Synthesis and Characterization of Nickel Manganite Ceramics by Polymeric Precursors Method

2016 ◽  
Vol 881 ◽  
pp. 123-127 ◽  
Author(s):  
A.C.B. de Oliveira ◽  
D.M.S. Ribeiro ◽  
C.G.P. Moraes ◽  
R.S. Silva ◽  
Nilson Santos Ferreira ◽  
...  

This work presents the synthesis and characterization of NTC ceramic (Negative coefficient Temperature) based on nickel manganite (NiMn2O4) produced by the polymeric precursor method. NiMn2O4 were sintered at 900-1200 °C during 3h to produce the ceramics samples. The effect of sintering temperature on microstructure and electric properties of the NiMn2O4 ceramics was studied by X-ray diffraction (XRD), scanning electron microscopy (SEM) and temperature dependent resistance R(T) measurements. The XRD measurement indicated formation of cubic spinel-type structure of NiMn2O4. The crystallite size (as confirmed by XRD) and the particle size (as confirmed by SEM) increased as the sintering temperature increased from around 18nm (900 °C) to 100nm (1200 °C). All samples showed NTC behavior and, among the studied ceramics, that one sintered at 1200 °C showed lower resistivity value (~103Ω.cm) at room temperature.

2014 ◽  
Vol 602-603 ◽  
pp. 19-22 ◽  
Author(s):  
Lin Qiang Gao ◽  
Hai Yan Chen ◽  
Zhen Wang ◽  
Xin Zou

Nanoscale LiTaO3 powders with perovskite structure were synthesized using the solvothermal technique with glycol as solvent at 240°C for 12h. The powders were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). XRD was used to elucidate room temperature structures using Rietveld refinement. The powders were pure single pervoskite phase with high crystallinity. FESEM and TEM were used to determine particle size and morphology. The average LiTaO3 grain size was estimated to be < 200nm, and TEM images indicated that LiTaO3 particles had a brick-like morphology. In addition, the effect of the temperature on the LiTaO3 power characterisitics was also detailed studied.


2020 ◽  
Vol 10 (2) ◽  
pp. 123-126
Author(s):  
Debasish Aich ◽  
Pijus Kanti Samanta ◽  
Satyajit Saha ◽  
Tapanendu Kamilya

Background: Iron oxide (γ-Fe2O3) nanoparticles have been prepared by a simplified coprecipitation method. Methods: X-ray diffraction peaks of the prepared nanoparticles match well with the characteristic peaks of crystalline g-Fe2O3 as per JCPDS data (JCPDS Card No. 39-1346) and absorption peak at 369 nm along with band gap 2.10 eV suggesting the formation of (γ-Fe2O3) nanoparticles. Results: The γ-Fe2O3 nanoparticles are spherical in nature with a diameter around ~10 nm. Conclusion: The crystalline g-Fe2O3 nanoparticles exhibit excellent super-paramagnetic behavior not only at room temperature (300K) but also at a temperature as low as 100K.


2011 ◽  
Vol 66 (2) ◽  
pp. 107-114 ◽  
Author(s):  
Stephanie C. Neumair ◽  
Johanna S. Knyrim ◽  
Oliver Oeckler ◽  
Reinhard Kaindl ◽  
Hubert Huppertz

The cubic iron hydroxy boracite Fe3B7O13OH・1.5H2O was synthesized from Fe2O3 and B2O3 under high-pressure/high-temperature conditions of 3 GPa and 960 °C in a modified Walker-type multianvil apparatus. The crystal structure was determined at room temperature by X-ray diffraction on single crystals. It crystallizes in the cubic space group F4̄3c (Z = 8) with the parameters a = 1222.4(2) pm, V = 1.826(4) nm3, R1 = 0.0362, and wR2 = 0.0726 (all data). The B-O network is similar to that of other cubic boracites.


2009 ◽  
Vol 67 ◽  
pp. 227-232 ◽  
Author(s):  
Gurpreet Singh ◽  
Amrish Panwar ◽  
Anjan Sil ◽  
Sudipto Ghosh

Nanocrystalline LiMn2O4 powder was synthesized by sol-gel method using citric acid as a chelating agent. The powders were characterized by X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM), Differential scanning calorimetry (DSC), Differential thermal analysis (DTA), Impedance spectroscopy (IS) and Electrochemical measurements. The powder particles having slight agglomeration characteristics were found to have prismatic morphology and a wider size distribution from 50 nm to 200 nm, which provides good packing density of the material. The electrical conductivity of the powder at room temperature is in the order of ~10-5 S/cm. The structural stability of LiMn2O4 cubic spinel over the temperature range of battery operation was assessed. Electrochemical performance of the material shows a discharge capacity of ~130 mAh/gm.


2012 ◽  
Vol 486 ◽  
pp. 309-312
Author(s):  
Rong Wu ◽  
Le Tian Tao ◽  
Ji Kang Jian

Mixed solvent of ethylenediamine (EDA) and ethylene glycol (EG) using MnCl4H2O, and (NH2)2CS as precursors was used to synthesize α-MnS micronsized architectures. Optimal α-MnS crystals were successfully grown from a mixed solvent of EDA:EG with a volume ratio of 1:1, reaction temperature of 140-180 °C and maintained for 6h. X-ray diffraction (XRD), scanning electron microscopy (SEM) was employed to characterize the structure and morphology of the product. The results show that the morphologies of α-MnS are found to be temperature dependent.


2016 ◽  
Vol 869 ◽  
pp. 884-889
Author(s):  
Nadia Sueli Vieira Capanema ◽  
Alexandra A.P. Mansur ◽  
Herman Sander Mansur

The need for obtaining new materials to replace human body parts that were destroyed or damaged led scientists from different areas of research for developing new biomaterials. Thus, the aim of this work was the synthesis and characterization of niobium-modified apatite bioceramics. Calcium phosphates (CaP) were synthesized with niobium partially replacing calcium sites using aqueous precipitation route at room temperature. The bioceramics, with and without Nb incorporation, were characterized by scanning electron microscopy (SEM) coupled with energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) as prepared and after heat treatments The results indicated that Nb was incorporated in the apatite structure promoting morphological and structural changes in the ceramic properties.


2014 ◽  
Vol 979 ◽  
pp. 232-235 ◽  
Author(s):  
C. Wichasilp ◽  
S. Introng ◽  
W. Maithong ◽  
N. Kruea-In ◽  
C. Kruea-In

In this research, the effects of ZnO nanoparticles additive on crystallization behavior, dielectric and ferroelectric properties of Bi0.5(Na0.81,K0.19)0.5TiO3 ceramics were investigated. The samples were synthesized by solid state reaction technique, where powders were calcined at 850 °C for 4 h and ceramics were sintered at 1100-1150 °C for 4 h. Phase formation was determined by X-ray diffraction technique (XRD). The X-ray diffraction analysis of the ceramics suggests that all samples exhibited a perovskite structure. The dielectric properties under room temperature and various temperatures were also determined. Dielectric measurement data showed that the additive influenced dielectric constant and dielectric loss. Furthermore, the hysteresis loop behaviors slightly changed with increasing the nanoparticles contents.


2004 ◽  
Vol 817 ◽  
Author(s):  
Fushan Wen ◽  
Jiesheng Chen ◽  
Jin Hyeok Kim ◽  
Taeun Kim ◽  
Wenlian Li

AbstractA new 3-dimensional zinc carbonate Zn(NH3)CO3 has been synthesized from a glycol system with urea and zinc acetate as raw materials. The crystal structure and photoluminescent properties have been investigated using X-ray diffraction, smart CCD and FL. The compound had an orthorhombic system with space group of Pna21 with M = 142.41, a = 9.1449(18) Å, b = 7.5963(15) Å, c = 5.4982(11) Å, V = 381.95(13) Å3, Z = 4, R = 0.0285 and RW = 0.0745. The NH3 and CO32- were connected through the Zn-N bond and Zn-O bond in the symmetric unit. Photoluminescent property was observed in the compound at room temperature and the exited and emission peaks were located at about 350 nm and 426 nm, respectively.


2011 ◽  
Vol 236-238 ◽  
pp. 2183-2186
Author(s):  
Yan Li ◽  
Yun Ling Zou ◽  
Yan Yan Hou

A novel missile-like ZnO structure has been synthesized solvo-thermally in absolute alcohol using Zn(NO3)2·6H2O and NaOH as starting materials, and characterized by Scanning Electron Microscopy, powder X-ray diffraction and room temperature photoluminescence. The missile-like ZnO crystal, with a wurtzite structure and a blue-green emission at 459 nm, is made up of two symmetrical rocket-like crystals possessing a prismatic base and a hexagonal pyramid linking with each other along plane (0001(_)).


2018 ◽  
Vol 2 (1) ◽  
pp. 7
Author(s):  
S Chirino ◽  
Jaime Diaz ◽  
N Monteblanco ◽  
E Valderrama

The synthesis and characterization of Ti and TiN thin films of different thicknesses was carried out on a martensitic stainless steel AISI 410 substrate used for tool manufacturing. The mechanical parameters between the interacting surfaces such as thickness, adhesion and hardness were measured. By means of the scanning electron microscope (SEM) the superficial morphology of the Ti/TiN interface was observed, finding that the growth was of columnar grains and by means of EDAX the existence of titanium was verified.  Using X-ray diffraction (XRD) it was possible to observe the presence of residual stresses (~ -3.1 GPa) due to the different crystalline phases in the coating. Under X-ray photoemission spectroscopy (XPS) it was possible to observe the molecular chemical composition of the coating surface, being Ti-N, Ti-N-O and Ti-O the predominant ones.


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