Abstract: Ceramics (including glasses and glass-ceramics) comprising nitrogen, and methods of making the same.

Abstract: A ceramic composition includes a glass composition and a filler including at least one of Al2O3 and TiO2, wherein the composition of the ceramic composition includes 0.15 to 0.55 mol of a, 0.45 to 0.85 mol of b, 0.01 to 0.2 mol of an oxide RO of an alkaline earth metal element R, and 0.1 to 0.4 mol of the filler, wherein a represents a molar quantity of an oxide Ln2O3 of a rare earth element Ln, b represents a molar quantity of boron oxide B2O3, and a+b=1 mol.

Abstract: Nanoscale particles, particle coatings/particle arrays and corresponding consolidated materials are described based on an ability to vary the composition involving a wide range of metal and/or metalloid elements and corresponding compositions. In particular, metalloid oxides and metal-metalloid compositions are described in the form of improved nanoscale particles and coatings formed from the nanoscale particles. Compositions comprising rare earth metals and dopants/additives with rare earth metals are described. Complex compositions with a range of host compositions and dopants/additives can be formed using the approaches described herein. The particle coating can take the form of particle arrays that range from collections of disbursable primary particles to fused networks of primary particles forming channels that reflect the nanoscale of the primary particles. Suitable materials for optical applications are described along with some optical devices of interest.

Abstract: Ceramics comprising (i) at least one of Nb2O5 or Ta2O5 and (ii) at least two of (a) Al2O3, (b) REO, or (c) at least one of ZrO2 or HfO2. Embodiments of ceramics according to the present invention can be made, formed as, or converted into optical waveguides, glass beads, articles (e.g., plates), fibers, particles (e.g., abrasive particles), and thin coatings.

Abstract: A low melting glass, which contains substantially no lead and contains 70-90% of Bi2O3, 1-20% of ZnO, 2-12% of B2O3, 0.1-5% of Al2O3, 0.1-5% of CeO2, 0-5% of CuO, 0-0.2% of Fe2O3 and 0.05-5% of CuO+Fe2O3 in mass %, wherein a content of alkali metal oxides in the glass composition is less than 0.1%, and the glass does not crystallize by pre-baking at a sealing temperature or more, can be used for sealing later, and can suppress deterioration of a material such as platinum or platinum-rhodium to provide a stable melting operation for a long period.

Abstract: A lens formed of a high-refractivity low-dispersion glass and free of fogging and scorching on its optical-function surface, which is obtained by precision press-molding of an optical glass having a refractive index (nd) of over 1.83, an Abbe's number (?d) of 40 or more and a glass transition temperature (Tg) of 640° C. or lower and containing no Li2O and has one form of a meniscus form, a biconcave form or a plano-concave form.

Abstract: Ceramics comprising (i) at least one of Nb2O5 or Ta2O5 and (ii) at least two of (a) Al2O3, (b) REO, or (c) at least one of ZrO2 or HfO2. Embodiments of ceramics according to the present invention can be made, formed as, or converted into optical waveguides, glass beads, articles (e.g., plates), fibers, particles (e.g., abrasive particles), and thin coatings.

Abstract: Ceramics comprising (i) at least one of Nb2O5 or Ta2O5 and (ii) at least two of (a) Al2O3, (b) Y2O3, or (c) at least one of ZrO2 or HfO2. Embodiments of ceramics according to the present invention can be made, formed as, or converted into optical waveguides, glass beads, articles (e.g., plates), fibers, particles (e.g., abrasive particles), and thin coatings.

Abstract: A method and apparatus for heating semiconductor wafers in thermal processing chambers. The apparatus includes a non-contact temperature measurement system that utilizes radiation sensing devices, such as pyrometers, to determine the temperature of the wafer during processing. The radiation sensing devices determine the temperature of the wafer by monitoring the amount of radiation being emitted by the wafer at a particular wavelength. In accordance with the present invention, a spectral filter is included in the apparatus for filtering light being emitted by lamps used to heat the wafer at the wavelength at which the radiation sensing devices operate. The spectral filter includes a light absorbing agent such as a rare earth element, an oxide of a rare earth element, a light absorbing dye, a metal, or a semiconductor material.

Abstract: A glass for press molding, containing substantially no lead, consisting substantially of, as represented by mol % based on oxides: Bi2O3 25 to 70%, B2O3 + SiO2 ?5 to 75%, CeO2 ?0 to 10%, Al2O3 ?0 to 20%, Ga2O3 ?0 to 20%, Al2O3 + Ga2O3 ?0 to 30%, and ZnO + TeO2 + BaO + WO3 ?0 to 40%, and having a refractive index of at least 1.9 to a light having a wavelength of 0.8 ?m.

Abstract: A novel apparatus for heat treating semiconductor wafers includes a heating device which comprises an assembly of light energy sources for emitting light energy onto a wafer. The light energy sources can be placed in various configurations. The tuning devices adjust the overall irradiance distribution of the light energy sources. The tuning devices can either be active sources of light energy or passive sources which reflect, refract, or absorb light energy. For instance, in one embodiment, the tuning devices can comprise a lamp spaced from a focusing lens designed to focus determined amounts of light energy onto a particular location of a wafer being heated.

Abstract: An optical glass which contains at least 20 mol % of TeO2 and has an internal transmittance of at least 80% in a thickness of 2 mm to a light having a wavelength of 405 nm and a refractive index of at least 1.85 to the same light, and which contains no alkali metal oxide or contains alkali metal oxides in a total amount of at most 15 mol %.

Abstract: The invention relates to uses of glasses and glass-ceramics in dental and orthodontic applications.

Abstract: Provided is an optical glass that has high-refractivity and high-dispersion properties and can give preforms for press-molding, which are excellent in shapability at high temperatures and suitable for precision press-molding. The optical contains, as essential components, 25 to 45 mol % of B2O3, 2 to 20 mol % of SiO2, 5 to 22 mol % of La2O3, 2 to 20 mol % of Gd2O3, 15 to 29 mol % of ZnO, 1 to 10 mol % of Li2O and 0.5 to 8 mol % of ZrO2, the optical glass having a B2O3/SiO2 molar ratio of from 2 to 5.5 and having an La2O3 and Gd2O3 total content of 12 to 24 mol % and a ZnO and Li2O total content of 25 to 30 mol %, the optical glass having a refractive index (nd) of 1.75 to 1.85 and an Abbe's number (?d) of 40 to 55, or the optical glass contains, as essential components, B2O3, SiO2, La2O3, Gd2O3, ZnO, Li2O and ZrO2 and has a viscosity of at least 6 dPa·s at a liquidus temperature thereof, a glass transition temperature (Tg) of 600° C. or lower, a refractive index (nd) of 1.75 to 1.

Abstract: An apparatus for heat treating semiconductor wafers is disclosed. The apparatus includes a heating device which contains an assembly linear lamps for emitting light energy onto a wafer. The linear lamps can be placed in various configurations. In accordance with the present invention, tuning devices which are used to adjust the overall irradiance distribution of the light energy sources are included in the heating device. The tuning devices can be, for instance, are lamps or lasers.

Abstract: A dielectric composition and a fabrication method for a dielectric layer in a plasma display panel, by which contrast of the plasma display panel can be improved through simple fabrication processes. The dielectric composition for the dielectric layer in the plasma display panel comprises: a glass of P2O5—B2O3—ZnO group; and a filler consisting of Nd2O3.

Abstract: A three-dimensional vertical memory with florescent photosensitive vitreous material is read and written to by a laser or respective lasers. The memory can be cerium and europium-doped fluorescent photosensitive glass, yttrium, europium and praseodymium-containing glass or TV-doped glass, etc. A confocal microscope may be used in the writing process and the memory may be scanned by rotating it.

Abstract: Nanoscale particles, particle coatings/particle arrays and corresponding consolidated materials are described based on an ability to vary the composition involving a wide range of metal and/or metalloid elements and corresponding compositions. In particular, metalloid oxides and metal-metalloid compositions are described in the form of improved nanoscale particles and coatings formed from the nanoscale particles. Compositions comprising rare earth metals and dopants/additives with rare earth metals are described. Complex compositions with a range of host compositions and dopants/additives can be formed using the approaches described herein. The particle coating can take the form of particle arrays that range from collections of disbursable primary particles to fused networks of primary particles forming channels that reflect the nanoscale of the primary particles. Suitable materials for optical applications are described along with some optical devices of interest.

Abstract: A high-refractivity low-dispersion optical glass that gives press-molding preforms excellent in high-temperature shapability and suitable for precision press-molding, including an optical glass comprising B2O3, La2O3, Gd2O3 and ZnO as essential components, substantially containing none of lead and fluorine, having a refractive index (nd) of 1.72 to 1.83, an Abbe's number (?d) of 45 to 55 and a glass transition temperature (Tg) of 630° C. or lower and having a viscosity of at least 0.6 Pa·s at its liquidus temperature, and an optical glass comprising, by mol %, 45 to 65% of B2O3, 5 to 22% of La2O3, 1 to 20% of Gd2O3, provided that the total content of La2O3 and Gd2O3 is 14 to 30%, 5 to 30% of ZnO, 0 to 10% of SiO2, 0 to 6.5% of ZrO2 and 0 to 1% of Sb2O3, substantially containing none of lead and fluorine, and having a refractive index (nd) of 1.72 to 1.83 and an Abbe's number (?d) of 45 to 55.

Abstract: A method and apparatus for heating semiconductor wafers in thermal processing chambers. The apparatus includes a non-contact temperature measurement system that utilizes radiation sensing devices, such as pyrometers, to determine the temperature of the wafer during processing. The radiation sensing devices determine the temperature of the wafer by monitoring the amount of radiation being emitted by the wafer at a particular wavelength. In accordance with the present invention, a spectral filter is included in the apparatus for filtering light being emitted by lamps used to heat the wafer at the wavelength at which the radiation sensing devices operate. The spectral filter includes a light absorbing agent such as a rare earth element, an oxide of a rare earth element, a light absorbing dye, a metal, or a semiconductor material.

Abstract: Homogeneously mixed rare-earth doped particles and methods of using such particles include nano to microsized particles having a concentration of at least about 0.0005 mole percent of a Rare-Earth Oxide (Re2O3). The particles can be used for detecting the presence of an analyte in a sample and for detecting interactions of biomolecules.

Abstract: The optical glass has an index of refraction (nd) greater than or equal to 1.70, an Abbé number (&ngr;d) greater than or equal to 35 and a density (&rgr;) less than or equal to 4.5 g/cm3. Optical elements made with this optical glass are especially desirable in optical data transfer applications, particularly in read-write devices with movable read-write heads. The glass compositions required to make optical glass with these properties are described.

Abstract: A tellurite-based glass composition for use in EDFAs exhibits higher phonon energy without sacrificing optical, thermal or chemical durability properties. The introduction of boron oxide (B2O3) into the Er3+-doped tellurite glasses increases the phonon energy from typically 785 cm−1 up to 1335 cm−1. The inclusion of additional glass components such as Al2O3 has been shown to enhance the thermal stability and particularly the chemical durability of the boro-tellurite glasses. Er:Yb codoping of the glass does further enhance its gain characteristics.

Abstract: A glass fiber comprising core glass and clad glass, wherein the core glass consists essentially of from 25 to 70 mol % of Bi2O3, from 5 to 74.89 mol % of B2O3+SiO2, from 0.1 to 30 mol % of Al2O3+Ga2O3, and from 0 to 10 mol % of CeO2.

Abstract: A family of tellurite glasses and optical components for telecommunication systems, the glasses consisting essentially of, as calculated in cation percent, 65-97% TeO2, and at least one additional oxide of an element having a valence greater than two and selected from the group consisting of Ta, Nb, W, Ti, La, Zr, Hf, Y, Gd, Lu, Sc, Al and Ga, that may contain a lanthanide oxide as a dopant, in particular erbium oxide, and that, when so doped, is characterized by a fluorescent emission spectrum having a relatively broad FWHM value.

Abstract: An optical amplifying glass having Er doped in an amount of from 0.01 to 10% as represented by mass percentage to a matrix glass comprising, by mol %, BiO2: 20 to 80, B2O3+SiO2: 5 to 75, Ga2O3+WO3+TeO2: 0.1 to 35, Al2O3≦10, GeO2≦30, TiO2≦30, and SnO2≦30, and containing no CeO2.

Abstract: An optical glass that substantially does not contain any Ta2O5 and has high-refractivity low-dispersion optical properties and various optical parts made of such optical glass are provided stably at a low cost, and an optical part made thereof is provided, the optical glass having a glass composition comprising, by weight %, 0 to 7% of SiO2, 18 to 30% of B2O3, provided that the total content of SiO2 and B2O3 is 23 to 35%, 2 to 10% of ZnO, 30 to 50% of La2O3, 0 to 20% of Gd2O3, 0 to 20% of Y2O3, provided that the total content of La2O3, Gd2O3 and Y2O3 is 45 to 60%, 3 to 8% of ZrO2 and 3 to 12% of Nb2O5, the total content of these components being at least 95% by weight, the optical glass having a refractive index [nd] and an Abbe's number [&ngr;d] which satisfy specified relational expressions.

Abstract: A glass for press molding, containing substantially no lead, consisting substantially of, as represented by mol % based on oxides: 1 Bi2O3 25 to 70%, B2O3 + SiO2  5 to 75%, CeO2  0 to 10%, Al2O3  0 to 20%, Ga2O3  0 to 20%, Al2O3 + Ga2O3  0 to 30%, and ZnO + TeO2 + BaO + WO3  0 to 40%,

Abstract: An optical amplifying glass comprising a matrix glass and, added thereto, from 0.01 to 10 wt % of Er, characterized in that said matrix glass substantially comprises, as represented by mol %, 20 to 80 of Bi2O3, 0 to 74.89 of B2O3, 0 to 79.99 of SiO2, 0.01 to 10 of CeO2, 0 to 50 of Li2O, 0 to 50 of TiO2, 0 to 50 of ZrO2, 0 to 50 of SnO2, 0 to 30 of WO3, 0 to 30 of TeO2, 0 to 30 of Ga2O3 and 0 to 10 of Al2O3, with the proviso that said matrix glass contains at least one of B2O3 and SiO2.

Abstract: An optical amplifier glass comprising a matrix glass containing Bi2O3 and at least one of Al2O3 and Ga2O3, and Er doped to the matrix glass, wherein from 0.01 to 10% by mass percentage of Er is doped to the matrix glass which has a total content of Al2O3 and Ga2O3 of at least 0.1 mol %, a content of Bi2O3 of at least 20 mol %, a refractive index of at least 1.8 at a wavelength of 1.55 &mgr;m, a glass transition temperature of at least 360° C. and an optical basicity of at most 0.49.

Abstract: A high-refractivity low-dispersion optical glass that gives press-molding preforms excellent in high-temperature shapability and suitable for precision press-molding, including an optical glass comprising B2O3, La2O3, Gd2O3 and ZnO as essential components, substantially containing none of lead and fluorine, having a refractive index (nd) of 1.72 to 1.83, an Abbe's number (vd) of 45 to 55 and a glass transition temperature (Tg) of 630° C. or lower and having a viscosity of at least 0.6 Pa•s at its liquidus temperature, and an optical glass comprising, by mol %, 45 to 65% of B2O3, 5 to 22% of La2O3, 1 to 20% of Gd2O3, provided that the total content of La2O3 and Gd2O3 is 14 to 30%, 5 to 30% of ZnO, 0 to 10% of SiO2, 0 to 6.5% of ZrO2 and 0 to 1% of Sb2O3, substantially containing none of lead and fluorine, and having a refractive index (nd) of 1.72 to 1.83 and an Abbe's number (vd) of 45 to 55.

Abstract: The optical glass has an index of refraction (nd) greater than or equal to 1.70, an Abbé number (&ngr;d) greater than or equal to 35 and a density (&rgr;) less than or equal to 4.5 g/cm3. Optical elements made with this optical glass are especially desirable in optical data transfer applications, particularly in read-write devices with movable read-write heads. The glass compositions required to make optical glass with these properties are described.

Abstract: An optical amplifying glass having Er doped in an amount of from 0.01 to 10% as represented by mass percentage to a matrix glass comprising, by mol %, BiO2: 20 to 80, B2O3+SiO2: 5 to 75, Ga2O3+WO3+TeO2: 0.1 to 35, Al2O3≦10, GeO2≦30, TiO2≦30, and SnO2≦30, and containing no CeO2.

Abstract: An optical glass that substantially does not contain any Ta2O5 and has high-refractivity low-dispersion optical properties and various optical parts made of such optical glass are provided stably at a low cost, and an optical part made thereof is provided, the optical glass having a glass composition comprising, by weight %, 0 to 7% of SiO2, 18 to 30% of B2O3, provided that the total content of SiO2 and B2O3 is 23 to 35%, 2 to 10% of ZnO, 30 to 50% of La2O3, 0 to 20% of Gd2O3, 0 to 20% of Y2O3, provided that the total content of La2O3, Gd2O3 and Y2O3 is 45 to 60%, 3 to 8% of ZrO2 and 3 to 12% of Nb2O5, the total content of these components being at least 95% by weight, the optical glass having a refractive index [nd] and an Abbe's number [&ngr;d] which satisfy specified relational expressions.

Abstract: Pyrogenically produced oxides of metals and/or metalloids doped with erbium oxide, in which the base component is a pyrogenically produced oxide doped with erbium oxide in an amount of 0.000001 to 40 wt %, in which the BET surface of the doped oxide lies between 1 and 1000 m2/g, are produced by feeding an aerosol into a flame, as used for production of pyrogenic oxide, in which an erbium salt solution is used as the starting product for the aerosol, the aerosol being produced by atomization with an aerosol generator, this aerosol is mixed homogeneously before reaction with a gas mixture for flame oxidation or flame hydrolysis, the aerosol-gas mixture is then allowed to react in a flame, and the formed pyrogenic oxides doped with erbium oxide are separated from the gas stream in a known fashion. The pyrogenic oxide of metals and/or metalloids doped with erbium oxide can be used as glass raw material.

Abstract: According to one aspect of the present invention an optically active glass contains Sb2O3, up to about 4 mole % of an oxide of a rare earth element, and 0-20 mole % of a metal halide selected from the group consisting of a metal fluoride, a metal bromide, a metal chloride, and mixtures thereof, wherein this metal is a trivalent metal, a divalent metal, a monovalent metal, and mixtures thereof. In addition, any of the glass compositions described herein may contain up to 15 mole % B2O3 substituted for an equivalent amount of Sb2O3.

Abstract: A low melting point glass for covering electrodes, which contains Cu in a content as calculated as CuO within a range of from 0.1 to 0.9% by mass percentage and which contains neither Mo or Sb.

Abstract: A glass composition well suited for use in optical amplification consists of an erbium-doped borate glass composition comprising at least 30 mole percent of B2O3, not over 30 mole percent of SiO2, preferably not over 5 mole percent of La2O3, a ratio of B2O3 to (&Sgr;X2O+&Sgr;YO) that is at least 3.5, preferably 4.5, where X2O represents monovalent metal oxides(s) and YO represents divalent metal oxides, the glass providing a wide useful bandwidth (50 nm and greater) for optical amplification around the 1545 nm region.

Abstract: An optical amplifier of the present invention is implemented by using a low phonon energy glass doped with praseodymium ions (Pr3+), whereby a wavelength of 1.6 &mgr;m band can be used for an optical transmission. The optical amplifier for amplifying an optical signal includes a low phonon energy optical medium doped with praseodymium ions (Pr3+) for utilizing as a gain medium to the optical signal, and a pumping means for pumping the low phonon energy optical medium, thereby to obtain an amplified optical signal.

Abstract: A bulk single phase glass comprising 23 molar % to 50 molar % rare earth oxides, RE203, and 50 molar % to 77 molar % aluminum oxide, A12O3 is provided. The glass contains at least 50 molar % of Al2O3+RE2O3 and smaller amounts of oxide glass forming agents and other oxides than are found in prior art glasses. The addition of small amounts of lanthanum oxide, La2O3, prevents phase separation. The single phase glass is useful for optical applications such as lasers and optical amplifiers.

Abstract: The present invention relates to an oxyhalide glass matrix including 0-70 mol. % SiO2, 5-35 mol. % Al2O3, 1-50 mol. % B2O3, 5-35 mol. % R2O, 0-12 wt. % F, 0-12 wt. % Cl, and 0 to 0.2 mol. % rare earth element, wherein R is Li, Na, K, Rb, or Cs. The present invention further relates to a method of producing the glass matrix and to a method of modifying the spectral properties of an oxyhalide glass.

Abstract: A glass consisting essentially of antimony oxide. An optically active glass consisting essentially of antimony oxide and up to about 4 mole % of an oxide of a rare earth element. A rare earth-doped, antimony oxide-containing glass including 0-99 mole % SiO2, 0-99 mole % GeO2, 0-75 mole % (Al, Ga)2O3, 0.5-99 mole % Sb2O3, and up to about 4 mole % of an oxide of a rare earth element. The oxide of the rare earth element may comprise Er2O3. The glass of the invention further includes fluorine, expressed as a metal fluoride. An optical energy-producing or light-amplifying device, in particular, an optical amplifier, comprising the above-described glass. The optical amplifier can be either a fiber amplifier or a planar amplifier, either of which may have a hybrid composition. Embodiments of the glass of the invention can be formed by conventional glass making techniques, while some of the high content antimony oxide embodiments are formed by splat or roller quenching.

Abstract: A novel amorphous optical device contributes to economic construction of optical computers. Since economic parallel processing of signals such as image information is made possible, the novel amorphous optical device contributes also to development of optical computers capable of performing ultra-high speed and parallel processing, object recognizing apparatuses in which image optical signals are processed by using image optical signals, motion picture extracting apparatuses used for eyes of robots and object movement monitors and optical surge absorbers. An amorphous optical device which is doped with an element having a negative optical input-output characteristic to incident light, wherein the number of ions and/or atoms of the element is 1×1026 to 2.

Abstract: A low melting point glass for covering electrodes, consisting, as represented by mass percentage based on the following oxides, essentially of: Mass percentage PbO 20 to 60%, Bi2O3  0 to 30%, B2O3 20 to 55%, SiO2  0 to 10%, Al2O3  0 to 15%, MgO + CaO  0 to 35%, SrO  0 to 35%, BaO  0 to 35%, ZnO  0 to 8%.

Abstract: A family of alkali-tungsten-tellurite glasses that consist essentially of, as calculated in mole percent, 10-90% TeO2, at least 5% W03 and at least 0.5% R2O where R is Li, Na, K, Cs, Tl and mixtures, that may contain a lanthanide oxide as a dopant, in particular erbium oxide, and that, when so doped, is characterized by a fluorescent emission spectrum having a relatively broad FWHM value.

Abstract: A family of fluorotellurite glasses, the composition of which consist essentially of, as calculated in mole percent, 30-75% TeO2, 15-60% ZnF2 and 0.005-10% of an oxide of erbium, thulium or holmium, and amplifying optical components produced from these glasses.

Abstract: An optical amplifier glass comprising a matrix glass containing Bi2O3 and at least one of Al2O3 and Ga2O3, and Er doped to the matrix glass, wherein from 0.01 to 10% by mass percentage of Er is doped to the matrix glass which has a total content of Al2O3 and Ga2O3 of at least 0.1 mol %, a content of Bi2O3 of at least 20 mol %, a refractive index of at least 1.8 at a wavelength of 1.55 &mgr;m, a glass transition temperature of at least 360° C. and an optical basicity of at most 0.49.

Abstract: The present invention relates to a transparent glass-ceramic material which includes a glass matrix and a crystalline phase of lanthanum fluoride crystals in the glass matrix, where the transparent glass-ceramic material contains no silica. The present invention further relates to a method of producing the transparent glass-ceramic material.

Abstract: The present invention provides an oxide glass capable of exhibiting a long lasting afterglow and photostimulated phosphorescence, can be used not only as a material for confirming an infrared laser or controlling an optical axis, but also as a material for recording or reproducing of &ggr;-rays, X-rays or UV-rays images and further can be used as an optical recording material of such a type that can be read. This glass material is represented, in term of atoms for making up the glass, by the following chemical composition (mol %): GeO2 21 to 80% ZnO 0 to 50% Ga2O2 0 to 55% (ZnO + Ga2O3 = 3 to 55%) Tb2O3 0 to 10% MnO 0 to 2% (Tb2O3 + MnO = 0.01 to 10%) R2O 0 to 45% (R: at least one atom selected from Li, Na, K and Cs) R′O 0 to 40% (R′: at least one atom selected from Mg, Ca, Sr and Ba) R2O + R′O 0.

Abstract: A family of aluminoborate glasses that are compatible with aluminum at elevated temperatures, and an article comprising such a glass with either an aluminum coating, or with aluminum particles dispersed within the glass, whereby the glass may be rendered polarizing. The base glass consists essentially of, 15-85% B2O3, 5-45% Al2O3 and 10-75% Li2O+RO, where RO represents the alkaline earth metal oxides MgO, CaO, SrO and BaO, and is free of oxides reacting with aluminum at elevated temperatures.