Copper Phosphate Glasses Research Articles

RETRACTED ARTICLE: Optical spectroscopic analysis of bandpass filter used for laser protection based on cobalt phosphate glass

A protection glass against laser beam was fabricated from a cobalt oxide-doped copper phosphate glass with series of 40P2O5–(20−x) Na2O–38ZnO– xCo3O4–1CuO in the molar ratio with x = 1, 2, 3, 4 and 5 using a conventional glass casting and quenching technique. The density was measured by Archimedes method, and the molar volume was calculated. Increasing the heavy element, cobalt oxide in a glass composition causes an unusual phenomenon between the density and molar volume that they have the same trend. The XRD technique has been used to investigate the glass systems and prove the complete glass state of the systems. Optical spectroscopic analysis from the transmittance data of the glass filter showed that these filters had a single band pass with a double band stop in the UV, visible and IR, which covers the region that is used in some laser protection glass like organic dye lasers, polymer lasers, solid-state dye lasers, excimer, quadrupled Nd:YAG laser and quintupled Nd:YAG laser. This can be used for a glass laser safety protection.

Optimization of electrical conductivity in copper phosphate glasses

Amorphous CuO-P2O5 glasses doped with ZnO and CdCl2 have been prepared by melt quenching. The electrical conductivity of CuO-P2O5 glasses were optimized over a range of frequency and temperature as 100 Hz − 1 MHz and 323–573 K, respectively. The trend of increasing conductivity was observed in prepared glasses as frequency and temperature increased. The obtained results ac and dc conductivity confirm the power law of Jonscher and Arrhenius law, on the basis of which it can suggest increased conductivity of glasses.

Structural origin of electrical conductivity of copper lithium metaphosphate glasses

We have sought the structural origin of the recently reported electrical conductivity of lithium copper phosphate glass system (50-x) Li2O-xCu2O-50 P2O5, as lithium oxide is gradually replaced by Cu2O. The structure of these glasses was determined by X-ray photoelectron spectroscopy, Fourier Transform Infrared Spectroscopy and Raman spectroscopy. The results show the presence of both mobile Cu+ and relatively immobile Cu2+ ions. The relative fraction of Cu2+ [Cu2+/Cutot] and non-bridging oxygen increases with x; the latter indicating a tendency towards depolymerization of the network. On the other hand, there is enhanced crosslinking within the network as PO⋯Li bonds are replaced by relatively covalent PO⋯Cu bonds. This leads to a more cross-linked structure and a progressive reduction of the optimum sites for the jumping of both Li+ and Cu+, in agreement with the observed increase of the energy barrier for ion transport as Li2O is replaced by Cu2O.

Design and Fabrication of Protection Window Against YAG Laser

Window protection glass against a YAG laser based on a bandpass absorption filter was fabricated from bismuth oxide doped copper phosphate glass with series of xBi2O3-(40-x) ZnO-10Na2O-6Cu2O-44P2O5 in molar ratio with x=0, 5 and 10 and were prepared by using a conventional glass casting and quenching technique. The density was measured by the conventional Archimedes method and the molar volume was calculated. Bismuth oxide is a heavy element; by increasing the doping in a glass composition it can cause an unusual phenomenon between the density and molar volume, they can have the same trend. The glass was investigated by using the XRD technique, which proved the systems are completely in the glass state. Optical spectroscopic analysis of the glass filter from the transmittance data showed the UV and the IR cut-off bands to the bandpass filter, which confirmed the band absorption in the IR cut-off included the Nd:YAG laser wavelength, which can be used for a glass laser safety window.

Spectral Investigation of Crystalline (CuHPO4, Cu2P4O12,and Cu2P8O22) and Glassy Copper Phosphates

Emerald green crystals of the new composition CuHPO4were synthesized and compared to (copper metaphosphate) Cu2P4O12and (copper ultraphosphate) Cu2P8O22. Various copper ultraphosphate and metaphosphate glasses of different compositions between pure P2O5and Cu2P4O12were melted in crucibles or in evacuated and sealed silica ampoules at 1473 K or 1373 K for 2 hrs. The UV-VIS-spectra and the IR-spectra of all crystals and glasses were measured and compared. The absorption band of Cu2+was resolved into more component Gaussian bands and differentiated between square-pyramidal and octahedrally coordinated copper. These structural changes are responsible for colour changes from green to turquoise. The infrared spectroscopic properties of the copper phosphate glasses differ between metaphosphate and ultraphosphate structures but show similarities between the crystals and the glasses of the same structure type. EPR studies of some of the glasses show different kinds of spectra, with increasing copper content.

Effect of laser irradiation on the structure and valence states of copper in Cu-phosphate glass by XPS studies

The effect of laser irradiation using three different wavelengths (IR, visible and UV) generated from Nd:YAG laser on the local glass structure as well as on the valence state of the copper ions in copper phosphate glass containing CuO with the nominal composition 0.30(CuO)–(0.70)(P 2O 5), has been investigated by X-ray photoelectron spectroscopy (XPS). The presence of asymmetry and satellite peaks in the Cu 2p spectrum for the unirradiated sample is an indication of the presence of two different valence states, Cu 2+ and Cu +. Hence, the Cu 2p 3/2 spectrum was fitted to two Gaussian–Lorentzian peaks and the corresponding ratio, Cu 2+/Cu total, determined from these relative areas clearly shows that copper ions exist predominately (>86%) in the Cu 2+ state for the unirradiated glass sample under investigation. For the irradiated samples the symmetry and the absence of satellite peaks in the Cu 2p spectra indicate the existence of the copper ions mostly in Cu + state. The O 1s spectra show slight asymmetry for the irradiated as well as unirradiated glass samples which result from two contributions, one from the presence of oxygen atoms in the P–O–P environment (bridging oxygen BO) and the other from oxygen in an P–O–Cu and P O environment (non-bridging oxygen NBO). The ratio of NBO to total oxygen was found to increase with laser power.

Characterization and electrical properties of V 2O 5–CuO–P 2O 5 glasses

Characterization and electrical properties of vanadium–copper–phosphate glasses of compositions xV 2O 5–(40− x)CuO–60P 2O 5 have been reported. X-ray diffraction (XRD) confirms the amorphous nature of these glasses. It was observed that, the density ( d) decreases gradually while the molar volume ( V m) increases with the increase of the vanadium oxide content in such glasses. This may be due to the effect of the polarizing power strength, PPS, which is a measure of ratio of the cation valance to its diameter. The dc conductivity increases while the activation energy decreases with the increase of the V 2O 5 content. The dc conductivity in the present glasses is electronic and depends strongly upon the average distance, R, between the vanadium ions. Analysis of the electrical properties has been made in the light of small polaron hopping model. The parameters obtained from the fits of the experimental data to this model are reasonable and consistent with glass composition. The conduction is attributed to non-adiabatic hopping of small polaron.

Universal hardness and elastic recovery in Vickers nanoindentation of copper phosphate and silicate glasses

Load/unload displacement (penetration) curves for yCuOx·(100−y)P2O5 glasses (y=45, 50) with different copper valence states, silica and soda-lime silicate glasses at room temperature (humidity ∼64%) have been measured using a Vickers nanoindentation technique, and universal hardness Hu and elastic recovery ER have been estimated in the load range of 0.1–1 N. Copper phosphate glasses have the values of Hu=1.7–2.5 GPa and ER=0.55–0.65, depending on the Cu+/Cu2+ ratio. The glasses with high Cu+ contents show large densifications (plastic deformation) during loading and small elastic recoveries during unloading compared with the glasses with no Cu+ ions. These deformation behaviors are well explained qualitatively by considering lower coordination number and more covalent bonding of Cu+ compared with Cu2+, which have been confirmed from X-ray photoelecton spectra. Silica glass has ER≒0.77, which is large compared with ER≒0.63 in a soda-lime silicate glass. This large difference leads to the smaller value in Hu of silica glass than that of a soda-lime silica glass. It is confirmed that load displacement curves in nanoindentation tests are well fitted with quadratic equations.

Unusual Elastic and Mechanical Behaviors of Copper Phosphate Glasses with Different Copper Valence States

Elastic and mechanical properties such as Young's modulus E, Poisson's ratio ν, Debye temperature θD, Vickers hardness Hv, fracture toughness Kc, and fracture surface energies γf of yCuOx·(100−y)P2O5 glasses (y= 45, 50, 55) with different copper valence states, i.e., R(Cu+) = Cu+/(Cu++ Cu2+), at room temperature (humidity 64%) have been examined. The following features have been found: (1) the glass transition temperature (218–434°C), Hv (2.7–4.4 GPa), E (50.6–78.2 GPa), and θD (358–434 K) decrease largely with increasing R(Cu+); (2) the mean atomic volume, Kc (0.56–1.14 MPa·m1/2), and γf (1.9–11.2 J·m−2) tend to increase with increasing R(Cu+); (3) 50CuOx·50P2O5 glasses with R(Cu+) = 0.42 and 0.55 have a high resistance against crack formation in Vickers indentation tests and no crack is observed in the 45CuOx·55P2O5 glass with R(Cu+) = 0.57 under an applied load of about 98 N. The results demonstrate that elastic and mechanical properties of yCuOx·(100−y)P2O5 glasses depend strongly on the copper valence state and the CuOx/P2O5 ratio. The unusal mechanical and elastic properties of copper phosphate glasses are well explained qualitatively by considering unique oxygen coordination and bonding states of Cu+ ions, i.e., lower coordination number and more covalent bonding compared with Cu2+ ions.

Raman spectroscopy of copper phosphate glasses

Raman spectra of binary copper phosphate glass samples, xCuO · (1 − x)P 2O 5, having x = 0.4, 0.5, and 0.55 and various [Cu 2+]/[Cu total] ratios have been measured. The Raman spectra of the samples changed with changing [Cu 2+]/[Cu total] ratio as well as CuO content. The smaller ionic size and the greater charge of the Cu 2+ ion than those of the Cu 1+ ion create larger in-chain POP bond angles and smaller out-of-chain PO 2 angle as well as greater CuO field strength. Differing local structures of Cu 1+ and Cu 2+ ions in phosphate glass results in a variation of Raman spectra of the glasses depending on the [Cu 2+]/[Cu total] ratio. Also, a decrease in phosphate chain length with increasing CuO content affected the Raman spectra of the glasses. Although the crystallization of the samples is not detected in the X-ray diffraction, the overlapping bands in the Raman spectra of the 0.55 CuO samples are attributed to crystalline phases.

Study of valence states of copper in copper-phosphate glasses

Phosphate glasses containing CuO with composition, [(CuO)x(P2O5)1−x], x=0.10, 0.20, 0.25, 0.30, 0.40 and 0.50, were studied by magnetization, X-ray photoelectron spectroscopy (XPS) and Rutherford backscattering spectrometry (RBS). It was observed that compositional changes take place in going from batch to glass and these changes are more pronounced for low copper concentration. The ratio [Cu2+/Cutotal] as a function of x was determined from XPS and magnetization combined with RBS. The magnetization measurements suggest that more than 90% of the copper ions exist in the Cu2+ state in the glasses, while the XPS data show that less than 50% of the copper ions may be in the Cu2+ state. The low Cu2+ states detected by XPS may have resulted form reduction of copper ions upon exposure of the samples to X-ray radiation during measurement.

X-ray photoelectron spectroscopy, fourier transform infrared spectroscopy and electrical conductivity studies of copper phosphate glasses

Phosphate glasses containing CuO with composition (CuO)x(P2O5)1-x, where x = 0.1, 0.2, 0.3, 0.4 and 0.5, were studied by X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR) and room temperature electrical conductivity, σ. The spin orbit components Cu 2p32 and Cu 2p12 show doublet structures which may be associated with Cu+ and Cu2+. The ratio C = Cu+Cutotal as a function of x was determined using the Cu 2p32 spectra. It is observed that the ratio, C, initially decreases with x, becomes minimum at x = 0.3 and then increases. Although the variation of σ with C was very small, it is close to the uncertainty in the measurement of its value; nevertheless it was maximum at C = 0.5, in agreement with the previous prediction. The FT-IR spectra indicated a maximum shift in the P = O absorption at 30% CuO contents in the glasses, which essentially follows the same pattern as the shift for the POP absorption. Further, the development of the high energy component peak in the O 1s (associated with POP oxygen) spectra follows a trend similar to the 760 cm−1 (also associated with POP) absorption band in the FT-IR spectra.

Internal friction in BiSrCaCuO glasses

The results of internal friction and d.c. conductivity measurements in Bi 2O 3CaOSrOCuO glasses and partially crystallized glasses are reported. Furthermore, a comparison between the internal friction spectra of superconducting ceramics and those of copper phosphate glasses has been done. The internal friction measurements were performed by means of low frequency vibrating reed and torsion pendulum methods. A mechanical loss peak observed at 150 K (at 200 Hz) in crystallized glass and bismuth superconducting ceramics can be correlated with the mechanism of the d.c. conductivity in crystallized glass. The comparable value of the relaxation parameters suggests the same mechanism to be responsible for both processes. In the glassy state the internal friction peak observed at about 275 K corresponds to the mechanism of small polaron hopping between copper ions in different valency states (Cu ICu II). The copper phosphate glass exhibits a mixed electronic—ionic behaviour. The large internal friction peak in the high temperature region can be related to Cu I ion and proton migration in the glass matrix.

Optical absorption of copper phosphate glasses in the visible spectrum

Abstract Optical absorption of copper phosphate glasses with batch compositions of 40, 50 and 55 mol% CuO have been examined in the visible and near-infrared range as a function of [Cu2+]/[Cutotal] in the glasses. An absorption band centered at about 11 000 cm−1 is produced due to an octahedral coordination of Cu2+ in the glass with strong tetragonal distortion. This absorption band is resolved into three-component Gaussian bands around 8500, 12 000 and 13 250 cm−1. These bands are assigned to the energy transitions 2 A 1 g → 2 B 1 g , 2 B 2 g → 2 B 1 g and 2 E g → 2 B 1 g , respectively. The degree of tetragonal distortion of Cu2+ coordination is slightly enhanced with increases in the [Cu2+] ratio and CuO content. A minimum absorption in the visible spectrum is produced by overlapping of the absorption bands of Cu2+ and Cu1+. The position of the minimum absorption shifts to higher wavenumber with increasing [Cu2+] ratio in the glass regardless of glass composition and is responsible for color changes.

Ultraviolet optical absorptions of semiconducting copper phosphate glasses

Ultraviolet optical absorptions of semiconducting copper phosphate glasses with batch compositions of 40%, 50%, and 55% CuO have been examined as a function of [Cu2+]/[Cutotal] in the glasses. The optical energy gap, Eopt, obtained from the fundamental absorption edge depends upon both glass composition and the ratio [Cu2+]/[Cutotal] in the glass. Eopt increases as CuO content and [Cu2+]/[Cutotal] in the glass are raised. This trend is explained by speculating upon the energy band structure of copper phosphate glass. However, the Urbach energy, ΔE, obtained from the tail of the optical absorption edge is affected solely by [Cu2+]/[Cutotal] in the glass. An absorption band of Cu1+ (in its crystal field) occurs in the vicinity of the absorption tail and is responsible for the increase of ΔE with reducing [Cu2+]/[Cutotal] in the glass.

Electron spin resonance in copper phosphate and copper tellurite glasses containing strontium

Two series of ternary copper phosphate and copper tellurite glasses containing strontium were prepared and the electron spin resonance spectra of glasses of compositions 65 (P2O5)-(35-x) CuO-xSrO and 65 (TeO2)-(35-x) CuO-xSrO where x varied from 0–10 mol % were investigated. From the results and the chemical analyses of the samples it was found that a reduction in the copper (II) signal intensity in the glass samples as the proportion of alkaline earth metal is raised, corresponds to an increase in the reduced valency ratio, C, in the glasses.

Structure of a copper sodium phosphate glass by neutron scattering with isotopic substitution

The structure of a sodium copper phosphate glass containing approximately equimolar concentrations of CuO, Na 2O and P 2O 5 (0.3CuO·0.35Na 2O·0.35P 2O 5) was studied. From the total structure factor, the oxygen environment of P and Cu can be established. The first- and second-neighbour environment of Cu can be measured more accurately by taking first differences between the normalised scattering intensities for specimens containing 63Cu and 65Cu. The first-neighbour shell is found to be narrow with a mean radius of 0.2 nm - almost identical to the value found in similar crystals and with a coordination number of 4.0 (as in the crystal). Further oxygens are observed at about 0.25 nm, suggesting that the shell exhibits Jahn-Teller distortions, again as in the crystal, where two atoms are found at the longer distance. The CuCu distribution has been measured directly using second difference techniques. The CuCu signal is extremely weak - due to the low Cu concentration (about 7%) but a peak near 0.6 nm is observed. This corresponds to the mean distance calculated for a random dispersion of Cu atoms in the glass but the peak is so narrow that the Cu environment is clearly not random. In particular, it is possible that the Cu is ‘solvated’ by a shell of NaO polyhedra.

Oxidation–Reduction Equilibrium in Copper Phosphate Glass Melted in Air

Copper phosphate glasses with 40, 50, and 60 mol% CuO in batch were melted in air at 1000°, 1100°, and 1200°C using quartz or alumina crucibles, and the [Cu2+]/[Cutotal] ratio variations with melting time were measured. Glasses were oxidized during melting and reached equilibrium [Cu2+]/[Cutotal] ratios which were independent of melting temperature and identical for the 40 and 50 mol% CuO content glasses. Structural considerations seemed to have determined oxidation‐reduction equilibrium rather than an equilibrium redox reaction. Also, the effects of crucible type on the oxidation‐reduction balance were examined. It was found that a quartz crucible is more inert and has less effect on the oxidation‐reduction equilibrium of glass than an alumina crucible. Crucible contamination and phosphorus vaporization were found to diminish as the CuO content in the batch was increased.

Some structural, electrical and optical properties of copper phosphate glasses containing the rare-earth europium

Various properties of copper phosphate glass containing small amounts of the rare-earth europium have been investigated in the two glass systems Eu2O3-CuO-P2O5 and Eu2O3-CaO-CuO-P2O5. Density and molar volumes showed an increase as Eu2O3 replaced CuO and CaO in the glass compositions. Enhanced reduction from Cu2+ to Cu+ valency states of the ions in the glasses due to the presence of europium has been inferred from the results of electron spectroscopy for chemical analysis, and confirmed by results of electron spin resonance measurements. Corresponding electrical and optical band-gap characteristics, however, showed little systematic variation. The tetrahedral structure of P2O5 appeared to dominate the structural characteristics and infrared behaviour of the glass. The results are interpreted in terms of molecular structure, electronic configuration and small polaron hopping models. The role of europium in the glass is discussed.

Investigation of infrared absorption spectra of copper phosphate glasses containing some rare earth oxides

The spectra of copper-lutetium-phosphate and copper-erbium-phosphate glasses have been studied within the spectral range 4000 to 400 cm− by Fourier transform infrared spectroscopy. Incorporation of a small amount of lutetium or erbium influences some band positions compared with binary copper phosphate glasses. The additional bands in the range 491 to 576 cm−1 are attributed to the presence of Lu-O and Er-O groups. It has been observed that annealing of the samples at 500 ° C leads to a slight shift in the peak positions.