Sr₃ P₃ N₇ : Complementary Approach by Ammonothermal and High-Pressure Syntheses

Area of Science:

• Solid-state chemistry
• Materials science
• Inorganic chemistry

Background:

• Nitridophosphates display diverse structural motifs, including chains, layers, and frameworks.
• The exploration of novel nitridophosphate structures is crucial for discovering materials with unique properties.

Purpose of the Study:

• To synthesize and characterize a new nitridophosphate, Sr3P3N7, with an unprecedented structural motif.
• To investigate the optical and luminescence properties of Sr3P3N7, particularly when doped with Europium (Eu2+).

Main Methods:

• Ammonothermal synthesis for crystalline powders and high-pressure multianvil technique for single crystals.
• Single-crystal X-ray diffraction for crystal structure determination.
• Powder X-ray diffraction, energy-dispersive X-ray spectroscopy, Fourier-transformed infrared spectroscopy, and UV/Vis spectroscopy for characterization.

Main Results:

• The novel nitridophosphate Sr3P3N7 was synthesized and its crystal structure determined in the monoclinic space group P2/c, revealing unprecedented dreier double chains.
• Chemical composition and absence of NHx functionality were confirmed.
• An optical band gap of 4.4 eV was determined. Europium (Eu2+)-doped Sr3P3N7 exhibited broad deep-red to infrared emission (λem = 681 nm) with 42% internal quantum efficiency.

Conclusions:

• Sr3P3N7 represents a new nitridophosphate structure with potential applications in optoelectronics due to its luminescence properties.
• The ammonothermal and high-pressure multianvil methods are effective for synthesizing novel nitridophosphates.
• Eu2+-doped Sr3P3N7 demonstrates promising deep-red/infrared emission characteristics.