Flexible relaxor materials: Ba(2)Pr(x)Nd(1-x)FeNb(4)O(15) tetragonal tungsten bronze solid solution.

Area of Science:

• Materials Science
• Solid State Chemistry
• Condensed Matter Physics

Background:

• Relaxor materials are typically limited to perovskite structures, restricting their design flexibility.
• Previous work identified relaxor behavior in Ba(2)PrFeNb(4)O(15) below 170 K and ferroelectric behavior in Ba(2)NdFeNb(4)O(15) with T(C) = 323 K.
• The tetragonal tungsten bronze (TTB) structure offers a unique network for exploring new material properties.

Purpose of the Study:

• To investigate the solid solution Ba(2)Pr(x)Nd(1-x)FeNb(4)O(15) for tunable ferroelectric and relaxor properties.
• To understand the structural basis for the observed phase behaviors.
• To expand the range of known relaxor materials beyond traditional perovskites.

Main Methods:

• Synthesis and characterization of the solid solution series Ba(2)Pr(x)Nd(1-x)FeNb(4)O(15) for x = 0, 0.2, 0.4, 0.5, 0.6, 0.8, and 1.
• Analysis of structural and dielectric properties across the entire composition range.
• Correlation of material behavior with the TTB crystal structure.

Main Results:

• A continuous crossover in behavior was observed across the solid solution.
• Intermediate compositions exhibit a coexistence of ferroelectricity and relaxor properties.
• The open TTB network facilitates the coexistence of long-range and short-range orders.

Conclusions:

• The Ba(2)Pr(x)Nd(1-x)FeNb(4)O(15) system demonstrates tunable ferroelectric and relaxor characteristics.
• The TTB structure is crucial for achieving this tunability and the coexistence of different ordering types.
• This research broadens the scope of materials exhibiting relaxor behavior.