Influence of lattice distortions on the emission wavelengths of Y3+– and Gd3+–substituted Lu3Al5O12:Ce3+ phosphors

(Lu1–xYx)2.94Al5O12:0.06Ce3+ (0 ≤ x ≤ 1.00) and (Lu1–yGdy)2.94Al5O12:0.06Ce3+ (0 ≤ y ≤ 0.75) phosphors are prepared by the sol−gel method. All the prepared phosphors are indexed as a cubic garnet crystal structure (Ia3‾d space group). The substitutions of Y3+ and Gd3+ for Lu3+ in the Lu3Al5O12:Ce3+ phosphors affect the environment of Ce3+ in the Lu(Ce)O8 dodecahedron and photoluminescence properties. In this work, to study the influence of lattice distortions on the emission wavelengths of the Y3+– and Gd3+–substituted phosphors, the lattice distortion factors and maximum emission wavelengths as functions of Y3+ and Gd3+ concentrations are investigated. The Y3+ and Gd3+ substitutions induce the lattice distortion around the Ce3+ ions and shift the emission band of Ce3+ towards a red spectral region. Through the photoluminescence and crystallographic studies, we propose empirical equations between the lattice distortion factors (dY and dGd) and the maximum emission wavelengths (λY and λGd) for the Y3+– and Gd3+–substituted phosphors as λY = 1343.67dY – 882.09 and λGd = 1703.79dGd – 1260.74, respectively. The Y3+– and Gd3+–substituted phosphors show tunable emission wavelength, which may have potential applications in white light–emitting diodes.