Borate glasses having the formula x CuO–(50 −x)B2O3–30Na2O–20ZnO where x=0, 0.2,
0.5, 1, 4 and 7 mol% were investigated. The samples were prepared using the conventional
melt-quenching technique. Physical properties were studied such as; X-ray difraction,
FTIR spectra, and UV–visible transmission. The optical basicity, average electro negativity
have been estimated. The estimated optical basicity, unlike electron negativity, exhibits an
increase with increasing the CuO content. FTIR spectra show that BO4 ratio decreases with
increasing CuO content leading to the formation of non-bridging oxygen’s. Some optical
parameters such as the optical band gap, band tail width, crystal feld strength and the UV
and NIR cut of were determined. The transmission spectrum revealed that the glassy samples containing high content of copper oxide behave as bandpass flters at higher content.
The characterized parameters of these flters were found to be highly afected by the addition of CuO. In these glasses the broad absorption band observed at the wavelength 550 nm
is characterized by the existence of Cu2+ ions. The optical absorption and ESR studies suggest that, the Cu-ions exist in the Cu2+ state and act as modifers by increasing the degree
of disorder in the glass network. Hence, the present system behaves as a bandpass flter in
the ultraviolet–visible region.