Phase equilibria, crystal growth and characterization of the novel ferroelectric tungsten bronzes (CBN) and (CSBN)

Role of structural modulation in electrical properties of tungsten bronze (Ca0.28Ba0.72)2.5−0.5Na Nb5O15 ceramics

“…One factor is due to the changes in the crystal structure varying from 'unfilled' to 'filled' TTB structure. For TTB compounds, the ferroelectrics with 'filled' structure usually show larger P r compared with those with 'unfilled' structure [4,8,9,17,21]. As mentioned in introduction, the distortion of polar unit NbO 6 octahedron can be affected by the ions-occupying-situation and disorder degree in A sites.…”

“…[(B1) 2 (B2) 8 ]O 30 have received considerable attention due to their superior electro-optic, dielectric, ferroelectric and pyroelectric properties [1][2][3][4][5]. In the formula and crystal lattice structure, A1, A2, B and C sites are 12-, 15-, 6-and 9-fold coordinated oxygen octahedral sites, respectively.…”

“…As one member of lead-free ferroelectric systems, tungsten bronze (TB) compounds with a unit-cell formula of [(A1) 2 (A2) 4 …”

Structural modulation and electrical properties in ferroelectric niobates (Ca0.28Ba0.72)2.5−0.5K Nb5O15 (0.0≤x≤0.6) ceramics

“…One factor is due to the changes of unfilled degree in the TTB crystal structure. For TTB compounds, the ferroelectrics with 'filled' structure usually show larger P r compared with those with 'unfilled' structure [10,11,23,24].…”

“…Since recently, Ca x Ba 1-x Nb 2 O 6 solid solutions (CBN, 0.24 < x < 0.31) with 'unfilled' TTB structure has attracted gradual attention due to the higher Curie temperature (T c ) in the range of 250-280 °C [2,[11][12][13][14], almost 200 °C higher than that of the iso-structural Sr x Ba 1-x Nb 2 O 6 (SBN) [15][16][17][18]. Though much work about recent TTB materials has been directly focused on the CBN niobates, they mainly discussed the effects of Ca/Ba ratio [10,19] or doping oxides [2] on dielectric properties, relaxor ferroelectric characteristics, and also elastic behavior of CBN crystals or ceramics.…”