Ferroelectric Phases and Relaxor States in the Novel Lead-Free ( 1 – X ) Bi1/2k1/2tio3 - X Bisco3 System ( 0 ≤ X ≤ 0.3 )
Ferroelectric phases and relaxor states
in the novel lead-free
( 1 – x ) Bi1/2K1/2TiO3 - x BiScO3 system ( 0 ≤ x ≤ 0.3 )
Leticia Martín-Arias, Miguel Algueró and Alicia Castro*. Instituto de Ciencia de Materiales de Madrid, CSIC. Cantoblanco, 28049 Madrid, Spain. acastro@icmm.csic.es * acastro@icmm.csic.es Tel: +34 91 334 9000 Fax: +34 91 372 0623
1
Abstract
The novel lead-free Bi-based ferroelectric system with perovskite structure (1 − x) Bi1/2K1/2TiO3 – x BiScO3 was synthesized by a conventional solid-state reaction method for compositions with 0 ≤ x ≤ 0.3. The phases obtained were characterized by X-ray powder diffraction and scanning electron
microscopy. Dense ceramics were prepared by a conventional sintering technique at 950-1000°C depending on composition, and their structure and electrical properties were systematically investigated. The XRD analysis shows that the samples possess a pure perovskite structure for x < 0.3 and reveals a phase evolution in the symmetry from tetragonal for x < 0.1 to pseudocubic for 0.1 ≤ x ≤ 0.3. Electrical properties clearly indicate that a transition from conventional ferroelectric to relaxor ferroelectric behavior occurs when increasing the (Bi, Sc) content between 5% and 10%. Implications in the design of novel lead-free piezoelectric materials are discussed.
Keywords: powders-solid state reaction, dielectric properties, ferroelectric properties, piezoelectric properties, perovskites.
2
1 Introduction
Environmental pollution is one of the main causes of concern nowadays, which has led to harsh environmental regulations being taken. In the case of piezoceramics, they require the search for lead-free materials with comparable properties to those of the well-known lead-based ferroelectric perovskites like Pb(Zr,Ti)O3 (PZT)1. In PZT ceramics with compositions lying near the morphotropic phase boundary (MPB) between the tetragonal and rhombohedral phases, high dielectric and piezoelectric
in the novel lead-free
( 1 – x ) Bi1/2K1/2TiO3 - x BiScO3 system ( 0 ≤ x ≤ 0.3 )
Leticia Martín-Arias, Miguel Algueró and Alicia Castro*. Instituto de Ciencia de Materiales de Madrid, CSIC. Cantoblanco, 28049 Madrid, Spain. acastro@icmm.csic.es * acastro@icmm.csic.es Tel: +34 91 334 9000 Fax: +34 91 372 0623
1
Abstract
The novel lead-free Bi-based ferroelectric system with perovskite structure (1 − x) Bi1/2K1/2TiO3 – x BiScO3 was synthesized by a conventional solid-state reaction method for compositions with 0 ≤ x ≤ 0.3. The phases obtained were characterized by X-ray powder diffraction and scanning electron
microscopy. Dense ceramics were prepared by a conventional sintering technique at 950-1000°C depending on composition, and their structure and electrical properties were systematically investigated. The XRD analysis shows that the samples possess a pure perovskite structure for x < 0.3 and reveals a phase evolution in the symmetry from tetragonal for x < 0.1 to pseudocubic for 0.1 ≤ x ≤ 0.3. Electrical properties clearly indicate that a transition from conventional ferroelectric to relaxor ferroelectric behavior occurs when increasing the (Bi, Sc) content between 5% and 10%. Implications in the design of novel lead-free piezoelectric materials are discussed.
Keywords: powders-solid state reaction, dielectric properties, ferroelectric properties, piezoelectric properties, perovskites.
2
1 Introduction
Environmental pollution is one of the main causes of concern nowadays, which has led to harsh environmental regulations being taken. In the case of piezoceramics, they require the search for lead-free materials with comparable properties to those of the well-known lead-based ferroelectric perovskites like Pb(Zr,Ti)O3 (PZT)1. In PZT ceramics with compositions lying near the morphotropic phase boundary (MPB) between the tetragonal and rhombohedral phases, high dielectric and piezoelectric
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