Citrate–nitrate Derived Sr0.5Ba0.5Ta2O6 Tetragonal Tungsten Bronze Nanorods: Investigation Of Their Optical And Dielectric Properties

¹Materials Chemistry Group, Department of Chemistry, University of Delhi, Delhi 110007, India

²Department of Physics and Astrophysics, University of Delhi, Delhi 110007, India

³Central Institute of Plastics Engineering and Technology, Lucknow 226 008, India

Adv. Mater. Lett., 2012, 3 (2), pp 118-125

DOI: 10.5185/amlett.2011.6278

Publication Date (Web): Apr 14, 2012

Copyright © IAAM-VBRI Press

E-mail: yksharma@chemistry.du.ac.in

Abstract

First time novel complex strontium barium tantalate, Sr_0.5Ba_0.5Ta₂O₆ was successfully synthesized in 1D structure (nanorods) by citrate-nitrate gel route. Their structural properties were examined via X-ray diffractometry (XRD) and revealed the formation of tetragonal tungsten bronze (TTB) structure at as low as 1100ºC. Also, FT-IR, FT-Raman, UV-vis, SEM, TEM and PL were used to identify the structure and properties of powders. Well isolated nanorods of the average diameter of ~200nm can be fabricated by this route. PL spectrum showed strong and broad visible emission band around 439nm due to particles with little surface defects. The frequency dependent dielectric dispersion of SBT50 powders sintered at 1300°C/4 h was investigated in a frequency range from 1 kHz-1MHz and at different temperatures (25°C- 450°C). It is observed that: (i) the dielectric constant (ε') and loss tangent (tan δ) are dependent on frequency, (ii) the temperature of dielectric constant maximum shift toward lower temperature side and the maximum dielectric constant (ε) was observed to be 2400 at 1 kHz. The Tc was found to be ~444-449°C and ferroelectric relaxor or diffuse phase transition like behavior was observed at around 449°C.

Keywords

Nanostructures, ceramics, sol-gel growth, X-ray scattering, dielectric properties