Mixed Alkali Effect in Li2O -Na2O-B2O3 Glasses Containing CuO-An EPR and Optical Study

نویسندگان

  • R. P. Sreekanth Chakradhar
  • Lakshmana Rao
چکیده

The “mixed alkali effect” is one of the classical anomalies of glass science. We report here an interesting phenomenon “Mixed Alkali Effect” observed for a series of Cu ions doped xLi2O-(30x)Na2O-70B2O3 (5 ≤ x ≤ 25) glasses, investigated by EPR and optical absorption techniques. The EPR spectra of all the investigated samples exhibit resonance signals characteristic of Cu ions in octahedral sites with tetragonal distortion. It is found that the spin-Hamiltonian parameters do not vary much with x. However, the number of spins participating in resonance (N) and the paramagnetic susceptibility (χ) exhibits the mixed alkali effect. The N is also measured as a function of temperature and the activation energy is evaluated. It is observed that the temperature dependence of paramagnetic susceptibility (χ) obeys Curie-Weiss law. The optical absorption spectra exhibit a strong band corresponding to the transition (B1g → B 2g) centered at 13280 cm . By correlating the EPR and optical absorption data, the molecular orbital coefficients α and β are evaluated. It is interesting to observe that the optical band gap and Urbach energies show the MAE.

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

منابع مشابه

Infrared and Raman Spectroscopic Studies on mixed alkali tungsten based glasses

Quaternary tungstate glasses containing K2O, Na2O and B2O3 have been prepared by melt quench technique and studied by IR and Raman spectroscopy. Raman and infrared spectroscopy have been employed to investigate the (30−x)Na2O–xK2O–10WO3–60B2O 3 glasses in order to obtain information about the competitive role of WO3 and B2O3 in the formation of glass network. IR spectral study reveals the exist...

متن کامل

Structural Investigation, Physical and Optical Properties of Mixed Alkali Bismuth Borate Glasses

Lead free, eco-friendly bismuth borate glasses doped with alkali oxides of composition xLi2O+(30-x)Na2O+55B2O3+15Bi2O3 (x = 5,10,15,20,25) were prepared by melt quenching technique. Amorphous nature of glasses was confirmed by X-ray diffraction. Density measurements were carried out at room temperature by standard principle of Archimedes with Xylene as an immersion liquid. The non-linear ...

متن کامل

Optical and Thermal Properties of Mixed Alkali Phosphate Based Glasses

Glassy samples with a composition of 40P2O5&ndash;30V2O5&ndash;(30-x)Li2O&ndash; xK2O, 0<x<30 (mol %) were prepared by the conventional melt quenching technique in two forms of bulk and blown film. X-ray diffraction patterns corroborated the amorphous feature of the samples. Density of samples was investigated by using Archimedes principle. Based on absorption and reflection spectra, indirect a...

متن کامل

Compositional dependency on dissolution rate and cytocompatibility of phosphate-based glasses: Effect of B2O3 and Fe2O3 addition

The unique property of phosphate-based glasses and fibres to be completely dissolved in aqueous media is largely dependent on the glass composition. This article focuses on investigating the effect of replacing Na2O with 3 and 5 mol% Fe2O3 on cytocompatibility, thermal and dissolution properties of P2O5-CaO-Na2O-MgO-B2O3 glass system, where P2O5 content was fixed at 45 mol%. The effect of incre...

متن کامل

Mixed Alkali Effect in Na2O-Li2O-Si O2 Glasses Studied by Isothermal Mechanical Spectroscopy

Several studies of internal fiiction have been performed on silicate glasses. This work has the specificity to refer to isothermal mechanical spectroscopy over a large frequency range and for temperatures between 290 K and 520 K. Experiments were carried out with a single alkali silicate glass and two mixed alkali silicate glasses in order to observe the mixed alkali effect, to follow its evolu...

متن کامل

ذخیره در منابع من


  با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

عنوان ژورنال:

دوره   شماره 

صفحات  -

تاریخ انتشار 2005