Direct Formation and Luminescence of Nanocrystals in the System Eu2Sn2O7–Gd2Sn2O7 Complete Solid Solutions

Nanocrystals with orange‐reddish luminescence based on the pyrochlore‐type complete solid solutions with cube‐like morphology in the Eu₂Sn₂O₇–Gd₂Sn₂O₇ system were directly formed from the precursor solutions of SnCl₄, GdCl₃, and EuCl₃ under weakly basic hydrothermal conditions at temperatures higher than 180°C for 5 h. The crystallite of Gd₂Sn₂O₇ pyrochlore gradually grew from 10 to 37 nm as the hydrothermal treatment temperature rose from 180°C to 240°C. The lattice parameter of cubic phase linearly increased with increased europium concentration according to the Vegard's law. The characteristic orange‐reddish photoluminescence spectra of Gd₂Sn₂O₇:Eu³⁺ cubelike nanocrystals with crystallite size from 34 to 37 nm that were formed at 240°C for 5 h were attributed to the most sharp orange (586 nm) luminescence with high intensity and quite broad red (610–630 nm) emission with weak intensity, according to the ⁵D₀→⁷F₁ and ⁵D₀→⁷F₂ transitions of Eu³⁺, respectively. At a composition of (Eu_0.09Gd_0.91)₂Sn₂O₇, the intensity of orange emission reached the maximum. The Red‐to‐Orange (⁵D₀→⁷F₂/⁵D₀→⁷F₁) (R/O) emission intensity ratio was in the low range from 0.10 to 0.14, which was a characteristic of Gd₂Sn₂O₇:Eu³⁺.