Crystal structure modeling, electrical and microstructural characterization of manganese doped barium zirconium titanate ceramics
Graphical abstract
Zirconium and manganese enter crystallochemically in the framework of nano ceramic barium titanate at the Ti site of the perovskite chain of TiO6 octahedra. The Rietveld refinement converges to a satisfactory fit with appropriate bond distances and bond angles. The dielectric study of 10 mol% zirconium substituted manganese barium titanate (MnBTZ-10) shows a diffuse ferro–para electric phase transition and relaxor behavior of the material. The dielectric response is dependent on the zirconium content and the particle size of the ceramic material.
Research highlights
► The manganese substituted barium zirconium titanates are nano structured ideal perovskite phases having no distortion of TiO6/ZrO6/MnO6 octahedral chains. ► Rietveld refinement of MnBTZ samples converges to a satisfactory structure fit. ► Composition, temperature and frequency dependant dielectric behavior of the materials have been observed.
Introduction
Solid solutions of BaTiO3 and BaZrO3 react to form BaTi1−xZrxO3 (where 0 < x < 0.1) or BTZ type ceramic phases, which are important materials for dielectric applications in multilayer ceramic capacitors [1], [2]. The high permittivity of BaTiO3 increases on addition of zirconium, with the temperature dependent ferroelectric–paraelectric phase transition. The ferroelectric phase transition at the Curie temperature (TC) in BTZ bulk ceramics is known to change strongly with Zr content [3]. Such materials have been widely used in designing Ni compatible dielectrics for small sized electronic components [4]. Further, it has been reported that doping in BTZ ceramics could greatly affect its dielectric properties [5]. In order to study the structure–property relationship of MnO2 doped BTZ type perovskite, the crystal structures of 0.0, 5.0 and 10 mol% zirconium substituted MnBTZ phases have been refined and their dielectric behavior investigated. Barium zirconium titanate BaTi1−xZrxO3 (BTZ) is synthesized by substituting ions at the B site of the perovskite BaTiO3 with the Zr4+ ion. Zirconium substitution is of interest because a different character of dielectric response with respect to the ferroelectric to paraelectric phase transition can be achieved by substitution of Zr4+ for Ti4+ in BaTiO3. The Zr4+ ion (atomic radius of 86 pm) is chemically more stable than Ti4+ (atomic radius of 74.5 pm) and has a larger ionic size to expand the perovskite lattice [6], therefore BTZ materials are promising materials for tunable microwave device applications such as electronically tunable mixers, delay lines, filters, capacitors, resonators and phase shifters [7], [8], [9]. Such applications demand good thermal stability, a high quality factor, appropriate dielectric constant, large tunability and low loss tangent [10].
Section snippets
Materials and methods
Polycrystalline powders with the stoichiometric compositions BaTi0.90Mn0.1O3, BaTi0.94Zr0.05Mn0.01O3 and BaTi0.89Zr0.10Mn0.01O3 were synthesized from analytical grade dry chemicals: BaCO3 (Merk), TiO2 (Loba), ZrO2 (Loba) and MnCO3 (Merk). The oxides/carbonates were mixed in appropriate molar ratios in propane-1,2,3-triol (glycerol) medium followed by sintering the semi solid paste at 1050 °C for 24 h to yield polycrystalline solid solutions. Powder X-ray diffraction data have been recorded on a
Crystallographic data
The sharp and single reflection peaks of each compound, which are quite different from those of the ingredient oxides and carbonates, confirm the presence of new phase pure material. Most of the prominent reflections of the MnBT phase matched in intensity and position with the standard diffraction pattern of barium titanate [12]. The diffraction profiles of MnBTZ-5 and MnBTZ-10 are similar to the reported diffraction pattern of BTZ ceramics [13]. The space group was chosen, while checking
Conclusions
The title ceramic phases are ideal perovskites having no distortion of the TiO6/ZrO6/MnO6 octahedral chains. The cell parameters and cell volume increase with the increase in zirconium content. The Rietveld refinement converges to a satisfactory fit with appropriate bond distances and bond angles. A model has been suggested for the substituted perovskite structure of the ceramic material using graphic softwares. The particle size of the MnBTZ-10 phase calculated from the XRD pattern was found
Acknowledgements
The authors are thankful to the Department of Science and Technology, Government of India New Delhi, India for funding the Research Project No. SR/S3/ME/20/2005-SERC-Engg under the SERC Program. Thanks are also due to the University Grant Commission (UGC), New Delhi, India for awarding the Dr. D.S. Kothari Post Doctoral Fellowship to one of the authors (Dr. Rashmi Chourasia).
References (29)
- et al.
Ceram. Int.
(2002) - et al.
Solid State Commun.
(2004) - et al.
Scripta Mater.
(2006) - et al.
Mater. Chem. Phys.
(1995) - et al.
J. Cryst. Growth
(2004) - et al.
Mater. Lett.
(2003) - et al.
J. Eur. Ceram. Soc.
(2001) - et al.
Ceram. Int.
(2007) - et al.
Mater. Lett.
(2006) - et al.
Solid State Sci.
(1999)
Jpn. J. Appl. Phys. Suppl
J. Am. Ceram. Soc.
J. Cryst. Growth
J. Cryst. Growth
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