The Effect of Ultrasonic Field on Synthesis of Nanometer Calcium Carbonate and its Growth Mechanism

2011 ◽  
Vol 287-290 ◽  
pp. 445-448 ◽  
Author(s):  
Jin Zhu Xue ◽  
Chao Huo ◽  
Jia Yuan Shen ◽  
Qing Hua Xia ◽  
Xiang Wei Cheng
Keyword(s):  
Particle Size ◽  
Calcium Carbonate ◽  
Calcium Hydroxide ◽  
Growth Mechanism ◽  
Fine Particles ◽  
Ultrasonic Field ◽  
Nucleation And Growth ◽  
Amorphous Calcium Carbonate ◽  
Initial Stage ◽  
Nucleation And Growth Mechanism

The effects of ultrasonic and Baumé degree of Ca(OH)2 suspension on the size of nano-CaCO3 prepared by carbonization were studied. The results indicated that ultrasonic could improve the dispersibility of powder, reduce the aggregation and decrease the particle size of nanometer calcium carbonate. The fine particles synthesized at 40 kHz were smaller but rougher than that obtained at 20 kHz. The frequency hardly influenced the morphology of nanometer calcium carbonate. Moreover, the lower Baumé degree of Ca(OH)2 suspension was adopted, the smaller the size of nano-CaCO3 were obtained. And in the process of carbonation, we were using SEM and XRD to study the nucleation and growth mechanism, it indicated that amorphous calcium carbonate particles acted as nuclei in the initial stage oriented absorption calcium hydroxide to form wirelike substances. In the end, these botryoidal shape crystals were disaggregated into calcium carbonate with the particle diameters of 30nm.

scholarly journals Nucleation and Growth Mechanism of Si Amorphous Film Deposited by PIAD

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
D. Li ◽  
G. L. Liu ◽  
Y. Yang ◽  
J. H. Wu ◽  
Z. R. Huang
Keyword(s):  
Growth Mechanism ◽  
Amorphous Film ◽  
Nucleation And Growth ◽  
Force Microscopy ◽  
Atomic Force ◽  
Initial Stage ◽  
Initial Nucleation ◽  
Si Films ◽  
20 Nm ◽  
Nucleation And Growth Mechanism

The nanoscale Si films with the thickness of 2 nm, 5 nm, 10 nm, and 20 nm were deposited by plasma ion assisted deposition (PIAD) on glass substrate, in order to investigate the initial stage and the nucleation and growth mechanism of the Si film. The atomic force microscopy (AFM) was used to investigate the surface topography of the as-deposited Si film. The initial nucleation and growth process of the film was described. The continuous film had been already formed when the film thickness was 10 nm. The growth of the deposited Si film accorded with the Volmer-Weber growth mode.

Formation of coherent twins in YBa2Cu3O7–δ superconductors

1989 ◽  
Vol 4 (4) ◽  
pp. 795-801 ◽  
Author(s):  
C. J. Jou ◽  
J. Washburn
Keyword(s):  
Oxygen Uptake ◽  
Growth Mechanism ◽  
Oxygen Uptake Rate ◽  
Nucleation And Growth ◽  
Electron Microscopic ◽  
Transmission Electron ◽  
Transmission Electron Microscopic ◽  
Twin Formation ◽  
Boundary Model ◽  
Nucleation And Growth Mechanism

A nucleation-and-growth mechanism for the twin formation in YBa2Cu3O7–δ superconductors based on the oxygen uptake rate curve and published transmission electron microscopic observations is proposed together with an oxygen-depleted twin boundary model. The difficulty of reaching stoichiometric YBa2Cu3O7 is explained.

scholarly journals Nucleation/Growth and Optical Proprieties of Co-doped ZnO Electrodeposited on ITO Substrate

2021 ◽  
Vol 12 (5) ◽  
pp. 6776-6787
Keyword(s):  
Cyclic Voltammetry ◽  
Growth Mechanism ◽  
Supporting Electrolyte ◽  
Saturated Calomel Electrode ◽  
Nucleation And Growth ◽  
Visible Range ◽  
Zno Films ◽  
Doped Zno ◽  
Nucleation And Growth Mechanism ◽  
Co Doped

A Co-doped ZnO layer was prepared by electrodeposition method on indium doped tin oxide (ITO) substrate using a cathodic reduction from nitrate medium with different doping percentages of cobalt. The bath temperature was controlled at 70 °C. The films were cathodically electrodeposited in a bath containing 5 mM Zn(NO3)2. 6H2O, while the source of Co is Co(NO3)2.6H2O where 0.1M KNO3 was used as supporting electrolyte. The nucleation and growth mechanism of Co-doped ZnO nuclei have been studied by cyclic voltammetry and chronoamperometry. The cyclic voltammetry shows that the electrodeposition of ZnO and Co-doped ZnO at a negative potential around -1.0 V versus saturated calomel electrode (SCE) is a quasi-reversible reaction controlled by the diffusion process. Comparing current transients curves obtained by the chronoamperometric method with the theoretical curves of current density j versus t ½ allows us to say that the nucleation is 3D instantaneous, as shown in SEM analysis. The presence of Co does not modify the nucleation and growth mechanism. The XRD patterns show that the substitution of zinc by cobalt does not change the würtzite crystal structure, but the crystallite size decreases with the cobalt percentage. The transmittance spectra indicate that the Co-doped ZnO films are transparent in the visible range. The optical gap increases with the doping percentage of cobalt.

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