Relaxor behavior and ferroelectric properties of a new Ba 4 SmFe 0.5 Nb 9.5 O 30 tungsten bronze ceramic

Though semiconductor technology has advanced significantly in miniaturization and processor speed the “ideal” nonvolatile memory - memory that retains information even when the power goes is still elusive. There is a large demand for non-volatile memories with the popularity of portable electronic devices like cell phones and note books. Semiconductor memories like SRAMs and DRAMs are available but, such memories are volatile. After the advent of ferroelectricity many materials with crystal structures of Perovskite, pyrochlore and tungsten bronze have been derived and studied for the applications in memory devices. Ferroelectric Random Access Memories (FeRAM) are most promising. They are nonvolatile and have the greater radiation hardness and higher speed. These devices use the switchable spontaneous polarization arising suitable positional bi-stability of constituent ions and store the information in the form of charge. This paper is focused on the synthesis and characterizations of BiFeO3 and xCrFe2O4-(1-x) BiFeO3 nanoceramics which are most promising FeRAM materials. The effect of various-dopant-induced changes in structural, dielectric, ac impedance, ferroelectric hysteresis, mechanism of the dielectric peak broadening and frequency dispersion have been addressed. It also deals with low temperature processing technique of those nanoceramics which has high dielectric and ferroelectric properties. These studies can be further extended to reinforce BiFeO3 and CrFeO4 materials with carbon nanotubes to obtain conductive composites using appropriate techniques.

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Ferroelectric properties and polarization dynamics in Ba4Sm2Ti4Ta6O30 tungsten bronze ceramics

Applied Physics Letters ◽

10.1063/1.4945742 ◽

2016 ◽

Vol 108 (15) ◽

pp. 152903 ◽

Cited By ~ 7

Author(s):

Xiao Li Zhu ◽

Xiang Ming Chen

Keyword(s):

Ferroelectric Properties ◽

Tungsten Bronze

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Processing and electrical properties of Pb0.6Ba0.4Nb2O6 ceramics

Journal of Materials Research ◽

10.1557/jmr.2010.0284 ◽

2010 ◽

Vol 25 (11) ◽

pp. 2143-2149 ◽

Cited By ~ 2

Author(s):

Sinan Dursun ◽

Cihangir Duran

Keyword(s):

Electrical Properties ◽

Single Phase ◽

Powder Processing ◽

Ferroelectric Properties ◽

Tape Casting ◽

Tungsten Bronze ◽

Liquid Phase Sintering ◽

Boundary Phase ◽

Lead Barium Niobate ◽

Reactive Mixture

Lead barium niobate (PBN or PbxBa1–xNb2O6) is a promising tungsten bronze ceramic system that has a morphotropic phase boundary between the orthorhombic and tetragonal phases at x ≈ 0.63, where the spontaneous polarization (Ps ≈ 60–70 μC/cm2) and other ferroelectric properties are known to be higher. However, even textured PBN60 ceramics have low Ps (∼23.9 μC/cm2) and piezoelectric charge coefficient (d33 ≈ 236 pC/N) as compared to the single crystal counterparts. The aim of this study is to control powder processing, green body formation, and sintering conditions to enhance both densification and electrical properties. Therefore, samples were prepared by tape casting methods using single phase PBN60 and reactive mixture of PbNb2O6 and BaNb2O6 powders. Three wt% excess PbO was found to be necessary for densification. Our results showed that undoped PBN60 ceramics reached Ps = 33 μC/cm2, d33 = 305 pC/N, and had a Tc = 340–350 °C. These results are much higher than the reported values in the literature, which can be attributed to the careful ceramic processing such as tape casting (e.g., homogenous green structure), annealing (e.g., control of excess grain boundary phase), and liquid phase sintering (e.g., higher densification).

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