Room Temperature Magnetic Rare-Earth Iron Garnet Thin Films with Ordered Mesoporous Structure

Abstract

Amphiphilic polymers are very attractive as porogens for the preparation of ordered mesoporous thin films and powders with pore sizes ranging from 40 down to a few nanometers in diameter because they are capable of both forming different superstructures and interacting with sol-gel precursors. In the present work, we report for the first time the synthesis of a series of highly crystalline rare-earth iron garnet (RE 3 Fe 5 O 12 , RE = Y, Gd-Dy) thin films with cubic networks of interconnected pores averaging 17 nm in diameter through facile polymer templating of hydrated nitrate salts. Despite intricate crystallization pathways, e.g., Y 3 Fe 5 O 12 via Y 4 Fe 2 O 9 and h-YFeO 3 , the nanoscale architecture of all these materials is only affected to a limited extent by solid-solid conversions at elevated temperatures.We specifically focus on the characterization of the morphology, microstructure and magnetic properties of polymer-templated Y 3 Fe 5 O 12 . This novel mesoporous material is single phase after heating to 900 °C, free of major structural defects and is also well-defined on the atomic level, as evidenced by a combination of in situ and ex situ scattering/diffraction techniques, electron microscopy, Raman and X-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectrometry. The high quality of the nanocrystalline Y 3 Fe 5 O 12 thin films with overall soft magnetic-like characteristics and moderate anisotropy is further confirmed by SQUID magnetometry measurements. The magnetization behavior in the temperature range 5-380 K well describes Bloch's T 3/2 law for a 3D Heisenberg-type ferromagnet.

Observation of direct magneto-dielectric behaviour in Lu3Fe5O12−δ above room-temperature

“…X-ray photoelectron spectroscopy (XPS) study X-ray photoelectron spectroscopy, a highly used surfacesensitive technique, 68,69 has been employed to identify the overall oxidation or chemical state of Fe ions in the prepared Lu 3 Fe 5 O 12Àd sample. X-ray photoelectron spectroscopy (XPS) study X-ray photoelectron spectroscopy, a highly used surfacesensitive technique, 68,69 has been employed to identify the overall oxidation or chemical state of Fe ions in the prepared Lu 3 Fe 5 O 12Àd sample.…”

Ordered Mesoporous LiFe5O8 Thin‐Film Photoanodes for Water Splitting

“…The EISA process was introduced in the late 1990s, and many important thin‐film materials with ordered mesoporous structures have been reported since then, including ferrites with garnet and spinel structures. For example, an interesting room‐temperature magnetic spinel ferrite, namely LiFe 5 O 8 , with large mesopores and nanocrystalline walls was reported, showing promise for use in micromagnetic actuation …”

Size-dependent optical and thermochromic properties of Sm3Fe5O12

“…tetragonal and octahedral sites, which could also be discriminated from XPS spectra. 41,42 The binding energy for tetrahedral site of Fe is 723.9 and 710.5 eV for Fe 2p 1/2 and Fe 2p 3/2 , respectively, while the binding energy for octahedral site of Fe is 727.2 and 712.7 eV for Fe 2p 1/2 and Fe 2p 3/2 , respectively. A comparison of two materials shows that the intensity of the peak of Sm 3 Fe 5 O 12 synthesized by solid state reaction method is enhanced.…”