Phase Formation, Microstructure, and Densification of Yttrium‐Doped Barium Zirconate Prepared by the Sonochemical Method

Abstract

Spherical monodispersed yttrium-doped barium zirconate (BaY 0.1 Zr 0.9 O 3 ; BYZ) particles were successfully prepared in single step without the requirement of calcination process by the sonochemical method in highly basic aqueous solution. The stoichiometric solution of BaCl 2 .2H 2 O, ZrOCl 2 .8H 2 O, and YCl 4 .6H 2 O was precipitated in a 20 M NaOH under high-intensity ultrasonic irradiation (20 kHz, 150 W/cm 2 ) for 15, 30, and 60 min. As-prepared powders were identified by XRD, FT-IR, and Raman spectroscopy as cubic perovskite BYZ. The microstructure examined by SEM and TEM showed spherical-shaped BYZ particles formed by aggregation of primary nanocrystals, and this unique morphology was induced by the effects of the ultrasonication and the strong alkaline environment. BYZ powders prepared under ultrasonication for 60 min had narrow-sized distribution with the average particle size of 267 AE 26 nm and the specific surface area of 40.2 m 2 /g. BYZ ceramics sintered in the air at 1550°C for 20 h showed good densification (95%) and consisted of large grain size (7.67 AE 2.79 lm).

Ultrasonically assisted surface modified CeO2 nanospindle catalysts for conversion of CO2 and methanol to DMC

“…There was no diffraction peak related to B- and Cu- phases observed in the XRD patterns of CeO 2 -B, CeO 2 -CuO and CeO 2 -B-CuO catalysts and this was probably because only low concentrations of B- and Cu- species existed in the CeO 2 based catalysts. The calculated lattice parameters and crystallite sizes using the Debye Scherrer equation [74] of all catalysts are shown in Table 1 . The lattice parameter and crystallite size of unmodified CeO 2 were 5.4165 ± 0.0022 Å and 19.36 ± 3.28 nm, respectively.…”

“…Debye-Scherrer’s equation shown in Eq. (1) was used for calculation of the crystallite size ( D ) from XRD data [74] : where k is a constant taken as 0.94, λ is X-ray wavelength (CuKα radiation 0.15418 nm), β hkl is the full width at half maximum (FWHM) of intensity of the diffraction peak, hkl are the Miller indices of the planes being analyzed, and θ is the diffraction angle. The lattice constant (a) was calculated from the Bragg equation and the crystal spacing formula as shown in Eq.…”

Electrochemical Investigations of BaCe0.7-xSmxZr0.2Y0.1O3-δ Sintered at a Low Sintering Temperature as a Perovskite Electrolyte for IT-SOFCs

“…Protonic conductivity also depends on the transport mechanism. In BaCe 0.7-x Sm x Zr 0.2 Y 0.1 O 3-δ compositions, Sm gets doped at the Ce position because of the partitioning property of the lanthanide elements, which reduce the Ce ions and increase the trapping effects, therefore resulting in reduced conductivity [42,43]. Moreover, in perovskites, the structure bandwidth reduces by the distortion produced in the M-O-M bond and minimizes the mobility of the charge carriers between the host and guest metal sites.…”