Frequency dependence and fuel effect on optical properties of nano TiO<sub>2</sub>-based structures

Ghasemifard, Mahdi; Ghamari, Misagh; Iziy, Meysam

doi:10.1142/s021798491650247x

Cited by 3 publications

(1 citation statement)

References 26 publications

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“…Xia等 [12] 采用溶液铸造法制备了直接与钯阳离子膜交联的壳聚糖 (chitosan, CS), 通过常规 CDB技术研究了与自由体积相关的亚纳米级分子堆积和 CS-cr-PM 中自由体积纳米孔的化学环境相关信息. Cao等 [60] 也制备了CS-Fe 3 O 4 纳米复合材料和Cu-CS材料, 并采用CDB技术证明了带正电的金属离子和CS分子中的活性基团子对正电子湮没的局部化学环境有很大影响.…”

Section: 同时离子注入也能够导致材料产生晶格畸变、开unclassified

Research progress of coincidence Doppler broadening of positron annihilation measurement technology in materials

Ye,

Zhang,

Zhang

et al. 2024

Acta Phys. Sin.

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Positron annihilation technique is an atomic-scale characterization method used to analyze the defects and microstructure of materials, which is extremely sensitive to open volume defects. By examining the annihilation behaviour of positrons and electrons in open volume defects, local electron density and atomic structure information around the annihilation site can be obtained, such as the size and concentration of vacancies, vacancy clusters, etc. In recent years, positron annihilation spectroscopy has evolved into a superior tool for characterizing features of material compared to conventional methods. The coincident Doppler broadening technique provides unique advantages for examining the local electronic structure and chemical environment (elemental composition) information around defects due to its effectiveness describe high momentum electronic information. The low momentum portion of the quotient spectrum indicates the Doppler shift generated by the annihilation of valence electrons near the vacancy defect. Changes in the peak amplitudes and positions of the characteristic peaks in the high momentum region can reveal elemental information around the positron annihilation point. The physical mechanism of element segregation, the structural features of open volume defects and the interaction between interstitial atoms and vacancy defects are well-developed in coincidence Doppler broadening technology. In recent years, based on the development of Doppler broadening technology, the sensitivity of slow positron beam coincidence Doppler broadening technology with adjustable energy has been significantly enhanced at a certain depth. Significantly, slow positron beam techniques can offer surface, defect, and interface microstructural information as a function of material depth. It compensates for the fact that the traditional coincidence Doppler broadening technique can only define the overall defect information. Positron annihilation technology has been applied to the fields of second phase evolution in irradiated materials, hydrogen/helium effect, and free volume in thin films, among others, as a result of the continuous development of slow positron beam and the improvement of various experimental test methods based on slow positron beam. In this paper, the basic principles of the coincidence Doppler broadening technique are briefly discussed, and the application research progress of the coincidence Doppler broadening technique in various materials is reviewed by combining the reported developments: 1) the evolution behaviour of nanoscale precipitation in alloys; 2) the interaction between lattice vacancies and impurity atoms in semiconductors; 3) the changes of oxygen vacancy and metal cation concentration in oxide material. In addition, coincidence Doppler broadening technology has been steadily implemented to estimate and quantify the size, quantity, and distribution of free volume holes in polymers.

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Section: 同时离子注入也能够导致材料产生晶格畸变、开unclassified

Research progress of coincidence Doppler broadening of positron annihilation measurement technology in materials

Ye,

Zhang,

Zhang

et al. 2024

Acta Phys. Sin.

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Frequency and composition dependency of optical and dielectric properties of PMMA/boehmite nano-hybrid prepared via facile aqueous one-pot process

Ghamari

Farzi

2017

Mod. Phys. Lett. B

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Optical properties of PMMA/boehmite nano-hybrid synthesized directly from their relevant precursors via facile aqueous one-pot process is studied. Silane coupling agent was applied to make compatible chemically the organic–inorganic counterparts. The chemical bond of SiOAl as the main link between organic and inorganic moieties was confirmed by Fourier transforms infrared (FTIR) spectra. The chemical bond of Si–O–Al as the main link between organic and inorganic moieties. Determining the refractive and absorption index, real and imaginary parts of dielectric constant, energy loss function, and their distribution for PMMA/boehmite nano-hybrid as a function of boehmite loading was assessed in the range of 12–120 THz using FTIR data and Kramers–Kronig relations. The inorganic/organic weight ratio varied from 0.7% to 5% and its impact on optical features was evaluated. It was demonstrated that the optical features of hybrids are frequency-dependent and less affected from boehmite incorporation.

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Bond length (Ti–O) dependence of nano ATO₃-based (A = Pb, Ba, Sr) perovskite structures: Optical investigation in IR range

2018

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In the current study, ABO3 (A = Pb, Ba, Sr and B = Ti) perovskite structures are produced by the auto-combustion route by using citric acid (CA) and nitric acid (NA) as fuel and oxidizer. The X-ray diffraction (XRD) patterns confirmed the perovskite nanostructure with cubic, tetragonal, and rhombohedral for SrTiO3, PbTiO3, and BaTiO3, respectively. Using Scherrer’s equation and XRD pattern, the average crystallite size of the samples were acquired. The effect of Ti–O bond length on the structure of the samples was evaluated. The type of structures obtained depends on Ti–O bond length which is in turn influenced by A[Formula: see text] substitutions. Microstructural studies of nanostructures calcined at 850[Formula: see text]C confirmed the formation of polyhedral particles with a narrow size distribution. The values of optical band gaps were measured and the impact of A[Formula: see text] was discussed. The optical properties such as the complex refractive index and dielectric function were calculated by IR spectroscopy and Kramers–Kronig (K–K) relations. Lead, as the element with the highest density as compared to other elements, changes the optical constants, remarkably due to altering titanium and oxygen distance in TO6 groups.

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Frequency dependence and fuel effect on optical properties of nano TiO₂-based structures

Cited by 3 publications

References 26 publications

Research progress of coincidence Doppler broadening of positron annihilation measurement technology in materials

Research progress of coincidence Doppler broadening of positron annihilation measurement technology in materials

Frequency and composition dependency of optical and dielectric properties of PMMA/boehmite nano-hybrid prepared via facile aqueous one-pot process

Bond length (Ti–O) dependence of nano ATO₃-based (A = Pb, Ba, Sr) perovskite structures: Optical investigation in IR range

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Frequency dependence and fuel effect on optical properties of nano TiO2-based structures

Cited by 3 publications

References 26 publications

Research progress of coincidence Doppler broadening of positron annihilation measurement technology in materials

Research progress of coincidence Doppler broadening of positron annihilation measurement technology in materials

Frequency and composition dependency of optical and dielectric properties of PMMA/boehmite nano-hybrid prepared via facile aqueous one-pot process

Bond length (Ti–O) dependence of nano ATO3-based (A = Pb, Ba, Sr) perovskite structures: Optical investigation in IR range

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Frequency dependence and fuel effect on optical properties of nano TiO₂-based structures

Bond length (Ti–O) dependence of nano ATO₃-based (A = Pb, Ba, Sr) perovskite structures: Optical investigation in IR range