Vibrational modes and structural characteristics of (Ba0.3Sr0.7)[(ZnxMg1−x)1/3Nb2/3]O3 solid solutions

Abstract

(Ba(0.3)Sr(0.7))[(Zn(x)Mg(1-x))(1/3)Nb(2/3)]O(3) (BSZMN) (x = 0.0, 0.2, 0.4, 0.6, 0.8, 1.0) solid solution ceramics were synthesized by the conventional solid-state sintering technique. Vibration spectra (Raman spectroscopy and Fourier transform far-infrared reflection spectroscopy, short for FTIR) and X-ray diffraction (XRD) were employed to evaluate the correlation between crystal structures and vibration modes of these solid solutions as a function of Mg(2+) ions replaced by Zn(2+) ions. It is verified that these ceramics present a phase transition, i.e., the crystal structure changes from hexagonal phase (P ̅3m1, where x≤ 0.4) to the pseudocubic phase (I4/mcm, where x≥ 0.8) with increasing Zn(2+) content. The phase transition is a gradual process, the sample where x = 0.6 is of the transition phase, i.e., at x = 0.6, phase transition begins to appear from hexagonal phase to pseudocubic phase but is not complete. The phase transition is also verified by the FTIR spectra. Tilting of oxygen octahedra is the main reason for the phase transition. The phonon modes of the vibration spectra were assigned, the position and width were determined, and the correlation of phonon vibrations with the microstructure for the different atoms substituted in B'-site was found.

Titanium and Zirconium Catalysts with [N,O] Ligands: Syntheses, Characterization, and Their Catalytic Properties for Olefin Polymerization

“…14,15 The desired products were separated through column chromatography on silica gel as white to yellow powders in moderate yields. A general synthetic route for titanium and zirconium complexes is shown in Scheme 2.…”

A low-firing melilite ceramic Ba2CuGe2O7 and compositional modulation on microwave dielectric properties through Mg substitution

“…Figure 7) for all compounds is alike, giving rise to their close average grain size, as shown in Figure 7f. Raman scattering is known to be highly sensitive to the local structure variations, especially those induced by composition [12,23]. For a tetragonal P-421m unit cell in Ba2CuGe2O7, theoretically, the Raman active vibration modes are predicted based on the factor group theory and listed in Table 1 along (Figure 8b), among which three strongest peaks appear around 775 cm -1 , 500 cm -1 , and 258 cm -1 , respectively.…”

“…For a tetragonal P-421m unit cell in Ba2CuGe2O7, theoretically, the Raman active vibration modes are predicted based on the factor group theory and listed in Table 1 along (Figure 8b), among which three strongest peaks appear around 775 cm -1 , 500 cm -1 , and 258 cm -1 , respectively. As well known, the Raman spectroscopy includes the internal vibrations of the framed polyhedron (either tetrahedron or octahedron for oxides) and the external ones from translational and liberational moves [23]. Generally, the binding energy intra the polyhedral is larger than the intergroup or crystal energy, and thus the internal Raman modes usually appear at high-frequency bands.…”

Effects of Y2O3 substitution on microwave dielectric properties of Ba(Co0.6Zn0.38)1/3Nb2/3O3 ceramics

“…In order to obtain relative high Q 9 f and adjust s f to zero, BCN and BZN have been modified using various valence states of different oxides, such as Al 2 O 3 [22], MgO [4,23], SnO 2 [24], SrO [25], WO 3 [24,26], ZrO 2 [1], Ta 2 O 5 [3], etc. Wu et al [26].…”