THE IR STUDY OF AMORPHOUS THIN FILMS OF MIXED OXIDES In2O3–SnO2 SYSTEM

2007 ◽  
Vol 14 (01) ◽  
pp. 5-16 ◽  
Author(s):  
M. ANWAR ◽  
S. A. SIDDIQI ◽  
I. M. GHAURI
Keyword(s):  
Film Thickness ◽  
Substrate Temperature ◽  
Mixed Oxides ◽  
Ir Absorption ◽  
Absorption Bands ◽  
Band Frequency ◽  
Annealing Temperatures ◽  
Ir Study ◽  
Indium Interstitials ◽  
Cation Sites

The IR spectra of thin amorphous films of mixed oxides In 2 O 3– SnO 2 system have been studied in the spectral range 4000–400 cm-1 by Fourier transform infrared technique. The effects of changes in composition, film thickness, substrate temperature and annealing on the IR absorption bands are observed. A shift in frequency and intensity of the bands with varying preparation parameters and an increase in ordering at higher annealing temperatures are observed in the infrared curves. Some new peaks appear, which reveal the presence of lower valency states both in In 2 O 3 and SnO 2. The disappearance of bands at higher annealing temperatures is assigned to the removal of point defects in which oxygen plays an important role. The shift in band frequency with an increase in (i) the Sn content is attributed to the incorporation of Sn 4+ ions in the In 2 O 3 lattice, (ii) the film thickness is attributed to the large concentration of donor centers, (iii) the substrate temperature is attributed to the increase in diffusion of Sn atoms from interstitial locations into the In cation sites, and (iv) the annealing temperature is attributed to the oxygen vacancies and indium interstitials.

scholarly journals Изотопные эффекты в спектрах комплексов с водородными связями. Ангармонические расчеты изотопологов комплекса [F(HF)-=SUB=-2-=/SUB=-]-=SUP=---=/SUP=-

2020 ◽  
Vol 128 (8) ◽  
pp. 1077
Author(s):  
В.П. Булычев ◽  
М.В. Бутурлимова ◽  
К.Г. Тохадзе
Keyword(s):  
Basis Set ◽  
Ir Absorption ◽  
Absorption Bands ◽  
Spectral Parameters ◽  
Basis Set Superposition Error ◽  
Band Frequency ◽  
Normal Vibrations ◽  
K Meson ◽  
Anharmonic Interactions ◽  
Good Agreement

The frequencies and intensities of IR absorption bands of symmetric and asymmetric H-bonded complexes [FL1FL2F]- (L1, L2 = K-meson Ka, proton H, deuton D, and triton T) are calculated. The equilibrium configuration and potential energy and dipole moment surfaces of isotopologues [FL1FL2F]- were calculated by the MP2/6-311++G(3df,3pd) method with the basis set superposition error taken into account. The calculations of spectral parameters with allowance for anharmonic interactions of all vibrations were carried out using the second-order vibrational perturbation theory. Variation of Li and L2 masses in wide regions allowed significant changes in the forms of normal vibrations and values of anharmonic interaction constants upon isotopic substitution to be obtained. The trends in the changes of spectral parameters were determined upon transition from one symmetric isotopologue to another and upon transition from symmetric to asymmetric isotopologues. The D-F stretching band frequency predicted for [FHFDF]- is in good agreement with the experimental value. The assignment of this band was improved.

Characterization of Microcrystalline Transition from Amorphous Silicon as a Function of Hydrogen Dilution and Substrate Temperature of Hot-wire CVD

2002 ◽  
Vol 715 ◽  
Author(s):  
Keda Wang ◽  
Haoyue Zhang ◽  
Jian Zhang ◽  
Jessica M. Owens ◽  
Jennifer Weinberg-Wolf ◽  
...  
Keyword(s):  
Substrate Temperature ◽  
Sudden Change ◽  
Chemical Vapor ◽  
Threshold Value ◽  
Ir Absorption ◽  
Sudden Increase ◽  
Hot Wire ◽  
Hydrogen Dilution ◽  
Integral Absorption ◽  
Two Peaks

Abstracta-Si:H films were prepared by hot wire chemical vapor deposition. One group was deposited at a substrate temperature of Ts=250°C with varied hydrogen-dilution ratio, 0<R<10; the other group was deposited with fixed R=3 but a varied Ts from 150 to 550°C. IR, Raman and PL spectra were studied. The Raman results indicate that there is a threshold value for the microstructure transition from a- to μc-Si. The threshold is found to be R ≈ 2 at Ts = 250°C and Ts ≈ 200°C at R=3. The IR absorption of Si-H at 640 cm-1 was used to calculate the hydrogen content, CH. CH decreased monotonically when either R or Ts increased. The Si-H stretching mode contains two peaks at 2000 and 2090 cm-1. The ratio of the integral absorption peaks I2090/(I2090+I2090) showed a sudden increase at the threshold of microcrystallinity. At the same threshold, the PL features also indicate a sudden change from a- to μc-Si., i.e. the low energy PL band becomes dominant and the PL total intensity decreases. We attribute the above IR and PL changes to the contribution of microcrystallinity, especially the c-Si gain-boundaries.

Nevirapine Pharmaceutical Cocrystal: Design, Development and Formulation

2019 ◽  
Vol 9 (3) ◽  
pp. 240-247
Author(s):  
Prabhakar Panzade ◽  
Priyanka Somani ◽  
Pavan Rathi
Keyword(s):  
Dosage Form ◽  
In Vitro Dissolution ◽  
Soluble Form ◽  
Ir Absorption ◽  
Stoichiometric Ratio ◽  
Design Development ◽  
Formulation Development ◽  
Scanning Calorimetry ◽  
Absorption Bands ◽  
Pharmaceutical Cocrystal

Background and Objective: The top approach to deliver poorly soluble drugs is the use of a highly soluble form. The present study was conducted to enhance the solubility and dissolution of a poorly aqueous soluble drug nevirapine via a pharmaceutical cocrystal. Another objective of the study was to check the potential of the nevirapine cocrystal in the dosage form. Methods: A neat and liquid assisted grinding method was employed to prepare nevirapine cocrystals in a 1:1 and 1:2 stoichiometric ratio of drug:coformer by screening various coformers. The prepared cocrystals were preliminary investigated for melting point and saturation solubility. The selected cocrystal was further confirmed by Infrared Spectroscopy (IR), Differential Scanning Calorimetry (DSC), and Xray Powder Diffraction (XRPD). Further, the cocrystal was subjected to in vitro dissolution study and formulation development. Results: The cocrystal of Nevirapine (NVP) with Para-Amino Benzoic Acid (PABA) coformer prepared by neat grinding in 1:2 ratio exhibited greater solubility. The shifts in IR absorption bands, alterations in DSC thermogram, and distinct XRPD pattern showed the formation of the NVP-PABA cocrystal. Dissolution of NVP-PABA cocrystal enhanced by 38% in 0.1N HCl. Immediate release tablets of NVP-PABA cocrystal exhibited better drug release and less disintegration time. Conclusion: A remarkable increase in the solubility and dissolution of NVP was obtained through the cocrystal with PABA. The cocrystal also showed great potential in the dosage form which may provide future direction for other drugs.

Properties of Al Films Depend on Substrate Temperature by DC Magnetron Sputter Deposition

2013 ◽  
Vol 662 ◽  
pp. 413-416
Author(s):  
Yi Shen ◽  
Ruo He Yao
Keyword(s):  
Grain Size ◽  
Film Thickness ◽  
Substrate Temperature ◽  
Sheet Resistance ◽  
Cross Section ◽  
Sputter Deposition ◽  
Surface Profiling ◽  
Magnetron Sputter Deposition ◽  
Magnetron Sputter ◽  
Substrate Temperatures

Al films were prepared by DC magnetron sputter deposition at different substrate temperatures. The sheet resistance of the films was measured by four point probe sheet resistance meter, and the film thickness, which was obtained by surface profiling system. The surface and cross-section morphology of the films was observed by AFM and FESEM. As a result, the resistivity of the films decreases obviously as the substrate temperature increases gradually. The higher substrate temperature is, the rougher the films surface is and the larger the grain size is.

XRD Investigations on Film Thickness and Substrate Temperature Effects of DC Magnetron Sputtered ZnO Films

2013 ◽  
Vol 845 ◽  
pp. 241-245
Author(s):  
Jian Wei Hoon ◽  
Kah Yoong Chan ◽  
Cheng Yang Low
Keyword(s):  
Film Thickness ◽  
Substrate Temperature ◽  
Zno Films ◽  
X Ray Diffraction ◽  
Glass Substrates ◽  
Direct Current Plasma ◽  
Crystallite Sizes ◽  
Magnetron Sputter Deposition ◽  
Magnetron Sputter ◽  
Diffraction Patterns

In this paper, direct current plasma magnetron sputter deposition technique was employed to deposit zinc oxide (ZnO) films on glass substrates. The magnetron sputtering process parameters including film thickness and substrate temperature were investigated. The crystallite sizes of the ZnO films were extracted from the measured X-ray diffraction patterns. The correlation of the crystallite size of the ZnO films with the film thickness and the substrate temperature will be discussed in this paper.

Structure of vacuum-deposited Zn3P2 films

1986 ◽  
Vol 64 (10) ◽  
pp. 1369-1373 ◽  
Author(s):  
U. von Sacken ◽  
D. E. Brodie
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Film Thickness ◽  
Substrate Temperature ◽  
Columnar Structure ◽  
Major Effect ◽  
Film Structure ◽  
Electron Bombardment ◽  
Initial Growth ◽  
Transmission Electron

The structure of polycrystalline Zn3P2 films has been studied for 1- to 2-μm-thick vacuum-deposited films on glass substrates. Transmission electron microscopy and X-ray diffraction techniques have been used to obtain a detailed, quantitative analysis of the film structure. The initial growth consists of small (≤ 10 nm), randomly oriented grains. As the film thickness increases, the growth of crystallites with the {220} planes oriented approximately parallel to the substrate is favoured, and a columnar structure develops along with a highly preferred orientation. This structure has been observed directly by transmission electron microscopy of thin cross sections of the films. The size of the grains at the free surface increases with the film thickness, reaching approximately 200–300 nm when the film is 1 μm thick. The effects of substrate temperature and low-energy (0.5–2 keV) electron bombardment of the film during growth have also been studied. Neither substrate temperature nor electron bombardment appear to have a major effect on the film structure. The primary effect of electron bombardment appears to be the creation of preferred nucleation sites on the substrate.

scholarly journals Local vibrational modes of vacancy-oxygen-related complexes at room temperature

2020 ◽  
Vol 56 (4) ◽  
pp. 480-487
Author(s):  
E. A. Tolkacheva ◽  
V. P. Markevich ◽  
L. I. Murin
Keyword(s):  
Absorption Band ◽  
Room Temperature ◽  
Clear Correlation ◽  
Ir Absorption ◽  
Oxygen Impurity ◽  
Interstitial Oxygen ◽  
Vibrational Modes ◽  
Oxygen Defect ◽  
Absorption Bands ◽  
Local Vibrational Modes

The isotopic content of natural silicon (28Si (92.23 %), 29Si (4.68 %) и 30Si (3.09 %)) affects noticeably the shape of IR absorption bands related to the oxygen impurity atoms. In the present work an attempt is undertaken to determine the positions of local vibrational modes (LVMs), related to quasimolecules 28Si16OS29Si and 28Si16OS30Si (OS – substitutional oxygen atom), for the absorption spectra measured at room temperature. An estimation of the isotopic shifts of corresponding modes is done by fitting the shape of the experimentally measured absorption band related to the vacancy–oxygen center in irradiated Si crystals. The LVM isotope shifts are found to be equal 2,2 ± 0.25 cm–1 for 28Si-16OS29Si and 4,3 ± 0,9 см–1 for 28Si-16OS30Si in relation to the basic band due to 28Si-16OS28Si, and the full width at half maximum of the A-center absorption band (28Si-16OS28Si) is 5,3 ± 0.25 cm–1. By means of infrared absorption spectroscopy a clear correlation between the disappearance of the divacancy (V2) in the temperature range 200–275 ºС and appearance of two absorption bands with their maxima at 825.8 and 839.2 cm–1 in irradiated oxygen-rich Si crystals is found. The band positioned at 825.8 cm–1 is assigned to a divacancy-oxygen defect V2O formed via an interaction of mobile V2 with interstitial oxygen (Oi ) atoms. The 839.2 cm–1 band is much more pronounced in neutron irradiated samples as compared to samples irradiated with electrons. We argue that it is related to a trivacancy–oxygen defect (V3O) formed via an interaction of mobile V3 with Oi atoms.

Magneto-Chemical Properties of Some New Ni and Co Rare-Earth Metal Tungstates

2007 ◽  
Vol 128 ◽  
pp. 207-212 ◽  
Author(s):  
Adam Worsztynowicz ◽  
Slawomir M. Kaczmarek ◽  
Elzbieta Tomaszewicz
Keyword(s):  
Rare Earth ◽  
Rare Earth Metal ◽  
Epr Spectroscopy ◽  
Chemical Properties ◽  
Earth Metal ◽  
Temperature Evolution ◽  
Ir Absorption ◽  
Absorption Bands ◽  
Metal Tungstates

New d-electron and rare-earth metal tungstates (CoRE2W2O10; CoRE4W3O16; Co2RE2W3O14 and NiRE2W2O10) were studied by the IR and EPR spectroscopy methods. The IR absorption bands with their maxima can be assigned to the symmetric and asymmetric stretching modes of W-O bonds in the joint of WO6 octahedra and also to the oxygen double WOOW bridge bonds. The wide, unstructured EPR powder spectra of these compounds and their temperature evolution have been analyzed and interpreted.

Method for determining the formation constants of intermolecular H-bonding from IR spectroscopy data

2021 ◽  
pp. 55-58
Author(s):  
N.U. Mulloev ◽  
◽  
N.L. Lavrik ◽  
J.O. Yusypova ◽  
N.A. Majidov ◽  
...  
Keyword(s):  
Optical Density ◽  
Formation Constants ◽  
Butyl Alcohol ◽  
Proton Donor ◽  
Proton Acceptor ◽  
Ir Absorption ◽  
Visible Spectroscopy ◽  
Absorption Bands ◽  
Intermolecular Hydrogen Bonds ◽  
Uv Visible

An experimental method is proposed for determining the efficiency of the formation of intermolecular hydrogen bonds by determining the formation constant of the H-complex (K). The essence of the experiment to determine the value of K is that for one initial concentration of the proton donor, it is necessary to register the change in the optical density at the absorption wavelength of the monomers and the change in the optical density of the complexes of IR absorption bands at two concentrations of the proton acceptor. This approach was tested on the example of the interaction of butyl alcohol (proton donor) with 4-chloromethyl-1.3-dioxolane (proton acceptor). The obtained value of the equilibrium constant was 72.2 M-1. It is concluded that the proposed method for determining the value of K can be used not only in IR, but also in UV-visible spectroscopy.

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