Thrust areas of research :
1. Glass and Glass Ceramics
1. Glass and Glass Ceramics
Work is in progress for the development of special coloured glasses, infrared filter glasses suitable for night vision and high density radiation shield glasses. Stains for sheet glasses with copper and silver and heat resistant coating on glasses are being developed. Studies on different micronutrient glasses have been carried out for their suitable application in agriculture for different soil conditions. These micronutrient glasses may be helpful in increasing the yield and quality of major crops like wheat, paddy etc. Valency of redox ions plays an important role in coloration, decolorization, refining and quality of glasses. Spectrometric methods are being developed for determination of different ions in glasses. Glass ceramics also have a number of diverse applications for electronic devices and circuits, which include microelectronic substrate, packaging, multilayer and barrier layer capacitors etc. Perovskite titanates show many useful properties for various electronic applications. Investigations are being carried out for preparation of glass ceramics with perovskite phases e.g. strontium titanate, lead strontium titanate in pure as well as solid solution form. The dielectric characteristics of the glass ceramics doped with various rare earth and transition metal oxides are also being investigated. Some of the glass ceramic samples show relaxor like behavior with high value of dielectric constant while other show temperature stable dielectric behavior.
Sintering and micro-structural studies of refractory oxides like Al2O3, ZrO2, Mgo, Cr2O3 etc. are carried out to attain the maximum sintered densities and desirable microstructure so that optimum refractory properties are obtained in the end product. The work is also in progress to develop sintered grains of single oxide or binary refractory oxides for the development of refractory castables of desirable preparation.3-Electrical and Electronic Ceramics
Valence compensated solid solution systems of the type A1-xAx'B1-xB'xO3 show interesting electrical and dielectric properties. Valence compensated perovskites are formed by substituting the cations at A and B site with heterovalent cations in equivalent amounts to maintain electrical charge neutrality and to reduce the electrical strains in the crystal structure. Over the last many years investigation have been carried for synthesis and characterization of Valence compensated alkaline earth titanates and stannates. These materials were prepared by solid state as well as various chemical methods. Extensive solid solutions form over wide range of compositions. Some of the compositions exhibit very high value of dielectric constant. Impedance and modulus analysis of electrical data for these materials show that the high value of dielectric constant is due to the formation of barrier layers at grain-grain boundary interfaces. Efforts are also being made to prepare and characterize giant dielectric constant materials of the type Ca Cu3Ti4O12. Gas sensing (CH4 and CO) characteristics of alkaline earth titanates are being studied. ZnO varistors are electronic ceramic devices having non linear V-I characteristics and are used to clamp transient voltage surges. Investigations have been carried out to synthesize cobalt and manganese doped varistors in the systems ZnO-BaO and ZnO-TiO2. Since the varistors characteristics depend on electrical characteristics of grains, grain boundaries, complex plane impedance and modulus techniques are utilized to separate their contributions on the overall characteristics of the varistors.
4. Cement and Advanced Building Materials
Portland cement concrete lands itself to a variety of innovative designs as a result of its many desirable properties. Concrete inherently is brittle and weak in tension. Several methods have been developed to impart ductile behavior. Broadly these can be grouped as mechanical and chemical methods. Reinforcing concrete by steel/fibers are mechanical means to impart ductile behavior and incorporation of polymeric materials form the chemical method of developing the ability of the material of exhibit ductile response. Portland cement is a complex mixture of inorganic minerals. The organic additives give a significant influence on the hydration and other properties of cement. Besides having physical effects which modify the bond between the particles and therefore the rheology of cementious mixes, some admixture can act on the chemical process of hydration and particularly on the nucleation and growth of new generation products. The polymer cement composites are useful in construction industry because excellent flexural strength, adhesion properties, water-proofness, carbonation resistance, resistance to chloricle and sulphate attack is observed in the resulting composites. Research work is in progress in the Dept. of Ceramic Engineering for producing corrosives resistant impermeable modified cement mortar and concrete of high durability which can give longer life to the structure and pre cast products. They are also being tested as protective coatings on ancient Indian monuments which are deteriorating fast in the present polluted environment.
5. Bio-glass and Ceramics
During the last two decades ceramic materials have become widely used in many medical applications, hip prosthesis, cardiac valves and dental implants. Hydroxyapatite (Hap) seems to be the most appropriate ceramic material for artificial teeth or bones due to excellent biocompatibility and bioactivity. Unfortunately, mechanical properties of pure HAp ceramics are poor. Its medical applications are limited to small-unloaded implants, powders, coatings, and low-loaded porous implants. At Present research is in progress for the synthesis of Magnesium and Strontium Substituted Hydroxyapatite by the Chemical route. These synthesized bioceramic powders are then characterized by various techniques e.g. SEM, XRD, DTA, TGA and FT-IR. Work is also in progress for preparation, crystallization and micro-structural characterization of glasses for biomedical applications.