“…Owing to the vast structural diversity and the variable properties of (oxo)nitridosilicates, there has been sustained interest in exploring new (oxo)nitridosilicates in chemistry and materials science. Over the past few years, Schnick et al have discovered a multitude of novel AB 2 -type tetrahedral network (oxo)nitridosilicates and (oxo)nitridophosphates. − These (oxy)nitride compounds exhibit a diverse range of properties and unique structural features, such as ammonia adsorptions and storage in clathrate compound P 4 N 4 (NH) 4 (NH 3 ), and new zeolite topologies, for example, the NPO (nitridophosphate one) framework type Li x H 12– x – y + z [P 12 O y N 24– y ]X with X = Cl, Br and Ba 19 P 36 O 6+ x N 66– x Cl 8+ x ( x ≈ 4.54) NPT (nitridophosphate two) framework type. The oxonitridosilicates Ba 3 Si 3 N 5 OCl and Ba 6 Si 6 N 10 O 2 (CN 2 ) are also under the category of NPO type. , Additionally, another significant application includes the phosphor host for Eu 2+ and Ce 3+ ions in the application of phosphor-converted light-emitting diodes (pc-LEDs) such as Ba 3 P 5 N 10 X:Eu 2+ (X = Cl, Br, I). , Furthermore, nitrides have exhibited promising properties and potential applications within the field of nonlinear optical (NLO) materials, for example, M 2 Si 5 N 8 with M = Ca, Sr, Ba, which exhibit high refractive indices and effective M eff ; these values were found to be comparable to those of the benchmark compound LiIO 3 . , The mixed-anion tetrahedra in oxonitridosilicates, e.g., (SiNO 3 ) 5– , (SiN 2 O 2 ) 6– , and (SiN 3 O) 7– , offer an alternative solution to address the limitations in birefringence of silicates.…”