A new type of modified bismuth silicate glass has been manufactured with vanadium and copper cati... more A new type of modified bismuth silicate glass has been manufactured with vanadium and copper cations in a traditional rapid cooling method. FTIR spectra have been used to identify the different structural units of this glass. The spectral analysis showed the presence of BiO 3 and BiO 6 as basic structural units in all studied samples and the presence of bismuth as a former the glass network with silica. The radiation shielding properties were explored using a narrow beam transmission method in 0.662, 1.173 and 1.33 MeV. The effective atomic numbers for the sample containing the highest CuO ratio showed higher energy values than the other studied samples studied. The mean free path of the prepared glasses has been compared to other commercial radiation shielding. The comparison indicates that the glasses produced are more efficient in relation to radiotherapy compared to conventional commercial radiation protection glass. Microhardness measurements were made of the glass recorded at load at 300 g. The replacement of CuO by V 2 O 5 has been found to increase the cross-link density in addition to the observed difference in the atomic mass of Cu and V, thus increasing the hardness.
Samples of pure poly(methyl methacrylate) (PMMA) and PMMA enhanced with metal complexes of Zn, Cd... more Samples of pure poly(methyl methacrylate) (PMMA) and PMMA enhanced with metal complexes of Zn, Cd, and Hg were synthesized via catalytic chain transfer polymerization. Structural analysis, by means of XRD, showed the amorphous nature of the studied samples which meant high homogenous dissolution of the metals (Zn, Cd and Hg) into the polymer matrix. Density values increased linearly with respect to atomic radius of the incorporated metals. Addition of such elements causes an increase in mass attenuation coefficients and a remarkable decrease in the Half Value Layer (HVL) values, in comparison to existing standard shielding materials. Thermal studies by DSC indicated highly homogenous internal structure of the studied samples, with slight decrease in the Tg value when introducing metals due to heterogeneous nucleation agent role of the Cd, Zn and Hg. All observations and results suggest the studied materials to be used as promising and proper aprons for medical radiation shielding ap...
Boro-phosphate oxide glass system doped with iron ions have been prepared by the conventional mel... more Boro-phosphate oxide glass system doped with iron ions have been prepared by the conventional melting quenching technique, all mixtures are in an agreement with the following chemical formula (25-x) mol% Na2O. x mol% NaCl.15 mol% FeO. 30 mol% B2O3. 30 mole% P2O5, where x = 0.0, 05, 10, 15, 20 and 25. Sample of x= 0, only, has been exposed to different doses of gamma rays (0.0, 05, 10 and 20 kGy). Mossbauer Effect ME spectroscopy have been carried out at RT for all irradiated {x =0.0} and for non-irradiated {x> 0.0} samples. ME parameters showed all samples in good glassy state. Also ME parameters showed the iron ions in two different coordination states, where all Fe2+ ions and some of Fe3+ ions shared the octahedral coordination states, while the tetrahedral coordination states occupied only by Fe3+ ions. It was observed that both the gamma irradiation process and the process of replacement Na2O by NaCl caused the Fe2+ ions to oxidize to Fe3+ ions.
Silver oxide was introduced, by weight addition, to the chemical mixtures of some calcium bismuth... more Silver oxide was introduced, by weight addition, to the chemical mixtures of some calcium bismuth niobium Borate glasses. The following formula was considered for preparation series of five samples (100-x) wt% [0.6 mol B2O3 – 0.2 mol CaO – 1.75 mol Bi2O3 – 0.25 mol Nb2O5] – x wt% Ag2O, where x = 0, 1, 2, 3 and 4 wt%. For characterization process some spectra like XRD, DSC and UV-Vis have been used. Where both Xray and DSC measurements indicated the amorphous state formation, for all compositions. UV-vis spectra exhibited two indirect (γ=1/2) and direct (γ=2) electronic transitions, for each sample. For direct transitions, the optical band gap was perturbed by the addition of Ag + cations. Keyword: XRD, DSC, UV-Vis., Borate Glass, Optical Properties -------------------------------------------------------------------------------------------------------------------------------------Date of Submission: 11-05-2018 Date of acceptance: 26-05-2018 -------------------------------------------...
Boletín de la Sociedad Española de Cerámica y Vidrio, 2020
b o l e t í n d e l a s o c i e d a d e s p a ñ o l a d e c e r á m i c a y v i d r i o x x x (2 ... more b o l e t í n d e l a s o c i e d a d e s p a ñ o l a d e c e r á m i c a y v i d r i o x x x (2 0 2 0) xxx-xxx muestras a granel. El análisis XRD confirmó la naturaleza amorfa de las películas delgadas estudiadas. La inclusión de indio en la matriz de vidrio contribuyó a elevar el índice de refracción y mostró una amplia ventana de transmisión en las regiones de espectro visible e IR-cercano. Los parámetros ópticos lineales y no lineales se calculan y analizan en términos de la composición del vidrio. Los resultados del índice de refracción, las susceptibilidades de primer y tercer orden nominan las películas delgadas estudiadas para aplicaciones en guías ópticas y sensores de ondas IR.
Some bismuth-borate oxide glass' samples were prepared by the fast quenching method, where B2... more Some bismuth-borate oxide glass' samples were prepared by the fast quenching method, where B2O3 was replaced with equal concentrations of ZnO and CaO. X-ray diffraction (XRD) was used to examine the internal structure and Fourier transform infrared (FTIR) to identify building units and bonds throughout the studied structural matrices. XRD showed that all samples have short range order structural nature, while FTIR demonstrated some of Zn2+ acted as glass network formers and all Bi3+ acted as glass. UV-visible measurements and calculations showed a decreasing in the energy band gap from 3.83 eV to 1.73 eV with decreasing B2O3 content. Also with decreasing B2O3 content, both real refractive index and metallization factor decreased from 3.1 to 1.9 and from 0.56 to 0.71, respectively. For the studied glass' samples, density and molar volume showed inverted behaviors, where the density decreased while the molar volume increases with decreasing B2O3.
Some bismuth borate glasses containing an equal concentration of both ZnO and CaO were prepared u... more Some bismuth borate glasses containing an equal concentration of both ZnO and CaO were prepared using the fast cooling method, in the air. X-ray diffraction and Fourier transform infrared techniques were used to characterize these glasses. All samples showed amorphous natures, with short-range order networks. Introducing of both ZnO and CaO caused BO 4 groups to convert to BO 3 with an observable decreasing in the molar volume. Linear refractive index decreased with increasing the wavelength of the incident light, while the nonlinear refractive index increased. Linear and nonlinear susceptibilities decreased with introducing ZnO and CaO.
International Journal of High Energy Physics, 2017
In an attempt to check the effect of the transition metal ions on the glass network, the followin... more In an attempt to check the effect of the transition metal ions on the glass network, the following chemical formula was used to prepare some of Iron sodium phosphate glasses doped with different transition metal (TM) ions. 50 mol% P 2 O 5 + 20 mol% Na 2 O + 15 mol% Fe 2 O 3 + 15 mol% M n O m , where M n O m represents V 2 O 5 , MnO, Co 3 O 4 , CuO and ZnO. Mossbauer Effect (ME) spectroscopic analysis showed that, the iron ions are located in two different oxidation states Fe 3+ and Fe 2+. A fraction of Fe 3+ ions act as glass network formers (GNFs), whereas the other in addition to all Fe 2+ ions act as glass network modifiers (GNMs). The electrical properties for all samples have been measured and then studied as a function of the TMIs atomic number. The D.C. conductivity showed a gradual decreasing with increasing the atomic number of TMIs, while the A.C. conductivity has a similar behavior as predicted by CBH model.
Boro-phosphate oxide glass system doped with iron ions have been prepared by the conventional mel... more Boro-phosphate oxide glass system doped with iron ions have been prepared by the conventional melting quenching technique, all mixtures are in an agreement with the following chemical formula (25-x) mol% Na 2 O. x mol% NaCl.15 mol% FeO. 30 mol% B 2 O 3. 30 mole% P 2 O 5 , where x = 0.0, 05, 10, 15, 20 and 25. Sample of x= 0, only, has been exposed to different doses of gamma rays (0.0, 05, 10 and 20 kGy). Mossbauer Effect ME spectroscopy have been carried out at RT for all irradiated {x =0.0} and for non-irradiated {x> 0.0} samples. ME parameters showed all samples in good glassy state. Also ME parameters showed the iron ions in two different coordination states, where all Fe 2+ ions and some of Fe 3+ ions shared the octahedral coordination states, while the tetrahedral coordination states occupied only by Fe 3+ ions. It was observed that both the gamma irradiation process and the process of replacement Na 2 O by NaCl caused the Fe 2+ ions to oxidize to Fe 3+ ions.
International Journal of Structural Glass and Advanced Materials Research, 2019
Samples of calcium borate glasses containing iron ions have been prepared with three different co... more Samples of calcium borate glasses containing iron ions have been prepared with three different concentrations of both boron and iron oxides. X-ray diffraction spectroscopy was performed and results revealed that samples are in good glassy state, with high homogeneity and short range ordered structure. Electrical conductivity was experimentally measured in the temperature range from 300 to 553 K. Conductivity results have been studied as a function of the static dielectric constant (ε) and the charge carrier's relaxation time (τ). The results were modeled by means of an empirical formula that fits the experimental data as a function of both the static dielectric constant and the electric activation energy ∆Ε; in addition to the exponent factor s. Total measured conductivity modeled using the proposed empirical formula fits neatly the correlated barrier hopping model.
International Journal of Structural Glass and Advanced Materials Research, 2019
Glasses with the chemical compositions 60% B 2 O 3-20% Na 2 O-(20−x) % Bi 2 O 3-x% Nb 2 O 5 (wher... more Glasses with the chemical compositions 60% B 2 O 3-20% Na 2 O-(20−x) % Bi 2 O 3-x% Nb 2 O 5 (where, x = 0, 5, 10 and 15 mol. %), were prepared by fast quenching of their melts. Characteristics of the obtained solids were checked by XRD, FTIR and optical absorption spectroscopy. XRD data confirmed the amorphous nature of the glass samples. FTIR results revealed no changes in the ratio of the structural units BO 3 :BO 4 when replacing Bi 2 O 3 by Nb 2 O 5. Moreover, both Bi 3+ and Nb 5+ cations occupied octahedral coordination states and both acted as glass network modifiers. Optical studies affirmed that the lowest value of both direct and indirect optical band gaps was obtained in samples with equal concentration of Nb 2 O 5 and Bi 2 O 3. All optical absorption bands were elucidated in terms of the terminal oxygen atoms around Nb 5+ and/or Bi 3+ cations. The optical nonlinearity of the glass samples was assessed in terms of absorption coefficient and the value of the optical band gap.
Series of five samples, named calcium bismuth niobium Borate glasses, were prepared by quenching ... more Series of five samples, named calcium bismuth niobium Borate glasses, were prepared by quenching their melts. The batches of all samples formed according to the chemical formula 60 mol% B 2 O 3-20 mol% CaO-20 mol% Bi 2 O 3-(20 − x) Nb 2 O 5 mol%, where x = 0, 2.5, 5, 7.5 and 10 1 mol%. XRD, FTIR and UV-vis. Were used to characterize the internal structure of these glasses. Both XRD and FTIR showed the amorphous character for all samples. FTIR showed that all Nb 5+ ions occupied some interstitial vacancies, as a glass network modifiers (GNM), while some of Bi 3+ ions share in the glass matrix, as a glass network formers (GNF) and some other occupied some other interstitial vacancies (GNM). The BO 4 was found to increase by replacing Bi 2 O 3 by Nb 2 O 5 , in other word, increase of the non-bridging oxygen atoms. For all samples, UV-vis. exhibited two indirect (γ = 1/2) and direct (γ = 2) electronic transitions. Both the optical band gap and refractive index for direct transition case were found to have slightly increase as x increase. The density of the studied samples was found to be inversely proportional to their molar volume.
Background: Multiple sclerosis (MS) can occur in pediatric age group with prevalence rates rangin... more Background: Multiple sclerosis (MS) can occur in pediatric age group with prevalence rates ranging from 2.2%-4.4% of all MS cases. This research conducted to compare adult multiple sclerosis with pediatric multiple sclerosis clinically and radiologically and to assess similarities and differences between them. Methods: 30 MS patients divided into 2 groups (Group A aged 18 years or more at first presentation, group B less than 18 years) underwent detailed history taking, general , neurological examination, MRI brain for location and number of lesions and disability assessment using Expanded Disability Status Scale. Results: No significant difference between the two groups as regard duration of first attack, frequency between monosymptomatic to polysymptomatic and complete to partial to no improvement from first attack and percentage of frequency of each of all MRI locations. Conclusion: Pediatric and adult MS are similar as regard presentation ,progression and localization.
Background In recent years, the preparation of transparent glass in the visible region has led to... more Background In recent years, the preparation of transparent glass in the visible region has led to the development of radiation shielding materials with measuring structure and optical properties. Also, the study on the interaction of neutron radiation with matter is important in the field of radiation protection. Purpose Preparation of transparent calcium and bismuth borate oxide glasses containing Nb 5+ ions can be used as a neutron radiation shield and determine refractive index with different methods for this glass. Methods Niobium bismuth borate glasses with composition 60B 2 O 3-20CaO-(20 − x)Bi 2 O 3-xNb 2 O 5 , where (x is in mol%, 0 ≤ x ≤ 10), have been prepared using conventional melt-quenching technique; the structure of each sample was studied by XRD, FTIR, and UV spectra chart analysis. Results XRD and FTIR showed that all glass samples were highly homogeneous and had structured with short-rangeorder/amorphous solids. The refractive index of each sample was estimated by charts of UV-Vis and FTIR, in addition to an empirical method, and we obtained values very close to each other. The refractive index values are relatively high, so this glass can be used in nonlinear studies as well as luminescence characterization. The macroscopic fast neutron removal cross sections (R/ρ) have calculated, for all samples, and the highest value was in sample containing 2.5% niobium pentoxide. Conclusion Bismuth borate glass containing a few niobium pentoxide can be used as a protective shield of neutrons.
American Journal of Materials Synthesis and Processing, 2017
This paper is a simple idea aims to how to get an imagination about the variation of glass refrac... more This paper is a simple idea aims to how to get an imagination about the variation of glass refractive index with its internal structure. In the present work an empirical equation for the refractive index of a glass sample has been achieved as function of both the glass molar Volume and the glass electronegativity. Like this equation, may be used to determine and estimate the refractive index value of an inorganic oxide glass sample, if its density measured with high accuracy.
In an attempt to take advantage of industrial wastes, Iron slag was used to prepare some of glass... more In an attempt to take advantage of industrial wastes, Iron slag was used to prepare some of glass samples in an attempt to re-use. The following chemical formula has considered in the preparation process. (25 + x) % slag + (75-x) % (Na 2 B 4 O 7 .10H 2 O), where x has varied among different values. The rapid quenching method has used to prepare the glass samples, of thier molten components at 1200°C. When x > 45 had not be obtained any glasses, in the conditions of preparation. Both FTIR and XRD showed that each sample contains x ≤ 45 had formed perfect glass state. Density and molar volume showed that the glass structure became more open with increasing concentration of the slag.
Glasses of (B 2 O 3) 0.6 (CaO) 0.2 (Bi 2 O 3) (0.2−x) (Nb 2 O 5) x were prepared utilizing a fast... more Glasses of (B 2 O 3) 0.6 (CaO) 0.2 (Bi 2 O 3) (0.2−x) (Nb 2 O 5) x were prepared utilizing a fast cooling method (where x = 0.0, 0.05 and 0.10). Fourier-transform infrared spectra FTIR revealed about shapes that characterize the amorphous solids, where broad overlapping bands were observed. Incorporation of niobium pent-oxide Nb 2 O 5 in the glass matrix caused BO 3 to BO 4 , an increasing glasses' molar volume and decreasing in glasses' opacity. Some linear and nonlinear optical parameters had been explored by means of UV-visible spectra within 200-845 nm wavelength range. The absorption coefficients, Urbach energy, direct and indirect optical band gaps increased with an increase in the niobium pent-oxide concentration, and the real linear refractive index decreased. On the other side, nonlinear refractive index, first linear and third nonlinear susceptibilities were observed to increase with increase in niobium pent-oxide.
A new type of modified bismuth silicate glass has been manufactured with vanadium and copper cati... more A new type of modified bismuth silicate glass has been manufactured with vanadium and copper cations in a traditional rapid cooling method. FTIR spectra have been used to identify the different structural units of this glass. The spectral analysis showed the presence of BiO 3 and BiO 6 as basic structural units in all studied samples and the presence of bismuth as a former the glass network with silica. The radiation shielding properties were explored using a narrow beam transmission method in 0.662, 1.173 and 1.33 MeV. The effective atomic numbers for the sample containing the highest CuO ratio showed higher energy values than the other studied samples studied. The mean free path of the prepared glasses has been compared to other commercial radiation shielding. The comparison indicates that the glasses produced are more efficient in relation to radiotherapy compared to conventional commercial radiation protection glass. Microhardness measurements were made of the glass recorded at load at 300 g. The replacement of CuO by V 2 O 5 has been found to increase the cross-link density in addition to the observed difference in the atomic mass of Cu and V, thus increasing the hardness.
Samples of pure poly(methyl methacrylate) (PMMA) and PMMA enhanced with metal complexes of Zn, Cd... more Samples of pure poly(methyl methacrylate) (PMMA) and PMMA enhanced with metal complexes of Zn, Cd, and Hg were synthesized via catalytic chain transfer polymerization. Structural analysis, by means of XRD, showed the amorphous nature of the studied samples which meant high homogenous dissolution of the metals (Zn, Cd and Hg) into the polymer matrix. Density values increased linearly with respect to atomic radius of the incorporated metals. Addition of such elements causes an increase in mass attenuation coefficients and a remarkable decrease in the Half Value Layer (HVL) values, in comparison to existing standard shielding materials. Thermal studies by DSC indicated highly homogenous internal structure of the studied samples, with slight decrease in the Tg value when introducing metals due to heterogeneous nucleation agent role of the Cd, Zn and Hg. All observations and results suggest the studied materials to be used as promising and proper aprons for medical radiation shielding ap...
Boro-phosphate oxide glass system doped with iron ions have been prepared by the conventional mel... more Boro-phosphate oxide glass system doped with iron ions have been prepared by the conventional melting quenching technique, all mixtures are in an agreement with the following chemical formula (25-x) mol% Na2O. x mol% NaCl.15 mol% FeO. 30 mol% B2O3. 30 mole% P2O5, where x = 0.0, 05, 10, 15, 20 and 25. Sample of x= 0, only, has been exposed to different doses of gamma rays (0.0, 05, 10 and 20 kGy). Mossbauer Effect ME spectroscopy have been carried out at RT for all irradiated {x =0.0} and for non-irradiated {x> 0.0} samples. ME parameters showed all samples in good glassy state. Also ME parameters showed the iron ions in two different coordination states, where all Fe2+ ions and some of Fe3+ ions shared the octahedral coordination states, while the tetrahedral coordination states occupied only by Fe3+ ions. It was observed that both the gamma irradiation process and the process of replacement Na2O by NaCl caused the Fe2+ ions to oxidize to Fe3+ ions.
Silver oxide was introduced, by weight addition, to the chemical mixtures of some calcium bismuth... more Silver oxide was introduced, by weight addition, to the chemical mixtures of some calcium bismuth niobium Borate glasses. The following formula was considered for preparation series of five samples (100-x) wt% [0.6 mol B2O3 – 0.2 mol CaO – 1.75 mol Bi2O3 – 0.25 mol Nb2O5] – x wt% Ag2O, where x = 0, 1, 2, 3 and 4 wt%. For characterization process some spectra like XRD, DSC and UV-Vis have been used. Where both Xray and DSC measurements indicated the amorphous state formation, for all compositions. UV-vis spectra exhibited two indirect (γ=1/2) and direct (γ=2) electronic transitions, for each sample. For direct transitions, the optical band gap was perturbed by the addition of Ag + cations. Keyword: XRD, DSC, UV-Vis., Borate Glass, Optical Properties -------------------------------------------------------------------------------------------------------------------------------------Date of Submission: 11-05-2018 Date of acceptance: 26-05-2018 -------------------------------------------...
Boletín de la Sociedad Española de Cerámica y Vidrio, 2020
b o l e t í n d e l a s o c i e d a d e s p a ñ o l a d e c e r á m i c a y v i d r i o x x x (2 ... more b o l e t í n d e l a s o c i e d a d e s p a ñ o l a d e c e r á m i c a y v i d r i o x x x (2 0 2 0) xxx-xxx muestras a granel. El análisis XRD confirmó la naturaleza amorfa de las películas delgadas estudiadas. La inclusión de indio en la matriz de vidrio contribuyó a elevar el índice de refracción y mostró una amplia ventana de transmisión en las regiones de espectro visible e IR-cercano. Los parámetros ópticos lineales y no lineales se calculan y analizan en términos de la composición del vidrio. Los resultados del índice de refracción, las susceptibilidades de primer y tercer orden nominan las películas delgadas estudiadas para aplicaciones en guías ópticas y sensores de ondas IR.
Some bismuth-borate oxide glass' samples were prepared by the fast quenching method, where B2... more Some bismuth-borate oxide glass' samples were prepared by the fast quenching method, where B2O3 was replaced with equal concentrations of ZnO and CaO. X-ray diffraction (XRD) was used to examine the internal structure and Fourier transform infrared (FTIR) to identify building units and bonds throughout the studied structural matrices. XRD showed that all samples have short range order structural nature, while FTIR demonstrated some of Zn2+ acted as glass network formers and all Bi3+ acted as glass. UV-visible measurements and calculations showed a decreasing in the energy band gap from 3.83 eV to 1.73 eV with decreasing B2O3 content. Also with decreasing B2O3 content, both real refractive index and metallization factor decreased from 3.1 to 1.9 and from 0.56 to 0.71, respectively. For the studied glass' samples, density and molar volume showed inverted behaviors, where the density decreased while the molar volume increases with decreasing B2O3.
Some bismuth borate glasses containing an equal concentration of both ZnO and CaO were prepared u... more Some bismuth borate glasses containing an equal concentration of both ZnO and CaO were prepared using the fast cooling method, in the air. X-ray diffraction and Fourier transform infrared techniques were used to characterize these glasses. All samples showed amorphous natures, with short-range order networks. Introducing of both ZnO and CaO caused BO 4 groups to convert to BO 3 with an observable decreasing in the molar volume. Linear refractive index decreased with increasing the wavelength of the incident light, while the nonlinear refractive index increased. Linear and nonlinear susceptibilities decreased with introducing ZnO and CaO.
International Journal of High Energy Physics, 2017
In an attempt to check the effect of the transition metal ions on the glass network, the followin... more In an attempt to check the effect of the transition metal ions on the glass network, the following chemical formula was used to prepare some of Iron sodium phosphate glasses doped with different transition metal (TM) ions. 50 mol% P 2 O 5 + 20 mol% Na 2 O + 15 mol% Fe 2 O 3 + 15 mol% M n O m , where M n O m represents V 2 O 5 , MnO, Co 3 O 4 , CuO and ZnO. Mossbauer Effect (ME) spectroscopic analysis showed that, the iron ions are located in two different oxidation states Fe 3+ and Fe 2+. A fraction of Fe 3+ ions act as glass network formers (GNFs), whereas the other in addition to all Fe 2+ ions act as glass network modifiers (GNMs). The electrical properties for all samples have been measured and then studied as a function of the TMIs atomic number. The D.C. conductivity showed a gradual decreasing with increasing the atomic number of TMIs, while the A.C. conductivity has a similar behavior as predicted by CBH model.
Boro-phosphate oxide glass system doped with iron ions have been prepared by the conventional mel... more Boro-phosphate oxide glass system doped with iron ions have been prepared by the conventional melting quenching technique, all mixtures are in an agreement with the following chemical formula (25-x) mol% Na 2 O. x mol% NaCl.15 mol% FeO. 30 mol% B 2 O 3. 30 mole% P 2 O 5 , where x = 0.0, 05, 10, 15, 20 and 25. Sample of x= 0, only, has been exposed to different doses of gamma rays (0.0, 05, 10 and 20 kGy). Mossbauer Effect ME spectroscopy have been carried out at RT for all irradiated {x =0.0} and for non-irradiated {x> 0.0} samples. ME parameters showed all samples in good glassy state. Also ME parameters showed the iron ions in two different coordination states, where all Fe 2+ ions and some of Fe 3+ ions shared the octahedral coordination states, while the tetrahedral coordination states occupied only by Fe 3+ ions. It was observed that both the gamma irradiation process and the process of replacement Na 2 O by NaCl caused the Fe 2+ ions to oxidize to Fe 3+ ions.
International Journal of Structural Glass and Advanced Materials Research, 2019
Samples of calcium borate glasses containing iron ions have been prepared with three different co... more Samples of calcium borate glasses containing iron ions have been prepared with three different concentrations of both boron and iron oxides. X-ray diffraction spectroscopy was performed and results revealed that samples are in good glassy state, with high homogeneity and short range ordered structure. Electrical conductivity was experimentally measured in the temperature range from 300 to 553 K. Conductivity results have been studied as a function of the static dielectric constant (ε) and the charge carrier's relaxation time (τ). The results were modeled by means of an empirical formula that fits the experimental data as a function of both the static dielectric constant and the electric activation energy ∆Ε; in addition to the exponent factor s. Total measured conductivity modeled using the proposed empirical formula fits neatly the correlated barrier hopping model.
International Journal of Structural Glass and Advanced Materials Research, 2019
Glasses with the chemical compositions 60% B 2 O 3-20% Na 2 O-(20−x) % Bi 2 O 3-x% Nb 2 O 5 (wher... more Glasses with the chemical compositions 60% B 2 O 3-20% Na 2 O-(20−x) % Bi 2 O 3-x% Nb 2 O 5 (where, x = 0, 5, 10 and 15 mol. %), were prepared by fast quenching of their melts. Characteristics of the obtained solids were checked by XRD, FTIR and optical absorption spectroscopy. XRD data confirmed the amorphous nature of the glass samples. FTIR results revealed no changes in the ratio of the structural units BO 3 :BO 4 when replacing Bi 2 O 3 by Nb 2 O 5. Moreover, both Bi 3+ and Nb 5+ cations occupied octahedral coordination states and both acted as glass network modifiers. Optical studies affirmed that the lowest value of both direct and indirect optical band gaps was obtained in samples with equal concentration of Nb 2 O 5 and Bi 2 O 3. All optical absorption bands were elucidated in terms of the terminal oxygen atoms around Nb 5+ and/or Bi 3+ cations. The optical nonlinearity of the glass samples was assessed in terms of absorption coefficient and the value of the optical band gap.
Series of five samples, named calcium bismuth niobium Borate glasses, were prepared by quenching ... more Series of five samples, named calcium bismuth niobium Borate glasses, were prepared by quenching their melts. The batches of all samples formed according to the chemical formula 60 mol% B 2 O 3-20 mol% CaO-20 mol% Bi 2 O 3-(20 − x) Nb 2 O 5 mol%, where x = 0, 2.5, 5, 7.5 and 10 1 mol%. XRD, FTIR and UV-vis. Were used to characterize the internal structure of these glasses. Both XRD and FTIR showed the amorphous character for all samples. FTIR showed that all Nb 5+ ions occupied some interstitial vacancies, as a glass network modifiers (GNM), while some of Bi 3+ ions share in the glass matrix, as a glass network formers (GNF) and some other occupied some other interstitial vacancies (GNM). The BO 4 was found to increase by replacing Bi 2 O 3 by Nb 2 O 5 , in other word, increase of the non-bridging oxygen atoms. For all samples, UV-vis. exhibited two indirect (γ = 1/2) and direct (γ = 2) electronic transitions. Both the optical band gap and refractive index for direct transition case were found to have slightly increase as x increase. The density of the studied samples was found to be inversely proportional to their molar volume.
Background: Multiple sclerosis (MS) can occur in pediatric age group with prevalence rates rangin... more Background: Multiple sclerosis (MS) can occur in pediatric age group with prevalence rates ranging from 2.2%-4.4% of all MS cases. This research conducted to compare adult multiple sclerosis with pediatric multiple sclerosis clinically and radiologically and to assess similarities and differences between them. Methods: 30 MS patients divided into 2 groups (Group A aged 18 years or more at first presentation, group B less than 18 years) underwent detailed history taking, general , neurological examination, MRI brain for location and number of lesions and disability assessment using Expanded Disability Status Scale. Results: No significant difference between the two groups as regard duration of first attack, frequency between monosymptomatic to polysymptomatic and complete to partial to no improvement from first attack and percentage of frequency of each of all MRI locations. Conclusion: Pediatric and adult MS are similar as regard presentation ,progression and localization.
Background In recent years, the preparation of transparent glass in the visible region has led to... more Background In recent years, the preparation of transparent glass in the visible region has led to the development of radiation shielding materials with measuring structure and optical properties. Also, the study on the interaction of neutron radiation with matter is important in the field of radiation protection. Purpose Preparation of transparent calcium and bismuth borate oxide glasses containing Nb 5+ ions can be used as a neutron radiation shield and determine refractive index with different methods for this glass. Methods Niobium bismuth borate glasses with composition 60B 2 O 3-20CaO-(20 − x)Bi 2 O 3-xNb 2 O 5 , where (x is in mol%, 0 ≤ x ≤ 10), have been prepared using conventional melt-quenching technique; the structure of each sample was studied by XRD, FTIR, and UV spectra chart analysis. Results XRD and FTIR showed that all glass samples were highly homogeneous and had structured with short-rangeorder/amorphous solids. The refractive index of each sample was estimated by charts of UV-Vis and FTIR, in addition to an empirical method, and we obtained values very close to each other. The refractive index values are relatively high, so this glass can be used in nonlinear studies as well as luminescence characterization. The macroscopic fast neutron removal cross sections (R/ρ) have calculated, for all samples, and the highest value was in sample containing 2.5% niobium pentoxide. Conclusion Bismuth borate glass containing a few niobium pentoxide can be used as a protective shield of neutrons.
American Journal of Materials Synthesis and Processing, 2017
This paper is a simple idea aims to how to get an imagination about the variation of glass refrac... more This paper is a simple idea aims to how to get an imagination about the variation of glass refractive index with its internal structure. In the present work an empirical equation for the refractive index of a glass sample has been achieved as function of both the glass molar Volume and the glass electronegativity. Like this equation, may be used to determine and estimate the refractive index value of an inorganic oxide glass sample, if its density measured with high accuracy.
In an attempt to take advantage of industrial wastes, Iron slag was used to prepare some of glass... more In an attempt to take advantage of industrial wastes, Iron slag was used to prepare some of glass samples in an attempt to re-use. The following chemical formula has considered in the preparation process. (25 + x) % slag + (75-x) % (Na 2 B 4 O 7 .10H 2 O), where x has varied among different values. The rapid quenching method has used to prepare the glass samples, of thier molten components at 1200°C. When x > 45 had not be obtained any glasses, in the conditions of preparation. Both FTIR and XRD showed that each sample contains x ≤ 45 had formed perfect glass state. Density and molar volume showed that the glass structure became more open with increasing concentration of the slag.
Glasses of (B 2 O 3) 0.6 (CaO) 0.2 (Bi 2 O 3) (0.2−x) (Nb 2 O 5) x were prepared utilizing a fast... more Glasses of (B 2 O 3) 0.6 (CaO) 0.2 (Bi 2 O 3) (0.2−x) (Nb 2 O 5) x were prepared utilizing a fast cooling method (where x = 0.0, 0.05 and 0.10). Fourier-transform infrared spectra FTIR revealed about shapes that characterize the amorphous solids, where broad overlapping bands were observed. Incorporation of niobium pent-oxide Nb 2 O 5 in the glass matrix caused BO 3 to BO 4 , an increasing glasses' molar volume and decreasing in glasses' opacity. Some linear and nonlinear optical parameters had been explored by means of UV-visible spectra within 200-845 nm wavelength range. The absorption coefficients, Urbach energy, direct and indirect optical band gaps increased with an increase in the niobium pent-oxide concentration, and the real linear refractive index decreased. On the other side, nonlinear refractive index, first linear and third nonlinear susceptibilities were observed to increase with increase in niobium pent-oxide.
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Papers by Hossam Gomaa