Mandate

• DDSD is comprised of three sections, namely Defect Studies Section, Accelerator & Radiation Damage Studies Section and Materials Modelling Section.


• DDSD focuses on studies on defects, defect-impurity interactions in reactor structural materials, supplemented by computations. Ion beam radiation damage studies are carried out using a 1.7 MV tandem accelerator and a 400 keV in-house built linear accelerator either in single or dual ion beam modes of irradiation to study defects and radiation response in materials of relevance for fusion and fission reactors. Defects, in particular, open volume defects such as vacancies and their clusters are studied using positron annihilation spectroscopy.


• Positron beam based Doppler broadening studies have been used mainly for depth resolved defects studies in irradiated materials. Ion beam based characterization techniques such as high resolution RBS, channeling are being used extensively in addition to ion beam induced luminescence studies. Irradiation creep studies are being planned with proton beam of energy 2-3 MeV and high beam current. Various experimental results related to defects are analyzed using detailed computations with a variety of simulation and ab-initio codes. High speed cluster computers at IGCAR are being extensively utilized for computation of materials properties.

Achievements

Radiation Damage Studies in Reactor Materials

Nuclear Structural Materials

• Indian Reduced Activation Ferritic/Martensitic (IN-RAFM) steels irradiated with He, H and Fe ions at doses and temperatures relevant to fusion first-wall irradiation conditions revealed injected interstitial effects and void stabilization with He above 673K using positron beam based Doppler broadening studies ?
• Formation and stability of dispersoids in Zr ODS alloys – Ion irradiation experiments and simulation.
• Radiation damage studies on W and V alloys irradiated with He and Au revealed complete defect recovery at 1273 K in both irradiations and no signature of bubble/void growth was observed.
• Evaluation of defects in Y₄Zr₃O₁₂ compounds using in-situ-ionoluminescence
• Radiation damage studies on ODS steels using positrons revealed Zr-ODS is more resistant to radiation damage as compared to Al-ODS.
• Development of irradiation texture in NC-Ni - Competition and synergies between temperature and irradiation.
• Void swelling studies in NC-Ni – Effect of internal sinks, surface and injected interstitials.
• Ion channelling Studies of oxygen impurity –defect interactions in Fe and FeCr model alloys
• HRBS studies of Cr segregation in FeCr alloy upon Xe+ ion implantation.
• Defect studies on sodium exposed SS316 revealed occurrence of ferromagnetic-ordered zones due to open volume defects, predominantly that of Ni vacancies as deduced by Mössbauer studies.
• Displacement Cascade characteristics in materials undergoing radiation damage in different materials like ODS steels, semiconductors, zirconate, titanate pyrochlores, yttria compounds and nuclear fuel materials using DFT and MD methods.

Nuclear Ceramics / waste storage matrices

• Investigation of nuclear waste loading capacity of Iron Phosphate Glass (IPG) using positron revealed 44% of Cs can be accommodated by open volume in IPG
• Aggregation and ordering of helium in thoria
• Ion Irradiation induced phase transformation in ZrO₂
• Ion irradiation induced crystallization in Iron Phosphate glasses (IPG)
• Appropriate interatomic potentials for Y₂Ti₂O₇, Y₂TiO₅ have been developed and available potential for the IPG have been improved by adding the ZBL contribution for small inter-atomic distances.
• Ionization-induced defect recovery in 3C-SiC
• Atomistic models of SiO₂ and Iron Phosphate glasses (IPG) using the potential free Monte-Carlo method has been developed for modelling amorphous materials.

Ion beam modification and synthesis

• Studies of photoluminescence and magnetic properties of C+ ion implanted ZnO thin films.
• Novel green method of graphene synthesis from graphene oxide by ion implantation
• Alloying of metal nanoparticles by ion-beam induced sputtering
• Bandgap opening in monolayer graphene by Ar ion impacts and in Ni/Gr/Ni/SiC
• Interdiffusion behaviour of Au and Ag into copper through graphene barrier layer
• Ionoluminescence studies in keV energy He ion irradiated ZrO₂.
• Defect studies in FeCrCoNi HEA irradiated with Ni did not show void formation upto 100dpa.
• Free volume studies on nanofibers of Polyamide-6 and Polyacrylonitrile revealed more free volume as compared to their bulk films.
• Positron annihilation studies on N implanted 6H-SiC revealed recrystallization and the recovery of deep level defects occurring above 1270K.
• Atomic scale understanding on nucleation and growth of BiFeO3 nanoparticles synthesized by sol-gel method and significant magneto electric coupling associated with the weak ferromagnetically ordered shell of the nanoparticles of BiFeO₃ using Mössbauer spectroscopy.
• Effects of La / Mn substitutions on the structural, magnetic and ferroelectric properties of nano BiFeO₃ particles and enhanced magnetoelectric coupling properties of cationic substituted nano BiFeO₃.
• Magneto, ferroelectric studies of BiFeO₃ based nano composites containing partially La_0.67Sr_0.33Mn_0.095Fe_0.05O₃ (LSMFO) and CoFe₂O₄.
• Understanding of the defects and disordering in terms of the local structure and magnetic properties at Fe atoms in Co₂FeAl subjected to different nonequilibrium treatments by means of detailed 57Fe-based Mössbauer spectroscopic studies.
• Defects and magnetic interactions inducing lattice disordering in Co₂Fe_0.5Cr_0.5Al Heusler compound.
• Microstructure studies & evolution of defects in nanoporous Au with annealing temperature using low-energy positron beam experiments.
• The changes in the electronic properties of transition metal doped graphene layers, thermodynamical stability of black phosphorene, SiB, the 2D analogue of silicene, 2D C3N5 and V2O5 layers for water chemistry applications.
• The structural phase transitions as a function of pressure in sesquioxides like La2O3, and thermal conductivity in IIA-VIA compounds in rock salt structure and LaPO₄ based alloys.
• Defect kinetics and nanocluster formation in Zr and Al added ODS steels, threshold displacement energies in Y₄Zr₃O₁₂, thermal expansion of UZr₂, effects of defects on the optical properties of SnO₂ quantum dots, have been simulated using the ab-initio MD.
• Study of the point defect formation, its stability, and diffusion barriers and pathways in metal matrix like the bcc-Fe and bcc-U using DFT techniques.

• High-temperature radiation damage studies of Reduced Activation Ferritic/Martensitic (RAFM) steel at fusion relevant He/dpa ratio using positron beam based Doppler broadening spectroscopy
• The behavior of the fission gas helium inside thorium oxide fuel was studied by irradiating thorium oxide.
• Irradiation effects and defect studies of High Entropy alloys.
• Synthesis & DFT studies of the effect of Zr additions in Al containing Oxide Dispersion Strengthened Steels (ODS) alloys and effect of irradiation.
• Computation of structural and thermal properties of nuclear fuel materials using ab-initio methods.
• Developed independent code for modeling the structural stability and waste storage capacity of iron phosphate glasses
• Modeling the thermal and anharmonic properties of 2D materials like graphene.
• Studies on the effect of doping on the stability and waste storage capacity of iron phosphate glasses for nuclear waste management applications.
• Bulk and local structural & magnetic studies of multiferroic materials and Co& Fe based Heusler compounds.
• Grain boundary electron emission mechanism in N+ ion implanted Ultra nano-crystalline cubic diamond (UNCD) & Enhanced Electron Field Emission in Au implanted UNCD.
• Non Equilibrium Green function’s study of spin transfer torque in non-collinear magnetic tunnel junctions exhibiting quasiparticle bands.
• First principles study of Uranium intermetallic U2Ti.
• Interatomic Potential Development & MD Simulations in Y-Ti-O Systems.
• Effects of Si ion-irradiations on Ag nanoparticles.

Expertise

• Investigation of heavy / light ion irradiation induced open volume defects such as vacancies and their clusters in bulk of reactor structural materials using Positron Annihilation Spectroscopy
• Depth resolved defects studies in irradiated materials using Low energy positron beam based Doppler broadening
• Simulation of neutron induced damage in reactor structural materials with simultaneous dual ion beam implantation of heavy and light ions tuned to suitable energies using 1.7 MV tandetron and 400 KV linear accelerators respectively
• Ion beam based characterization of defects using high resolution RBS, Channeling and ion beam induced luminescence studies developed in-house.
• Theoretical studies to validate various experimental results related to defects in reactor structural and waste storage matrices besides basic research studies on novel materials by using detailed computations. Variety of simulation and ab-initio codes namely Density Functional Theory (DFT), Molecular dynamic (MD) and Monte Carlo (MC) simulations are extensively utilized using High Performance Cluster Computing facility at IGCAR.
• Developed in-house an advanced low energy positron beam based spectrometer for deducing Doppler broadening of annihilated photons for depth resolved defects studies in irradiated samples
• Development of dual ion beam irradiation facilities, unique in India, using Accelerators to emulate better the irradiation conditions of fission and fusion candidate materials for purposes such as material screening and evaluation of basic mechanisms or model calibration.
• Indigenous development of 400 keV accelerator
• Development of High Resolution RBS spectrometer
• Development of in-situ Iono luminescence system
• Designed and developed a fibre optically linked distributed control electronics and instrumentation to facilitate control and monitoring of the UHV beam line and the 400kV accelerator. Some of the important features of the control system include fibre optic communication for high voltage isolation, fast data rate(1.2 MBaud) and no transient pick up, modular design, high resolution, high update rate upto 32k channels/sec, rugged and reliable operation through fault-tolerant and self-correcting software and built-in diagnostics.
• Development of photonic sources as bipartite quantum systems with tunable entanglement content.
• Reconstruction of two-photon entangled states through tomographic methods.
• Carried out studies involving single-photon and two-photon interferometers.
• Development of novel schemes for improving the quality of entanglement, through the process of distillation and their experimental verification
• Generation of light beams having arbitrary superpositions of spin and orbital angular momenta.
• Development of novel polarization based gadgets for complex beam shaping and for the generation of structured light beams through tailoring of their polarization, phase and amplitude.
• Development of discrete-time quantum walks have been implemented using the spin and orbital angular momentum of photons.
• Development of theoretical tools for exploiting Pancharatnam-Berry Optical Elements (PBOEs) for realizing arbitrary beams shaping.
• Development of theoretical tools for exploiting discrete Winger function formalizing for characterizing entanglement in single qubit as well as multi-partite quantum systems.
• Studies of accoustic phonon oscillations in semi-conductors using time-resolved spectroscopy. In pure GaAs, the lineshape of these oscillations is shown to have a pronounced asymmetry close to the bandgap

Infrastructure / Facilities

• Dual ion irradiation facility for the studies of radiation response in fission and fusion reactor materials has been developed at MSG . This work has been awarded with Group Achievement award from DAE.
• State of art high-resolution RBS facility is developed at MSG which is coupled with Molecular Beam Epitaxy (MBE) for addressing defects studies and advanced solid state physics problems
• Ion-Beam Induced Luminescence and Optical Absorption Spectroscopy System is setup for the in-situ studies of irradiation and defects dynamics in oxides
• 200 kV Accelerator has been setup at UGC-DAE-CSR, Kalpakkam Node for the benefit of the researchers from the Universities in India
• Design and development of indigenous control system for 1.7 MV accelerator & Development of fibre optic linked Control and monitoring system for 400kV accelerator
• Installation of Materials Science beamlines and optimization of irradiation experiments at Medical Cyclotron, Kolkata
• Irradiation and ion implantation Facilities:
  • 1.7 Mev Accelerator.
  • 400 KeV Accelerator
  • 150 kV Accelerator
• XRD
• Microscopic Characterisation :SEM & TEM
• RBS (Rutherford Backscattering Spectrometry), Ion Channeling (depth profiling, lattice locations of impurities)
• Spectrometer for Iono luminescence
• Scanning Tunneling Microscopy (atomic resolution topography)
• Defect characterisation
  • Positron lifetime spectrometer
  • Coincidence Doppler Spectrometer
• Variable low energy positron beam for depth resolved defects studies
• Mossbauer & TDPAC spectrometers for local structural & magnetic properties
• Auger Electron spectroscopy
• Fourier Transform Infrared (FTIR) Spectroscopy
• Entangled photon source for quantum information studies
• Femto second spectrometer