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Title: Physics of the multi-functionality of lanthanum ferrite ceramics

In the present work, we have illustrated the physics of the multifunctional characteristics of nano-crystalline LaFeO{sub 3} powder prepared using auto-combustion synthesis. The synthesized powders were phase pure and crystallized into centro-symmetric Pnma space group. The temperature dependence of dielectric constant of pure LaFeO{sub 3} exhibits dielectric maxima similar to that observed in ferroelectric ceramics with non-centrosymmetric point group. The dielectric relaxation of LaFeO{sub 3} correlates well with small polaron conduction. The occurrence of polarization hysteresis in LaFeO{sub 3} (with centro-symmetric Pnma space group) is thought to be spin current induced type. The canting of the Fe{sup 3+} spins induce weak ferromagnetism in nano-crystalline LaFeO{sub 3}. Room temperature saturation magnetization of pure LaFeO{sub 3} is reported to be 3.0 emu/g. Due to the presence of both ferromagnetic as well as polarization ordering, LaFeO{sub 3} behaves like a single phase multiferroic ceramics. The magneto-electric coupling in this system has been demonstrated through the magneto-dielectric measurements which yield about 0.8% dielectric tuning (at 10 kHz) with the application of 2 T magnetic field. As a typical application of the synthesized nano-crystalline LaFeO{sub 3} powder, we have studied its butane sensing characteristics. The efficient butane sensing characteristics have been correlated to their catalytic activity towards oxidationmore » of butane. Through X-ray photoelectron spectroscopy analyses, we detect the surface adsorbed oxygen species on LaFeO{sub 3} surface. Surface adsorbed oxygen species play major role in their low temperature butane sensing. Finally, we have hypothesized that the desorbed H{sub 2}O and O{sub 2} (originate from surface adsorbed hydroxyl and oxygen) initiate the catalytic oxidative dehydrogenation of n-butane resulting in weakening of the electrostatics of the gas molecules.« less
Authors:
; ;  [1]
  1. Materials Science Centre, Indian Institute of Technology, Kharagpur 721302 (India)
Publication Date:
OSTI Identifier:
22304283
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 115; Journal Issue: 20; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; CERAMICS; DEHYDROGENATION; FERRITES; FERROELECTRIC MATERIALS; FERROMAGNETISM; LANTHANUM COMPOUNDS; MAGNETIC FIELDS; MAGNETIZATION; NANOSTRUCTURES; ORTHORHOMBIC LATTICES; OXYGEN; PERMITTIVITY; POLARIZATION; RELAXATION; SATURATION; SPACE GROUPS; SURFACES; TEMPERATURE DEPENDENCE; X-RAY PHOTOELECTRON SPECTROSCOPY