Effect Of Thermal Treatment Temperature Research Articles

Preparation and characterization of LaNiO 3 nanocrystals

Ten to twenty-three nanometers of LaNiO 3 nanocrystals were prepared by glycine combustion method using nickel nitrate and lanthanum nitrate as raw materials, glycine as gelating agent and fuel. The preparation process was monitored by thermogravimetric analysis and differential thermal analysis (TG-DTA); the final products were characterized by X-ray diffraction (XRD), electron diffraction (ED), high-resolution transmission electron microscopy (HRTEM) and scanning electron microscopy (SEM). The effect of thermal treatment temperature on crystal size of the nanocrystals was studied and the activation energy of LaNiO 3 nanocrystals formation during calcinations was calculated to be 41.9 kJ/mol. Moreover, the interplanar distances of d 110 and d 101 measured from the TEM images were 0.272 and 0.363 nm, respectively, coinciding with the theoretical values.

Effects of Sn dopant on the photoinduced charge property and photocatalytic activity of TiO2 nanoparticles

In this paper, Sn-doped TiO2 nanoparticles were prepared by a sol–gel method, and also were characterized by X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), infrared spectrum (IR), ultraviolet–visible diffuse reflection spectrum (UV–vis DRS), photoluminescence spectrum (PL), surface photovoltage spectroscopy (SPS) and electrical field induced surface photovoltage spectroscopy (EFISPS). The sample activity was evaluated by photocatalytic oxidation reactions of phenol solution. The effects of thermal treatment temperature and Sn amount on photoinduced charge property, mainly involving charge separation and bound excitons resulting from surface states, and photocatalytic activity of TiO2 nanoparticles were principally investigated. The results show that an appropriate calcination temperature and Sn dopant amount can greatly enhance the SPS responses of TiO2 nanoparticles related not only to the band–band transitions but also to the bound excitons, and obviously weaken the PL signal, while the photocatalytic activity remarkably raises. These demonstrate that the separation rate of photoinduced charges of TiO2 nanoparticles can be effectively improved by doping Sn, which is responsible for the obvious increase in the photocatalytic activity. Moreover, the existence of bound excitons related to surface states also favor the photocatalytic activity. In addition, it can be found that the SPS responses related to the bound excitons could easily exhibit in the TiO2 sample consisting of much of anatase and little of rutile, which is possibly ascribed to the heterojunction between the anatase and rutile phase.

Temperature Dependence of Nickel Stabilization in Inorganic Oxide Matrices

Scanning electron microscopy, X‐ray diffractometry, X‐ray absorption spectroscopy, and other means are used to investigate the effect of thermal treatment temperature, 105–1100 °C, on the immobilization of nickel (Ni) by the inorganic oxides of latosol. Ni is more firmly immobilized by the latosol with increasing temperature. Spectral analyses indicate that a shoulder toward the edge‐jump appears in the spectra of X‐ray absorption near‐edge structure for the samples heated at 900 and 1100 °C. Moreover, the intensity of the main peak at the edge increases with higher temperature; this information indicates the distortion of the divalent nickel [Ni(II)] environment in the samples heated at 900 and 1100 °C. Nevertheless, the distortion is absent from the samples heated at 105 and 500 °C. The fact of the distortion of the Ni(II) environment suggests the occurrence of a chemical reaction between the Ni compound and the inorganic matrices of the latosol soil during the heating process at 900 and 1100 °C. In addition, the extended X‐ray absorption fine structure results correspond well to the X‐ray absorption near‐edge structure results; the former are supportive of the occurrence of a distorted Ni(II) environment in the samples heated at 900 and 1100 °C. The wet‐chemistry results show that the samples heated at 900–1100 °C leach less Ni than the 105–500 °C samples do. The change of the Ni environment is related to the observation that less Ni is leached from the samples heated at 900–1100 °C. Furthermore, the pore closing phenomenon is observed only in the 1100 °C sample; this phenomenon corresponds with the fact that the 1100 °C sample leaches less Ni than the 900 °C sample does.

Effect of Thermal Treatment Temperature on the Crystallinity and Morphology of LiTaO3 Thin Films Prepared from Polymeric Precursor Method

Lithium tantalate thin films (LiTaO3) with (50:50) stoichiometry were prepared by spin coating method using a polymeric organic solution. The films were deposited on silicon (100) substrates with 4 layers. The substrates were previously cleaned and then the solution of lithium tantalate was deposited by adjusting the speed at 5000 rpm. The thin films deposited were thermally treated from 350 to 600∘C for 3 hours in order to study the influence of the thermal treatment temperature on the crystallinity, microstructure, grain size and roughness of the final film. X-ray diffraction (XRD) results showed that the films are polycrystalline and secondary phases free. The thickness of films was observed by scanning electron microscopy (SEM). The atomic force microscopy (AFM) studies showed that the grain size and roughness are strongly influenced by thermal treatment.

Formation of NiFe 2O 4 nanoparticles by mechanochemical reaction

Preparation of nanosized NiFe 2O 4 particles by mechanochemical reaction(NiO+α-Fe 2O 3) and subsequent thermal treatment was investigated using X-ray diffraction (XRD). Thermal treatment of the as-milled powder at 700 °C for 1 h led to the formation of NiFe 2O 4 nanoparticles with an average crystal size of about 23 nm. Effect of thermal treatment temperature on the crystal size of the nanoparticles was studied. The mechanism of nanoparticles growth was primarily discussed. The activation energy of NiFe 2O 4 nanoparticle formation during calcination was calculated to be 16.6 kJ/mol.

FBAR 응용을 위한 ZnO 압전 박막의 증착 특성에 관한 연구

ZnO thin films were deposited on Al and Pt electrodes by an RF reactive sputtering system for the fabrication of FBAR (film bulk acoustic wave resonator), and the effect of thermal treatment temperature on their c-axis preferred orientation was investigated. SEM experiments show that columnar structure of ZnO thin films were grown with c-axis normal to electrode material, and XRD experiments show that both ZnO films were grown with (002) plane preferred orientation, but larger diffraction peak was observed with Pt electrode. The peak intensity increased with higher thermal treatment temperature, but c-axis preferred orientation was diminished. The surface roughness of Al thin film was higher than that of Pt, and these affect the surface roughness of ZnO film deposited on the electrode. Though the preferred orientation with respect to Pt(111) plane was improved with higher thermal treatment temperature, this could not improve the c-axis orientation of ZnO film.

Modification of the adsorptive properties of a betonitic clay

The technological characteristics of a bentonite supplied from Kütahya region were determined by chemical analysis, differential thermal analysis, particle size analysis and x-ray diffraction techniques. The bentonite containing calcium montmorillonite and illite as clay minerals and also a-cristobalite, a non clay mineral was treated thermally between 100°C-1300°C. The changes in the adsorptive properties, such as the specific surface area and specific pore volume, under the effect of thermal treatment temperature, which are determined by the adsorption and desorption of nitrogen at 77K, were discussed. The bentonite was activated by the “wet process” with sulfuric acid at various acid ratios from 10% to 70% in add and clay mixture. The dependency of adsorptive properties of the bentonite on the add ratio by the activation procedure was discussed

Effect of thermal treatment temperature on the structure and properties of carbon fibers

1. It has been shown that the presence of a maximum in the dependence of strength on Young's modulus for carbon fibers made from PAN fiber may be explained by an effect of the process of temperature stress accumulation which takes place under the conditions of isometric heating. The start of this process, which causes a rearrangement of the internal structure of the high-modulus fiber, coincides with the start of the anomalous rise in fiber density.