NUV light-induced-visible emissions and dopant concentration-dependent optical thermometric behaviors in Y2Mo4O15:2xEr3+ phosphors

Highlights: • Upon 377 nm irradiation, all the samples emitted visible emission from the 4f-4f transitions of Er³⁺ ions. • The optimal dopant content was 4 mol% and the dipole-dipole interaction leaded to the quenching effect. • With the aid of FIR route, the optical thermometric properties of the resultant phosphors were studied. • The sensor sensitivities of the studied samples were dependent on the doping concentration. • The maximum sensitivity of the Y₂Mo₄O₁₅:0.02Er³⁺ phosphor was as high as 0.01 K⁻¹ at 473 K. We reported the photoluminescence (PL) and optical thermometric properties of Er³⁺-doped Y₂Mo₄O₁₅ phosphors synthesized by a facile sol-gel method. Upon the light excitation at a wavelength of 377 nm, all the compounds emitted visible green emissions with high color purity of 94.8%. A gradual enhancement in PL emission intensity was observed with increasing the Er³⁺ ion concentration in resultant compounds, reaching its optimal value when x = 0.04. The concentration quenching mechanism of Er³⁺ ions in the Y₂Mo₄O₁₅ host lattice was dominated by the dipole-dipole interaction and the critical distance was estimated to be around 36.7 Å. With the aid of fluorescence intensity ratio technique based on the thermally coupled levels of Er³⁺ ions, the optical thermometric behaviors of the resultant phosphors were studied by analyzing the temperature-dependent PL emission spectra. It was found that the sensor sensitivities of the as-synthesized samples were sensitive to the Er³⁺ ion concentration. The maximum sensor sensitivity of the obtained phosphors reached up to 0.01 K⁻¹ at 473 K when the doping concentration was 1 mol%. These observed results reveal that the Er³⁺-doped Y₂Mo₄O₁₅ phosphors have promising applications in noninvasion optical thermometry.