Abstract
The luminescence of K6Nb6Si4O26 and K8Nb14Si4O47 is reported. Three emission bands have been observed, each with its own excitation band. In the case of K8Nb14Si4O47 these emissions can be ascribed to the three crystallographically different niobate octahedra. The emission from the edge-sharing octahedron is exceptional, because the Stokes shift is
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