Objectives: To develop Zirconium based glassy metals of Zr–Cu–Ag–Al systems by reactive magnetron sputtering and Pulsed laser deposition which would be applied on the surfaces of bio medical implants made of stainless steel (AISI 316L), titanium and titanium alloys (Ti-6Al-4V) and to investigate the microstructural, mechanical properties. In vitro bio corrosion studies will be done using SVET, DC polarization and AC impedance. Biocompatibility will be evaluated by thrombogenecity and cytotoxicity studies. Synthesis of inorganic nano-particles and their nano-composites as anti-microbial agents to prevent undesirable effects such as degradation, staining and deterioration of fibers in textiles. A wide range of nanoparticles with various structures will be immobilized on the fibers, which will bring new and medicinal properties to the final textile product.

The following inorganic nano-structured anti-microbial agents will be studied: TiO2 nano-particles, Metallic and non-metallic TiO2 nano-composites, Titania nanotubes (TNTs), Zinc oxide nano-particles and nano-rods, Copper oxide nano-particles. Techniques such as sol-gel method, electrospinning, chemical and photocatalytic reduction process, sonochemical irradiation and magnetron sputtering will be used. The antibacterial activities of the nano-structured materials will be tested against Escherichia coli (Gram negative) and Staphylococcus aureus (Gram positive) cultures. Zr48Cu36Al8Ag8 (at.%) thin film metallic glasses were deposited on 316L stainless steel substrates by magnetron sputtering as thin homogeneous layers. Potentiodynamic polarization and AC impedance analysis in SBF showed that the as sputtered Zr48Cu36Al8Ag8 on 316L SS specimen had higher corrosion resistance without any localized pitting compared to the crystalline base alloy.

Metallic Oxide coated cylindrical and flat plate sensor electrodes have been prepared with various thickness. Their corrosion related parameters and sensing behavior in concrete structures will be studied. Sensors are to be embedded in concrete structures and multifunctional parameters such as half-cell potential, chloride level, resistivity, alkalinity and corrosion rate of reinforcements to be monitored. The integrated sensor along with online monitoring sensor platform to be the expected outcome of the project.

The main objective is to prepare the transition metal nitride composite coatings such as Ti–X–N (where X=B, Si, V, C and Cr) by reactive pulsed magnetron sputtering after optimizing the process parameters such as substrate temperature, pressure, power, Ar/N2 flow rate variation etc. The structural properties of these coatings will be studied in detail. The mechanical strength of the coatings will be tested by measuring hardness, adhesion and abrasion wear. Scanning Vibrating Electrode Technique (SVET) will be used to investigate localized electrochemistry and corrosion phenomena Electrochemical Noise (EN) measurements Microstructure of the coatings will be studied before and after the corrosion tests.

Chromium nitride films were coated on D9 steel substrates by reactive DC magnetron sputtering process. The XRD pattern confirmed the grown films have polycrystalline nature and exhibited CrN and Cr2N phases. The coated D9 steel showed higher charge transfer resistance values compared to bare substrate. The corrosion current density (Icorr) was found to decrease from 1.31 x10-7A for bare substrate to 1.88 x 10-8 A for CrN coated D9 steel specimen. A decrease in the porosity value was noticed for coated substrate. The polarisation resistance was found to be higher for the coated specimens. From electrochemical noise analysis, the current transient was found to decrease with increasing the immersion time for CrN coated substrate and potential noise shifted to the positive direction. The noise resistance was found to be higher for coated specimen than bare substrate.

Optimization of the process parameters of titanium dioxide (TiO2), Zinc Oxide using magnetron sputtering is performed. Titanium dioxide (TiO2) thin films as block layers are prepared by DC reactive magnetron sputtering at a substrate temperature of 450°C. X-ray diffraction (XRD) and TEM-(SAED) analyses of the films reveal that they are polycrystalline in nature and have tetragonal structure with preferred orientation along the (101) direction. The presence of characteristic Raman peaks is observed along 173, 200, 400, 517, 640 cm-1 corresponding to anatase structure.

The surface morphological studies by FESEM, AFM reveal the uniform surface coverage of the grains on the surface of the films. An optical transmittance value of 80% in the visible light region with the optical band gap value of 3.2 eV is measured. These sputtered TiO2 thin film is used as blocking layer over which thick layer of TiO2 of about 10µm is prepared using TiO2 paste and this stack is used as photoanode of DSSC cell. Electron beam evaporated platinum thin film on FTO coated glass substrate is used as counter electrode. The cell stack is shown below. The performance of the cell with an efficiency of 4.15% is achieved.

The dye-sensitized photoelectrodes with block layers displayed improved Voc and Jsc without lowering the FF, which improved the device performance. Studies are underway to further enhance the performance of DSSCs that include a compact nitrogen doped TiO2 layer using newly developed working electrode, and a report will be forthcoming.

Oxide semiconductor thin films with nanostructure, as porous silicon matrix, transition metal oxides in thin film form and in powder were developed, through chemical routes. Various techniques such as RF sputtering, electron beam evaporation, electrochemical techniques, spray pyrolysis, were engaged for device development like; gas sensors, electrochromic windows, photoluminescent devices and batteries.

Important achievements:

Chemically stable and highly crystalline MgIn2O4 films was prepared using spray pyrolysis deposition technique on quartz substrate.Low resistivity NiO films, possessing anodic electrochromic properties, was deposited by the electron beam evaportation technique.Titanium nitride(TiN) films were deposited on AISI 316L stainless steel substrate by reactive magnetron sputtering using a Ti target. Corrosion resistance and hemocompatibility of TiN coated AISI 316L SS were studied for clinical applications.Deposition of nanocrystalline Indium TinOxide (ITO) was carried out using Radio frequency (RF) sputtering and spray pyrolysis technique.

Fabrication of Next generation TiO2-Lithium ion batteries:

Recently TiO2 based materials have also been demonstrated as potential anode material in rechargeable lithium ion batteries. TiO2 has a lithium insertion voltage around 1.5 V which is far above the lithium plating voltage thus leading to safer lithium (/-ion) batteries when compared to carbonaceous materials. Also of importance TiO2 is chemically stable, environmentally benign and low effective cost. By virtue of its exceptionally fast Li insertion and extraction kinetics, TiO2- based materials (anatase) have drawn the research interest as anode materials for nextgeneration lithium ion batteries.

Charge- discharge curves of TiO2 electrode at different conditions

The potential plateaus at 1.73 and 1.88V correspond to Li-ion insertion into and extraction from the interstitial octahedral sites of the TiO2 nanotubes, and these Li ions are easily reversible. The lithium insertion/ extraction reaction in TiO2 electrode can be written as

LixTiO2 ↔ xLi+ +x e- +TiO2

The maximum value of the insertion coefficient x has been determined to be about 0.5 that corresponds to a theoretical capacity of 167 mAh g-1. Figure shows the charge- discharge curves of TiO2 electrode at C/10, C/5 and C-rates.

The structural, mechanical, corrosion properties and biocompatibility of TiN/TiAlN, TiN/NbN, TiN/VN multilayer and Ti-Si-N nanocomposite coatings prepared by reactive dc magnetron sputtering in an Ar-N2 gas mixture was studied. Morphological study showed uniform coatings with columnar surface morphology. 

The characteristic peaks were observed from Laser Raman spectrum of Ti-Si-N. The lower friction coefficient and wear rate observed for the multilayer coated sample indicated that the better wear resistance.

A maximum hardness value of 39GPa was observed for Ti-Si-N.Multilayer coatings and had better hemocompatability than single layer and bare AISI 316LSS substrates. The attachment of bacteria on multilayer coatings was found to be very minimum and without colonization. The multilayer coated 316L surfaces showed a significant reduction of the presence of bacteria, and this fact could probably be important in the decrease of the inflammation of the peri-implant soft tissues. It is concluded that by using the transition metal nitride based multilayer coated 316L SS as a human body implant, improvement of corrosion resistance as an indication of biocompatibility could be obtained.

Hard coating of transition metal nitrides was developed by magnetron sputtering technique to have high mechanical strength and high corrosion resistance.

At present, solar lighting systems employ LMLA lead-acid batteries to store the electrical energy during daytime, which is retrieved on demand during night. These batteries have poor energy densities and are prone to sulphonation/stratification due to the large electrolyte volume. Besides, these batteries require periodic maintenance. Hence, new type of batteries like, VRLA-AGM, VRLA-GEL and Hybrid-AGM/GELVRLA batteries were assembled and tested with the objective to develop the most prudent maintenance-free solar lighting system.

 Computer controlled spin coating unit and a pulse console was fabricated to make semiconductor thin films. Spin coater unit can be used for making oxide thin films using sol-gel precursors. Pulse console can be used to electrodeposit semiconductor films by using ON and OFF pulses of varying current density.

WO3, MoO3, SnO2, In2O3 oxide films and their ternary compounds were prepared by the electrochemical, spray pyrolysis, vacuum evaporation and electron beam evaporation techniques for electrochromic devices and for use as transparent electrodes. Porous silicon (PSi) structure with nano Si pillars was formed on P-Si wafer by electrochemical route.

SrAl2O4:Eu2+, Dy3+ phosphors were synthesized using the solid state reaction of Sr, Al, Eu and Dy carbonates/oxides taken in desired molar ratio.ZnS:xMn2+ & ZnS:xTb3+ nanoparticle powders were prepared by sol-gel and combustion synthesis routes.

Copper, Chromium, cobalt and zinc substituted spinel were synthesized by solid state reaction and sol gel methods. The powders were characterized by XRD, FTIR, DTA, TGA, SEM and impedance studies.

MgIn2O4, MgSnO3 and MgSn2O4 powders and thin films were prepared by different routes and their opto electronic properties were studied. Thin films of MgIn2O4 were also prepared by oxidizing evaporated Mg+In alloy.MgIn2O4 have been synthesized adopting different precursor routes by solid state reaction. Indates of Mg, Cd and Zn were synthesized both by solid state reaction route (SSR) and combustion synthesis. Zinc gallate was synthesized by SSR, Combustion synthesis (CS) and sol-gel routes. Monophase powders could be obtained only by SSR and CS only. ZnGa2O4 and MgIn2O4 have very high potentiality as transparent conducting oxide materials in electronic industries

Principal Collaborator :- (CNP 0999) (Rs.0.90 Lakhs)

Sn (S, Se) is a layered compound semiconductor. It is also a very good material for solar energy conversion. These materials were prepared in the form of thin film through electrodeposition techniques.

In this consultancy work, initially we did some feasibility studies on sputter coating of Titanium Nitride on needles and blades made of stainless steel and mild steel by optimizing the process parameters. After the satisfactory results, we have advised Nano Marker’s Trichy to purchase DC Magnetron sputtering facility with the
complete required specifications. A DC magnetron sputtering equipment with a 4” dia cathode assembly was purchased from VR Technologies, Bangalore and installed it at Nano Marker’s Trichy. We performed few experiments in front of the client and trained them. Thereafter, we have made few visits to their company and discussed with them on the results of the experiments. They are advised to use the equipment for doing other coatings such as Silver, Sn, Chromium, Copper and Brass. It is understood from the discussion that they are able to fabricate successfully these coatings now. The work has been completed to the satisfaction of the client. The photographs of the products are shown here.