Energy transfer in solid solutions ZnxMg1−xWO4

•An increase of light output was detected in ZnxMg1−xWO4 with maximum at x = 0.5.•Numerical simulation of the relaxation of hot electrons and holes was performed.•Distance between relaxed charge carriers depend on x and influence light output.

It is shown that the light output of ZnxMg1−xWO4 solid solutions has a maximum at x = 0.5 under X-ray excitation. Excitation spectra of exciton emission under vacuum ultraviolet excitation also show the increase of the probability of exciton creation by the geminate e–h pairs for the intermediate values of x. Numerical simulation of the relaxation of hot electrons and holes demonstrates that the observed effects are due to the decrease of the mean distance between thermalized charge carriers.