Electron Momentum Distribution
Around Vacancy Cluster in CdO
Nanoparticles
Anjan Das
Abstract Very small-sized cadmium oxide nanoparticles were prepared by sol–gel
process using cadmium chloride and sodium hydroxide as precursor. Two solutions
of 0.2 M CdCl 2 and 0.2 M NaOH were used with a mixture of 1:2 ethylene glycol
and methanol. The particles are in the range 9–22 nm. X-Ray Diffraction (XRD)
crystallography and High-Resolution Transmission Electron Microscopy (HRTEM)
were carried out to characterize the samples. They are found polycrystalline in nature
and possessed fcc (NaCl-type) structure with lattice parameter varying with annealing
temperature. In the XRD spectra, the (111), (200), (220), (311), and (222) peaks of
fcc structure can be seen without any other phases. HRTEM pictures show that the asprepared samples are hexagonal in structure. Positron annihilation spectroscopy was
carried out to investigate the Doppler-broadened spectra of the samples. The CDBS
ratio curve showed a characteristic peak at p L = 18.7 × 10
–3 m 0 c in the spectra of all
the samples. It indicated the sites of positron annihilation inside the nanoparticles. The
S and W parameters revealed the chemical surroundings and momentum distribution
of the vacancy clusters varying with crystallite size. The lineshape (S) parameter
showed a remarkable change and wing (W) parameter continuously increased with
decreasing crystallite size.
1 Introduction
In this era, the nanomaterials have drawn much attention for its wide application
and an increase in basic knowledge in material (Das et al. 2018) research. It is
possible that structural, optical, and electrical properties of a metal oxide nanomaterial be changed with its particle size or thickness. Cadmium oxide (CdO) is a
wide bandgap p-type semiconductor (Yao et al. 2013). Various methods have been
adopted to synthesize CdO nanoparticles (Liu et al. 2002, 2003) in low cost to use
A. Das (B)
Department of Physics, A.P.C. Roy Government College, Siliguri, Darjeeling 734010,
West Bengal, India
e-mail: anjan802002@yahoo.co.in
© Springer Nature Singapore Pte Ltd. 2021
D. Ramkrishna et al. (eds.), Advances in Bioprocess Engineering and Technology,
Lecture Notes in Bioengineering,
https://doi.org/10.1007/978-981-15-7409-2_45
449
Around Vacancy Cluster in CdO
Nanoparticles
Anjan Das
Abstract Very small-sized cadmium oxide nanoparticles were prepared by sol–gel
process using cadmium chloride and sodium hydroxide as precursor. Two solutions
of 0.2 M CdCl 2 and 0.2 M NaOH were used with a mixture of 1:2 ethylene glycol
and methanol. The particles are in the range 9–22 nm. X-Ray Diffraction (XRD)
crystallography and High-Resolution Transmission Electron Microscopy (HRTEM)
were carried out to characterize the samples. They are found polycrystalline in nature
and possessed fcc (NaCl-type) structure with lattice parameter varying with annealing
temperature. In the XRD spectra, the (111), (200), (220), (311), and (222) peaks of
fcc structure can be seen without any other phases. HRTEM pictures show that the asprepared samples are hexagonal in structure. Positron annihilation spectroscopy was
carried out to investigate the Doppler-broadened spectra of the samples. The CDBS
ratio curve showed a characteristic peak at p L = 18.7 × 10
–3 m 0 c in the spectra of all
the samples. It indicated the sites of positron annihilation inside the nanoparticles. The
S and W parameters revealed the chemical surroundings and momentum distribution
of the vacancy clusters varying with crystallite size. The lineshape (S) parameter
showed a remarkable change and wing (W) parameter continuously increased with
decreasing crystallite size.
1 Introduction
In this era, the nanomaterials have drawn much attention for its wide application
and an increase in basic knowledge in material (Das et al. 2018) research. It is
possible that structural, optical, and electrical properties of a metal oxide nanomaterial be changed with its particle size or thickness. Cadmium oxide (CdO) is a
wide bandgap p-type semiconductor (Yao et al. 2013). Various methods have been
adopted to synthesize CdO nanoparticles (Liu et al. 2002, 2003) in low cost to use
A. Das (B)
Department of Physics, A.P.C. Roy Government College, Siliguri, Darjeeling 734010,
West Bengal, India
e-mail: anjan802002@yahoo.co.in
© Springer Nature Singapore Pte Ltd. 2021
D. Ramkrishna et al. (eds.), Advances in Bioprocess Engineering and Technology,
Lecture Notes in Bioengineering,
https://doi.org/10.1007/978-981-15-7409-2_45
449