Concentrations Of Bi2O3 Research Articles

Gamma ray shielding characteristic of BiZnBo-SLS and PbZnBo-SLS glass

The radiation shielding and optical properties of x [RmOn] (0.5−x) [ZnO] 0.2 [B2O3] 0.3 [SLS], where RmOn are Bi2O3 and PbO with x = 0.05, 0.10, 0.20, 0.30, 0.40, and 0.45 have been prepared by using the melt-quenching method at 1200 °C and was investigated on their physical, structural and gamma ray shielding properties. Field-emission scanning electron microscope (FESEM) data revealed that the particle morphologies is aggregated and irregular in shapes and size. Energy dispersive x-ray spectroscopy (EDS) elemental mapping data confirmed that all mentioned element all present on the prepared glass. Soda Lime Silica (SLS) that is mainly composed of SiO2 has been utilized in this study as the source of SiO2 for fabrication of glass system. From the result, the density and molar volume of both glass samples increased as Bi2O3 and PbO content increased. The gamma ray shielding properties, such as linear attenuation and mass attenuation coefficient, were increased while half value layer (HVL) and mean free path (MFP) were decreased as the increased in Bi2O3 and PbO concentrations. It is recognized that the mass attenuation coefficient value of Bi2O3 and PbO glass are slightly different. From this study, it can be concluded that from the non-toxicity and shielding point of view, the bismuth glass is a good shield to gamma radiation as compared to lead glass.

Determination of gamma-ray shielding properties for silicate glasses containing Bi2O3, PbO, and BaO

The mass attenuation coefficients (μm), effective atomic cross section (σa), effective atomic number (Zeff) and effective electron density (Neff) of silicate glasses containing different concentrations of Bi2O3, PbO, and BaO (30–70% by weight) were obtained using MCNP-4C code, XCOM and XMuDat programs, in the energy range of 10 keV–10 MeV. The interpolation method was employed to extract Zeff and Neff. The Auto-Zeff software was used to determine the Zeff as well. The MCNP-4C Code, XCOM and XMuDat programs and Auto-Zeff results were in good agreement. It was found that the μm and σa values decrease with photon energy. Also the results indicate that σa and Zeff of glasses improve by increasing their Bi2O3, PbO and BaO contents, while increasing these contents to the same fraction has no significant effect on μm in the energy range of 0.3–5 MeV, where the Compton Effect takes over as dominant process and Neff do not follow certain rule. Above 0.1 MeV, lead oxide silicate glass showed the highest values of Zeff and σa. Wherever possible, the simulated and calculated values were compared with experimental data.

Synthesis and characterization of bismuth phosphate nanoparticle in glass matrix

Glasses having composition 5Li2O–5ZnO– xBi2O3 –(90 − x) P2O5 (x = 5, 10, 15, 20 and 25 mol%) were prepared by the normal melt quenching technique. Nanocomposite glass containing bismuth phosphate BiPO4 nanocrystals was obtained, which can be attributed to homogeneous nucleation process. The formation of BiPO4 nanocrystals was confirmed and characterized by X-ray diffraction patterns (XRD), transmission electron microscopy (TEM), differential scanning calorimetry, optical absorption (UV–Vis) and micro-hardness studies. The morphological analysis by XRD and TEM microscopy showed the formation of hexagonal BiPO4 nanocrystals, and its estimated nanocrystalline sizes were found to be varying from 5.35 to 11.53 nm depending on the Bi2O3 concentrations. The density (ρ) and molar volume (V m) were also determined and found to be in compositional dependence. Glass transition temperature (T g) and glass crystallization temperature (T c) were obtained and found to be increased (from 240.0 to 337.2 °C) with increasing Bi2O3 up to 20 mol% and then decreased (from 337.2 to 331.8 °C) due to the structural changes in the glass network. Effect of BiPO4 content on the optical properties had been investigated. From the UV–Vis spectra, it was observed that the fundamental absorption edge shifts toward lower wavelengths, i.e., blueshifts with increasing Bi2O3 mol% up to 20 mol%, and then shifts toward higher wavelengths, i.e., redshifts beyond 20 mol%. It was also observed that the obtained E opt (for indirect and direct transitions) increases with gradual increase in Bi2O3 content up to 20 mol% and then decreases beyond 20 mol%. This may be due to the introduction of Bi cations into the glass network as a network former up to 20 mol% causing a decrease in ΔE values, beyond 20 mol%, the introduction of Bi ions into the glass network interstitially leads to increase the values of ΔE. The optical properties of the present nanocrystallized glasses showed a quantum size dependence, in which the optical band gap energy (E opt) was changed as a function of BiPO4 nanocrystalline sizes.

Structural influence of Bi3 + ions on physical properties of Na2CuSiO4 glasses photoluminescence and thermoluminescence studies

CuO doped sodium silicate glasses mixed with different concentrations of Bi2O3 are synthesized. Photoluminescence, thermoluminescence characteristics have been investigated. Photoluminescence emission spectra exhibited a broad band in the bluish green region under excitation at 325nm. This band is attributed to 3D1→1S0transition of (Cu+)2 pairs. The intensity of this emission band is observed to increase with the concentration of Bi2O3 up to 20mol%. The increase is attributed to the increase in the concentration of Cu+ ions. Thermoluminescence (TL) emission exhibited a dosimetric peak at about 250°C. The TL output under this glow peak is observed to decrease with increase of γ–ray dose and also with the increase of Bi2O3 content. The mechanisms responsible for TL emission and the variation in TL output with the concentration of Bi2O3 are quantitatively discussed in terms of electron and hole centers developed due to interaction of γ–rays with the glass network.

Amplification of green emission of Ho3+ ions in lead silicate glasses by sensitizing with Bi3+ ions

This investigation is mainly devoted to the studies on enrichment of green emission of Ho3+ ions in PbOSiO2 glasses containing 1.0 mol% of Ho2O3 by co-doping with different concentrations of Bi2O3 (0–9.0 mol%). The optical absorption spectra, photoluminescence spectra, photoluminescence decay, IR and Raman spectral studies on the above mentioned glasses have been performed as a function of Bi2O3 concentration. The emission spectra of Bi2O3 free glasses exhibited green and red emissions due to 5S2 + 5F4 → 5I8 and 5F5 → 5I8transitions of Ho3+ ions, respectively, when excited at 450 nm. The spectra also exhibited NIR emission due to the5I7 → 5I8transition at 2.0 μm. The intensity of green emission is found to be significantly enhanced (nearly three times) when the glasses are mixed with 5.0 mol% of Bi2O3. The reason for this enhancement has been identified as being due to the energy transfer from Bi3+ to Ho3+ ions. The predominant participation of Bi3+ ions in modifying positions and due to the de-clustering of Ho3+ ions are found to be the other reasons. The overall enhancement of emission has further been explained with the help of rate equations. The quenching of luminescence emission observed in the glasses containing more than 5.0 mol% of Bi2O3 is attributed to the reason that in these glasses the Bi3+ ions largely participate in the network forming positions and increase the phonon losses. These arguments have been quantitatively explained with the help of IR and Raman spectral studies.

Effects of excess Bi2O3 on grain orientation and electrical properties of CaBi4Ti4O15 ceramics

A CaBi4Ti4O15 (CBTO) ceramic in which the Bi2O3 concentration was controlled from 0 to 10 wt% was fabricated using a solid-state reaction method. Structural analysis by field-emission scanning electron microscopy (FE-SEM) and X-ray diffraction (XRD) indicated differences in the preferred grain orientation and size of the plate-like grains according to the Bi2O3 concentration. The orientation of plate-like grains was also found to vary with the Bi2O3 concentration. There was no noticeable change trend of dielectric properties with different Bi2O3 concentrations. Relatively low dielectric constants (about 135) were exhibited by the CBTO ceramic with 1 wt% Bi2O3 and CBTO ceramic with 10 wt% Bi2O3 only, and similar values (about 150) were exhibited by the other ceramics. The dielectric loss exhibited a low value in the range of 0.01–0.09 for all samples (frequency range of 1–100 kHz). Regarding the ratio changes of the piezoelectric coefficient (d33) and the ratio of a-axis orientation of plate-like grains, the trends of these two values were shown to be similar. These results suggest that the addition of Bi2O3 greatly influences the microstructure of CBTO ceramics, including the grain size and orientation of plate-like grains. In particular, the change in the preferred grain orientation is closely related to the change in the piezoelectric properties.

Effect of coloration with various metal oxides on zirconia

The aim of this study was to evaluate the coloration of zirconia ceramic by adding three kinds of metal oxide. This was done with different concentrations of Fe2O3, CeO2, and Bi2O3 in tetragonal zirconia polycrystals stabilised with 3Y‐TZP powder compacted at 200 MPa using cold isostatic pressure and full sintering. X‐ray diffraction analysis was used to examine the structure of the shaded 3Y‐TZP. The chromaticity of sintered bodies was measured on a spectrophotometer. The coloration of zirconia by the three kinds of metal oxide was determined. With the addition of CeO2, the lightness of the zirconia was about 84–87, a* decreased slightly, and the colour shifted to a more yellow‐green hue. With an increasing content of Fe2O3, the chroma of the ceramic became more intense, the lightness decreased, and the colour changed to a red‐yellow hue. With an increasing concentration of Bi2O3, the colour of the materials shifted to a light saffron yellow. X‐ray diffraction spectra revealed only tetragonal phase. Results show that zirconia ceramic can be colourised using Fe2O3, CeO2, and Bi2O3.

Gamma radiation shielding and optical properties measurements of zinc bismuth borate glasses

In this work, the zinc bismuth borate (ZBB) glasses of the composition 10ZnO:xBi2O3:(90−x)B2O3 (where x=15, 20, 25 and 30mol%) were prepared by the melt quenching technique. Their radiation shielding and optical properties were investigated and compared with theoretical calculations. The mass attenuation coefficients of ZBB glasses have been measured at different energies obtained from a Compton scattering technique. The results show a decrease of the mass attenuation coefficient, effective atomic number and effective electron density values with increasing of gamma-ray energies; and good agreements between experimental and theoretical values. The glass samples with Bi2O3 concentrations higher than 25mol% (25 and 30mol%) were observed with lower mean free path (MFP) values than all the standard shielding concretes studied. These results are indications that the ZBB glasses in the present study may be developed as a lead-free radiation shielding material in the investigated energy range.

Influences of Bi2O3/V2O5 Additives on the Microstructure and Magnetic Properties of Lithium Ferrite

Lithium ferrite materials with different concentrations of Bi2O3 and V2O5 additives are prepared by the conventional ceramic technique. The x-ray diffraction analysis proves that the additives do not affect the final crystal phase of the lithium ferrite in our testing range. Both Bi2O3 and V2O5 additives could promote densification and lower sintering temperature of the lithium ferrite. The average grain size first increases, and then gradually decreases with the Bi2O3 content. The maximal grain size appears with 0.25 wt% Bi2O3. The average grain size first increases, and then is kept almost unchanged with the V2O5 content. The maximal average grain size of the samples with V2O5 additive is much smaller than that of the samples with Bi2O3 additive. Furthermore, the V2O5 additive more easily enters the crystal lattice of the lithium ferrite than the Bi2O3 additive. These characteristics evidently affect the magnetic properties, such as saturation flux density, ratio of remanence Br to saturation flux density Bs, and coercive force of the lithium ferrite. The mechanisms involved are discussed.

Magnetodielectric Ni ferrite ceramics with Bi2O3 additive for potential antenna miniaturizations

This paper reports on the preparation and characterization of nickel ferrite (NiFe1.98O4) ceramics doped with Bi2O3 as sintering aid. Focus has been on the effects of concentration of Bi2O3 and sintering temperature on the densification, grain growth, dielectric, and magnetic properties of the NiFe1.98O4 ceramics, with an aim at developing magnetodielectric properties, with almost equal real permeability and permittivity, as well as sufficiently low magnetic and dielectric loss tangents, over 3 to 30 MHz (high frequency or HF band). X-ray diffraction results indicated that there is no obvious reaction between NiFe1.98O4 and Bi2O3, at Bi2O3 levels of up to 7 wt% and temperatures up to 1150 °C. The addition of Bi2O3 facilitated a liquid phase sintering mechanism for the densification of NiFe1.98O4 ceramics. The addition of Bi2O3 not only improved the densification but also promoted the grain growth of NiFe1.98O4 ceramics. To achieve sufficiently low dielectric loss tangent, the concentration of Bi2O3 should not be less than 5 wt%. The low dielectric loss tangents of the samples doped with high concentrations of Bi2O3 can be attributed to the full densification of the ceramics. Magnetic properties of the NiFe1.98O4 ceramics, as a function of sintering temperature and Bi2O3 concentration, can be qualitatively explained by the Globus model. Promising magnetodielectric properties have been obtained in the sample doped with 5% Bi2O3 and sintered at 1050 °C for 2 h. The sample has almost equal values of permeability and permittivity of ∼12, together with low dielectric and magnetic loss tangents, over 3 to 30 MHz. This material might be useful for the miniaturization of HF (3 to 30 MHz) antennas.

Structural investigations of sodium diborate glasses containing PbO, Bi2O3 and TeO2: Elastic property measurements and spectroscopic studies

Pseudo-binary sodium borate glasses containing (1−y)Na2B4O7–yMaOb (where MaOb=PbO, Bi2O3 and TeO2) (y=0.25, 0.5, 0.67 and 0.79) have been investigated. Sound velocities (longitudinal and shear) have been measured at 10MHz frequency using quartz transducers. Density increases with increase of y and the molar volume decreases. Sound velocities also decrease with increasing y till y≈0.66 above which it increases slightly. Steeper decrease in velocities has been observed in TeO2 containing glasses. Elastic moduli, Poisson’s ratio and Debye temperature have been calculated. Glass transition temperatures have also been determined and it decreases with increase of y. Tg also exhibits a dependence on the cationic charge in MaOb. Infrared spectra of the glasses reveal that the strong network consisting of diborate units is affected only by PbO and only very marginally by Bi2O3 and TeO2. Only glasses with high concentrations of Bi2O3 and TeO2 reveal the presence of mixed bridges such as Bi–O–B and Te–O–B. Consistent with the IR spectral observations, the N4 values of 11B MAS-NMR remain close to the ideal value of 0.5 of the diborate composition in most of the glasses. A structural model based on the observation that the diborate network is unaffected by Bi2O3 and TeO2 where as PbO opens up and breaks the diborate units is shown to be consistent with all of the experimental observations including mechanical properties.

Ni-Cu-Zn Ferrites for low temperature firing: II. Effects of powder morphology and Bi2O3 addition on microstructure and permeability

The morphology of Ni-Cu-Zn ferrite powders obtained by milling of a calcined raw materials mixture strongly effects the densification behavior during sintering at 900∘C. In order to obtain dense samples sub-micron powders with enhanced reactivity are required. The addition of Bi2O3 as sintering additive is beneficial: the density of samples sintered at 900∘C increases with the bismuth oxide concentration up to 0.75 wt.%. The process of liquid phase sintering was studied by dilatometry. The grain size of the sintered samples slightly increases for 0.25 wt.% Bi2O3 compared to bismuth-free samples, whereas for 0.3–0.5 wt.% Bi2O3 additions bimodal grain growth is observed with a significant fraction of very large grains. For > 0.5 wt.% Bi2O3 a homogeneous coarse-grained microstructure is obtained. The permeability increases for small bismuth oxide additions, but decreases for a Bi-oxide content of more than 0.5%. Maximum permeability of μi = 900 is observed for intermediate Bi2O3 concentrations.

Dielectric dispersion in ZnF2-Bi2O3-TeO2 glass system

Dielectric constant ɛ′, loss tan δ and ac conductivity σ of ZnF2-Bi2O3-TeO2 glasses with varying concentrations of Bi2O3 (from 5 to 20%) are studied as a function of frequency and temperature over moderately wide ranges. The dielectric breakdown strength for these glasses is also determined in air medium. From the analysis of these studies along with the IR spectra & DTA recordings of these glasses, the structural changes in ZnF2-Bi2O3-TeO2 glass system with change in the concentration of Bi2O3, are discussed.

Third-order optical nonlinearities and their ultrafast response in Bi_2O_3–B_2O_3–SiO_2 glasses

Nonresonant-type homogeneous Bi2O3–B2O3–SiO2 glasses were prepared by melting. The third-order optical nonlinear susceptibility χ(3), which was determined by measurement of third-harmonic generation, increased with increasing concentrations of Bi2O3 in the glass. The maximum χ(3) estimated was 9.3×10-12 esu in glass that contained 92 wt. % of Bi2O3.χ(3) values of these glasses were enhanced by the small optical bandgap. These glasses also exhibited an ultrafast response time, less than 200 fs, when a degenerate four-wave mixing method with a femtosecond laser was used, indicating that the nonlinearity of these glasses originated mainly from pure electronic polarization.

Origin of Solid‐State Activated Sintering in Bi2O3‐Doped ZnO

Activated sintering in Bi2O3‐doped ZnO has been studied with emphasis on the mechanistic role of intergranular amorphous films. The atomic‐level microstructures and bismuth solute distributions in doped powders have been investigated using high‐resolution electron microscopy and scanning transmission electron microscopy. Densification is observed to be significant below the bulk eutectic temperature in the presence of Bi2O3 concentrations as low as 0.58 mol%. Transmission electron microscopy of as‐calcined and sintered powders shows that significant neck growth and particle coarsening occur in the solid state. Intergranular amorphous films of ∼1 nm thickness, terminating in wetting menisci at sinter‐necks, are observed to form concurrently with the onset of activated sintering. In a few instances, amorphous films are also observed at surfaces of the ZnO particles. These films appear to be the free‐surface counterpart to equilibrium‐thickness intergranular films. Activated sintering in this binary system is attributed to rapid mass transport through subeutectic, equilibrium‐thickness intergranular films, with the amorphous phase also providing capillary pressure.

Influence of the Addition of Bi2O3 on the Grain Growth and Magnetic Permeability of MnZn Ferrites

Additions of Bi2O3 were used to promote grain growth and to increase magnetic permeability during sintering of MnZn ferrites. The results showed that small additions of Bi2O3 of <0.05 wt% remarkably increase the permeability of MnZn ferrites. On the other hand, addition of 0.05 wt% Bi2O3 induced the formation of a microstructure composed of giant grains with trapped pores embedded in a normal microstructure. The permeability of these samples showed a pronounced secondary maximum in permeability. At still higher Bi2O3 concentrations, above 0.2 wt%, the grain growth was retarded and a normal microstructure appeared; however, the magnetic permeability was strongly reduced.

Particle size dependence of rotational responses in Ni–Zn ferrite

Active powders of Ni–Zn ferrite were synthesized by soft chemical approaches and were processed with varying concentrations of Bi2O3. The sintered products were characterized extensively using a vibrating sample magnetometer, scanning electron microscopy, and resistivity techniques. The loss factor and the permeability have been evaluated. At an optimum concentration of Bi2O3 doping the loss factor has been reduced by 20%. The rotational responses are found to be strongly dependent on particle size.

Effect of impurities on sintering and conductivity of yttria-stabilized zirconia

The effect of low concentrations of Fe2O3, Al2O3 and Bi2O3 on the sintering behaviour of (ZrO2)0.83 (YO1.5)0.17, made by alkoxide synthesis, has been investigated. The best results are achieved with Bi2O3 as a sinter agent and a relative density of 95% is obtained at 1200 K. The effects of these impurities on the electrical conductivity of the bulk and the grain boundaries has been investigated using frequency dispersion analysis (101-106 Hz). All investigated impurities have a negative influence on both the bulk and grain-boundary conductivity. For Fe2O3 and Al2O3 grain-boundary segregation factors of about two are calculated.