IGNOU MPHE 27 SOLVED ASSIGNMENT

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MPHE 027 (January 2025 - July 2025) - ENGLISH

Tutor Marked Assignment

NANOSCIENCE

Course Code: MPHE-027

Assignment Code: MPHE-027/TMA/2025

Max. Marks: 100

Note: Attempt all questions. The marks for each question are indicated against it.

PART A

1. a) Explain the use of nanotechnology in the Prehistoric and Ancient Era.

b) Outline the role of developments in quantum mechanics and microscopy techniques in understanding the nanostructures.

2. a) Calculate the surface energy for a copper crystal for (110) plane. Copper has FCC structure with atomic radius 1.28 A. The heat of vaporization is 341 kJ mol.

b) Describe the phenomenon of Ostwald Ripening based on the solute concentration given by Thompson-Freundlich relation. 

3. a) Explain the principle used in sonochemical method of synthesizing nanoparticles.

b) Which chemical components in the plant extracts make them active for metal nanoparticle synthesis? What is the difference between the static and dynamic self assemblies?

4. a) Draw a labeled schematic diagram of the system used to synthesize Fullerenes. How was the presence of cage molecules of carbon first discovered?

b) Given for a single wall carbon nanotube that rolls on, chiral vector is r = na,+ mas, Find out the chiral angle and diameter of CNT with (n, m) = (5,5). (5)

5. a) Describe the features of Type II semiconductor@semiconductor core-shell particles with the help of band diagram. How can longer wavelength optical tuning be achieved in Type II particles?

b) Explain the origin of two absorption peaks in the absorption spectra in the visible range for nanorod structures of metals like gold.

PART B

6. a) Derive the expression for the quantum conductance of a nanowire connected to two reservoirs of electrons with chemical potentials µ₁ and µ₂ with µ₁ με

b) Describe the variation of Hall resistance Pxy and longitudinal resistance px with magnetic field in integer quantum Hall effect and fractional quantum Hall effect. Can these phenomena be explained using free electron theory?

7. a) Explain Neel relaxation time and blocking temperature for a superparamagnetic particle. How does the blocking temperature change with the size of the particle?

b) Draw a typical hysteresis loop for a superparamagnetic material and state its characteristics.

c) How does the structure of a multilayer system exhibiting GMR differ from that exhibiting TMR?

8. a) How can the blue colour of a morpho butterfly be explained using the concept of a photonic crystal?

b) What is a photonic band gap? How is it different from an electronic band gap?

c) What is a topological insulator? Explain how a thin film of Bi₂Se(Te) is transformed into a topological insulator.

9. a) What are nanocomposites? Describe the applications of nanoparticle reinforced ceramic nanocomposites.

b) Describe the use of nanotechnology in improving the masks used by health workers..

10. a) Explain the use of nanotechnology in targeted drug delivery. What are its advantages?

b) Describe the mechanism of photocatalytic degradation of toxic pollutants like Volatile Organic Compounds (VOCs) using nanomaterials like fullerenes and CNTs.

MPHE 027 (January 2026 - July 2026) - ENGLISH

Tutor Marked Assignment

NANOSCIENCE

Race Code: MPHE-027

Assignment Code: MPHE-027/TMA/2026

Max. Marks: 100

Note: Attempt all questions. The marks for each question are indicated against it.

PART A

1. a) For an icosahedral cluster calculate the number of atoms present in its 7th shell. Find the total number of atoms in this cluster and its surface to bulk atom ratio.

b) Draw the LaMer diagram and explain the particle growth in its three regions.

2. a) Describe the set up used for ionized cluster beam (ICB) deposition. What are the advantages of this method?

b) Explain the steps of sol-gel synthesis of silica gel. Differentiate between the structure and method of formation of xerogel and aerogel.

c) What is meant by bio-template? With an example explain how it can be used in nanostructure synthesis. State the advantages of using green methods for nanomaterial synthesis.

3. a) Explain the structure and bonding pattern in C60 Fullerene. Which nanocrystalline allotropes of carbon are obtained using the electric arc deposition set-up with graphite rods?

b) What are Dirac point and Dirac cone in case of graphene? What are the specialties of a Dirac cone? What is the difference between graphene and graphyne?

4. a) Explain with examples, what are Janus particles. Which synthesis methods can be used to form such particles?

b) Calculate the surface plasmon energy of a metal with free electron density of . 

c) What are surface plasmon polaritons (SPP)? State any two technological applications of SPP. 

d) What is exciton? What is the difference between Frenkel and Mott-Wannier excitons? Calculate the radius of an exciton in a semiconductor with dielectric constant , and . (1+2+2)

PART B

5. a) Explain the difference between ballistic transport and normal (diffusive) transport in a material. Using the Landauer formula, calculate the conductance of a quantum device in which the conduction take place through three channels, each of which has a transmission coefficient . 

b) Derive the expression for the conductivity matrix in integer quantum Hall effect. 

6. a) What is the difference between single domain and superparamagnetic particles? A superparamagnetic material has a characteristic time of 10^-11 seconds and a Néel relaxation time of 2.0 second at 300 K. Calculate
i) the energy barrier (in eV); and
ii) the blocking temperature if the measurement time is 120s.
Take . 

b) What are single negative and double negative materials? Explain with the help of a diagram, the characteristics of the propagation of electromagnetic waves through a double negative material. 

c) Describe the property of band inversion in a topological insulator. Hence explain why a topological insulator cannot be transformed into a normal insulator. 

7. a) Explain the construction and working principle of a microfluidic cantilever sensor. What is the resolution attained by such sensor? 

b) Describe the detection mechanism of a virus with the use of Up-Conversion Nanoparticles (UCNPs). 

8. a) What are triboelectric nanogenerators? Explain the different modes of their operation.

b) Describe the role of Nanotechnology in the reduction of air pollution.

c) Explain the lotus effect based on contact angle. Describe two practical applications of lotus effect. 
 

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