Use Of Rare Earths Research Articles

LPE growth of InGaAsP:InP high purity layers using rare earth elements

Use of rare earth (RE) elements has allowed the growth of high purity InGaAsP:InP layers in liquid phase epitaxial (LPE) systems. Experiments show that purification of material takes place on account of interaction between the RE and mainly group VI donor impurities.

Comparison of x-radiation doses between conventional and rare earth panoramic radiographic techniques

The radiation dose to radiobiologically critical organs at various anatomic sites in a phantom was compared with the use of rare earth screen/film combinations and calcium tungstate screen/film combinations. Rare earth screens and films produced a reduction in dose up to 40% to 50% depending on the anatomic site.

A clinical comparison of image quality and patient exposure reduction in panoramic radiography with heavy metal filtration

Laboratory and clinical studies with the use of rare earth intensifying screens and four different forms of heavy metal elements serving as additional beam filtration were performed for panoramic radiography to identify the most efficacious system. Balanced density images were evaluated for contrast indices, resolution, relative dose reduction, and subjective image quality. Clinical studies were performed with a standard calcium tungstate imaging system and the four most promising experimental imaging systems that showed improvement over the standard system. Dosimetric studies were performed with the use of ionization chambers and thermoluminescent dosimetry (TLD) dosimeters. Exposure reductions of 34% to 79%, depending on the anatomic site and the imaging system used, were achieved. Subjective image quality was evaluated and analyzed statistically. This study concluded that the use of a Kodak Lanex regular screen/T-Mat G film with either Lanex screen or yttrium added beam filtration results in reduced patient exposure in panoramic radiography while image quality is maintained or improved.

Rare earths and color: Properties and industrial applications

The selective absorption of, or emission from, rare earths provides the grounds for a number of industrial applications in the field of color. Practical aspects of the use of rare earths are reviewed in the field of subtractive (glass and ceramics) as well as additive coloration (phosphors industry in television, lighting, and radiological applications).

The use of rare earths in ceramics

Three main areas are covered: ceramic tiles, electronic ceramics, engineering ceramics. In ceramic tiles praseodymium oxide in a zirconium silicate matrix is used as a yellow stain. Cerium oxide is used as an opacifier or to give esthetic effects in the glaze. In electronic ceramics barium titanate powder for capacitors and PTC thermistors are doped with lanthanides in order to modify both aging and Curie temperature. Yttrium is used to make ferrites for high frequencies and to stabilize zirconia in oxygen sensors for automative fuel control. Engineering ceramics are new materials which can replace metals. Among them PSZ (where yttrium is used to stabilize zirconia) and Si 3N 4 (where yttrium is used as a sintering agent) are the most promising materials. A survey is made of each sector with respect to final application, areas (U.S.A., Japan, Europe), nature of the rare earths and their function, volumes and major trends.

A rare earth screen‐film system for dental panoramic radiography

Abstract— The use of rare earth intensifying screens and green sensitive film can contribute substantially to radiation reduction in dental panoramic tomography without loss of image quality. Reduced radiation output means a shorter cooling period for the X‐ray tube between exposures. Thus the equipment can be used more efficiently and it can also be expected that the tube life will be increased.

New fluorescent lamps for interior lighting

The birth of a new generation of 'de luxe' fluorescent lamps with both a high luminous efficacy and good colour rendering properties coincides more or less with the introduction of improved amalgam lamps. The paper surveys the characteristic properties of both the new generation lamps and amalgam lamps, and discusses the use of these in luminaires. Although the use of rare earth activated phosphors makes these lamps more expensive than conventional 'de luxe' lamps, calculations show that the higher lamp prices are more than counterbalanced by the savings. New technology, making use of a mercury capsule in the lamp, has brought the amalgam lamp within practical reach. These two developments mean a significant step forward in interior lighting.

High affinity calcium binding sites on erythrocyte membrane proteins. Use of lanthanides as fluorescent probes

1. 1.We have explored the utility of lanthanide cations as probes for calcium binding sites in biomembranes using the erythrocyte ghost as a model system. 2. 2.Interaction of terbium with erythrocyte ghosts produces appearance of a new excitation peak (295 nm), enhancement of terbium fluorescence and quenching of tryptophan fluorescence. 3. 3.The excitation characteristics of bound terbium and the enhancement of its fluorescence by intramolecular energy transfer suggest that tyrosyl hydroxyls are ligands for this cation. 4. 4.Excess calcium can displace terbium from its membrane binding sites. Magnesium is a less effective competitor. 5. 5.The use of rare earths as proximity probes is also discussed.

The use of X-ray fluorescence in rapid in vivo measurements of iodine, gold and mercury

Efforts are being directed towards developing a rapid method of in vivo measurements of these elements, requiring simple and fast sample preparations. Several methods of exciting the material of interest have been investigated. 241Am is used as a direct source for irradiating the iodine in solution. The use of rare earths as secondary sources in conjunction with an X-ray tube is also being studied. Also the coincidence counting technique is being investigated. The X-ray fluorescence is measured on a KeVeX Si(Li) semiconductor detector.

Considerations on Organic Compounds in Solution and Inorganic Ions in Glasses as Fluorescent Standard Reference Materials.

The use of various organic compounds in solution and inorganic ions in glasses has been investigated as possible fluorescence Standard Reference Materials. Emphasis was placed on measuring physical and chemical parameters such as stability, reproducibilities of absorbance and fluorescence measurements, relative quantum efficiencies as a function of excitation wavelength, etc., for quinine derivatives and selected organic compounds. A brief discussion is included on the use of rare earth and non-rare earth inorganic ions in glasses as standards.

The use of rare earths in color TV

The use of rare earths in color TV

The use of rare earths for coloring glass

The use of rare earths for coloring glass

The use of Rare Earths in Electric Illuminants

The use of Rare Earths in Electric Illuminants