High performance luminescent materials possess low symmetry, high color purity, no charge compensating defects, and high quantum yield. In this work, we have synthesized Lu2Hf2O7 (LuHO) and Lu2Hf2O7:Eu3+ (LuHOE) nanocrystals (NCs) using a molten salt synthesis and confirmed that both are stabilized in defect fluorite structure with a high degree of structural disordering. The LuHO NCs depicted green emission under ultraviolet irradiation, which decreases and increases after being treated in oxidizing and reducing environments, respectively, confirming the role of oxygen vacancies in the emission process. The LuHOE NCs (i) show excitation wavelength-dependent host to dopant energy transfer efficiency, (ii) give a singular red emission with high color purity of ~95%, (iii) have a dominant occupation of the Lu3+ sites by Eu3+ ions without the formation of charge compensating defects (CCDs), and (iv) possess low non-radiative channels with a quantum yield of ~88%. We believe these LuHOE NCs with singular red emission, high quantum yield, and color purity acquired through structural disordering and the absence of CCDs warrant further investigation as efficient phosphors
