Adamantane-Type Nitridophosphate Phosphors AE x Li 10-2x P 4 N 10  : Eu2 + via Medium-Pressure Ion-Exchange Reactions.

Nitridophosphates have emerged as promising host compounds in the field of solid-state lighting. Their industrial relevance has increased significantly, mainly due to recent advances in synthetic approaches under medium-pressure (MP) conditions, including ammonothermal synthesis and hot isostatic pressing (HIP). In this study, we report on the synthesis and characterization of the quaternary representatives Ca _x Li _10-2x P ₄ N ₁₀ (x=2, 2.7, 4) and Sr ₃ Li ₄ P ₄ N ₁₀ , prepared via a simplified ion exchange reaction under MP conditions, starting from the nitridophosphate-based lithium ion conductor Li ₁₀ P ₄ N ₁₀ . The synthesis route allowed for the preservation of the anionic [P ₄ N ₁₀ ] ^10- structural motif of the starting material, while simultaneously introducing potential doping sites for Eu ²⁺ by incorporating divalent alkaline earth cations (Ca ²⁺ /Sr ²⁺ ). Upon excitation of Eu ²⁺ doped samples with blue light, strong luminescence due to parity-allowed 4f ⁶ ( ⁷ F)5d ¹ →4f ⁷ ( ⁸ S _7/2 ) transition can be observed in the red (Ca ₂ Li ₆ P ₄ N ₁₀  : Eu ²⁺ : λ _max =626 nm), yellow/orange (Ca _2.7 Li _4.6 P ₄ N ₁₀  : Eu ²⁺ : λ _max1 =506 nm, λ _max2 =592 nm and Sr ₃ Li ₄ P ₄ N ₁₀  : Eu ²⁺ : λ _max =596 nm) and green (Ca ₄ Li ₂ P ₄ N ₁₀  : Eu ²⁺ : λ _max =546 nm) spectral regions of the visible light. The compounds presented, together with the simplified synthetic approach, demonstrate the significant potential of ion exchange on Li ion conductors for the development of novel nitridophosphates in the future.
(© 2024 The Author(s). Angewandte Chemie International Edition published by Wiley-VCH GmbH.)