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Abstract  

57Fe Mössbauer spectroscopy was applied to the crystallization study of IR-transmitting calcium aluminate glass, 60CaO·32Al2O3·5Fe2O3·3Eu2O3, in which Fe(III) atoms occupy tetrahedral Al(III) sites. Heat treatment of calcium aluminate glass below and above the crystallization temperature causes the formation of mayenite, 12CaO·7Al2O3, and brownmillerite, 4CaO·Al2O3·Fe2O3, respectively. Mössbauer spectra of the glass ceramics indicate that Fe(III) atoms substitute Al(III) sites, having less covalent Fe(III)-O bonds and more distorted Fe(III)O4 tetrahedra than they do in the original glass. DTA revealed that crystallization of calcium aluminate glass is triggered by simultaneous cleavage of Ca-O and Al-O bonds.

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Abstract  

151Eu Mössbauer spectrum of IR-transmitting calcium aluminate glass, 60CaO·32Al2O3·5Fe2O3·3Eu2O3, consists of a broad peak due to distorted Eu(III) with and values of 0.91 and –2.02 mm·s–1, respectively. Debye temperatures ( D) of 360 and 320 K were obtained from the temperature dependence of absorption area (A) and that of , respectively. These D values indicate that Eu(III) atoms occupy substitutional sites of distorted Al(III)O4 tetrahedra in calcium aluminate glass. The value of 0.62 mm/s obtained from the heat-treated sample (glass ceramic) indicates that Eu(III)-O bonds became less covalent. A smaller value of –1.20 mm·s–1 was obtained for Eu(III) in the glass ceramic, indicating less distorted Eu(III)O4 tetrahedra.

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Abstract  

This paper describes first the application of neutron depth profiling (NDP) for measuring the distribution of6Li in LiAlO2 ceramics. Using a surface barrier detector for detecting3H produced in6Li(n, )3H,6Li was profiled to a depth of 14 m in the ceramics. Secondly, a new methodology is presented for NDP with enhanced capabilities based on measuring the energy of recoiling nuclei from (n, p) and (n, ) reactions by time-of-flight mass spectrometry. The scope of recoil nucleus time-of-flight mass spectrometry (RN-TOF-MS) includes profiling of10B,14N,17O,33S,35Cl,40K. Probe depths may be of a few tens nanometers. RN-TOF-MS complements and refines NDP based on charged particle (p or ) spectrometry.

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Abstract  

The enthalpies of formation of 13 calcium silicates, aluminates, alumino-silicates and ferro-alumino-silicates were measured by dissolution calorimetry with the help of a high-temperature Calvet calorimeter. Dissolution experiments were performed in a lead metaborate (2PbO−B2O3) baths at 1173 K. The synthesis of the samples was realized by melting together pure silica, alumina, ferric oxide and calcium carbonate in appropriate ratios. The samples obtained in this way were examined by X-ray diffraction and scanning electronic microscopy. The free lime content was also determined by chemical analysis. The enthalpy of formation of silicates and aluminates obeys two different linear relations with respect to the ratio Ca/X (X=Al or/and Si) except for Ca12Al14O33 which does not exist in its pure form but has to be stabilized by anions as OH or Cl. The data corresponding to the two aluminosilicates are located between these lines. The enthalpy of formation of tricalcium silicate (Ca3SiO5 i.e. C3S according to the Bogue terminology) from dicalcium silicate and lime could be calculated as −6kJ·mol−1. This reaction is the most important one in the industrial process of clinkerization.

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Abstract  

PbO based phosphate glasses having composition 40P2O5�12Al2O3�6B2O3�9PbO�xNa2O�(33−x)K2O (x=0−33) [F=Na/(Na+K)] have been prepared using conventional melt quench technique. Density, morphology, thermal expansion coefficient (α) and glass transition temperature (T g) were studied as a function of Na/(Na+K) ratio. Formation of transparent, bubble free and clear glass was observed up to x=18 mol%. Density was found to vary from 2.70 to 3.69 g cm−3. The significant changes were noticed in external morphologies at temperatures corresponding to softening, half ball and melting points under high temperature microscope for three compositions (x=0, 10 and 15 mol%). These glasses recorded the softening and half ball temperatures in the range 454–470�C and 523–576�C respectively and melting temperatures agree well with DTA studies within the experimental limits. Glass transition temperature showed a broad maxima while thermal expansion coefficient (TEC) a broad minima around Na/(Na+K)=0.54. This behaviour is explained on the basis of bond formation/phase separation.

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A svéd tanügyigazgatás változásai: egy radikális modellváltás

Shifts in Swedish Education Administration: A Radical Change of Models

Educatio
Author:
András Semjén

Paper No. 33. 32 Szalai Ákos (2002) Fiskális föderalizmus. Áttekintés. Közgazdasági Szemle , XLIX. évf., május (424–440. o.) 33

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A hazai genetikai talajosztályozás megújításának szükségessége - 1.

A nevezéktan és a struktúra korrekcióra szoruló elemeinek azonosítása

The necessity of the renewal of the Hungarian genetic soil classification system - 1.

Identification of the elements of the nomenclature and structure to be corrected
Agrokémia és Talajtan
Authors:
Tibor József Novák
,
Tibor Tóth
,
András Makó
,
Mihály Kocsis
,
Zsófia Bakacsi
,
András Bidló
,
Károly Bartha
,
Szabolcs Czigány
,
Gergely Tóth
,
Adrienn Horváth
, and
Hilda Hernádi

textúra esetén<1,5%) IV. 18. (193. o.); 19. (194. o.); 21. (198. o.) VI. 29. (210. o.); 30. (212. o.); 31. (214. o.); 33. (217. o.) - felső 20 cm humusztart.<2% (homoknál <1,5%) VI. 29. (210. o.); 30. (212. o.); 31. (214. o.); 33. (217. o.) 3. felszíntől

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filtered and dried in air. Elemental analysis. Found (%): C, 32.48; H, 4.88; N, 26.24; Cl, 5.75; calculated for C 52 H 98 Cl 3 N 36 O 33 Co (%) : C, 32.52; H, 5.14; N, 26.25; Cl, 5.54 [ 2 ]. There are two different crystallographic forms

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:2 – eicosadienoic acid; 18: C20:3 – dihomo-gamma-linolenic acid; 19: C20:4 – arachidonic acid; 20: C22:0 – behenic acid) Saturated fatty acids (SFA) were found in the highest amount in HM (nBMI: 48.33%; O: 54.21%), followed by MUFAs (nBMI: 33.35%; O: 33.52%) and

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compounds were identified by elemental analysis as the formula C 9 H 8 O 5 Na 2 (Calculated: C, 44.64%; H, 3.33%; O, 33.04%. Found: C, 44.26%; H, 3.61%; O, 33.28%) and C 8 H 5 O 4.5 Na 2 (Calculated: C, 43.85%; H, 2.30%; O, 32.86%. Found: C, 43.29%; H, 2

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