Investigation on the Optical, Electrical and Dielectric Properties of La0.7Ca0.3MnO3 (LCMO) Via. Different Routes: A Comparative Analysis of Micro and Nanoparticles

2020 ◽  
Vol 978 ◽  
pp. 390-396
Author(s):  
Bandana Panda ◽  
Dhrubananda Behera

In the proceeding way of material research in the field of manganites, LCMO micro and nanoparticles are synthesized via. the solid-state reaction route, glycine-nitrate combustion method respectively. The phase confirmation is done by XRD, FT-IR technique and the surface morphology viewed by Scanning Electron Microscope (SEM). The energy band gap obtained from Diffuse Reflectance Spectroscopy clearly suggests that the band gap of nanoparticles (2.06eV) is larger than that of the microparticles (1.58eV). Both samples comprise of wide band-gap semiconductor, so the refractive index is calculated using Herve and Vandamme relation. The impedance spectroscopy and dielectric properties of the two samples are studied from room temperature to 100oC over the frequency range 102-106 Hz. The Cole-Cole plot of impedance is fitted using the RC-Circuit R(QgRg)(QgbRgb)(CRin). The dielectric property is found to be enhanced in nanoparticles as compared to the microparticles. The findings suggest the nanoparticles be promising candidates in the field of high frequency devices as compared to micro.

2015 ◽  
Vol 2015 ◽  
pp. 1-11 ◽  
Author(s):  
Ying Huang ◽  
Chang-Feng Yan ◽  
Chang-Qing Guo ◽  
Shi-Lin Huang

A series of new two semiconductor catalysts, Co3O4/CeO2, were prepared by glycine-nitrate combustion method for photocatalytic reduction of carbon dioxide to produce methanol and ethanol under visible light (λ>400 nm) irradiation. The catalysts were characterized by BET, UV-vis spectra, XRD, SEM, PL, and XPS and the results indicated that the catalyst with 5 wt.% of Co3O4has the highest yield among all kinds of tests with the methanol yield of 1.52 μmol·g−1·h−1and the ethanol yield of 4.75 μmol·g−1·h−1, which are about 2.34 and 1.71 times as large as those of CeO2. However, methanol and ethanol can hardly be detected for Co3O4under the same condition because of its too narrow band gap. The improvement of the photoreduction activity of Co3O4doped CeO2was caused by the separation of electron-hole pairs of Co3O4/CeO2and charge transfer between Co3O4and CeO2, mimicking the Z-scheme in photosynthesis.


Author(s):  
Joanna L. Batstone

Interest in II-VI semiconductors centres around optoelectronic device applications. The wide band gap II-VI semiconductors such as ZnS, ZnSe and ZnTe have been used in lasers and electroluminescent displays yielding room temperature blue luminescence. The narrow gap II-VI semiconductors such as CdTe and HgxCd1-x Te are currently used for infrared detectors, where the band gap can be varied continuously by changing the alloy composition x.Two major sources of precipitation can be identified in II-VI materials; (i) dopant introduction leading to local variations in concentration and subsequent precipitation and (ii) Te precipitation in ZnTe, CdTe and HgCdTe due to native point defects which arise from problems associated with stoichiometry control during crystal growth. Precipitation is observed in both bulk crystal growth and epitaxial growth and is frequently associated with segregation and precipitation at dislocations and grain boundaries. Precipitation has been observed using transmission electron microscopy (TEM) which is sensitive to local strain fields around inclusions.


Author(s):  
Raquel Caballero ◽  
Leonor de la Cueva ◽  
Andrea Ruiz-Perona ◽  
Yudenia Sánchez ◽  
Markus Neuschitzer ◽  
...  

2013 ◽  
Vol 28 (6) ◽  
pp. 671-676 ◽  
Author(s):  
Yu-Qing ZHANG ◽  
Li-Li ZHAO ◽  
Shi-Long XU ◽  
Chao ZHANG ◽  
Xiao-Ying CHEN ◽  
...  

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