ISSN:0049-8246    

DOI:10.1002/xrs.1300170502

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractIt is shown that samples exposed under total reflection conditions obey the relationshipIi/Iinc=KCi, whereIiis the x‐ray fluorescence intensity due to elementiof concentrationCi,Iincis the intensity of the scattered incoherent radiation andKis a constant. An experiment on the determination of sulphur in diesel fuel confirmed this derivation. This relationship affords a simple and fast method for quantitative trace element determination, requiring virtually no sample preparation and extremely small amounts (

ISSN:0049-8246    

DOI:10.1002/xrs.1300170503

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractModels of the dependence of the background intensity on the chemical composition of a specimen for different conditions of analysis are presented. On the basis of these models, a new technique for background correction in the x‐ray spectrometry of homogeneous materials with widely varying composition is suggested. Criteria for evaluation of the necessity for background correction are discusse

ISSN:0049-8246    

DOI:10.1002/xrs.1300170504

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractPyrophyllite was heat treated up to 1000°C in the presence of fluxes such as Li2CO3, Na2CO3, K2CO3and CaCO3and the products were examined by scanning electron microscopy (SEM). It is shown that the surface morphology of the mineral varies with both temperature and flux. The dehydroxylation reaction in the mineral commences at 500°C and continues above 900°C. Dehydroxylated phases are observed even at 950‐1000°C. The formation of free Al2O3, cristobalite, mullite and other phases from pyrophyllite was detected by the SEM examin

ISSN:0049-8246    

DOI:10.1002/xrs.1300170505

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractAn analysis has been made of Cameron's data on the variation of the cell dimensions of mullite for compositions with additions of more than 1.0% of Fe + Ti for samples crystallizing out of the melt phase. It was observed that, depending on the amount of either iron oxide or titania added, the cell dimensions change with respect to changes in cell volume, exhibiting shrinkage along either theborccell edges. Increasing amounts of titania appear to influence theccell edge in preference to theaandbedges. The overall cell symmetry, however, is preserved with a simultaneous increase in theacell edge with change in the cell volume.

ISSN:0049-8246    

DOI:10.1002/xrs.1300170506

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractCorrelation of the variation in the distance between cobalt ions and its nearest neighbours with the variation in the covalency of the metal—ligand bond was estimated from the shape and the extended fine structure of cobalt K‐absorption discontinuity in some cobalt mixed‐ligand comp

ISSN:0049-8246    

DOI:10.1002/xrs.1300170507

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractThe determination of niobium, molybdenum, tungsten, iron and titanium in tantalum metal is described. After dissolution of the metal and extraction of the tantalum by a chromatographic method using tributyl phosphate, the trace elements are determined on thin‐film samples by x‐ray fluorescence spectrometry. The thin‐film samples are prepared either by spotting the sample solutions directly on to filter‐paper or by coprecipitation with indium. The limits of detection on the thin film are 0.05–0.7 μg, depending on the element bein

ISSN:0049-8246    

DOI:10.1002/xrs.1300170508

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractThe critical specimen thickness up to which the Cliff‐Lorimer method can be used without additional corrections was measured on some steels and nickel‐base alloys for soft x‐rays with line energies between 1 and 3 keV. The critical thickness values measured are 50 nm at 1 keV and 450 to 500 nm at 3 keV. These results indicated that verification of the calibration measurements used for determining the correction factors was necessary in the case of soft radiation. The measurements led to a further optimization of the parameters in the equation used for calculating the ionization cross‐sectionThe published equations for absorption correction, which becomes necessary when the critical specimen thickness is exceeded, were found to lead to an overcorrection in the case of very thin foils and an insufficient correction in the case of thicker specimens. However, it is only of significance if the specimens are very thick or errors less than 5% are ai

ISSN:0049-8246    

DOI:10.1002/xrs.1300170509

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

ISSN:0049-8246    

DOI:10.1002/xrs.1300170501

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY