Characterizing xBa(Mg1∕3Ta2∕3)O3+(1−x)Ba(Mg1∕3Nb2∕3)O3 microwave ceramics using extended x-ray absorption fine structure method

Abstract

The structures of TaO6 and NbO6 oxygen octahedra in xBa(Mg1∕3Ta2∕3)O3+(1−x)Ba(Mg1∕3Nb2∕3)O3 perovskite ceramics with x=0, 0.25, 0.50, 0.75, and 1.0 were investigated by the extended x-ray absorption fine structure method. The decline in the microwave dielectric constant as x increases is caused mainly by the decrease of the mean volume of the oxygen octahedra, regardless of the 1:2 ordered structure and the distortion of the oxygen octahedron. The low Qf values of the TaO6 and NbO6 mixed samples are caused by not only the degrading of the 1:2 ordered structure but also the distortion of oxygen octahedral cages.

Crystal structure and microwave dielectric properties of Li2(Mg1–xCux)2Mo3O12 ceramics sintered at ultra‐low temperature

“…For a given Raman mode, the full width at half maximum (FWHM) is typical inversely proportional to the phonon survival time, and Raman peaks with relatively narrow FWHMs tend to have longer phonon survival times and fewer phonon interactions 49 . These phonon vibrations consume a large amount of energy, which in turn leads to an elevated dielectric loss in the MWDC 51,52 . The FWHM of the main peak v7 of Li 2 (Mg 1– x Cu x ) 2 Mo 3 O 12 is shown in the inset of Figure 6B, and the FWHM decreases with an increase in the x value.…”

“…49 These phonon vibrations consume a large amount of energy, which in turn leads to an elevated dielectric loss in the MWDC. 51,52 The FWHM of the main peak v7 of Li…”

Calculation of the optical phonons in ordered Ba2MgWO6 perovskite using short‐range force field model

“…Particularly, the ordered A 2 B'B″O 6 perovskite with cubic symmetry exhibits four Raman bands in their Raman spectra following the reducible representation A 1g ⊕ E g ⊕ 2 F 2g . The A 1g breathing‐type mode can be applied to evaluate both short‐ and long‐range order achievement in double perovskites by probing its peak parameters such as intensity, position, and width . Not only this band but also all the remaining Raman modes can be correlated with the order parameter (η, being extracted from X‐ray diffraction data) that describes the degree of long‐range order in complex perovskites .…”