Dr. E. G. Rini Post Doctoral Fellow Centre for Material Science & Engineering.

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Research work focuses on: Lattice dynamics of materials using Rigid Ion Model, Shell Model, Density Functional Theory (DFT) Synthesis, characterization and physical properties of nanomaterials. Dr. E.

1 Research work focuses on: Lattice dynamics of materials using Rigid Ion Model, Shell Model, Density Functional Theory (DFT) Synthesis, characterization and physical properties of nanomaterials. Dr. E. G. Rini Post Doctoral Fellow Centre for Material Science & Engineering. Lattice dynamics of PrMnO3 & NdMnO3. (Work collaborated with BARC, Mumbai). The lattice dynamical properties of PrMnO3 and NdMnO3 were studied using shell model and First Principle Density Functional Theory (DFT). The investigations include the computation of the vibrational modes, leading to the phonon dispersion curves, phonon density of states, Raman and infrared frequencies, specific heat and electronic structure calculation which includes band structure, electron density of states of PrMnO3 & NdMnO3. These studies aimed at providing an understanding of the microscopic aspects of the thermodynamic properties of these parent manganites of the colossal magnetoresistance materials. Study of cohesion & structural properties of RMnO3 perovskite (R= La, Pr, Nd, Tb, Dy, Ho, Er). (Work collaborated with Dr. Savas Kaya, Cumhuriyet University, Turkey) A study of the cohesion and structural properties of RMnO3 perovskite have been carried out by means of an interatomic potential, which consists of the long-range Coulomb interactions & short range overlap repulsive interactions. Structural properties include cohesive energy, molecular force constant, bulk modulus, Debye temperature

2 & Reststrahlen frequency. The variation of Madelung energy & structural properties with decreasing ionic radii of R 3+ along the series RMnO3 (R=La to Er) has been studied. It is noticed that the short-range overlap repulsion is less than 15% of the total cohesive energy. This feature is indicative of the fact that major contribution to the cohesion in RMnO3 (R= La, Pr, Nd, Tb, Dy, Ho, Er) perovskite materials is due to coulomb attraction. It is well known that these static properties of the materials originate from the interatomic interactions between their atoms. Therefore, theoretical studies of static properties are very important because these properties are directly calculated from interatomic potential. Static properties like bulk modulus, molecular force constant, Reststrahlen frequency provides information regarding the stability & hardness of the material. Debye temperature gives information about the highest temperature that can be achieved due to a single normal vibration & hence it is important. Effect of Silicon substitution in ZnO: First Principle Density Functional Study. Band structure calculation, Electronic Density of States and phonon frequencies have been calculated for pure and silicon substituted ZnO. Project Proposal: First Principle Studies & Synthesis, characterization, physical properties of multiferroics RFeO3(R=Bi, Ga, La, Nd) nanoparticles submitted to DST. Ongoing Research Projects: *Study of effect of substitution of Vanadium in TiO2 using

3 DFT. *Study of effect of substitution of Iron in CuO2 using DFT. *Study of effect of substitution of Nickel in CeO2 using DFT. These studies focus on how physical and optical properties are affected with substitution. Publications: A. Book Cohesive and Thermal Properties of Colossal Magnetoresistive La0.88 Sr0.12 MnO3. E. G. Rini, N.K. Gaur, Vilas Shelke, M.P. Verma & R.K. Singh, in Phonons in Condensed Materials eds. S. P. Sanyal and R. K. Singh, (Allied, New Delhi, 2004), p.352. B. International Journals Phonon dynamics of lanthanum manganite LaMnO3 using an interatomic shell model potential E. G. Rini, Mala N. Rao, S. L. Chaplot, N. K. Gaur, and R. K. Singh, Phys. Rev. B 75 (2007) Phonon dispersion curves of CsCN N. K. Gaur, Preeti Singh, E. G. Rini, Jyotsna Galgale and R.K. Singh, Pramana 63 (2004) 419. Specific heat of LaMnO3+ δ at 50 K T 160 K. E.G. Rini, N.K. Gaur, Vilas Shelke, J. Galgale, M.P. Verma & R.K. Singh. Journal of Superconductivity, 15 (2002) 583. Effect of lattice distortion on bandgap decrement due to vanadium substitution in TiO2 nanoparticles Nasima Khatun, E. G. Rini, Parasharam Shirage, Parasmani Rajput, S. N. Jha and Somaditya Sen, Journal Material Science and Semiconducting Processing 50 (2016) 7-13.

4 Structural distortion and bandgap increment in nanocrystalline wurtzite Si substituted ZnO. Tulika Srivastava, E.G.Rini, Ashutosh Joshi, Parasharam Shirage and Somaditya Sen, J. Nanosci. Nanotechnol.16 (2016) 1 4. Structural and Mechanical characterization of Si doped ZnO. Gaurav Bajpai, Mohd Nasir, E. G. Rini, Sunil Kumar, Parasharam Shirage, and Somaditya Sen, Accepted in J. Nanosci. Nanotechnol. (2016). C. Conference Proceedings Thermodynamic properties of the orthorhombic manganites, LaMnO3 and YMnO3 Mala N. Rao, E.G. Rini, Nupinderjeet Kaur, N.K. Gaur, R.K. Singh and S.L. Chaplot, Presented in International Conference on Advanced Materials held at Bangalore, 8-13 October Lattice dynamics of the orthorhombic manganites, LaMnO3 and YMnO3 Mala N. Rao, E.G. Rini, Nupinderjeet Kaur, S. L. Chaplot, N.K. Gaur and R. K. Singh, Presented at International Symposium on Materials Chemistry held at BARC, 4-8 December Thermodynamic Properties of Colossal Magnetoresistance La1-x Srx MnO3 (0 x 0.16 ) compound. E.G. Rini Presented in XVIII Madhya Pradesh Young Scientist Congress Specific Heat of LaMnO3+ δ at 50 K T 160 K. E.G. Rini, N.K. Gaur, Vilas Shelke, J. Galgale, M.P. Verma & R.K. Singh. Presented in International Conference on Superconductivity, CMR and Related Materials at Giens, France during June1-8, 2002.

5 Static Shear Elasticity of (KCN)x(NaCN)1-x System. mixed Jyotsna Galgale, E. G. Rini, R.K. Singh & N.K. Gaur, Solid State Phys. (India), 44 (2001) 67. Phonon Dynamics of orientationally Disordered mixed Crystals rubidium cyanide & bromide. N.K. Gaur, Jyotsna Galgale, E. G. Rini, M. Manke & R.K. Singh, Solid State Phys. (India), 44 (2001) 295. Static Shear Elasticity of Disordered mixed Crystals. Jyotsna Galgale, E. G. Rini, D.C. Gupta, R.K. Singh & N.K. Gaur, Solid State Phys. (India), 43 (2000), pp

The Effect of Potassium Doping on Specific Heat of Rare Earth Manganite RMnO 3 (R=La, Pr).

The Effect of Potassium Doping on Specific Heat of Rare Earth Manganite RMnO 3 (R=La, Pr). Abstract Archana Srivastava * and N.K.Gaur 1 Department of Physics, Sri Sathya Sai College for Women, Bhopal 46224,