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J.A. Duffy

Bio: J.A. Duffy is an academic researcher. The author has contributed to research in topics: Electronegativity & Donor number. The author has an hindex of 1, co-authored 1 publications receiving 238 citations.

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TL;DR: In this article, it is shown that the Lewis basicity of oxide (expressed in terms of the optical basicity, Λ) is reduced by highly polarizing cations such as S6+, P5+, Si4+, etc.

248 citations


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TL;DR: In this article, the basicity of an oxide glass can be measured experimentally from the frequency shifts in the ultra-violet (UV) (s-p) spectra of probe ions such as Pb2+ and can be expressed on the numerical scale of optical basicity Λ (ideally Λ lies between zero and unity).
Abstract: The basicity of an oxide glass can be measured experimentally from the frequency shifts in the ultra-violet (UV) (s-p) spectra of probe ions such as Pb2+ and can be expressed on the numerical scale of optical basicity Λ (ideally Λ lies between zero and unity). It is possible to relate Λ with (i) the constitution, and (ii) the electronegativity of the cations (e.g. Na+, Si4+, etc.) of the glass, and the relationship allows microscopic optical basicities λ to be assigned to individual oxides and oxy-groups in the glass. These microscopic optical basicities are used for interpreting various aspects of the physics and chemistry of glass including refractivity, network coordination number changes, chemical durability, the glass electrode, UV transparency and the host behaviour of glass towards metal ions generally. Changes in glass basicity in going from one alkali metal oxide to another are also discussed. Finally, the concept of optical basicity, both as an experimentally obtained quantity and as a number calculated from glass constitution and electronegativity, is discussed in relation to the traditional approach to acid-base behaviour in glass.

686 citations

Journal ArticleDOI
TL;DR: The solubility of sulfur as S 2 − has been experimentally determined geological processes, such as: the origin of magmatic for 19 silicate melt compositions in the system CaO- sulfide ores; sulfur degassing from volcanic eruptions and MgO-Al2O3-SiO2(CMAS) ± TiO2 ± FeO, at 1400°C and hence global climate change; the geochemical behaviour 1 bar, using CO-CO2-SO2 gas mixtures to vary oxygen fugacity of the chalcophile trace
Abstract: The solubility of sulfur as S 2– has been experimentally determined geological processes, such as: the origin of magmatic for 19 silicate melt compositions in the system CaO– sulfide ores; sulfur degassing from volcanic eruptions and MgO–Al2O3–SiO2(CMAS) ± TiO2 ± FeO, at 1400°C and hence global climate change; the geochemical behaviour 1 bar, using CO–CO2–SO2 gas mixtures to vary oxygen fugacity of the chalcophile trace elements, including the platinum ( fO2) and sulfur fugacity ( fS2). For all compositions, the S solubility group elements and the Re–Os isotopic system, and is confirmed to be proportional to (fS2/fO2), allowing the definition their use as tracers of core–mantle and crust–mantle of the sulfide capacity (CS) of a silicate melt as CS = [S]( fO2/ differentiation in the Earth. The solubility of sulfur in fS2). Additional experiments covering over 150 melt compositions, silicate slags is also an important topic in extractive including some with Na and K, were then used to determine CS as metallurgy, and has been much studied in this context, a function of melt composition at 1400°C. The results were fitted both theoretically and experimentally. In a classic paper, Fincham & Richardson (1954) proposed that at low f O2 to the equation CS = A0 +

338 citations

Journal ArticleDOI
TL;DR: The network forming of the B2O3 and the SiO4 is affected with the addition of some metal cation additives Pb, Zn, Cd, and so forth, and the optical properties of the borate glasses have been changed significantly.
Abstract: Borate glasses are the technologically important class of glasses and play a significant role in various applications. Borate glasses contain planar BO3 groups as structural units, rather than tetrahedral SiO4 groups. The oxygen atoms are, as in SiO2, again connected to two network-forming atoms, in case of boron. The radial distribution analysis describes the B2O3 glass structure as consisting of boroxol rings, that is, planar rings containing three boron atoms and three oxygen atoms. The network forming of the B2O3 and the SiO4 is affected with the addition of some metal cation additives Pb, Zn, Cd, and so forth. These additives also work as a network modifier and a nucleating agent for crystallization of glass. Therefore, the optical properties of the borate glasses have been changed significantly.

335 citations

Journal ArticleDOI
TL;DR: The concept of optical basicity and its applicability as a means of correlating the available data on the sulfide capacity of metallurgical slags has been reviewed in this article.
Abstract: The concept of optical basicity and its applicability as a means of correlating the available data on the sulfide capacity of metallurgical slags has been reviewed. An excellent correlation based on very extensive data at 1500 °C, which was discussed in a previous paper, is combined with good correlations based on considerably less data at 1550 °C and 1650 °C to quantify the effect of temperature on the sulfide capacity of slags. The combined effects of slag composition and temperature have been expressed in the equation, logC s = [(22690 – 54640A)/7] + 43.6A − 25.2. Use of this equation permits the calculation of the sulfide capacity of a slag at any temperature between 1400 °C and 1700 °C simply from a knowledge of its chemical composition, and can be employed for virtually any oxide slag of interest in the field of iron and steelmaking. This, in turn, permits calculation of the equilibrium distribution of sulfur between this slag and iron or steel, provided that the oxygen potential is known or can be calculated from the degree of deoxidation applied.

169 citations

Journal ArticleDOI
TL;DR: Acting as complementary spectroscopic techniques, both types of measurements, IR and Raman, revealed that the network structure of the studied glasses is mainly based on BO(3) and BO(4) units placed in different structural groups, the BO( 3) units being dominant.
Abstract: A lithium-potassium-borate glass system containing manganese and iron cations has been thoroughly investigated in order to obtain information about the mixed alkali effect and the structural role of both the manganese and iron in such glass hosts. Mixed alkali borate glasses of the (30 - x)Li(2)O - xK(2)O - 10CdO/ZnO - 59B(2)O(3) (x = 0, 10, 15, 20, and 30) doped with 1MnO(2)/1Fe(2)O(3) system were prepared by a melt quench technique. The amorphous phase of the prepared glass samples was confirmed from their X-ray diffraction. The spectroscopic properties of glass samples were studied using infrared (IR) and Raman spectroscopic techniques. The density of all the prepared glasses was measured using Archimedes principle. Molar volumes were estimated from the density data. IR spectra of these glasses revealed a dramatic variation of three- and four-coordinated boron structures as a function of mixed alkali concentration. The vibrations due to Li-O, K-O, and MnO(4)/FeO(4) arrangements are consistent in all the compositions and show a nonlinear variation in the intensity with alkali content. Raman spectra of different alkali combinations with CdO and ZnO present drastic changes in the intensity of various Raman bands. The observation of disappearance and reappearance of IR and Raman bands as a function of various alkali concentrations is an important result pertaining to the mixed alkali effect in borate glasses. Acting as complementary spectroscopic techniques, both types of measurements, IR and Raman, revealed that the network structure of the studied glasses is mainly based on BO(3) and BO(4) units placed in different structural groups, the BO(3) units being dominant. The measured IR and Raman spectra of different glasses are used to clarify the optical properties of the present glasses correlating them with their structure and composition.

155 citations