Temperature dependence of corundum roentgenoluminescence and thermoluminescence

Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 54, No. 3, pp. 438–444, March, 1991.     

Basic principles of technological shaping of optical properties and radiation hardness of PWO crystals

Technological conditions ensuring growth of optically homogeneous lead tungstate (PWO) crystals are reported. It is shown that the basic scintillator characteristics of PWO grown from highly purified raw material and properly doped with lanthanides are mainly determined by inclusions of oxides W_1−yL_yO_3−x (L=Y, La, Gd; 0<x<0.3). Moreover, surface-located inclusions with structure close to tungstenite may also be of importance. It is demonstrated that the scintillation properties can be intentionally designed by varying the oxygen content in the inclusions x and the surface structure. The optimal value for x and the most favorable surface structure are achieved by proper thermal regimes and environment content during the crystal annealing. The results enabled low-cost fabrication of PWO scintillators with steady and reproducible characteristics acceptable for the CERN project ALICE and ensured production of PWO on an industrial scale by “North Crystals” company at a rate of 125–135 crystals per year from every growth apparatus.     

Chromatographic properties of silica modified with 6,10-ionene and sodium lignosulfonate

Adsorbents for hydrophilic chromatography: silica layer-by-layer modified with 6,10-ionene and sodium lignosulfonate (Sorbent-1), and silica modified with chitosan and sodium lignosulfonate (Sorbent-2) have been investigated. The influence of the nature of polycation used for the synthesis of adsorbents and the composition of the mobile phase on the retention and separation of phenol carboxylic acids have been studied. It was found that the retention of organic acids and the selectivity of their separation are higher on Sorbent-1. The possibility of the isocratic separation of a mixture of caffeine, sorbic, benzoic, vanillic, gallic, salicylic, sinapic, ferulic, p-cumaric, and caffeic acids in 30 min on a column filled with Sorbent-1 was demonstrated.     

Nitrogen-containing heterocycles from metal β-diketonates

Factors determining the reaction of metal β-diketonates with hydrazine, in particular the nature of central metal ion and structure of β-diketonate ligand, are discussed. The possibility for the preparation of other heterocyclic compounds via reaction of metal acetylacetonates with phenylhydrazine, o-phenylenediamine, urea, and thiourea was studied.     

Thermal decomposition of silicon-containing chromium and cobalt γ-[(alkylthio)(alkoxy)phosphorylthio]acetylacetonates

Thermal decomposition of silicon-containing chromium and cobalt γ-[(alkylthio)(alkoxy)phosphorylthio]acetylacetonates in air was studied by derivatography. Thermal decomposition of the monomeric metal chelates containing triethylsilyl groups starts from the elimination of the substituent at P, followed by oxidation of the γ-thioacetylacetonate group. Thermal oxidation of polyorganylsiloxanes with phosphorus-substituted γ-thioacetylacetonate fragments starts with the oxidation of the γ-thioacetylacetonate groups, followed by oxidation of the alkoxy and vinylthio groups at phosphorus.