Size induced modification of boron structural unit in YBO3: systematic investigation by experimental and theoretical methods

Abstract

Nanocrystalline YBO₃ (∼4–8 nm) was prepared using polyol method. Structural features of these nanoparticles have been investigated jointly by experimental and theoretical methods and compared with corresponding bulk phase of YBO₃. The symmetry around Y³⁺ has been examined by photoluminescence measurements of Eu³⁺ doped YBO₃ sample, while the local structure around boron has been probed through ¹¹B MAS-NMR studies. XRD and photo-luminescence investigations reveal that YBO₃ nanoparticles are structurally distorted in comparison to their bulk counterpart. Judd–Ofelt analysis shows that local environment around Y³⁺/Eu³⁺ is more polarizable in nanoparticles. ¹¹B MAS-NMR studies confirmed that contrary to bulk phase where only BO₄ units are present, nanoparticles of YBO₃ have both BO₃ and BO₄ structural units in almost equal proportion. DFT calculation also predicts the existence of both BO₃ and BO₄ structural units in YBO₃ nanoparticles where BO₃ units are primarily distributed on surface of the nanoparticles. We expect that such nanoparticles, rich in unsaturated boron oxides on the surface, will help in the synthesis of inorganic–organic hybrid phosphors for next generation flexible display devices.