Direct Formation and Luminescence of Nanocrystals in the System Eu 2 Sn 2 O 7 –Gd 2 Sn 2 O 7 Complete Solid Solutions

Nanocrystals with orange‐reddish luminescence based on the pyrochlore‐type complete solid solutions with cube‐like morphology in the Eu 2 Sn 2 O 7 –Gd 2 Sn 2 O 7 system were directly formed from the precursor solutions of SnCl 4 , GdCl 3 , and EuCl 3 under weakly basic hydrothermal conditions at temperatures higher than 180°C for 5 h. The crystallite of Gd 2 Sn 2 O 7 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 Gd 2 Sn 2 O 7 :Eu 3+ 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 5 D 0 → 7 F 1 and 5 D 0 → 7 F 2 transitions of Eu 3+ , respectively. At a composition of (Eu 0.09 Gd 0.91 ) 2 Sn 2 O 7 , the intensity of orange emission reached the maximum. The Red‐to‐Orange ( 5 D 0 → 7 F 2 / 5 D 0 → 7 F 1 ) (R/O) emission intensity ratio was in the low range from 0.10 to 0.14, which was a characteristic of Gd 2 Sn 2 O 7 :Eu 3+ .