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Determination of tin in bismuth
SpectmchSmtcaActa,lQW.Vol7.~~.395sad 597. Pe~BmonPm~Ztd,
London
SPECTROCHEMICAL
NOTES
Determination of tin in bismuth ILANA LEVITAN Wemnann Imtltute of Scmnce, Rehovoth, Ismel (Remud
10 Odober 1966)
Ah&a&--A method IEdescribed for the dete rmmatlon of 0 01 to 1 00 per cent of tm in bismuth. Analyses may be carried out with samples as small as 0.02 g. IlltTOdUCtiOIl A RELIABLE and rapid method for the determination of tin in bismuth was called for m connection with studies of conductivity and galvanomagnetic effects 111smgle cry&& of bismuth-tin. The crystals were prepared 1n the Solid State Laboratory of the Weizmann Institute. They took the form of rods, normally about 1 mm diameter by 5 mm in length, but occasionally only half this size. The range of concentrations of interest was from 0.01 to 1.00 per cent of tin in bismuth. RAIKEBAKJM [l] has reported on the analysis of lead-bismuth-tin alloys His method mvolved total combustion of the sample in a d c. arc, and gave satisfactory results for concentrations of tm between 3 and 97 per cent in the alloy However, the method is not applicable to alloys containing a very small t1n content
Ekperimental The spectrum was excited by a high-voltage condensed spark with the sample supported on a 6Gmm hameter graphte electrode Considerable attention had to be paid to the form of the latter. If the electrode had the usual shape of a shallow cup, it was found that the force of the discharge elected the specimen before 1t had properly melted If, on the other hand, the specimen werg placed 1n a deep cup in order to avoid this, it would not melt, and the spectrum would not appear Accordingly for each m&vidual sample a separate electrode was prepared, having a shallow cylinhcal recess of a diameter slightly less than the length of the crystal. The latter was then placed horizontally on the electrode and forced into the recess by applymg pressure By these means 1t was held f%rmly until fused by the discharge The counter electrodes were of the same diameter, 6.5 mm, and pointed The spark-gap was 4 mm. The exposures were 20 set in duration. Samplea melted 1n as little aa one second after the initiation of the discharge, and accordingly exposures were made without preliminary sparking. Standards were prepared from spectroscopically pure bismuth and tm. The metals were placed in small Pyrex tubes and fused in an induction furnace. In order to assure a homogeneous alloy and to avoid crystallization, the specimen was agitated vigorously during the entire period of fusion and resolidification. The process was carried out in vacuum to avoid oxidation. A satisfactory pair of analysis lines was found to be Sn-3034.12 A and B1-3034.87 A. 395
Sipeetrochemical notes
The lines were of equal intensity for an alloy conteinmg about O-14 per cent tm, under the experimental conditions used. This value fell neatly within the range of concentrations of interest to us. The plate calibration ww carried out with a six-step neutral filter A working curve is shown in Fig. 1.
001
005
01
Porconi
05
IO
Sn
Ftg. 1. Workmg curve for the determmatlon of tm m buunuth.
The principal items of the equipment were aa follows. Source: ARL spark unit Model 4. Spectrogra,ph: Hilger E-478 Littrow, with quartz prism. Photographic plate: Word ordinary. [l] RAIKHBAUM, Ya. D.;
Zavodekaycc Lab.
1939, 8 1101.
Eine Kapillarelektrode aus Metall zur direkten, spektmchemischen Untmsuchung von Likmngen H. J. EIOEEO~~ und K. PIUARD* Anorganisch-Chemleches Instltut der Uruver&&t Mamz Abatr&-Description of a mvestig&iona of solutions.
simple arrangement of metal electrodes for direct speotrochemmal
direkte, spektrochemische Untersuchung von Ldsungen mit relativ hohem Salzgehalt dureh Eindampfen eines Lijsungsvolumens auf emer Metallelektrode und anschliessende Anregung im Funken, Abreissbogen oder Dauerbogen stijsst im allgemeinen auf Schwierigk&en, da die entstandenen Salzkruaten nicht feat auf den Elektroden haften und bei der DIE
* This paper was completid m 1963,but hae been wlthheld until now, for teohmcal rcaaons 396
London
SPECTROCHEMICAL
NOTES
Determination of tin in bismuth ILANA LEVITAN Wemnann Imtltute of Scmnce, Rehovoth, Ismel (Remud
10 Odober 1966)
Ah&a&--A method IEdescribed for the dete rmmatlon of 0 01 to 1 00 per cent of tm in bismuth. Analyses may be carried out with samples as small as 0.02 g. IlltTOdUCtiOIl A RELIABLE and rapid method for the determination of tin in bismuth was called for m connection with studies of conductivity and galvanomagnetic effects 111smgle cry&& of bismuth-tin. The crystals were prepared 1n the Solid State Laboratory of the Weizmann Institute. They took the form of rods, normally about 1 mm diameter by 5 mm in length, but occasionally only half this size. The range of concentrations of interest was from 0.01 to 1.00 per cent of tin in bismuth. RAIKEBAKJM [l] has reported on the analysis of lead-bismuth-tin alloys His method mvolved total combustion of the sample in a d c. arc, and gave satisfactory results for concentrations of tm between 3 and 97 per cent in the alloy However, the method is not applicable to alloys containing a very small t1n content
Ekperimental The spectrum was excited by a high-voltage condensed spark with the sample supported on a 6Gmm hameter graphte electrode Considerable attention had to be paid to the form of the latter. If the electrode had the usual shape of a shallow cup, it was found that the force of the discharge elected the specimen before 1t had properly melted If, on the other hand, the specimen werg placed 1n a deep cup in order to avoid this, it would not melt, and the spectrum would not appear Accordingly for each m&vidual sample a separate electrode was prepared, having a shallow cylinhcal recess of a diameter slightly less than the length of the crystal. The latter was then placed horizontally on the electrode and forced into the recess by applymg pressure By these means 1t was held f%rmly until fused by the discharge The counter electrodes were of the same diameter, 6.5 mm, and pointed The spark-gap was 4 mm. The exposures were 20 set in duration. Samplea melted 1n as little aa one second after the initiation of the discharge, and accordingly exposures were made without preliminary sparking. Standards were prepared from spectroscopically pure bismuth and tm. The metals were placed in small Pyrex tubes and fused in an induction furnace. In order to assure a homogeneous alloy and to avoid crystallization, the specimen was agitated vigorously during the entire period of fusion and resolidification. The process was carried out in vacuum to avoid oxidation. A satisfactory pair of analysis lines was found to be Sn-3034.12 A and B1-3034.87 A. 395
Sipeetrochemical notes
The lines were of equal intensity for an alloy conteinmg about O-14 per cent tm, under the experimental conditions used. This value fell neatly within the range of concentrations of interest to us. The plate calibration ww carried out with a six-step neutral filter A working curve is shown in Fig. 1.
001
005
01
Porconi
05
IO
Sn
Ftg. 1. Workmg curve for the determmatlon of tm m buunuth.
The principal items of the equipment were aa follows. Source: ARL spark unit Model 4. Spectrogra,ph: Hilger E-478 Littrow, with quartz prism. Photographic plate: Word ordinary. [l] RAIKHBAUM, Ya. D.;
Zavodekaycc Lab.
1939, 8 1101.
Eine Kapillarelektrode aus Metall zur direkten, spektmchemischen Untmsuchung von Likmngen H. J. EIOEEO~~ und K. PIUARD* Anorganisch-Chemleches Instltut der Uruver&&t Mamz Abatr&-Description of a mvestig&iona of solutions.
simple arrangement of metal electrodes for direct speotrochemmal
direkte, spektrochemische Untersuchung von Ldsungen mit relativ hohem Salzgehalt dureh Eindampfen eines Lijsungsvolumens auf emer Metallelektrode und anschliessende Anregung im Funken, Abreissbogen oder Dauerbogen stijsst im allgemeinen auf Schwierigk&en, da die entstandenen Salzkruaten nicht feat auf den Elektroden haften und bei der DIE
* This paper was completid m 1963,but hae been wlthheld until now, for teohmcal rcaaons 396