[en] The solid solution series SrLaNaWsub(1-x)Usub(x)0₆ was examined crystallographically and spectroscopically. Preparation of the compounds is described. X-ray diffraction measurements were made on SrLaNaU0₆. The infrared spectrum of SrLaNaU0₆ was measured. It is concluded that U is present as octahedral uranate groups and not as uranyl. The emission spectra of the luminescence of samples SrLaNaWsub(1-x)Usub(x)0₆ were measured at liquid nitrogen and liquid helium temperature under long-wavelength UV excitation. The conclusion is that a few per cent of uranium can be introduced in SrLaNaW0₆ as uranyl, or at least with two oxygen neighbours at relatively short distance. The results are further discussed. (U.K.)