Theoretical and Experimental investigation of structural, vibrational and ferroic properties of AgNbO3 and AgNb1/2 Ta1/2O3 systems

K, Ganga Prasad and Niranjan, Manish K and Asthana, Saket (2016) Theoretical and Experimental investigation of structural, vibrational and ferroic properties of AgNbO3 and AgNb1/2 Ta1/2O3 systems. PhD thesis, Indian Institute of Technology Hyderabad.

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Abstract

The lead based piezoelectric solid solutions such as lead zirconium titanate (PZT) are widely used as sensors, actuators, imaging devices, accelerometers. Increasing effort is now being made to develop novel materials to replace the hazardous Pb - containing piezoelectrics (PZT) because lead content is more than 60 wt% in PZT materials. For environmental concern, there is growing interest in the development of high performance of lead free piezoelectrics. Recently , silver niobate (AgNbO 3 ) and its solid solutions with other compound s have been identified as high performance piezoelectrics with their large electromechanical response rendering them potential candidate materials for technological applications. With growing interest in green technologies and environmental friendly materials, the interest in AgNbO 3 is only expected to grow as potential substitute material for toxic lead based piez oelectrics which currently find wide range of applications in various sensor technologies. AgNbO 3 is also a photocatalyst in visible - light range of radiat ion spectrum which makes it an attractive candidate for clean hydrogen production. The room temperature crystal structure of AgNbO 3 is orthorhombic with either centrosymmetric ( Pbcm ) or non - centrosymmetric ( Pmc 2 1 ) space group symmetries . In most of the rep orted studies, the room temperature AgNbO 3 crystal structure has been refined by the orthorhombic Pbcm spacegroup symmetry . Recently, based on neutron and synchrotron diffraction studies, a noncentrosymmetric orthorhombic Pmc 2 1 space group has been propose d for room temperature AgNbO 3 . The high temperature crystal structures are detectable by X - ray, DTA, d ielectric and domain structure investigations .

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