ZnO thin films were coated on amorphous glass substrate at various temperatures in the
range 160-500 0C by spray pyrolysis method. The as deposited films were characterised by
using XRD and SEM. Wurtzite phase of ZnO was formed at a substrate temperature of
400 0C, highly oriented (002) phase was developed with respect to increase of substrate
temperature from 450 to 500 0C. Morphological and growth mode of these films were
analyzed with respect to structural orientation of films from wurtzite to highly (002)
oriented phase. Present study reveals that substrate temperature was one of the important
parameters which determine the crystalline quality, population of defects, grain size,
orientation and morphology of the films
Description:
Journal of Optoelectronics and Biomedical Materials Vol. 5 Issue 1, January - March 2013 p. 1 - 8