The dependence of the emission spectra on compositional variations has been studied in binary alkaline earth orthosilicate systems activated by divalent europium. Isotherms at 1200°C were run in the systems (i) Ba2SiO4‐Sr2SiO4 , (ii) Ca2SiO4‐Sr2SiO4 , and (iii) Ca2SiO4‐Ba2SiO4 . Phosphors produced in the Ba2SiO4‐Sr2SiO4 system were considerably more efficient than those in either of the other two systems and consequently were studied in much greater detail. A complete series of crystalline solutions exist between the end‐members at 1200°C. The corresponding emission spectra vary in a fairly continuous manner from 505 nm for the pure barium end‐member to 575 nm for the pure strontium end‐member. X‐ray diffraction data revealed complete crystalline solution between β‐Ca2normalSi04 and Sr2SiO4 at 1200°C. However, the low level of brightness and the pronounced asymmetry of the emission peaks rendered this system less amenable to a detailed investigation. Emission spectra indicated the formation of an intermediate compound in the Ca2SiO4‐Ba2SiO4 system. The existence of this compound, Ba5Ca3Si4O16 , was verified by x‐ray diffraction. The emission spectrum of this compound peaks at a considerably lower wavelength (∼490 nm) than those of its bounding compositions. The two later systems were further complicated due to the polymorphism of Ca2SiO4 . Frequently the Ca2SiO4 phase was partially converted from β‐Ca2SiO4 to γ‐Ca2SiO4 .

The death of a 23-year-old man resulting from digoxin-like toxicity and heart failure was attributed to ingestion of a West Indian aphrodisiac known as “Love Stone.” GC/MS analyses identified bufotenine, a controlled substance under both US and New York State statutes. In addition, a series of bufadienolides, namely resibufogenin, bufalin, and cinobufagin, were also identified. Bufadienolides, which are derived from toad venom or secretions, are cardiotonic steroids that cause symptoms similar to digoxin. GC/MS analyses of the Chinese medication “Chan Su,” a product derived from toads, produced a highly similar elution profile and contained the same compounds as “Love Stone.” The data demonstrate that the aphrodisiac was also derived from toads.

The incorporation of divalent europium in the compounds Ca3MgSi2O8 , Sr3MgSi2O8 , and Ba3MgSi2O8 produces phosphors of high luminescence yield. These phosphors respond well to both long and short wavelength ultraviolet excitation, as well as to cathode ray bombardment. The peak of the emission band occurs at progressively shorter wavelength and narrows as the radius of the major alkaline earth ion (Ca, Sr, or Ba) is increased. A 1200°C isotherm on compositions intermediate to Sr3MgSi2O8 and Ba3MgSi2O8 shows a complete series of crystalline solutions to exist at this temperature. Using an orthorhombic cell the d‐spacings of the (222) reflection vary continuously from 1.956Aå for Sr3MgSi2O8:Eu2+ normalto 2.012Aå for Ba3MgSi2O8:Eu2+ . The emission spectra of these samples, however, vary in a discontinuous manner. Complete crystalline solution is likewise observed in a 1200°C isotherm for compositions intermediate to Sr3MgSi2O8 and Ca3MgSi2O8 . Here the d‐spacings of the (222) reflection from the orthorhombic cell vary continuously from 1.909Aå for Ca3MgSi2O8:Eu2+ to 1.956Aå for Sr3MgSi2O8:Eu2+ . Again the peak of the emission spectra varies discontinuously with composition even for the complete crystalline solution series.Emission spectra and x‐ray diffraction data collected on samples prepared in the 1200°C subsolidus isotherm intermediate in composition to Ca3MgSi2O8 and Ba3MgSi2O8 show an intermediate compound to be formed. This compound BaCa2MgSi2O8 has luminescent properties which more closely resemble those of the calcium end‐member. Several compositions were prepared in the subsolidus, 1200°C, isothermal, ternary section bounded by Ca3MgSi2O8 , Sr3MgSi2O8 , and Ba3MgSi2O8 . The samples prepared show the major feature of the section to be a large single phase region. In general, broadening of spectral energy distributions is observed as compositions move into the ternary section. All the compositions prepared resulted in phosphors of relatively high efficiency.

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