Spectroscopic investigations on Cu(II) ions doped in alkali lead borotellurite glasses

Abstract

Electron paramagnetic resonance, optical absorption spectra, Raman spectra and physical properties of copper(II) ions in (85 − x/2)R 2 B 4 O 7 -xPbO-yCuO-(15 − x/2 − y)TeO 2 (x = 0,10; y = 0.1-1.5; R = Li, Na or K) glasses were studied. EPR spectra of all the glasses show resonance peaks characteristic of Cu 2+ ions. The number of spins participating in the resonance was measured as a function of temperature and the activation energy was calculated. From the EPR and density measurements, the ratio of number of copper ions in +2 state to the total copper ions (i.e., N 2 /N T ) was calculated. The paramagnetic susceptibility was calculated from the EPR data at various temperatures and the Curie constant was calculated from the 1/χ -T graph. The optical absorption spectra of all the samples show a broad absorption band; the position of the band maxima varies from 14 500 to 12 700 cm −1 for glasses with different alkali ions. The optical energy gap E opt and Urbach energy E were calculated for all the glass samples from their ultraviolet edges. The optical energy gap varies between 3.4 and 2.7 eV and increases from Li to K glasses. Also, it was observed that as copper ion concentration is increased, E opt decreases while E increases. This was explained as due to change in non-bridging oxygen content. Raman spectra of three samples were recorded at room temperature. The bands were assigned as due to various groups of boron.

Microstructure, mechanical, EPR and optical properties of lithium disilicate glasses and glass–ceramics doped with Mn2+ ions

“…From Table 3, the optical band gap energy is found to decrease slightly with the increase of concentration. The optical band gap energies obtained in the present work are of the same order as reported in the literature [38,39]. It is observed that in LDS glass ceramics there is a huge decrease in the optical band gap energies.…”

Mixed alkali effect in Li2O–Na2O–B2O3 glasses containing CuO – An EPR and optical study

“…The spectra recorded in the ultraviolet wavelength region were used to get the optical absorption edges for the study of optical band gap energies. signals similar to those reported for Cu 2+ ions in other glass systems [15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32]. The Cu 2+ ions with S = 1/2 has a nuclear spin I = 3/2 for both 63 Cu (the natural abundance 69%) and 65 Cu (natural abundance 31%) and therefore (2I + 1) i.e., four parallel and four perpendicular hyperfine components would be expected.…”

Copper ion as a structural probe in PbO–CaF2–P2O5 glass system by means of spectroscopic and dielectric studies

“…Because g ll > g ⊥ > 2.0023(g e ), the ground state of the paramagnetic electron is d x 2 −y 2 orbital ( 2 B 1g state). A comparison of g factors of present glass system with other composition of various oxide glasses [37][38][39][40][41] shows a reasonable agreement. The ESR and optical absorption spectral data can be correlated to understand the environment of Cu 2+ ions in PbO-CaF 2 -P 2 O 5 glass network as follows [42]:…”