PREPARATION OF HOLLOW TIO2 NANOSPHERES FOR BIOMEDICAL APPLICATIONS

2016 ◽  
Vol 2 (2) ◽  
pp. 68-73
Author(s):  
Himani Kalita ◽  
Amita Pathak
Keyword(s):  
Anatase Phase ◽  
Thermal Studies ◽  
Rutile Phase ◽  
Titanium Tetraisopropoxide ◽  
X Ray Diffraction ◽  
Electron Microscopic ◽  
Templating Method ◽  
Microscopic Studies ◽  
Hydrolysis Of ◽  
Mn Concentration

The present work reports the preparation of hollow TiO2 nanospheres through sacrificial core templating method where, the sacrificial core of carbon spheres were indigenously synthesized and mixed into the starting ethanolic solution of titanium tetraisopropoxide (TTIP) under ambient condition. The solid obtained on the hydrolysis of TTIP were dried and calcined in air to acquire the hollow nanospheres of TiO2 in anatase phase. The acquired samples were further doped with varying mole % of Mn(II) to invoke magnetism in the material. X-ray diffraction and thermal studies reflected the anatase to rutile phase transformation of TiO2 at 550 °C when the dopant (i.e., Mn) concentration was increased from 0 to 6 mol % (with respect to Ti). The hollow and spherical morphology of the TiO2 nanostructures were confirmed through scanning electron microscopic studies while their ferromagnetic behaviour (at 300 K) was affirmed through SQUID analysis. For intracellular applications, the biocompatibility of the nanospheres was tested through conventional MTT assay, performed on MDA-MB 231 cancer cell lines.

Structural and Thermal Studies of Titanium Dioxide Gel Modified with Anatase Isostructural Zircon Silicate

2018 ◽  
Vol 930 ◽  
pp. 73-78
Author(s):  
Eduardo Felipe de Carli ◽  
Natali Amarante da Cruz ◽  
Hiana Muniz Garcia ◽  
Jusinei Meireles Stropa ◽  
Lis Regiane Vizolli Favarin ◽  
...  
Keyword(s):  
Phase Transition ◽  
Titanium Dioxide ◽  
Rietveld Method ◽  
Anatase Phase ◽  
Sol Gel ◽  
Thermal Studies ◽  
Rutile Phase ◽  
Structural Rearrangements ◽  
X Ray Diffraction ◽  
X Ray

Important changes in anatase crystal structure are responsible for the consequent anatase-to-rutile phase transition in titanium dioxide powders. In order to investigate several structural rearrangements occurring in anatase phase obtained by hydrolysis-based method such as Sol-Gel method the X-ray diffraction techniques followed by Rietveld method seems to better approach. Several alterations in anatase lattice parameters can occur by doping insertion and the investigation of isostructural zircon silicate can provide interesting ones. In the present paper, the monitoring of anatase structure reordering and the consequent anatase-to-rutile phase transition along the thermal treatment up to higher temperatures were monitored carrying out DSC and XRD characterizations. The insertion of 6 mol% of zircon silicate leads to the fully anatase stabilization up to 900 °C due the control of ordering process, even that a continuous increasing in anatase tetragonality is present during the entire process. We can conclude the reconstructive anatase-to-rutile phase transition is delayed to very higher temperatures can consequence of more stable cross-linked metal oxide bond in anatase phase.

Influence of Mass Ratio of Aquadest and TTIP on the Synthesis of TiO2 Nanoparticles to Improve the Performance of DSSC with Beta-Carotene as Sensitizer

2014 ◽  
Vol 896 ◽  
pp. 481-484 ◽  
Author(s):  
Nafi'ah Ardhani ◽  
Agus Supriyanto ◽  
Akhmad Herman Yuwono ◽  
Risa Suryana
Keyword(s):  
Crystal Size ◽  
Anatase Phase ◽  
Sol Gel ◽  
Beta Carotene ◽  
Rutile Phase ◽  
Bandgap Energy ◽  
Mass Ratio ◽  
Titanium Tetraisopropoxide ◽  
X Ray Diffraction ◽  
X Ray

TiO2 nanoparticles have been successfully synthesized using the sol-gel method with main materials of titanium tetraisopropoxide (TTIP) and HClO4 solutions. Mass ratios (Rw) of aquadest and TTIP were 0.85, 2.00, and 3.50 which were going to be investigated in crystallization of TiO2 phases. Pre-heating was performed on TiO2 at 60°C for one day then it was annealed at 150°C for 3 hours. The DSSC structure was formed by using the synthesized-TiO2 as semiconductor material and beta-carotene as dye sensitizer. The x-ray diffraction (XRD) spectrum indicated that TiO2 peaks had anatase phases on crystal orientation of (101), (004), and (200) while TiO2 of rutile phase only appeared on orientation of (211). The highest intensity for all Rw was dominated by (101) anatase phase. From XRD spectrum data of (101) peak, the Scherrer’s method predicted that crystal size of TiO2 was 3.48 nm, 4.36 nm, and 4.47 nm for Rw of 0.85, 2.00, and 3.50, respectively. The Tauc’s method was applied on the UV-Vis data that predicted the bandgap energy (Eg) of TiO2 for Rw of 2.00 (Eg=3.14 eV) was higher than Rw of 0.85 (Eg=3.02 eV) and 3.50 (Eg=3.04 eV). The I-V characteristic calculation of DSSC structures were obtained that the efficiency optimum is 0.01% for Rw of 2.00. It is considered that bandgap energy value correlated to stability of Ti-OH bonds that caused the exited-electrons are easily injected to conduction band of TiO2. The performance of DSSC using the synthesized-TiO2 which consists of anatase and rutile can be improved about ten times compared to that using the pure-TiO2 rutile.

Probing the Phase Transition in Nanocrystalline TiO2 Powders by Positron Lifetime (PAL) Technique

2011 ◽  
Vol 319-320 ◽  
pp. 151-159 ◽  
Author(s):  
E.M. Hassan ◽  
Basma A.A. Balboul ◽  
M.A. Abdel-Rahman
Keyword(s):  
Positron Annihilation ◽  
Anatase Phase ◽  
Rutile Phase ◽  
Bet Surface Area ◽  
X Ray Diffraction ◽  
Positron Annihilation Lifetime ◽  
Nanocrystallite Size ◽  
Heat Treated ◽  
Degussa P25

Positron annihilation techniques (PAT) have recently been successfully employed for the characterization of phase transitions in metals and compounds. In the present study, positron annihilation lifetime (PAL) measurements have been carried out on a nanocrystalline titania (TiO2) in the form of powders that had been heat-treated at temperatures ranging from 300 to 1273K. The PAL spectra were analyzed into two lifetime components. The shorter lifetime τ1 (185-300 ps) is attributed to positron annihilation in vacancies and the longer lifetime τ1 (400-580 ps) to positrons in microviods at interfaces. The rutile phase of TiO2 powders was utilized as a reference in order to compare their behavior with the commercially supplied and widely available anatase phase (Degussa P25). The influence of the heat-treatment upon the nanostructure during the transition of the anatase to rutile phase were also investigated by X-ray diffraction (XRD), TEM and BET surface area methods. Understanding of this effect is expected to enhance our knowledge of the morphology and nanocrystallite size of TiO2 powders and their T-dependence, and hence their physical properties.

scholarly journals THE RELATIONSHIP BETWEEN MYOFILAMENT PACKING DENSITY AND SARCOMERE LENGTH IN FROG STRIATED MUSCLE

1967 ◽  
Vol 33 (2) ◽  
pp. 255-263 ◽  
Author(s):  
Philip W. Brandt ◽  
Enrique Lopez ◽  
John P. Reuben ◽  
Harry Grundfest
Keyword(s):  
Cross Sections ◽  
Packing Density ◽  
Sarcomere Length ◽  
Striated Muscle ◽  
X Ray Diffraction ◽  
Electron Microscopic ◽  
Semitendinosus Muscle ◽  
Direct Function ◽  
Microscopic Studies

In cross-sections of single fibers from the frog semitendinosus muscle the number of thick myofilaments per unit area (packing density) is a direct function of the sarcomere length. Our data, derived from electron microscopic studies, fit well with other data derived from in vivo, low-angle X-ray diffraction studies of whole semitendinosus muscles. The data are consistent with the assumption that the sarcomere of a fibril maintains a constant volume during changes in sarcomere length. The myofilament lattice, therefore, expands as the sarcomere shortens. Since the distance between adjacent myofilaments is an inverse square root function of sarcomere length, the interaction of the thick and the thin myofilaments during sarcomere shortening may occur over distances which increase 70 A or more. The "expanding-sarcomere, sliding-filament" model of sarcomere shortening is discussed in terms of the current concepts of muscle architecture and contraction.

Synthesis of nanometer-sized particles of barium orthotitanate prepared through a modified reverse micellar route: Structural characterization, phase stability and dielectric properties

2004 ◽  
Vol 19 (10) ◽  
pp. 2905-2912 ◽  
Author(s):  
Tokeer Ahmad ◽  
Ashok K. Ganguli
Keyword(s):  
Martensitic Transition ◽  
Line Broadening ◽  
X Ray Diffraction ◽  
Electron Microscopic ◽  
X Ray ◽  
Transmission Electron ◽  
Transmission Electron Microscopic ◽  
Microscopic Studies ◽  
Size Of Particles ◽  
Reverse Micellar

Nanoparticles of barium orthotitanate (Ba2TiO4) was obtained using microemulsions (avoiding Ba-alkoxide). Powder x-ray diffraction studies of the powder after calcining at 800 °C resulted in a mixture of orthorhombic (70%) and monoclinic (30%) phases. The high-temperature orthorhombic form present at 800 °C was due to the small size of particles obtained by the reverse micellar route. Pure orthorhombic Ba2TiO4 was obtained on further sintering at 1000 °C with lattice parameters a = 6.101(2) Å, b =22.94(1) Å, c = 10.533(2) Å (space group, P21nb). The particle size obtained from x-ray line broadening studies and transmission electron microscopic studies was found to be 40–50 nm for the powder obtained after heating at 800 °C. Sintering at 1000 °C showed increase in grain size up to 150 nm. Our studies corroborate well with the presence of a martensitic transition in Ba2TiO4. The dielectric constant was found to be 40 for Ba2TiO4 (at 100 kHz) for samples sintered at 1000 °C. The dielectric loss obtained was low (0.06) at 100 kHz.

Effect of Vapor Pressure of H2O on the Formation of Nano-Crystalline TiO2 Ultrafine Powders

1999 ◽  
Vol 581 ◽  
Author(s):  
K. R. Lee ◽  
S. J. Kim ◽  
J. S. Song ◽  
S. Park
Keyword(s):  
Vapor Pressure ◽  
Reaction Rate ◽  
Ph Value ◽  
Anatase Phase ◽  
Rutile Phase ◽  
Precipitation Process ◽  
Nano Crystalline ◽  
Natural Decrease ◽  
Spontaneous Hydrolysis ◽  
Hydrolysis Of

ABSTRACTMono-dispersed TiO2 ultrafme particles with diameters 40-400nm were obtained from aqueous TiOCl2 solution with 0.67M Ti4+ concentration prepared diluting TiCl4 by homogeneous precipitation process in the ranges of 17-230°C. With the spontaneous hydrolysis of TiOCl2, which means the natural decrease of pH value in the aqueous solution, all mono-dispersed precipitates were crystallized with the anatase or rutile TiO2 phase. TiO2 precipitate with the pure rutile phase was fully formed at the temperatures below 65 °C, not involving the evaporation of H2O, and above 155 °C, which were available by suppressing it. TiO2 precipitate with rutile phase including a small amount of the anatase phase started to be formed in the intermediate temperatures above 70 °C showing the full formation of the anatase above 95 °C under the free evaporation of H2O. However, in the case of completely suppressing H2O evaporation at the temperatures above 70°C, TiO2 precipitate with anatase phase was fully transformed into the precipitate with the rutile phase by the vapor pressure of H2O. Therefore, the formation of TiO2 precipitates with the rutile phase around room temperature would be caused due to the existence of the capillary pressure between the agglomerated needle-shaped particles or the ultrafme clusters, together with the slow reaction rate.

Synthesis of TiO2 and F-Doping TiO2 Powders via "Reverse" Hydrolysis of Titanium Tetraisopropoxide

2015 ◽  
Vol 1085 ◽  
pp. 95-100 ◽  
Author(s):  
Elena Fakhrutdinova ◽  
Anastasiia V. Shabalina ◽  
Elena Sudareva
Keyword(s):  
Heat Treatment ◽  
Particle Size ◽  
Phase Transformation ◽  
Rutile Phase ◽  
Bet Surface Area ◽  
Titanium Tetraisopropoxide ◽  
Prolonged Heat ◽  
Hydrolysis Of ◽  
Prolonged Heat Treatment ◽  
Reverse Hydrolysis

TiO2 and F-TiO2 powders were prepared by hydrolysis of titanium tetraisopropoxide with reversed mixing of different hydrolytic reagents. The typeof the hydrolytic agentstronglyinfluences particle size, morphology and phase composition ofpowder.It was found, that the amount of injected water is significantly affects on BET surface area and particle size ofbare TiO2.The presence offluorinemakes the samplemore porous and preventsanatase to rutile phase transformation under prolonged heat treatment, also particle formed are bigger in comparison with un-doped TiO2.

scholarly journals Characterization and evaluation of the photocatalytic activity of oxides based on TiO2 synthesized by hydrolysis controlled by the use of water/acetone mixtures

2020 ◽  
Vol 2 ◽  
pp. e11
Author(s):  
Werick A. Machado ◽  
Antonio Eduardo da Hora Machado
Keyword(s):  
Pure Water ◽  
Synthesis Process ◽  
Titanium Tetraisopropoxide ◽  
X Ray Diffraction ◽  
X Ray ◽  
A Value ◽  
Ponceau 4R ◽  
Crystalline Oxides ◽  
Hydrolysis Of ◽  
Controlled Hydrolysis

New photocatalysts based on TiO2 were synthesized and characterized. The synthesis involved the controlled hydrolysis of titanium tetraisopropoxide using water containing different proportions of acetone. X-ray diffraction analyses combined with Raman spectroscopy revealed crystalline oxides characterized by the coexistence of the anatase and brookite phases. The Rietveld refinement of diffractograms showed that the presence of acetone in the synthesis process influenced the composition of these crystalline phases, with the proportion of brookite growing from 13% to 22% with the addition of this solvent in the synthesis process. The BET isotherms revealed that these materials are mesoporous with surface area approximately 12% higher than that of the oxide prepared from hydrolysis using pure water. The photocatalytic potential of these oxides was evaluated by means degradation tests using the dyes Ponceau 4R and Reactive Red 120 as oxidizable substrates. The values achieved using the most efficient photocatalyst among the synthesized oxides were, respectively, 83% and 79% for mineralization, and 100% for discoloration of these dyes. This same oxide loaded with 0.5% of platinum and suspended in a 5:1 v/v water/methanol mixture, produced 56 mmol of gaseous hydrogen in 5 h of reaction, a specific hydrogen production rate of 138.5 mmol h−1g−1, a value 60% higher than that achieved using TiO2 P25 under similar conditions.

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