Fuel-free low-temperature self-combustion synthesis and characterization of praseodymium-substituted bismuth titanate ceramics

Abstract

This paper presents the preparation of bismuth titanate (Bi 4 Ti 3 O 12 ; BIT) and praseodymium-substituted bismuth titanate (Bi 4¹x Pr x Ti 3 O 12 : BPT) with various molarities of praseodymium ion (Pr 3+ : x = 0.2, 0.6 and 1.0) via a fuel-free low-temperature self-combustion synthesis process (FLSC). FLSC offers a remarkable ability to produce polycrystalline BIT powder with an orthorhombic structure, and BPT powder with a tetragonal structure. The substitution of Pr 3+ into the BIT system retarded the crystal growth, as revealed by the decrease in the crystallite size from 106 to 41 nm by incorporating Pr 3+ with x = 1.0. Besides, the substitution caused the structure transformation from platelet-like structure to aquiaxed structure. Such structure provides an essential role to enhance the ceramic density. High relative density of about 99.3% was achieved for the BPT ceramic compared to BIT ceramic with a relative density of 89.7%. The results underline the possibility to control the anisotropic grain growth of BIT ceramic by incorporating Pr 3+ into the BIT system through FLSC. The ceramic sintered at 1100°C exhibited high dielectric permittivity (269.38) with a low dissipation factor as low as 0.00203.