Investigation of factors affecting the synthesis of nano-cadmium sulfide by pulsed laser ablation in liquid environment

https://doi.org/10.1016/j.saa.2015.08.007Get rights and content

Highlights

  • Experimental parameters

  • Ablated materials and its medium parameters

  • Monodispersed CdS synthesized by pulsed laser ablation in water

Abstract

Pulsed laser ablation in a liquid medium is a promising technique as compared to the other synthetic methods to synthesize different materials in nanoscale form. The laser parameters (e.g., wavelength, pulse width, fluence, and repetition frequency) and liquid medium (e.g., aqueous/nonaqueous liquid or solution with surfactant) were tightly controlled during and after the ablation process. By optimizing these parameters, the particle size and distribution of materials can be adjusted. The UV–vis absorption spectra and weight changes of targets were used for the characterization and comparison of products.

Introduction

In the last few decades, research on semiconductor materials in nanoscale had been increased enormously and has been extremely attractive and of interest to several fields which include optoelectronic devices, solid-state lasers and solar cells [1], [2], [3]. Among semiconductor materials, cadmium sulfide (CdS) nanostructures in the form of quantum dots, nanowires, and thin films are widely investigated by many researchers [4]. For these applications it is important to synthesize nanoparticles with the adequate size distribution, morphology and crystallinity. There are different techniques for producing materials in the nanoscale such as pulsed laser deposition, flame metal combustion, chemical reduction, photo-reduction, electrochemical reduction, solvothermal, electrolysis, microwave-induced, sono-electrochemical, aerosol flow reactor, photochemical reduction, chemical fluid deposition, spray pyrolysis, and spark discharge [5], [6], [7], [8], [9], [10], [11], [12], [13], [14], [15], [16], [17], [18], [19], [20]. Many of these techniques use precursors and solvents, or imply chemical reactions which can contaminate the obtained nanoparticles. Pulsed laser ablation of solids in liquid environment (PLAL), one of these techniques, enables obtaining nanoparticles with no need of chemical precursors. Its simplicity together with the advantage of producing nanoparticles with small size, narrow distribution and weak agglomeration make it suitable for metal nanoparticle fabrication. This alternative physical nanofabrication method opened new routes for material processing based on the pulsed laser ablation of solids in various liquids. It could be used to produce a wide range of novel materials, such as nano-diamond and related nanocrystals, metallic nanocrystals, nanocrystal alloys, and metal oxides [21], [22], [23], [24].

In the PLAL method, three main steps contribute to form nanoparticles from a target immersed in liquid. Only in a short period of time, typically about a few microseconds, all these steps take place and nanoparticles are synthesized. Firstly, laser pulse heats up the target surface to the boiling point, and thus, plasma plume containing vapor atoms of target is generated. Then, plasma expands adiabatically; and finally, nanoparticles are generated when condensation occurs [24]. During the condensation step, nucleation takes place, and the fine nuclei either collide and stick to each other or precipitate new materials on them which result in growth.

The efficient size control approaches employ variations of physical parameters of laser radiation, such as laser pulse energy, repetition rates, laser wavelength, focal spot size and focusing conditions [25], [26], [27]. Therefore, there are number of factors that should be taken into account during the laser–matter interaction in liquid environment. In this paper, CdS nanostructures were investigated under different promising factors, focusing conditions and ablation mechanisms, that help us to optimize laser parameters and focus on conditions to produce and control the shape/size of the desired nanostructures.

Section snippets

Materials

The materials used are Cadmium chloride hemipentahydrate (CdCl2·xH2O) of M.W. 228.35, specification assay 95%, from S.d. Fine-Chem. Ltd.; and Sulfur (S) of A.W. 32.97 from S.d. Fine-Chem. Ltd., Cadmium Sulfide (CdS) of M.W. 144.48 from S.d. Fine-Chem. Ltd. All chemicals were of analytical grade and used without further purification.

Experiment

CdS nanostructures were synthesized by a Nd:YAG laser which is a Q-switched solid state laser, which emits its fundamental line (λ) at 1064 nm producing a pulsed 7 

Optimization of PLAL process

The parameters of the PLAL-experiment were tightly controlled during and after the ablation process. These parameters were found to play a crucial role in controlling the shape and size of the produced nanostructures. Hence, it is worthwhile to optimize the PLAL process which can be divided into:

  • i)

    Adjustment of the PLAL system

  • ii)

    Adjustment of the ablated materials and its medium

Conclusion

By using the information of absorption from the UV–visible spectra, there are a number of factors affected by the synthesis of materials (e.g., CdS) in the nanoscale using the PLAL technique studied: Effect of the different types of media (distilled water, deionized water or tap water), effect of different concentrations of solution (Na2S solution), effect of sintering of the target, and effect of the position of the material surface with respect to the focusing of the pulsed laser inside the

Acknowledgments

We thank the Laser Technology Unit (LTU), Center of Excellence for Advanced Sciences (CEAS) in National Research Center (NRC) of Egypt for funding.

References (37)

  • E. Caponetti et al.

    Mater. Sci. Eng. C

    (2003)
  • T. Donnelly et al.

    Appl. Surf. Sci.

    (2007)
  • S. Yang et al.

    Powder Technol.

    (2010)
  • C. Wu et al.

    Mater. Lett.

    (2006)
  • H. Jia et al.

    Thin Solid Films

    (2006)
  • P.Y. Lim et al.

    Chem. Phys. Lett.

    (2006)
  • M.J. Rosemary et al.

    J. Colloid Interface Sci.

    (2003)
  • J. Gu et al.

    Sol. State Chem.

    (2008)
  • O.R. Musaev et al.

    Chem. Phys. Lett.

    (2010)
  • G.W. Yang

    Prog. Mater. Sci.

    (2007)
  • A. Baladi et al.

    Appl. Surf. Sci.

    (2010)
  • A.S. Nikolov et al.

    Appl. Surf. Sci.

    (2014)
  • S.A. Al-Mamun et al.

    J. Colloid Interface Sci.

    (2013)
  • J.O. Winter et al.

    Colloids Surf. A Physicochem. Eng. Asp.

    (2005)
  • K.S. Babu et al.

    Mater. Res. Bull.

    (2007)
  • K. Dutta et al.

    Synth. Met.

    (2009)
  • D.M. Bagnall et al.

    Appl. Phys. Lett.

    (1997)
  • Z.K. Tang et al.

    Appl. Phys. Lett.

    (1998)
  • Cited by (78)

    • Customization of structure, morphology and optical characteristics of silver and copper nanoparticles: Role of laser fluence tuning

      2023, Applied Surface Science
      Citation Excerpt :

      Subsequently, the expanding cavitation bubbles are created owing to the energy transfer from the hot plasma into the immersion liquid, releasing several tiny fragments from the target material. Thereafter, the generated cavitation bubbles support the nucleation and growth process [29–31]. Hence, some of the material can be ruptured and dispersed away from the bulk target as tiny droplets, vapors or even expanding plasma plume during a laser ablation process.

    View all citing articles on Scopus
    View full text