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Your search keyword '"Pradhan, A. K."' showing total 3 results
Start Over Author "Pradhan, A. K." Topic ceramics Topic phase transitions
3 results on '"Pradhan, A. K."'

1. Compositional induced structural phase transitions in (1 − x)(K0.5Na0.5)NbO3–x(Ba0.5Sr0.5)TiO3 ferroelectric solid solutions.

Author

Sahoo, Satyaranjan, Pradhan, Dhiren K., Kumari, Shalini, Samantaray, Koyal Suman, Singh, Charanjeet, Mishra, Anupam, Rahaman, Md. Mijanur, Behera, Banarji, Kumar, Ashok, Thomas, Reji, Rack, Philip D., and Pradhan, Dillip K.

Subjects
*PHASE transitions, *SOLID solutions, *PHASE diagrams, *FERROELECTRIC materials, *PERMITTIVITY, *LEAD-free ceramics, *BARIUM titanate, *LEAD titanate, *CERAMICS
Abstract

Ferroelectric materials exhibiting switchable and spontaneous polarization have strong potential to be utilized in various novel electronic devices. Solid solutions of different perovskite structures induce the coexistence of various phases and enhance the physical functionalities around the phase coexistence region. The construction of phase diagrams is important as they describe the material properties, which are linked to the underpinning physics determining the system. Here we present the phase diagram of (K0.5Na0.5NbO3)–(Ba0.5Sr0.5TiO3) (KNN-BST) system as a function of composition and their associated physical properties. Lead-free (1 − x)KNN–xBST (0 ≤ x ≤ 0.3) solid solution ceramics were synthesized by conventional solid-state reaction technique. The X-ray diffraction and Raman spectroscopic studies indicate composition-dependent structural phase transitions from an orthorhombic phase for x = 0 to orthorhombic + tetragonal dual-phase (for 0.025 ≤ x ≤ 0.15), then a tetragonal + cubic dual-phase (x = 0.2) and finally a cubic single phase for x ≥ 0.25 at room temperature (RT). Among these, the orthorhombic + tetragonal dual-phase system shows an enhanced value of the dielectric constant at room temperature. The phase transition temperatures, orthorhombic to tetragonal (TO-T) and tetragonal to cubic (TC), decrease with the increase in BST concentrations. The ferroelectric studies show a decrease of both 2Pr and EC values with a rise in BST concentration and x = 0.025 showed a maximum piezoelectric coefficient. [ABSTRACT FROM AUTHOR]

Published
2023
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2. Effect of Mn doping on structural, dielectric and ferroelectric properties of (K0.5Na0.5)NbO3 lead free ceramics.

Author

Sahoo, Satyaranjan and Pradhan, Dillip K.

Subjects
*DIELECTRIC properties, *CERAMICS, *FERROELECTRIC ceramics, *PHASE transitions, *MANGANESE, *PERMITTIVITY, *RIETVELD refinement, *LEAD titanate
Abstract

Lead free ferroelectric ceramics of (K0.5Na0.5)(Nb1-xMnx)O3 (x = 0, 0.01) were prepared by solid state reaction technique and the effect of Mn doping on their crystal structure, dielectric and ferroelectric properties was investigated. Rietveld refinement on the XRD data was carried out using an orthorhombic crystal structure having Amm2 space group, suggesting the formation of single phase compounds. The temperature dependent dielectric properties for both the compounds show two phase transitions, one corresponding to orthorhombic to tetragonal (TO-T) phase transition and the other to the tetragonal to cubic phase transition (TC). An improved dielectric constant of 345 (at RT) and 5175 (at TC) in Mn doped KNN is observed compared to pure KNN (285 at RT and 4610 at TC). Ferroelectric properties measurement at room temperature indicates a significant enhancement of remnant polarization (2Pr) in Mn doped KNN (25.26 µC/cm2) ceramics with respect to pure KNN (16.38 µC/cm2). [ABSTRACT FROM AUTHOR]

Published
2024
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3. Electrical behaviour of Ca substituted HoMnO3 electroceramics.

Author

Rout, P. P., Pradhan, S. K., Das, S. K., and Roul, B. K.

Subjects
*MANGANATES, *CERAMICS, *SUBSTITUENTS (Chemistry), *POLYCRYSTALS, *PHASE transitions, *PERMITTIVITY
Abstract

Polycrystalline Ho1-xCaxMnO3(x = 0.05,0.1,0.2) bulk ceramic samples were prepared by conventional solid state reaction route. The effect of Ca doping on structural, dielectric and ferroelectric behaviour were investigated carefully. All samples showed orthorhombic phase without any structural transformation after substitution of Ca at Ho site. Interestingly dielectric constant value increase significantly with increase in concentration of x upto 0.1 and decrease with further substitution, which reveals that Ca substitution increase the dipole alignment due charge ordering. Similarly the sample showed a well shaped ferroelectric hysteresis loop having saturation polarization value of 1.5μC/cm2 for x = 0.1. [ABSTRACT FROM AUTHOR]

Published
2013
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