Machinery & Energetics

The set of the samples in glass ceramics and polycrystalline states were made using amorphous Li₂O-7GeO₂ glass (LGO) as starting material and then they were studied using luminescence spectroscopy procedure. The X-ray diffraction analysis had revealed that the glass-ceramics state samples are built by the grains of the lithium tetragermanate, Li₂Ge₄O₉, micro/ nanocrystals incorporated into amorphous germanium oxide, GeO₂, matrix. When the transition to polycrystalline state occurs the tetragermanate phase crystals vanishes, while heptagermanate crystals, Li₂Ge₇O₁₅ are formed. The results of luminescent study of the doped with chromium ions materials had confirmed in the whole mentioned above. In fact, luminescence propertied to radiation transitions in Cr³⁺ ionsplaced mainly in tetragermanat, Li₂Ge₄O₉, was found for glass-ceramics state, while such luminescence propertied both to heptagermanate and tetragermanat was found for polycrystalline state. It was shown that just multiphase structure of the chromium doped lithium germanate compounds promotes designing luminescent transformers of violet radiation to the broad band green-red radiation. The studied material scan be used as luminescent thin film covers aimed to menhance effectiveness of the silicon solar cells, or to design white light emitting diodes.

glass, ceramics, lithium-germanate, chromium ions, luminescence