الفهرس 
Chapter 1: Introduction and Literature ReviewOnly 14 pages are availabe for public view
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Abstract
Glasses have been widely developed due to their diverse and interesting optical properties, making them particularly interesting materials for optical and micro-optical elements, such as gratings, optical recording media, fiber optics and waveguided devices in integrated optics since they exhibit a good transparency in the infrared region, especially at the telecommunication Wavelengths at 1.30 and 1.55 μ m.
The purpose of this thesis is to provide some insight into the structural, thermal analysis and optical properties of (Se90Te10)95X5, (X= In, Sb, Zn and S) are set by melt-quench procedure. The incorporated elements were selected as examples from basic metal, semimetal, Transition metal and nonmetal groups, respectively. Films of these glasses were evaporated onto glass substrates under vacuum of 10-5 Torr.
Chapter 1: gives an introduction of the current work and literature review of the former work
Chapter 2: provides some sample preparation details, vacuum evaporation techniques, characterization of samples, such as structural, thermal analysis and optical properties
Chapter 3: gives the theoretical approaches to the present work.
Chapter 4: presents physical behavior of the prepared (Se90Te10)95X5, (X= S, Zn, In, Bi and Sb) bulk system and then their structure investigations and thermal properties.
Chapter 5: gives the optical properties of the thin films of (Se90Te10)95X5, (X= S, Zn, In, Bi and Sb)
Chapter 6: presents the abstract and conclusion of the present work.
In the present work X-ray diffraction (XRD) patterns of the as-deposited (Se90Te10)95X5, (X= S, Zn, In, Bi and Sb) bulk samples confirmed their amorphous nature. These results were consistent with scanning electron microscopy (SEM) investigations.
Differential Scanning Calorimetry (DSC) thermograms under nonisothermal conditions for the as-prepared powder samples showed one glass transition temperature and one stage of crystallization on heating. Therefore, the glass transition temperature (Tg) and the peak of crystallization temperature (Tp) were determined. The activation energy for glass transition Eg and that for crystallization Ec were evaluated and their composition dependences were discussed. The activation energy, Eg, of glass transition crystallization, Ec, was utilized for determining various kinetic models. The analysis and experimental data revealed that Eg and EC differ for the additive elements. The effective Ec of crystallization was calculated based on the Kissinger formula. Thus, the Sestak–Berggren model was used for characterizing the DSC crystallization information when it agreed to the experimental results. Consequently, it was found that the Johnson–Mehl–Avrami model can be applied at high heating rates. the activation of crystallization energy was computed with various isoconversional methods. According to the JMA model, The JMA model is appropriate only in the range of low heating rates in non-isothermal status and the nucleus grows slowly after the nucleation process. The SB model gives the best fit of DSC curves calculated at all heating rates.
The optical properties of as-deposited (Se90Te10)95X5, (X= S, Zn, In, Bi and Sb) films have been studied. Various optical constants such as refractive index (n) and extinction coefficient (Kex) of the films were determined and have been calculated for the studied compositions. The transmission (T) and reflection spectra (R) of as-prepared (Se90Te10)95X5, (X= S, Zn, In, Bi and Sb) films were measured at normal incidence in the spectral range 200-2500 nm. Analysis of the optical absorption data showed that indirect transition is participating.
It is found that the optical band gap Eg(in) decreases in the basic metal and semimetal groups, whereas it increases in the Transition metal and nonmetal group. The optical constants were estimated according to the single-oscillator model in the high wavelength range. The estimated results confirmed that the modified samples can be employed in the optoelectronic applications.
The films were found to obey the single oscillator model and the oscillator parameters changed with element content. Also, the high frequency dielectric constant ( ) and the ratios of the free carrier concentration to its effective mass ( ) were studied as a function of compositions. The results are discussed and correlated in terms of amorphous-crystalline transformations.