Brief Resume of the Research Works

Since 1983 to May2009

a) Fabrication and characterization of Fe/zeolite catalyst (Fabrication and studies by: Magnetic curve, Mössbauer spectra, IR spectra, Atomic absorption, Surface area measurement, X-ray spectra, particle size measurement by SEM and magnetic curve, Simulation, etc):

 

1.      R. t. Obermyer, L. N. Mulay, C. Lo, and M. Oskooie- Tabrizi, V. U. S. Rao “Magnetic, Mössbauer, and catalytic properties of the zeolite catalyst ZSM-5(Fe)” J. Appl. Phys. 53(3), March 1982  

The present investigation was undertaken to determine the nature of the transition metal at various stages in the preparation and use of the catalyst ZSM-5(Fe), where Fe has been introduced using two different methods of impregnation. (a- impregnation with an iron nitrate solution until the point of incipient wetness was reached, b- impregnation with the iron carbonyl Fe3(Co)12 by using an extraction technique with cyclohexane as the solvent). Magnetic and Mössbauer studies have been used to characterize the catalysts to obtain correlations between the state of the catalyst and its activity, selectivity, and aging characteristics. The magnetic measurements were performed by the Faraday technique and by VSM in the temperature range 78-1200K up to 20 kOe applied magnetic field.

 

2.      M. Oskooei, C. Lo and L. N. Mulay “Magnetic and Mössbauer characterization of transition metal catalyst supported” IEEE on magnetic vol. 52 sept. 1983

The magnetization and susceptibility measurements were performed using the Faraday technique in the temperature range 78 to 1000 K and applied fields up to 20 kOe. The freshly impregnated zeolites indicated the presence of Fe species from an analysis of the paramagnetic susceptibility, which showed an effective moment of about 5.96 Bohr magnetons. The magnetization studies on the reduced samples of ZSM-5 (14.7% Fe) and Silicalite (13.6% Fe) indicate that iron is in the metallic state with 86% and 85% reduction, respectively. The magnetization vs. tem­perature curves for ZSM-5 (11.1% Fe). The carbided sample of ZSM-5 (11.1% Fe) appears to be the high Curie point form (Hagg carbide) with Tc = 540 K. The used sample of ZSM-5 (11.1% Fe) exhibited a magnetic transition with Tc = 650K, which corresponds to the hcp phase of (Fe2C). The magnetic transition of cementite (Fe3C) was masked in the magnetization (M vs. T) curve. Since Tc of Fe3C is about 490 K, well below that of the hcp carbide. The hcp phase of Fe2C is considered to be stable below 470 K in an atmosphere of synthesis gas. Its presence in the used sample may indi­cate that it was formed while the catalyst was cooled after the reaction.

            The Mössbauer spectra of the different catalysts were recorded at various stages; namely, (a) after impregnation with Fe (NO3)3; (b) on reduction in H2 at 450 °C for 24 h; (c) on carbide in 1:1 H2/CO syn-thesis gas at 250°C for 24h; and (d) finally after utilization of the catalyst in the conversion of the synthesis gas to gasoline-range hydro­carbons. The spectra have revealed the existence of various phases, formed at different stages, and have given clues to the nature of the active component (s) responsible for the efficient conversion of synthesis gas into gasoline. The spectrum of a fresh catalyst, in general, consisted of a doublet with an isomer shift of about +0.35 mm/s and a quadrupole splitting of about 0.75 mm/s, which indicate that the valence state of iron in the starting material is Fe3+. A typical spectrum for a fresh catalyst of Silicalite impregnated with 13.6% iron using Fe(NO3)3 was obtained.

 

3.      M. Oskooei. Tabrizi, Thomas Pannaparayil, C. Lo, and L. N. Mulay, G. A. Melson, V. U. S. Rao “Magnetic and Mössbauer study of metal-Zeolite interaction in catalysts” J. Appl. Phys. 55(6), 15 march 1984

The conversion of CO + H2 (mixture of synthesis gas) in one step to mixture of hydrocarbon species which constitute high octane range gasoline appears possible with catalysts such as ZSM-5 and a group VIII metal. The influence of metal–zeolite interaction on metal cluster size and product study mordenite was chosen as the zeolite since it can be synthesized over a wide range of SiO2 / Al2O3 mole ratio and its acidity has been characterized. The catalytic activity and acidity (number and strength of the Brönsted or H+ sites) were found to exhibit maxima at a ratio of [SiO2 / Al2O3] = 17. Hence, it was important in this study to examine if parameters associated with metal cluster size and the Fe-mordenit interaction show a parallel trend as a function of the above ratio in mordenites.   

 

4.      C. Lo., M. Oskooei. Tabrizi, and L. N. Mulay “Mössbauer, Infrared and Magnetic Characterization of Iron / Cobalt species in cage structure alumino – silicates” Mat. Res. Bull. , Vol 19, pp.1411-1425, 1984

The magnetic properties of Nanosized clusters of magnetically ordered materials (ferro, ferri, and antiferromagnetic) were shown to behave differently than those of the corresponding bulk materials. The intensity of this O-H band varies with the SiO2 / Al2O3 ratio and has a maximum for sample B (SiO2 / Al2O3 = 17) and a minimum for sample D (SiO2 / Al2o3 = 60). This observation suggests that the number of Brönsted or H+ sites in the H-mordenite sample varies with silica to alumina ratio and reaches a maximum at the ratio 17 in conformity with relation to n-pentane isomerization activity of Pd / H-mordenite. In addition, a slight shift in the frequency of the O-H band with the SiO2 / Al2O3 ratio seems to indicate an interaction between such O-H groups on the zeolite support and the metal cations such as Fe3+

 

5.      M. Oskooei. Tabrizi and L. N. Mulay “Synthesis and Characterization of Fe / Zeolite Catalysts for Production of Hydrocarbons” 2nd international Non – Renewable Energy Sources Congress. INRESC – 98  Tehran, I.R.IRAN.

 

The group VIII metal and the zeolite together play a bifunctional role for synthesis gas conversion to hydrocarbon. While the metal serves to activate the reactants and to initiate the reaction and polymerization     processes of the synthesis gas to hydrocarbons, the pore structure of the zeolite limits the size of the hydrocarbon products. The acidic zeolites have the ability to catalytically crack higher molecular weight products, and with their shape selective properties (cavity, channel or pore sizes), to also limit these hydrocarbon chain lengths to < C11. It is belived that the acid sites (Brönsted and Lewis) associated with the zeolites are not only effective in the cracking of the heavier molecular weight hydrocarbons of lighter fractions, but also are involved in the isomerization of hydrocarbons and for the conversion of  methanol and olefins to aromatic fractions. Thus the H-Mordenite zeolite was chosen to use as a support, because of factors as its acidic nature, pore size, channel structure and thermal stability.

 

6.      M. Oskooie “Preparation of Iron / H-Modenite for Light Hydrocarbons Production” Research Institute of Petroleum Industry (R.I.P.I) spring and summer 2006, Volume 16, No.35

 

Effect of two different solvents, such as CHX (cyclohexane) and THF (tetrahydrofurm) for Iron carbonyl and also no. of acidic sites in the substrate (mordenite with different SiO2 / Al2O3 ratio) were investigated. By using CHX as a solvent results in formation of smaller average particle sizes of Iron species, specially for the ratio of 17.Most percentage of light hydrocarbons (C1-C4­) could be obtained for this catalyst. If the ratio changes (increasing or decreasing) than the percentage of higher hydrocarbonsmuch as wax will be increased. For the mordenite with the ratio of 17 and CHX used as a solvent shorter time and less preparation process needs for activation.

 

7.  M. Oskooie and C. Lo “Mössbauer and magnetic studies of Iron-zeolite and Iron-Cobalt zeolite catalysts used     in synthesis gas conversion” International journal of engineering, Volome 20, number 3, December 2007.

 

                  Medium-pore (diameter ~ 6A) zeolites such as ZSM-5 and impregnated with Group VIII metals provide selective catalytic pathways for the conversion of synthesis gas to gasoline or olefins. Mössbauer and magnetic studies on these catalysts containing iron or iron plus cobalt are reported. The zeolites were impregnated with metal nitrate solutions, reduced, and carbided to yield showed Fe3+ type spectra. The ZSM-5 (14.7 % Fe) and Silicalite (13.6 % Fe) samples exposed to H2 (450oC) showed an approximate 85% reduction to the metallic state. The carbided ZSM-5 (14.7 % Fe) revealed a spectrum of Hägg carbide (Fe5C2), an active component of the catalyst. The used catalysts shown mixtures of Hagg carbide (Fe5C2) and cementite (Fe3C). it is suggested that the selectivity of ZSM-5 (5.6 % Fe. 4.5 % Co) resulted from iron-cobalt alloy formation.

 

   8.   M. Oskooie, “Magnetic studies of fine Fe and co species formed in Fe/Zeolite catalysts”      International journal of engineering, Vol.21 number 2, June 2008

 

Magnetic, Mössbauer, and I.R. studies of Nanosize particles of Fe and Co species dispersed in a cage of aluminosilicates structure, in relation to syngas (CO+H2) Fischer-Tropsch conversion. The differences in the catalytic activity of such have shown dependency on their degree of dispersion. The carbonyl impregnation gave ultra-fine Super Paramagnetic Fe3O4, whereas the nitrate impregnation gave larger size particles of Fe3O4 or α-Fe2O3. The active Fe5C2 component was converted to Fe3C during the above reaction. 

 

 

b) Epitaxial Growth of GaAs and AlxGa1-x As (making GaAs devices by epitaxy, and their characterization by X-ray, SIMIS, AFM, SEM, TEM, PIXE, Simulation, etc):

 

9.      M. Oskooie, A. Amini, M. Tarkashvand and F. Avari “Characterization fabrication of multilayers of AlxGa1-xAs/ GaAs by epitaxy” Iranian Journal of Crystallography and Mineralogy, Vol.3, No.1, spring 1995.

 

               Five layers of GaAs:Te(n=2x1018 cm-3), Al0.4Ga0.6As:Sn(n=5x1016 cm-3), GaAs, Al0.4Ga0.6As: Ge(p=3x1017 cm-3), GaAs: Ge(p=1x1018 cm-3) were grown by super cooled Liquid Phase Epitaxy on n-GaAs(100) substrate. The cooling rate of the furnace was set up with 0.1oC / min at T=845oC. The first layer was grown at T=840oC and the last one at T=827oC. The thickness was varied between 0.1 to 8 µm by controlling the super cooling temperature and growth time. Quality and quantity of epitaxial layers were examined by TEM, SEM, PIXE, and X-ray.

 

10.  M. Oskooie, A. Amini and M. Tarkashvand “single-longitudinal –mode of Alx Ga1-x As / GaAs diod laser” 4th International Symposium on Advanced Materials, September 17-21-1995, Islamabad PAKISTAN.

 

Five layers of type n,p GaAs / AlxGa-xAs were grown by super-coole liquid phase epitaxy on (100) orientation of n-GaAs. Initially one gram of Ga was weighted for each well in the graphite boat. After chemical etching process it was backed at 900oC for 4 hours. Undoped polycrystal GaAs plus impurity materials weighted and added to Ga at room temperature in atmosphere of inert gas. Aging the graphite boat was heated at 900oC for 30 min and then it decreased to 845oC for one hour. At this temperatue the solution of the first well was contacted the seed and then cooling rate of 0.3oC/min was established.

    

11.  M. Oskooie, A. Amini and F. Anvari “Fabrication and characterization of AlxGa1-xAs heterojunction phototransistor” 4th International Symposium on Advanced Materials, September 17-21-1995, Islamab PAKISTAN.

 

The HPT were fabricated by multilayer’s of AlxGa1-xAs / AlyGa1-yAs (x= 0.2, y = 0.7) on (100) on n-GaAs. Supercooled liquid phase Epitaxy was for this study. Initially one gram of Ga were placed in each well of high pure graphite sliding boat and backed at 900oc for 4 hours with flow of H2 (purity 99.9999%). Our results indicated that the surface morphology can be obtained when GaAs concentration in the solution was about 72% as that in the saturated solution. The HPT were fabricated with and without spacer layer. By inserting an undoped spacer layer the interface state between the base and emitter was improved.

12.  M. Oskooie and H. Faripoor “Ridge –Waveguide AlGaAs Heterostructure laser for single mode operation” Proc. 5th International Symposium on Advanced Materials, 21-25th September, 1997 Islamabad PAKISTAN.

 

In this paper, we provide results on a ridge-waveguide large optical cavity structure for single mode operation. It requires only epitaxial growth and a single self-aligned etch step for current restriction and optical confinement. Five layers were grown on an n-GaAs: Si substrate by liquid phase epitaxy (LPE) in a confined graphite boat. The base structure consists of n-GaAs: Te (4µm), n-Al0.4 Ga0.6 As: Sn (2 µm), undoped GaAs (0.1-0.3 µm) active later, p-Al0.4 Ga0.6 As: Ge (1.5 µm), and p-Ga As: Ge (1.5 µm).

 

13.  M. Oskooie and M. Amir Manouchehry “Optimization of optical gain by thin layers in QW diode lasers” Iranian Journal of Crystallography and Mineralogy number 2 fall & winter 2007.

 

Advanced diode laser consists of a two dimensional thin layer which is about 10 nanometers size. Optical gain of thin layers has a great deal of importance in light amplification. Thin layers cause a modification in conduction and valance bands of bulk materials. Subbands have been computed through effective mass equations. As a result of this method, particular effective masses are available. These specific equations are formed by numerical methods. Studied structure in this research includes a two dimensional thin layer of GaAs with a quantum well width from 7.5 to 8.5 nanometers, cladded by two layers of AlGaAs which has a larger band gap. Aluminum percentage has been chosen 15 to 45percent. Results from this study demonstrates that quantum well width should be adjusted according to Aluminum percentage, and the final optimized result, based on the developed optical gain model, is a thin layer of 8.5 nanometers width cladded by a 25 percent of aluminum in AlxGa1-xAs materials. 

 

14.   M. Oskooie and M. Amir Manouchehry, “Simulation and Optimization of optical gain   in quantum well semiconductor lasers”

 

In this paper we try to find important parameters of a Quantum well laser. Subband energy levels of conduction using effective mass equation and numerical methods (such as Newton method). Here material chosen for the active region as a GaAs quantum well layer surrounded by an AlGaAs barrier layers. Also,Quasi-Fermi levels depending on carrier injection level has been calculated. Gain versus energy is simulated considering the gain broadening interband relaxation effect. Gain is sketched for different values Aluminum percentage and quantum well layer width from 7.5 to 8.5 nanometers. Those results can be used to improve our theoretical view about affective parameters in a quantum well laser and how they should be considered in a quantum well laser design based on our needs.

 

c) Miscellaneous Research Works (studies by: PIXE, X-ray, AFM, SIMIS, Simulation, etc):

 

15. D. L. Questad and M. Oskooie “Dielectric studies of amorphous polymers at high  pressures” J. Appl. Phys. 53(10), October 1982

The main purpose of this study is to examine effect of pressure on the glass transition for a number of different polymers. Of particular interest will be the high pressure limiting effects. Dielectric methods have been used to study α transition from which changes Tα can be related changes in Tg.

 

16. M. Oskooie, “particle size distribution from magnetization Curve” The 4th Crystallogaraphical and minerallogical seminar of Iran, October 1994

 

By new definition of Langevin function, the correlation between particle size distribution and its magnetization curve were derived. The computer program was developed based on the magnetization curve of a sample. The program was tested on several catalyst samples. Also the surface area and the average particle size were measured from the knowledge of their particle size distribution function.

 

17.  M. Oskooie, “preparation and characterization of Fe clusters” The 4th Crystallographic and mineralogical seminar of Iran, October 1994

  

A special reactor was designed for evaporation of Fe(CO)5 on different type of mordenites in order to produce the particle clusters of Fe. It was shown that the size of the clusters can be controlled by changing the ratio of Si/Al in the substrate (mordenite). Particle size distribution obtained from magnetization curve indicated that the smallest particle were formed in mordenite with Si/Al=17. Catalytic activity showed that the sample with smallest clusters (Fe/ mordenite with Si/Al=17) had the highest conversion efficiency for CO+H2 in to CH4. IR spectroscopy of all mordenite samples indicated that the acidity was highest with the sample with Si/Al=17. Isomer shift from Mössbauer confirmed the metal-support interaction in this sample.

 

  18.  H. Golnabi and S. Bahrami, M. Oskooie. “Design and operation of a fiber optic probe  for fluid level  switching and detection”  proceeding of 13th international conference on flexible automation & intelligent manufacturing Tampa Florida University of  south Florida Tampa, Florida, USA. June 2003.                     

Many industries use reservoirs and tanks for containing fluid for supply or operating processes such as cooling or lubrication detergents. The level of fluid in such containers must be kept at a certain height in order to prevent overfill and also for granting a continuous operation of the liquid flow line. For checking and controlling the flow line, level switches and sensors are often required. Although, it is possible to use electrical or other switches, but in the recent years there has been a great interest in the development of optical devices to replace other devices. The goal of this study is to present the state of art in optical devices and to characterize the performance of various systems. In this investigation several criteria of such devices suitable for practical applications are described in this respect, design and construction of a simple, sensitive, and small size device developed in our laboratory is reported.

       

     19. M. Oskooie, H. Soleymani, M. Pourmadani. “Preparation of Iron-Zeolite for hydrogenation” 7th National Iranian chemical engineering congress.

 

Deposition of iron compound was used for the catalyst. Also, iron penta carbonyl was used in solution to make the catalyst. H-ZSM-5 used as a substrate with different ratio of SiO2/ Al2O3. For this purpose a micro reactor was fabricated and a percentage of iron was obtained by Atomic Absorption and average particle size was calculated based on the magnetization curve. Also, the particle size of metallic iron obtained from this calculation. The behavior and effect of metallic iron on selectivity were investigated.

 

20.   H. Golnabi, H. Ahmadi, S. Bahrami, and M. Oskoie “Dynamic Modeling of a Long Range Nanoactuator” proceeding of 13th international conference on flexible automation & intelligent manufacturing  Tampa  Florida University of south Florida Tampa, Florida, USA. June 2003.

 

The goal of (his study is to develop a dynamic model that describes precise by the performance of a long-range Nanoactuator for all the possible conditions. First, a model is established for a stick-slip type operation and differential equations governing the motion of the two masses involved are established. By solving such a system of equations numerically, the position and velocity of each mass is obtained as a function of time. In this study dynamic behavior of actuated object in terms of position and velocity as a function of the piezoelectric parameters, object mass, and forces involved are investigated. In the second study the developed model is extended to the case in which one of the masses is clamped down and the related equations reduce to a single second order differential equation. Solving this differential equation, mass position and its velocity are studied as a Junction of the piezoelectric parameters and loading forces in stick phase. The results obtained here explain the dynamic behavior thoroughly and can be used for optimizing  the operating condition of such a Nanoactuator.