Microstructural Evolution of Titania Sol-Gel Thin Films

1994 ◽  
Vol 346 ◽  
Author(s):  
Yongan Yan ◽  
S. Ray Chaudhuri ◽  
Din-Guo Chen ◽  
Barry Bolker ◽  
Arnab Sarkar

ABSTRACTThin films of crystalline titania with different grain sizes and porosities were prepared by dip-coating on Si (100) substrates starting from a sol-gel process. Three synthesis procedures were developed and compared, using acetylacetone (acac, with HCI) and acetic acid (HOAc) as modifying agents or directly using hydrochloric acid as catalyst. The structural evolution of the films was characterized by Glazing Angle X-ray Diffraction (XRD), Spectroscopic Ellipsometry and Atomic Force Microscopy (AFM). Anatase phase was observed on all of the films calcined at 440° C. The grain sizes and crystallinity generally increased with calcination temperature. Thin films obtained from acac- and HOAc-modified titanium sols had fine grains (50–80 nm) and less porosity (<10%) after calcination at 1000° C. Thin films derived from the sol catalyzed directly with acid had the largest grains (90–130 nm), higher crystallinity and greater porosity (17%).

2004 ◽  
Vol 19 (5) ◽  
pp. 1492-1498 ◽  
Author(s):  
Stacey W. Boland ◽  
Suresh C. Pillai ◽  
Wein-Duo Yang ◽  
Sossina M. Haile

Solid solution Pb1-xBaxTiO3, with particular emphasis on Pb0.5Ba0.5TiO3, was prepared using a sol-gel process incorporating lead acetate trihydrate, barium acetate, and titanium isopropoxide as precursors, acetylacetone (2,4 pentanedione) as a chelating agent, and ethylene glycol as a solvent. The synthesis procedure was optimized by systematically varying acetylacetone: Ti and H2O:Ti molar ratios and calcination temperature. The resulting effects on sol and powder properties were studied using thermogravimetric analysis/differential scanning calorimetry, Fourier transform infrared spectroscopy, Brunauer-Emmett-Teller analysis, and x-ray diffraction (XRD). Crystallization of the perovskite structure occurred at a temperature as low as 450 °C. Thin films were prepared by spin coating on (100) MgO. Pyrolysis temperature and heating rate were varied, and the resultant film properties investigated using field-emission scanning electron microscopy, atomic force microscopy, and XRD. Under optimized conditions, highly oriented films were obtained at a crystallization temperature of 600 °C.


2011 ◽  
Vol 1352 ◽  
Author(s):  
Marcelo M. Viana ◽  
Nelcy D. S. Mohallem

ABSTRACTColloidal precursor solutions, obtained from a mixture of titanium isopropoxide, isopropyl alcohol and silver nitrate, were used to fabricate amorphous TiO2 and Ag/TiO2 thin films by sol-gel process. The films were deposited on borosilicate substrates, which were heated at 400 °C for 30 minutes and cooled rapidly to the formation of amorphous coatings. The films were investigated by X-ray diffraction, scanning electron microscopy, atomic force microscopy and UV-vis spectroscopy. The thickness, roughness, refraction index, and particle size of the TiO2 and Ag/TiO2 films were determined and compared. Finally, hydrophobic-hydrophilic property was evaluated to the thin films produced.


2005 ◽  
Vol 475-479 ◽  
pp. 3693-3696
Author(s):  
Wen Xiu Cheng ◽  
Ai Li Ding ◽  
Ping Sun Qiu

Amorphous and crystalline (Zr0.8,Sn0.2)TiO4 (ZST) thin films deposited on Si(100) substrates have been prepared by a sol-gel process. The crystal structure and surface morphologies of the thin films have been studied by X-ray diffraction and atomic force microscopy. The crystalline ZST films on Si(100) substrata with a (111) orientation The refractive index n and extinction coefficient k of the amorphous and crystalline thin films were obtained by spectroscopy ellipsometry as a function of phone energy in the range from 0.7 to 5.4 eV. The absorption edges for amorphous and crystalline ZST are 3.83 and 3.51eV of indirect–transition type respectively.


2015 ◽  
Vol 1109 ◽  
pp. 148-152
Author(s):  
A.K.M. Muaz ◽  
U. Hashim ◽  
Sharipah Nadzirah ◽  
M. Wesam Al-Mufti ◽  
Fatimah Ibrahim ◽  
...  

In the present research, nanocrystalline TiO2thin films have been prepared via a sol-gel method using Ti {OCH(CH3)2}4act as a precursor. The morphological effect of sets of as-deposited and annealed samples (100, 300, 500 and 700°C for 1 hour) and thickness variation on the structural properties were investigated by Atomic Force Microscopy (AFM) measurements. The observation showed that the size of grain increases with film thickness, indicating that the size of the particles in the films can be effectively controlled by changing the temperature of thermal treatment. AFM topology images of the as-deposited and annealed TiO2films at 100 and 300°C indicates the films are rather smooth, compact, bulky, not uniform and column-like structure. TiO2thin films annealed at 500 and 700°C showed homogenous morphology surface with regular size of spherical particles.


1970 ◽  
Vol 17 (2) ◽  
pp. 191-196
Author(s):  
Artūras ŽALGA ◽  
Brigita ABAKEVIČIENĖ ◽  
Aleksej ŽARKOV ◽  
Aldona BEGANSKIENĖ ◽  
Aivaras KAREIVA ◽  
...  

The synthesis of nanostructured films of 20 mol% Y2O3 stabilized ZrO2 on corundum (Al2O3) substrates was performed from different sols using dip-coating technique. All obtained samples were repeatedly annealed at 800 °C temperature after each dipping procedure and fully characterized by X-ray diffraction (XRD) analysis. XRD data exhibited that at 800 °C temperature nano-sized Y0.2Zr0.8O2 thin films with cubic (Fm-3m) crystal structure have been formed. The morphological features of obtained coatings were investigated by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The surface tension and hydrophility of the synthesized films were determined by contact angle measurements (CAM).http://dx.doi.org/10.5755/j01.ms.17.2.491


2019 ◽  
Vol 16 (39) ◽  
pp. 64-70
Author(s):  
Ansam H. Hasan

This paper presents the effect of Cr doping on the optical and structural properties of TiO2 films synthesized by sol-gel and deposited by the dip- coating technique. The characteristics of pure and Cr-doped TiO2 were studied by absorption and X-ray diffraction measurement. The spectrum of UV absorption of TiO2 chromium concentrations indicates a red shift; therefore, the energy gap decreases with increased doping. The minimum value of energy gap (2.5 eV) is found at concentration of 4 %. XRD measurements show that the anatase phase is shown for all thin films. Surface morphology measurement by atomic force microscope (AFM) showed that the roughness of thin films decrease with doping and has a minimum value with 4 wt % doping ratio.


2011 ◽  
Vol 233-235 ◽  
pp. 2863-2870 ◽  
Author(s):  
Sudjit Sanguanruang ◽  
Rachan Leotphayakkarat ◽  
Nitikarn Fangern ◽  
Nattamon Koonsaeng ◽  
Chamorn Chawengkijwanich

Dipping borosilicate glass in modified sol-gel solution was used to prepare thin film TiO2. The sol was prepared from titaniumtetraisopropoxide(TTIP), hydrochloric acid (conc. HCl), ethanol(EtOH), TritonX-100 surfactant and acetic acid(AcOH). The mole ratios of the starting solution were surfactant: EtOH: AcOH: TTIP: conc.HCl= R: 45: 6: 1: 0.1. The amounts of surfactant (R value) were varied as 0, 0.5, 1, 2, 3 and 4 moles, respectively. After dip-coated, the borosilicate glasses were dried at room temperature and heated for 15 minutes at 500 °C (rate3°C/min). The obtained films were uniform; however, varied in transparency, decreasing when the TritonX-100/TTIP mole ratios had been increased. The crystal structure, optical property and the morphology of thin films TiO2 were characterized by X-ray diffraction (XRD), UV–Vis spectroscopy, Environment Scanning Electron Microscope (E-SEM) and Atomic Force Microscopy (AFM). Spectra of XRD showed that all the TiO2 thin films were anatase phase. From UV–Vis technique, it was found that their UV absorption edges were approximately 380 nm. A cracking on the surface of TiO2 thin films appeared when the amounts of the surfactant were increased. From AFM image, TiO2 particles were spherical size, ranged from 11.2 to 35.5 nm and the roughness of the films increased with the increasing of TritonX-100/TTIP mole ratios. Under UV illumination, the photodegradation results of Reactive Yellow17 was pseudo the first order reaction and the film of TritonX-100/TTIP mole ratio = 1 : 1 was the highest removal efficiency with the apparent rate constant (k) = 2x10-2 min-1 and half life (t1/2) = 34.65 min.


1999 ◽  
Vol 14 (7) ◽  
pp. 2712-2715 ◽  
Author(s):  
Jianming Zeng ◽  
Chenglu Lin ◽  
Jinhua Li ◽  
Kun Li

A novel sol-gel-hydrothermal process for preparation of highly oriented thin films of Pb(Zr0.52Ti0.48)O3 is reported. Pb(Zr0.52Ti0.48)O3 thin films with fully (111) orientation were successfully prepared on platinized silicon substrates at low temperature (100–200 °C) by combining a conventional sol-gel process and hydrothermal method, i.e., sol-gel-hydrothermal technique. The x-ray rocking curve for the (111) reflection as measured by a high-resolution four-crystal diffractrometer showed a narrow full width at half-maximum value of 0.20° for the as-prepared films. A dense, pinhole-free, and uniform surface morphology was observed from atomic force microscopy images of the films. The low leakage current density of the prepared films was also found.


2003 ◽  
Vol 784 ◽  
Author(s):  
Y. X. Liu ◽  
C. Caragianis-Broadbridge ◽  
A. H. Lehman ◽  
J. McGuinness ◽  
T. P. Ma

ABSTRACTWe report sol-gel process of Pb5Ge3O11 (PGO) as well as the microstructure and physical properties of ferroelectric PGO films for memory applications. The PGO sol was prepared from lead acetate hydrate, germanium isopropoxide, and di(ethylene glycol) ethyl ether. The reactions taking place during the sol-gel process were examined in detail. Diethanolamine (DEA) was added to help maintain the desired species ratio and prevent germanium oxide precipitation. The preferred orientation of the PGO thin films was well controlled by the heating and reflux procedures in the sol-gel preparation process. Additionally, to examine the impact of postdeposition processing, selected samples were oxygen annealed at temperatures ranging from 450–650°C. The samples were characterized with X-ray diffraction (XRD), non-contact (planview) atomic force microscopy (NC-AFM). The resulting data indicate that the microstructure and physical properties of PGO films depend strongly on the precursor preparation as well as the post deposition annealing temperature.


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