The Ba2LnFeNb4O15 Tetragonal Tungsten Bronze: towards RT composite multiferroics

TL;DR

This study synthesizes and characterizes Ba2LnFeNb4O15 compounds with TTB structure, revealing room-temperature multiferroic behavior due to coexistence of ferroelectricity and magnetism, with potential for multiferroic applications.

Contribution

It reports new synthesis and characterization of Ba2LnFeNb4O15 compounds, demonstrating room-temperature multiferroic properties and analyzing structure-property relationships.

Findings

Neodymium, Samarium, Europium compounds are ferroelectric with T_C 320-440K.

Praseodymium and Gadolinium compounds are relaxors below 170 and 300K.

Room-temperature magnetic and ferroelectric hysteresis indicate multiferroicity.

Abstract

Several Niobium oxides of formula Ba2LnFeNb4O15 (Ln = La, Pr, Nd, Sm, Eu, Gd) with the Tetragonal Tungsten Bronze (TTB) structure have been synthesised by conventional solid-state methods. The Neodymium, Samarium and Europium compounds are ferroelectric with Curie temperature ranging from 320 to 440K. The Praseodymium and Gadolinium compounds behave as relaxors below 170 and 300 K respectively. The Praseodymium, Neodymium, Samarium, Europium and Gadolinium compounds exhibit magnetic hysteresis loops at room temperature originating from traces of a barium ferrite secondary phase. The presence of both ferroelectric and magnetic hysteresis loops at room temperature allows considering these materials as composites multiferroic. Based on crystal-chemical analysis we propose some relationships between the introduction of Ln3+ ions in the TTB framework and the chemical, structural and physical properties of these materials.