Aliovalent anion substitution as a design concept for heteroanionic Ruddlesden-Popper hydrides

Area of Science:

• Materials Science
• Solid-State Chemistry
• Inorganic Chemistry

Background:

• Heteroanionic compounds offer tunable electronic and structural properties.
• The K2NiF4 structure type is known for its layered perovskite-like arrangement.
• Previous research has explored oxide and nitride materials, but heteroanionic hydrides are less common.

Purpose of the Study:

• To synthesize and characterize novel heteroanionic hydrides with a K2NiF4 type structure.
• To investigate the structural and electronic properties of these new materials.
• To explore the potential of substituting oxide anions with nitride and hydride anions.

Main Methods:

• Solid-state reactions using lithium nitride (Li3N), lanthanum hydride (LaH3), and lanthanum oxide (La2O3).
• Crystallographic analysis to determine the crystal structure and site occupancies.
• Characterization of electronic properties, including band gap determination.

Main Results:

• Successful synthesis of dark-brown heteroanionic hydrides, LiLa2N1.5H2.5 and LiLa2N0.84(6)H1.56(3)O1.16(6).
• Crystallization in the K2NiF4 type structure with mixed hydride/nitride sites and nitride/oxide sites.
• Identification of LiLa2N0.84(6)H1.56(3)O1.16(6) as a semiconductor with a small band gap and partial covalent Li-H interaction.

Conclusions:

• The substitution of oxide anions with nitride and hydride anions is a viable route to novel heteroanionic compounds.
• The synthesized materials possess unique structural features and semiconducting properties.
• These findings contribute to the understanding of hydride materials and their potential applications in electronics.