Simple top-down preparation of magnetic Bi_0.9Gd_0.1Fe_1−xTi_xO₃nanoparticles by ultrasonication of multiferroic bulk material

Abstract

We present a simple technique to synthesize ultrafine nanoparticles directly from bulk multiferroic perovskite powder. The starting materials, which were ceramic pellets of the nominal compositions of Bi0.9Gd0.1Fe1−xTixO3 (x = 0.00-0.20), were prepared initially by a solid state reaction technique, then ground into micrometer-sized powders and mixed with isopropanol or water in an ultrasonic bath. The particle size was studied as a function of sonication time with transmission electron microscopic imaging and electron diffraction that confirmed the formation of a large fraction of single-crystalline nanoparticles with a mean size of 11-13 nm. A significant improvement in the magnetic behavior of Bi0.9Gd0.1Fe1−xTixO3 nanoparticles compared to their bulk counterparts was observed at room temperature. This sonication technique may be considered as a simple and promising route to prepare ultrafine nanoparticles for functional applications.

Size dependent magnetic and electrical properties of Ba-doped nanocrystalline BiFeO3

“…The lower binding energy peak is associated with the intrinsic O 1s core spectra and higher energy peak is ascribed to the oxygen vacant sites in BFO ceramics. 31 It is depicted in Fig. 2(c) that 10 % Ba-doping significantly curtails oxygen vacancies in BBFO nanoparticles.…”

Dy doped BiFeO 3 : A bulk ceramic with improved multiferroic properties compared to nano counterparts

“…For the synthesis of nanoparticles, a portion of the micrometer sized powder was subsequently mixed with isopropanol. We then put the mixtures of isopropanol and powder with a mass percentage of ∼0.5% [16] into an ultrasonic probe and sonicated the solutions for 30, 60 and 90 minutes respectively, for three different samples. After around six hours, ∼40% of the mass was collected as supernatant and was used for characterization.…”

“…The pellets were ground again into powder materials. The nanoparticles were fabricated directly from these bulk powder materials using the ultrasonic probe dispersion technique with varying amount of sonication time by the application of ultrasonic energy generated from a probe [16]. For the synthesis of nanoparticles, a portion of the micrometer sized powder was subsequently mixed with isopropanol.…”

“…Most importantly, a significant improvement in magnetic and ferroelectric properties were observed in the undoped and cation doped BFO nanoparticles with particle size less than periodicity of helical order ∼62 nm [15]- [18] compared to that of parent BFO. In previous investigations, we also observed improved structural and magnetic properties for Gd doped and Gd-Ti co-doped BFO nanoparticles compared to their corresponding bulk ceramics [16], [17]. Withstanding the fact that improved multiferroic properties of undoped and cation doped BFO nanoparticles were reported in various investigations [18]- [22], the associated jeopardy was that rigorous synthesis procedure had to be adopted to obtain nanoparticles with sizes less than 62 nm.…”

“…Thus the agglomerations can be broken down utilizing the effects of ultrasound [44], resulting in reduction of particle size. In our previous investigation [16], Gd and Ti co-doped BiFeO 3 nanoparticles were produced using ultrasonic energy through bath sonication (indirect process) from their bulk powder materials. Noticeably, in our current investigation for ultrasonic probe dispersion (direct process) sonication, 30 minutes of sonication was enough to produce nanoparticles within the range of 75 nm to 150 nm, whereas, within the same timeframe, bath sonication (indirect) process was able to produce 150 to 250 nm grains only.…”