Impact of crystal structure and microstructure on electrical properties of Ho doped lead-free BCST piezoceramics. Issue 8 (1st June 2019)

• Record Type: Journal Article
• Authors: Chitra, ; Khandelwal, Ankit; Gupta, Rahil; Laishram, Radhapiyari; Singh, K. Chandramani
• Is Part Of: Ceramics international. Volume 45:Issue 8(2019)
• Page Start: 10371
• Page End: 10379
• Publication Date: 2019-06-01
• Subjects: Sintering -- Grain size -- Electrical properties -- BaTiO3 and titanates; Ceramics -- Periodicals; Céramique industrielle -- Périodiques; Ceramics; Periodicals; Electronic journals; 666
• DOI: 10.1016/j.ceramint.2019.02.095
• Languages: English
• ISSNs: 0272-8842

Abstract

Abstract: Conventional solid state sintering method was used to synthesize lead-free (Ba0.91 Ca0.09 Sn0.07 Ti0.93 )O3 - x Ho2 O3 ( x = 0, 1.2, 1.4, 1.6, 1.8 and 2.0 mol%) ceramics. The influence on electrical properties of the system as a result of the structural and microstructural changes introduced by the incorporation of rare earth Ho 3+ ions has been investigated. The X-ray diffraction analysis reveals that Ho 3+ ions completely diffuse into the (Ba0.91 Ca0.09 Sn0.07 Ti0.93 )O3 lattice to form a homogeneous solid solution with a pure perovskite structure having tetragonal symmetry. Evidence of Ho 3+ substituting Ti 4+ via the oxygen vacancy compensation mechanism exists in the range of 0–1.6 mol % Ho content, while the self-compensation mode is the preferred mechanism beyond 1.6 mol %. The average grain size exhibits a drastic reduction from 16 μm to 0.7 μm as the Ho content increases from 0 to 1.6 mol%, followed by a slight increase at higher Ho concentration. It suggests that addition of Ho 3+ inhibits grain growth in the ceramics. In the composition range studied, increasing Ho 3+ content produces a gradual decrease in the relative density from 93% to 81%, room temperature dielectric constant ( ε rt ) from 3997 to 807, electromechanical coupling factor ( k p ) from 0.23 to 0.06, and piezoelectric charge constant ( d 33 ) from 102 to 38 pC/N. This degradation in the properties is attributed to the crystalline and microstructural changes driven by the increasing presence of Ho content in the ceramics.