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

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

doi:10.1038/s41598-023-45713-z

Compositional induced structural phase transitions in (1 - x)(K_0.5Na_0.5)NbO₃-x(Ba_0.5Sr_0.5)TiO₃ ferroelectric solid solutions

Sci Rep. 2023 Nov 4;13(1):19096. doi: 10.1038/s41598-023-45713-z.

Authors

Satyaranjan Sahoo¹, Dhiren K Pradhan², Shalini Kumari³, Koyal Suman Samantaray⁴, Charanjeet Singh^{5

6}, Anupam Mishra⁷, Md Mijanur Rahaman⁸, Banarji Behera⁹, Ashok Kumar^{5

6}, Reji Thomas^{10

11}, Philip D Rack², Dillip K Pradhan¹²

Affiliations

¹ Department of Physics and Astronomy, National Institute of Technology Rourkela, Rourkela, Odisha, 769008, India.
² Department of Materials Science and Engineering, University of Tennessee, Knoxville, TN, 37996, USA.
³ Department of Materials Science & Engineering, The Pennsylvania State University, University Park, PA, 16802, USA.
⁴ Department of Physics, Indian Institute of Technology Indore, Indore, 453552, India.
⁵ CSIR-National Physical Laboratory, Dr. K. S. Krishnan Marg, New Delhi, 110012, India.
⁶ Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India.
⁷ Department of Materials Engineering, Indian Institute of Science, Bangalore, 560012, India.
⁸ Department of Materials Science and Engineering, University of Rajshahi, Rajshahi, 6205, Bangladesh.
⁹ School of Physics, Sambalpur University, Jyoti Vihar, Burla, 768019, India.
¹⁰ Division of Research and Development, Lovely Professional University, Jalandhar-Delhi G.T. Road, Phagwara, Punjab, 144411, India.
¹¹ School of Chemical Engineering and Physical Sciences, Lovely Professional University, Jalandhar-Delhi G.T. Road, Phagwara, Punjab, 144411, India.
¹² Department of Physics and Astronomy, National Institute of Technology Rourkela, Rourkela, Odisha, 769008, India. dillip.pradhan79@gmail.com.

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 (K_0.5Na_0.5NbO₃)-(Ba_0.5Sr_0.5TiO₃) (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 (T_O-T) and tetragonal to cubic (T_C), decrease with the increase in BST concentrations. The ferroelectric studies show a decrease of both 2P_r and E_C values with a rise in BST concentration and x = 0.025 showed a maximum piezoelectric coefficient.