ИСТИНА

Copper (+2) ions give us wide possibilities for modifying glass colour from blue to green. In order to study the dependence of colour on glass composition 3 series of M2O-PbO-SiO2 (M = Li-Cs) glasses were prepared: series 1 10K2O-xPbO-(89,5- x)SiO2-0,5CuO (x = 10÷60 mass%), series 2 11M2O-10,5PbO-78SiO2-0,5CuO (mol%) (M = Li-Cs) and series 3 10K2O-10PbO-(80-x)SiO2-xCuO (x = 0,5; 2 mass%) The glasses were molten at 1500oC in alundum crucibles in an electric furnace with MoSi2 heating elements. The melt was poured and quenched into 7-10 mm thick disks with further annealing in a muffle furnace. The material obtained is a transparent glass coloured from green to light-blue. According to ESR data Cu+2 ions (d9-configuration) occupy tetragonally distorted octahedral sites in glass matrix. Different alkali metals non-equally influence (Fig. 1) the tetragonal distortion that increases from Li to Cs. Various ways of colour tuning are available un this system. Increasing of PbO or CuO concentration leads to batochromic shift of the absorption edge. As a result glass becomes green instead of light-blue. In the same time d-d transitions intensity is responsible for the saturation of colour. Therefore, the more CuO is present in glass, the more deep colour can be obtained.