Stable double perovskite Cs₂AgInCl₆ has been reported as a direct gap semiconductor with a wide band gap of 3.23 eV obtained experimentally and 3.33 eV obtained by DFT calculation.

This paper reports the development of new phosphors using the chemical unit cosubstituting solid solution design strategy. Starting from Lu₃Al₅O₁₂, the Al³⁺–Al³⁺ couple in respective octahedral and tetrahedral coordination was simultaneously substituted by a Mg²⁺–Si⁴⁺ pair forming the Lu₃(Al_2−xMg_x)(Al_3−xSi_x)O₁₂:Ce³⁺ (x = 0.5–2.0) series; as a result, the CeO₈ polyhedrons were compressed and the emission got red-shifted from green to yellow together with the broadening. The evolution of, the unit cell, the local structural geometry as well as the optical properties of Ce³⁺ in these garnet creations, in response to the gradual Mg–Si substitution for Al–Al, were studied by combined techniques of structural refinement and luminescence measurements. The new composition Lu_2.97Ce_0.03Mg_0.5Al₄Si_0.5O₁₂ was comprehensively evaluated regarding its potential application in blue LED-driven solid state white lighting: the maximum emission is at 550 nm under λ_ex = 450 nm; the internal and external quantum efficiencies can reach 85% and 49%, respectively; a 1-phosphor-converted wLED lamp fabricated using the as-prepared phosphor exhibits the luminous efficacy of 105 lm W⁻¹, the correlated color temperature of 6164 K and the color rendering index (R_a) of 75.6. The new solid solution composition series is open for further optimization to enhance the competence for commercial consideration.