New Layered Oxide-Fluoride Perovskites: KNaNbOF5 and KNaMO2F4 (M = Mo6+, W6+)

Hydrothermal crystal growth, piezoelectricity, and triboluminescence of KNaNbOF5

“…In either case, temperature, concentration, and pH are critical factors. Crystal growth of the NCS polymorph of KNaNbOF 5 faces an additional challenge since both polymorphs of KNaNbOF 5 can be grown hydrothermally, sometimes from the same solution [11,[14][15][16][17]. Because hydrothermal crystal growth can take multiple days to weeks to obtain large single crystals, crystal growth conditions that ensure the correct polymorph crystallizes must also be targeted.…”

How Lewis Acidity of the Cationic Framework Affects KNaNbOF5 Polymorphism

“…Knowledge of factors that can yield polar structures and align dipoles is important when attempting to synthesize new SHG materials. The KNaNbOF 5 system is appealing for study, since both centrosymmetric (CS) 7 and polar NCS polymorphs 8 are known. This allows for direct comparison, since the identities of the cations are the same.…”

Atomic scale imaging of competing polar states in a Ruddlesden–Popper layered oxide

“…While much of the focus thus far has been on simple perovskites, a survey of the inorganic crystal structure database (https://icsd.fiz-karlsruhe.de/) reveals that of the nearly 55,000 complex oxides listed today, >99% are layered structures; surprisingly, only ∼2% of these compounds have been explored. However, recent advances in unit-cell level control in the epitaxial growth of thin films and heterostructures are opening up large families of layered oxide topologies in thin film form, such as the A 2 A ′ n −1 B n O 3 n +1 Ruddlesden–Popper (RP), AA ′ n −1 B n O 3 n +1 Dion–Jacobson, (Bi 2 O 2 )( A n −1 B n O 3 n +1 ) Aurivillius and ( AB O 3 ) m /( A′B′ O 3 ) n perovskite superlattices678910111213141516171819202122232425. The layer dimensions (subscripts m and n ) of these materials along with strain and chemical ordering can be tuned to modify or activate new phenomena, such as ferroelectricity2627, colossal-magnetoresistance2829, ferromagnetism3031, multiferroicity32, superconductivity33 and ionic conductivity34.…”