Nalini G Sundaram

Dr. Nalini G Sundaram,
Associate Professor
Email:nalini[at]poornaprajna[dot]orgMaterials Science

Our research deals with the study of functional nanomaterials as applied in the energy sector. We study a broad range of materials systems such as:

  1. Photoluminescent Materials for Solid state lighting Devices
  2. Photocatalytic Materials active under visible light for degradation of dyes and other contaminants
  3. Nanomaterials for Gas sensor applications
  4. Metal Organic Precursors for Optoelectronic devices

Research Expertise

  • Preparation of inorganic nanomaterials, mostly oxides, tungstates, oxychlorides,phosphates, organometallic precursors etc., under optimum, easier conditions
  • Characterization of these nanomaterials using tools like PXRD, TEM, DSC etc.
  • Measurement of photoluminescence,photocatalytic activity etc.
  • Expertise in studying the detailed crystal structure of the phase using powder X-ray and powder Neutron diffraction techniques
  • Finally correlating the structure with the property to generate materials with improved properties
  • Oxide nanoparticles, Nanocomposites and Thick films selective Gas Sensors
  • Rare Earth Photoluminescent nano-oxides for  Theronastic applications
  • Ceramic Nanomaterials  Photocatalysts for dye degradation and organic reactions
  • Design and Structure of Lead free Ferroic Materials
  • Structure-Property Relationships in Functional energy nanomaterials
  • Synthesis, structural studies, polymorphism, local structure and  phase transitions in multifunctional materials using Single Crystal, Powder X-ray as well as Neutron diffraction techniques
  1. Bi4TaO8Cl Nano-Photocatalyst: Influence of Local, Average and Band Structure,Swetha S. M. Bhat, Diptikanta Swain, Mikhail Feygenson, Joerg C. Neuefeind, Abhishek K. Misra, Janardhan L. Hodala,  Chandrabhas Narayana, Ganapati V.Shanbhag and Nalini G. Sundaram, Inorganic Chemistry,    DOI: 10.1021/acs.inorgchem.6b01970
  2. Investigation of Ca substitution on the Gas Sensing Potential of LaFeO3 Nanoparticles Towards Low Concentration SO2 Gas Sowmya Palimara, S. D Kaushik, V. Siruguri, Diptikanta Swain, Alison E. Viegas, Chandrabhas Narayana , Nalini G. Sundaram, Dalton Transactions,2016,45, 13547-13555
  3. Na2.44Mn1.79(SO4)3: a new member of the alluaudite family of insertion compounds for sodium ion batteries Debasmita Dwibedi,  Rafael B. Araujo,  Sudip Chakraborty,   Pradeep.P. Shanbogh,   Nalini G. Sundaram,   Rajeev Ahuja and  Prabeer Barpanda  J. Mater. Chem. A, 2015,3, 18564-18571
  4. Invitedarticle titled ‘Fullerenes Revisited: Materials Chemistry and Applications of C60 Molecules’    Pradeep P. Shanbogh Nalini G. Sundaram, Resonance,  February 2015, 20 (02), (p.123)
  5. Photocatalysis of Bi4NbO8Cl hierarchical nanostructure for degradation of dye under Solar/UV irradiation, Swetha S M Bhat and Nalini Sundaram  New J. Chem., 39,3956-3963, 2015
  6. Controlled inversion and surface disorder in zinc ferrite nanocrystallites and their effects on magnetic properties, Ranajit Sai, Suresh D. Kulkarni, Swetha S. M. Bhat, Nalini G. Sundaram, Navakanta Bhat and S. A. Shivashankar, RSC Adv., 2015,5, 10267-10274
  7. ‘Photoluminescence tuning of Na1_xKxNdW2O8 (0.0 r x r 0.7) nanoparticles: synthesis, crystal structure and Raman study’ Swetha S. M. Bhat, Ashfia Huq, Diptikanta Swain, Chandrabhas Narayana and Nalini G. Sundaram, Phys.Chem.Chem.Phys.,2014, 16, 18772 Total Number of Publications in National and International Journals: 26

A. Photocatalysis

Semiconductor photocatalysis has received much attention during last few decades as a promising solution for both energy generation and environmental problems because it represents an easy way to utilize clean solar energy abundantly available everywhere in the world. Semiconductor photocatalysis is initiated by electron-hole pairs after bandgap excitation. When a photocatalyst is illuminated by light with energy equal to or greater than band-gap energy, the valence band electrons can be excited to the conduction band, leaving a positive hole in the valence band. The excited electron-hole pairs can recombine, releasing the input energy as heat, with no chemical effect. However, if the electrons (and holes) migrate to the surface of the semiconductor without recombination, they can participate in various oxidation and reduction reactions bwith adsorbed species such as water, oxygen, and other organic or inorganic species. Potential applications of photocatalysis are found mainly in four aspects a) Photocatalytic degradation of organic pollutants, b) Photoc atalytic water splitting to produce H2 and O2, c) Photocatalytic  reduction of CO2. d) Photocatalytic synthesis for organic substances. These oxidation and reduction reactions are the basic mechanisms of photocatalytic water-air remediation and photocatalytic hydrogen production, respectively.

1. Average, Local  and Band Structure  of Rare earth Substituted  Bi2WO6  (RE = Nd, Eu, Tb) Nanoparticles: Implications on their Photocatalytic Activity

 Aruvillius phases with layered perovskites are shown to be good photocatalysts and better luminescent materials. Bi2WO6 is the basic structure in the layered perovskite structure, which exhibits polymorphism, hence crystallographically also very interesting to explore the structure-property relationship. Nanoparticles of rare earth ion substituted Bi2WO6 were synthesized by varying temperature, pH and composition. The obtained nanoparticles were characterized by PXRD, PL and photocatalytic activity of the materials are being studied

B. Photoluminescent  Nanomaterials for Solid State Lighting and Theronastic Applications

Alkali rare earth double tungstates with general formula ARE(WO4)2 (A=alkali metal ion, RE= rare earth ions) are promising materials for optoelectronics, solid state lighting and in stimulated Raman scatterin shift due to their unique optical, elastic and magnetic properties1. However, luminescent properties heavily rely on the crystal chemistry of host material i.e., local environment of an activator ion. Crystallographic features of these materials are isostructural to the tetragonal Scheelite structure2. It is found that the substitution of a pair of A+ and RE3+ ion in the place of Ca2+ could results in crystallographic changes such as distortion in crystal structure, lowering of the parent structure and phase transitions3. These could eventually influence physical properties such as luminescence as a function of crystal structure4. Nowadays most of the research is focused on rare earth doped upconverison materials because of their potential uses in in-vitro and in-vivo applications as drug delivery systems In recently times especially ytterbium and erbium doped oxides, fluorides, sulphides and molybdates are used since the electronic energy levels of Er3+.and Yb3+ are more suitable for green emission under IR excitation5

1. Design, Crystal structure and Photoluminescence of  Lithium Rare Earth Tungstate Nanoparticle Polymorphs  (RE=La,Ce,DyYb)

The alkali rare earth double tungstate materials are found to be multifunctional used as solid state luminescent hosts and undergo high temperature polymorphic phase transition that results in a different luminescence properties. First time  polymorphism observed in these materials by different synthesis methods. These materials show PL in red and green region. These are promising potential for up conversion materials. They are a very important class of compounds for both solid state lighting devices as well as biological applications.Currently, tetragonal and monoclinic polymorphs of some rare earth tungstate nanoparticles have been synthesized by conventional hydrothermal and solution combustion method  Photoluminescent measurements of these materials was carried out and found that both compounds show good emission in the visible region.

C. Gas Sensors

1.Design of Lanthanum based Perovskite Nanoparticles for the Development of Thick Film Gas Sensor

 Lanthanum (La) based perovskite nanoparticles have been designed and developedas selective and sensitive thick film gas sensors to detect toxic and flammable gases. The work involves investigation of the effect of substitution and particle size on the crystal structure of the nanoparticles and then to obtain good quality thick films from the particles in order to study their sensing properties to different gases such as sulphure dioxide acetone, ammonia, hydrogen sulphide, hydrocarbons and L.P.G. Sulphur dioxide (SO2) is a highly toxic gas which is released during various reactions in chemical and petrochemical industries. This gas posions the victim by inhalation through lungs and the threshold limit of this gas is 5 ppm. Thus there is a great demand to develop low concentration SO2 gas sensor. To establish selectivity further gas sensing study will be performed with other gases. These materials showed a significantly good response to SO2 gas at a lower temperature with remarkably  good response and recovery time, whereas at this temperature a significantly low response was seen for higher ppm of other gases such as methane

2. Design of Transition Metal Oxide -SnO2 Based Nanocomposites for Highly Selective Gas Sensors

Tin oxide has been proven to be a highly gas sensitive material for detection of both reducing and oxidizing gases. However it has a few disadvantages such as low selectivity, low stability and higher operating temperature. Hence our approach is to couple n-type semiconducting SnO2 to V2O5, Nb2O5 and Ta2O5 to derive a nanocrystalline composite as a selective gas sensing material. SnO2 was prepared by conventional different surfactant assisted hydrothermal and Co-precipitation methods.

D. Ferroic Materials

In recent years much research is focused on obtaining nanomaterials that exhibit multifunctional applications. For example, focus is on the relaxor ferroic as well as  magnetoelectric effect exhibited by materials. In the magnetoeelectric materials control of electric polarization can be achieved by a magnetic field and magnetization by electric field. This opens up many new applications such as magnetic/ferroelectric data storage, magnetocapacitive devices, magnetic sensors, non-volatile memories. Many of these materials have layered structures that can be tuned by substitution to obtain the application

1. Design of Bismuth based Nanomaterials for Magnetoelectric Properties:Oxide materials belonging to the Aurivillius family or the Aurivillius-Sillen phase of oxides has gained significant attention due to their unique layered structure. Among these the isostructural Bi2WO6 and Bi2MoO6 are the simplest (n= 1) members of the large family of layered perovskite related (Aurivillius phases). The structure of these isostructural materials consist of alternating Bi2O2 sheets and perovskite-like layers of corner linked BO6 octahedra (B=W.Mo). Substitution to this layered material with a magnetic ion can alter the crystal structure resulting in magnetoelectric materials.

2.      Structural Analysis of Lead Free Relaxor Dielectrics with TiO2 Rutile Structure

Multiferroic oxides have wide range of applications as sensors, transducers and other switching devices Eg:Novel relaxor ferroic oxides, FeTiTaO6, FeTiNbO6. Low-temperature dielectric measurements depict anomalous dielectric relaxations with frequency dispersion in these materials. To investigate the dielectric anomalies a series of solid solutions of FeTiTaxNb1-xO using high temperature sold state reactions was synthesized and low temperature X-ray data from 20K to 300K were collected.The dielectric anomalies reported are clearly seen in the variations in  cell parameter and volume of the unit cell with temperature

Sponsored Projects at PPISR

Starter grant of $1000 under the  ICDD (International Centre for Diffraction Data)Grant-In-Aid program for the year 2016-2017.

Sanctioned: Phase Transitions in BiMWO6 (M=Ce,fe,Cr) Smart Functional Nanomaterials by UGC-DAE CSR Mumbai Centre, India for three years (2016-2019)

Ongoing: “Design and development of lanthanum based nanoparticles for Thick film gas Sensors.”: Sponsored by DST-India, Under Extra Mural Research grant (April 2015-April 2018)

Ongoing: Influence of Electron Beam Irradiation on the Crystal Structure and Photoluminescence of Rare Earth doped Tungstate Nanophosphors: Sponsored by BRNS, DAE, India for three   years (April 2013-March 2016)

Completed: Design and Development of Nanocrystalline Bismuth Oxychlorides for Degradation of dyes and Organic Pollutants: Sponsored by DST, India, under the Fast track scheme for Young Scientists for three years (Jan 2012- Jan 2015)

  • 2010-Present: Asst. Professor, PPISR, Bangalore, India.
  • 2005-2008: Postdoctoral Researcher , Dept. of Physics,University of California, Santa Cruz, USA.
  • 2004-2005: Postdoctoral Reseacher, Los Alamos National Laboratory, New Mexico and Stanford Synchrotron Laboratory,Stanford, U.S.A
  • 1997-2003: Ph.D. Solid State Chemistry ,Indian Institute of Science, Bangalore, India,2003 

Awards and Scholarship

  • Awarded a project by DST, India for three years under the SERC- Fast Track Scheme For Young Scientists (FAST)
  • Senior Research Fellowship from Council of Scientific and Industrial Research (CSIR) Government of India
  • Recipient of the Joshi award for securing first rank in M.Sc. (Physical Chemistry)
  • Awarded a project by DST ,India for three years under the SERC- Fast Track Scheme For Young Scientists (FAST)
  • Senior Research Fellowship from Council of Scientific and Industrial Research (CSIR) Government of India
  • Recipient of the Joshi award for securing first rank in M.Sc. (Physical Chemistry)
  • Reviewer for “Bulletin of Materials Science” journal

Mr. Pradeep P. Shanbogh,(CSIR , SRF)

Research topic:Rare earth substituted Bismuth based   Nanoparticles  for Visible Light  Photocatalytic Applications

My research interests are designing new functional oxide nanomaterials for energy applications via low temperature solution based approach. Understanding the fundamentals of the mechanism of phase formation in inorganic materials and morphology controlled synthesis. Structural elucidation of inorganic materials using X-rays, neutron and electron scattering techniques and establishing the structure-property relationship of the materials.

Ms. Archana K M, JRF

Research topic: Design of Photoluminescent Oxide Nanomaterials for Theranostic Applications

Ms. Archana is working on rare earth based nanomaterials for photoluminescent and theranostic applications. Her area of research focuses on the design of photoluminescent oxide materials via soft chemical techniques such as solvothermal, sonochemical and modified sol-gel methods followed by their surface fuctionalization for bioconjuction with the materials of interest.  She is mostly concentrating on the  crystal structure analysis of these materials and specifically on the local environment of luminescent ion and how it influences the observed fluorescent properties to achieve structure property correlation via synchrotron and neutron diffraction studies. Furthermore, she is also working on the design of upconverison nanomaterials which converts IR/near IR to visible light for photoactivated drug delivery applications.

Ms. Brunda, JRF

Research topic:  Investigation of the Lanthanum based Perovskite nanoparticles for the gas sensing applications.

Area of interest:

Miss Brunda G, works on the perovskite oxides(ABO3) nanoparticles for the gas sensing applications. These materials are particularly attractive for sensor applications because in addition to high melting temperatures, they provide microstructural and morphological stability to improve reliability and long term sensor performance. Her area of study is on the gas sensing property measurement of the different materials for the various gasses at different concentration by using the resistivity based gas sensing technique in the form of the pellet, thick or thin films.

Her other interest includes the Study of phase transition in Bismuth based nanoparticles for smart functional applications like magnetic/ferroelectric data storages ,magnetocapacitive devices  etc.

Dr. Swetha .S. M.
Alumni

Thesis Title:Investigation of smart oxide nanomaterials for photoluminescent and photocatalytic applications

Currently Post-Doc at Seoul National University, South Korea

Dr. Srinidhi R
Alumni

Thesis Title:Carbonaceous, Nanostructured Metal Oxides Obtained From Metalorganic Precursors through Inert-Ambient, Sealed-Tube Pyrolysis

Currently Post-Doc  at CeNSE, IISc Bangalore