04/15/2023 1

CENTRAL UNIVERSITY OF PUNJAB, BATHINDA

Credit seminar

Size dependent optical properties of Zn doped Cr2O3 nanoparticles

Submitted by:Name: Gaurav Kumar Yogesh

Program: M.Sc. Physics (Nanophysics)Reg. No. CUPB/M.Sc./PMS/SBAS/2013-14/01

Supervisor: Dr. Kamlesh Yadav

Centre for Physical and Mathematical Sciences

04/15/2023 2

Content Introduction Historic background Method to prepare nanoparticles Properties of nanoparticles Material and methods Experimental analysis Results and discussion Conclusions Review of literature References

04/15/2023 3

introduction

Technologies ,which incorporate the materials, to

manipulate measures or features with atleast one of its

critical dimensions between 1 nm to 100nm.

Nanomaterials can be of two types; engineered or non-

engineered

Engineered nanoparticles are intentionally created to meet

the specific applications e.g. CNT, Fullerene etc.

Non-engineered nanoparticles are unintentionally created

by nature such as volcanic ash, DNA and protein.

04/15/2023 4

How big or small are nanoparticles?

www.essentialchemicalindustry.org

04/15/2023 5

Nanotechnology Through History

Gold colloids were used for

aesthetic (decoration) and

curative purposes

the Lycurgus Cup (4th

Century B.C) is ruby red in

transmitted light and green

in reflected light, due to the

presence of gold colloids

1857: Faraday reported

formation of deep-red

solutions of colloidal Au LS-FCM University di Bologna

04/15/2023 6

Why small thing ?

Fasters

Lighters

Can get into small spaces

Cheaper

More energy efficient

Less waste product

Use less materials to produce

Different properties

http://snf.stanford.edu/Education/Nanotechnologynt scales

04/15/2023 7

Methods to achieve the nanoparticles Top-Down approach

These approach use larger (macroscopic) initial structure,

which can be eternally controlled in the process of

nanostructure.

Typical examples are etching through the mask and ball

milling and applications of several plastic deformation. Bottom-Up approach

These approaches include the miniaturization of materials

components (up to atomic level) with further self assembly

process leading to the formation of nanostructure

Typical examples are quantum dot formation during

epitaxial growth and formation of nanoparticles from

colloidal dispersion.

04/15/2023 8

Why nanoparticles exhibit different properties then bulk ?

Two of the reasons:

1. Ratio of surface area-to-volume of structure

increases most atoms are at or near the surface,

which make them more weakly bonded and

more reactive.

2. Quantum mechanical effects are important, size

of structure is on same scale as the wavelengths

of electrons, and quantum confinement occurs

resulting in changes in electronic and optical

properties

04/15/2023 9

Examples of Nanotechnology Applications Supercomputer in your palm,

Very tiny motors, pumps, micro sensor, and accelerometers;

Energy storage (batteries) and conversion (solar cells) using nanowires and nanotubes

Stain and wrinkle resistant clothes, transparent zinc oxide sunscreen, fast-absorbing drugs and nutrients.

04/15/2023 10

objective

To synthesise the nanoparticles by using the novel solvent

and cost effective

To study the doping effect on its optical and structural

properties.

To compare the various results on its process of

synthesising the nanoparticles and doping effects

04/15/2023 11

Material and methods

All the reagents were of AR/GR quality and were purchased

from the Sigma-Aldrich, Loba- Chemi Pt. Ltd., and were

used without further purification.

Infrared (IR) spectra of nanoparticles were recorded with

KBr on a Bruker FT-IR spectrometer.

Surface morphology and size of the particles has been

recorded with gold coating on the samples

UV-visible spectroscopy was used to record the optical band

of the nanoparticles.

04/15/2023 12

Experimental analysisFor the characterisation of the samples we do the following

analysis

1. Morphological and structural analysis: FESEM had been used to study the morphological and

structure of prepared samples.

2. Optical analysis: The optical band gap of the material had been calculated

by the (Shimazdu 02206) UV-visible spectrometer

3. Spectroscopical analysis: The various functional groups and the characteristics

peaks due to the various compounds can be observed by (Brucker Ltd) FTIR spectrometer

All the experimental analysis has been performed at the lab of (Centre for Physical and Mathematical sciences) central university of Punjab, Bathinda

04/15/2023 13

Results and discussion

http://www.iitk.ac.in/meesa/SEM/tutorial/SEM_MS

04/15/2023 14

Morphlogical and structural analysis FESEM image of the prepared samples of respective particle sizes are 55,

41, 26, 22 nm.

Fig. FESEM image of Zn doped Cr2O3 nanoparticles

04/15/2023 15

Spectroscopical analysis FTIR stands for Fourier Transform Infrared Spectroscopy. Works on the principle of the Michelson's Interferometer. FTIR spectrometer acquires broadband NIR and FIR spectra. FTIR is method of obtaining the infrared spectra by collecting an inferogram

of a sample signal, using the interferometer and then a Fourier transform on the inferogram to obtain the spectrum

FTIR spectrometer collects and digitised the interferogram, perform the FT function and display the spectrum

Every bond or the functional groups requires the different frequency for absorption, hence characteristic peaks is observed for the every functional groups or the part of the molecules.

According to principle

Applied Infrared frequency = Natural frequency of vibration

04/15/2023 16

Spectroscopical results

Fig. FTIR characteristics peaks of the Zn doped Cr2O3 nanoparticles

04/15/2023 17

FTIR set-up

Fig. FTIR set-up of central university of Punjab, Bathinda

04/15/2023 18

Optical analysis

Optical band gap of the following samples are calculated by Tauc relation, by extrapolating the slope of the peaks gives the optical band of the nanomaterials.

Fig. Optical band of the samples are obtained by the FTIR data

04/15/2023 19

Samples characterisations and results

Name of the samples

Method of preparation of the samples

Average particles size(nm)

Optical band gap(eV)

Characteristic peaks observed in FTIR (Cr-O Vibration) cm-1

Sample-1 Sol-gel 55 1.50 619

Sample-2 Sol-gel 26 3.50 484

Sample-3 Hydrothermal

22 3.70 760

Sample-4 Sol gel 41 2.09 803

04/15/2023 20

Size dependent optical properties of the nanoparticles

Decrease in the size of nanoparticles results in the

increase in the optical band gap of the nanomaterials.

It arises due the quantum confinement .

Surface Plasmon resonance: The resonance condition is

established when the frequency of

incident photons matches the natural frequency of surface

electrons oscillating against the restoring force of positive

nuclei. SPR in subwavelength scale nanostructures can be

polaritonic or plasmonic in nature.

04/15/2023 21

Contd..

Fig. Variation of the particle size withBand gap of nanoparticles

Fig. Variation of the refractive of the Nanoparticles with Band gap

04/15/2023 22

Conclusions

Size dependent optical properties of nanomaterials.

Refractive index of the nanomaterials is decreases with the

increases in the band gap.

Confirmation of the quantum size effect.

Cr2O3 nanoparticles can be used in creating the highly efficient

solar cells and optoelectronic devices.

Because of large band gap(≈ 3 eV) used in the insulating materials.

The band gap of the nanoparticles can altered by changing the

environmental conditions or the preparing technique.

It can used in manufacturing the Transparent conducting Oxide

(TCO) materials which have both simultaneous property of

conducting and transparent.

04/15/2023 23

References Abdullah, M., Rajab, F. M., & Al-Abbas, S. M. (2014). Structural and optical

characterization of Cr2O3 nanostructures: Evaluation of its dielectric properties. AIP Advances, 4(2), 027121.

Athar, M., & Das, A. J. (2014). Therapeutic Nanoparticles: State-of-the-art of nanomedicine. Advanced Materials Review, 1(1), 25-37.

Bañobre-López, M., Vázquez-Vázquez, C., Rivas, J., & López-Quintela, M. A. (2003). Magnetic properties of chromium (III) oxide nanoparticles. Nanotechnology, 14(2), 318.

Cao, H., Qiu, X., Liang, Y., Zhao, M., & Zhu, Q. (2006). Sol-gel synthesis and photoluminescence of p-type semiconductor Cr 2 O 3 nanowires. Applied physics letters, 88(24), 241112-241112-241113.

Esparza, I., Paredes, M., Martinez, R., Gaona-Couto, A., Sanchez-Loredo, G., Flores-Velez, L. M., & Dominguez, O. (2011). Solid State reactions in Cr 2 O 3-ZnO nanoparticles synthesized by triethanolamine chemical precipitation. Materials Sciences and Applications, 2(11), 1584.

Farzaneh, F. (2011). Synthesis and Characterization of Cr2O3 Nanoparticles with Triethanolamine in Water under Microwave Irradiation. Journal of Sciences, Islamic Republic of Iran, 22(4), 329-333.

Fernandez-Garcia, M., Martinez-Arias, A., Hanson, J., & Rodriguez, J. (2004). Nanostructured oxides in chemistry: characterization and properties. Chemical Reviews, 104(9), 4063-4104.

04/15/2023 24

Contd.. Jaswal, V. S., Arora, A. K., Singh, J., Kinger, M., & Gupta, V. D. (2014). Synthesis

and Characterization of Chromium Oxide Nanoparticles. Oriental Journal of Chemistry, 30(2), 559-566.

Jin, H., Huang, Y., & Jian, J. (2015). Plate-like Cr 2 O 3 for highly selective sensing of nitric oxide. Sensors and Actuators B: Chemical, 206, 107-110.

Kawabata, A., Yoshinaka, M., Hirota, K., & Yamaguchi, O. (1995). Hot Isostatic Pressing and Characterization of Sol‐Gel‐Derived Chromium (III) Oxide. Journal of the American Ceramic Society, 78(8), 2271-2273.

Lei, S., Peng, X., Liang, Z., Li, X., Wang, C., Cheng, B., . . . Zhou, L. (2012). Self-template formation and properties study of Cr 2 O 3 nanoparticle tubes. Journal of Materials Chemistry, 22(4), 1643-1651.

Li, D., Han, Z., Zheng, J., Wang, X., Geng, D., Li, J., & Zhang, Z. (2009). Spin canting and spin-flop transition in antiferromagnetic Cr 2 O 3 nanocrystals. Journal of Applied Physics, 106(5), 053913-053913-053915.

Li, L., Yan, Z. F., Lu, G. Q., & Zhu, Z. H. (2006). Synthesis and structure characterization of chromium oxide prepared by solid thermal decomposition reaction. The Journal of Physical Chemistry B, 110(1), 178-183.

Lota, G., Frackowiak, E., Mittal, J., & Monthioux, M. (2007). High performance supercapacitor from chromium oxide-nanotubes based electrodes. Chemical physics letters, 434(1), 73-77.

04/15/2023 25

Contd.. Meenambika, R., Ramalingom, S., & Chithambara Thanu, T. (2013). Effect of

calcinations temperature on the structure of Cr 2 O 3 nanoparticles prepared by novel solvent free synthesis. Paper presented at the Advanced Nanomaterials and Emerging Engineering Technologies (ICANMEET), 2013 International Conference on.

Mohanapandian, K., & Krishnan, A. (2014). Effect of Concentration of Ni 2 on the Physio Chemical Properties of Cr2o3 Nano Particles.

Pei, Z., Xu, H., & Zhang, Y. (2009). Preparation of Cr 2 O 3 nanoparticles via C 2 H 5 OH hydrothermal reduction. Journal of Alloys and Compounds, 468(1), L5-L8.

Rao, T. M., Yang, Y., & Sayari, A. (2009). Ethane dehydrogenation over pore-expanded mesoporous silica supported chromium oxide: 1. Catalysts preparation and characterization. Journal of Molecular Catalysis A: Chemical, 301(1), 152-158.

Robertson, J. (2004). High dielectric constant oxides. The European physical journal applied physics, 28(03), 265-291.

Vayssieres, L., & Manthiram, A. (2003). 2-D mesoparticulate arrays of α-Cr2O3. The Journal of Physical Chemistry B, 107(12), 2623-2625.

Vigil, O., Cruz, F., Morales-Acevedo, A., Contreras-Puente, G., Vaillant, L., & Santana, G. (2001). Structural and optical properties of annealed CdO thin films prepared by spray pyrolysis. Materials Chemistry and Physics, 68(1), 249-252

04/15/2023 26

Thank You