Microstructure and microwave dielectric properties of Ba5Nb4O15–BaWO4 composite ceramics

The Crystal Structure of Ba3Nb2O8 Revisited: A Neutron Diffraction and Solid-State NMR Study

“…Our characterisation of powder samples via X-ray and neutron diffraction, 93 Nb NMR and FTIR spectroscopy reveal Nb 5+ to be in octahedral coordination and that the decomposition of the phase is instead due to the inclusion of carbonate (Figure 1 (inset)). It is also notable that the unit cell parameters from the single crystal study 1 (a = 6.0477 (13), c = 21.289(5) Å) are significantly larger than those reported here (a = 5.90849 (10), c = 20.9491(12) Å). There is also precedent in that there are many reported perovskite-based materials that have an affinity for carbonate inclusion due to their high content of alkali-earth metal cations, one such example being Ba3Co2O6(CO3)0.60 50 .…”

“…There are two crystallographically distinct Nb sites, with one showing considerable distortion compared with the other, as determined by both powder and single crystal studies 1,9 . As a result of this distortion, Ba5Nb4O15, exhibits excellent microwave dielectric properties with a high relative permittivity (ɛr), high quality factor (Q) and a low temperature coefficient of resonator frequency (τf) 9,10 .…”

Low-loss microwave dielectrics using SrTiO3-modified (Mg0.95Co0.05)2TiO4 ceramics

“…Requirements for these dielectric resonators must be the combined dielectric properties of a high dielectric constant for miniaturization, a high quality factor (Q × f) for better selectivity and a near-zero temperature coefficient of resonant frequency ( f ) for stable frequency stability [2,3]. However, high quality factor has been playing a more prominent role recently because of the raise of carrier frequency in the communication systems [1,4]. Consequently, the search on new high-Q dielectric materials, such as the MgO-TiO 2 binary system, has brought much more attention in the last few years [5][6][7][8][9][10][11].…”

Synthesis and properties of BaCe1−xYxO3−δ–BaWO4 composite protonic conductors

“…As the second phase, the BaWO 4 was chosen. Barium tungstate, material commonly used in electrochemical, optical or gas sensor applications [24][25][26], is often prepared by solid state reaction method [27]. It is also known that introducing tungsten to perovskite type structure of Ba(Mg 1/3 Ta 2/3 )O 3 results in formation of oxygen vacancies [28] which leads to the increase of protonic conductivity.…”