Print ISSN: 1681-6900

Online ISSN: 2412-0758

Keywords : gel

Synthesis of Dopant Zno Thin Films with Al Using Dip Coating for Gas Sensors

S.H. Sabeeh; R.H. Jassam

Engineering and Technology Journal, 2017, Volume 35, Issue 8, Pages 842-844

The sol-gel technique (dip coating method) used to synthesize pure Zinc Oxide and Aluminum doped Zinc Oxide thin films on glass substrate for gas sensing application. Zinc acetate dehydrate was used as source of Zinc ions. The influence of annealing temperature of pure ZnO thin films with three different temperatures (300,400,and 500 ) °C, Aluminum dopant concentration with two different concentration (3wt% and 5wt% ) and annealing temperature for AZO thin films with three different temperatures (300,400,and 500 ) °C on gas sensing properties was studied. The results show that ZnO was to be sensitive toward CO gas and its sensitivity decrease with increase in annealing temperature of pure ZnO and (5wt.%) AZO thin films. It is found that the sensitivity of pure ZnO thin films decrease from 67% at 300 °C to 54% and 38% at 400 and 500 °C respectively. Likewise, for 5wt. % AZO thin film the sensitivity improved by increase the Aluminum dopant concentration with fixed annealing temperature 500 °C. It is found that the sensitivity increase form 49% to 57% when doped with Al at (3 wt. %) and (5 wt. %) respectively.

Characterization of the Structural and Electrical Properties of Transparent Conductive Oxides Prepared by Sol-Gel Method

Ali J Addie; Azhar I Hassan; Saleema S Saad

Engineering and Technology Journal, 2016, Volume 34, Issue 6, Pages 209-216

Nano crystalline powder of the System Cu-Al-O have been prepared by Sol-Gel technique, copper nitrate and aluminum nitrate have adopted as raw materials for the reaction, and subsequently solid state reactions have used to synthesize different compounds and phases at the calcination stage. Effects of calcination temperature and time in the range 800-1100oC and 1hr-6hr respectively have been investigated. XRD results show that the system have a multiphase and it depends on the calcination time and temperature, the higher the temperature and time the higher the percentage of the compound CuAlO2, whereas the SEM microscopy show that the Nano powder have particle size of 40nm, and Raman spectroscopy reveals the presence of Eg and A1g modes which belong to the structure CuAlO2. The work emphasize that the control of the technique parameters could provide high degree of control on the final required phases and structures.

Judd–Ofelt analysis of Spectroscopic properties of Nd+3:SiO2 Prepared via Sol-Gel

Mohammed. A. Hamza; Majeda A. Ameen; Hanaa M. Yaseen

Engineering and Technology Journal, 2015, Volume 33, Issue 5, Pages 848-855

Doped and undoped nano particular silicate dioxide was prepared via sol–gel method under varying conditions. The optical properties of prepared samples were investigated by a variety of techniques, including X-ray diffraction, UV- Visible spectroscopy, FTIR spectroscopy and fluorescence spectroscopy. The peak of the fluorescence spectrum was recorded at the wavelength around to 1048nm, which it is close to known fluorescence peaks of Nd:YAG crystal in NIR region. A Judd-Ofelt analysis is performed to calculate the spectroscopic properties of Nd3+ions embedded in SiO2 and compare it with spectroscopic properties of Nd:YAG crystal.The conclusions behind this study show that the doped silicate samples have a high peak emission cross-section σp , which gives an acceptable indication in the direction of using Sol-Gel technique to prepare Nd:SiO2 as a solid state laser active medium.

Developing the Alumina Hybrid Sol-Gel Coating for Steel Oxidation Protection at High Temperatures

Atia; Mohammed Hussein J. Al

Engineering and Technology Journal, 2014, Volume 32, Issue 4, Pages 744-758

The use of nano alumina thin film by hybrid sol-gel route to protect steel from high-temperature oxidation is limited due to the low thermal stability of this coat. In this work, study has been conducted to minimize this effect. The chemical compositions of solid gel (xerogel) obtained from normal alumina hybrid sol-gel were thermally varied, and then recombining with water to form the modified coating solutions at constant concentration of 0.25mol/l alumina. Laser diffraction technique has been used to measure the growth of clusters sizes in different modified solutions. X-ray diffraction analysis to characterize the alumina phase's changes as a function of temperatures. Also gravimetric weight change method to determine the oxidation rate of steel before and after coating. The results showed five changes in alumina phase during heating to 9500C, which are similar to that recorded for the natural ore of boehmite, and the partial removal of non stable by-products constituents associated with xerogel has considerable effect on the degree of particles aggregation and agglomeration in solutions. This worked to improve the thermal stability of the coating layer, and show considerable resistance to cracks formation. At 40-50% removal, the oxidation rate of HSLA steel specimens was enhanced by 88 % at 9500C compared to the steel before coating.