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GB2259098A - Electrochemical preparation of single phase lead telluride - Google Patents

Electrochemical preparation of single phase lead telluride Download PDF

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Publication number
GB2259098A
GB2259098A GB9118659A GB9118659A GB2259098A GB 2259098 A GB2259098 A GB 2259098A GB 9118659 A GB9118659 A GB 9118659A GB 9118659 A GB9118659 A GB 9118659A GB 2259098 A GB2259098 A GB 2259098A
Authority
GB
United Kingdom
Prior art keywords
lead
reaction medium
range
tellurium
sulphamate
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
GB9118659A
Other versions
GB9118659D0 (en
GB2259098B (en
Inventor
Mineo Muracki
David Michael Rowe
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
University College Cardiff Consultants Ltd
Cardiff University
JFE Steel Corp
Original Assignee
University College Cardiff Consultants Ltd
Cardiff University
Kawasaki Steel Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by University College Cardiff Consultants Ltd, Cardiff University, Kawasaki Steel Corp filed Critical University College Cardiff Consultants Ltd
Priority to GB9118659A priority Critical patent/GB2259098B/en
Publication of GB9118659D0 publication Critical patent/GB9118659D0/en
Priority to JP29896791A priority patent/JP3152976B2/en
Publication of GB2259098A publication Critical patent/GB2259098A/en
Application granted granted Critical
Publication of GB2259098B publication Critical patent/GB2259098B/en
Anticipated expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

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Classifications

    • CCHEMISTRY; METALLURGY
    • C01INORGANIC CHEMISTRY
    • C01BNON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B19/00Selenium; Tellurium; Compounds thereof
    • C01B19/007Tellurides or selenides of metals
    • CCHEMISTRY; METALLURGY
    • C25ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25BELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B1/00Electrolytic production of inorganic compounds or non-metals

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Inorganic Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Crystals, And After-Treatments Of Crystals (AREA)
  • Manufacture And Refinement Of Metals (AREA)
  • Electrodes Of Semiconductors (AREA)

Abstract

Single phase lead telluride is electrodeposited from a reaction medium containing free sulphamate ions, reactive lead species eg. lead carbonate and reactive tellurium species eg. tellurium dioxide, the deposition electrode being maintained at a potential of minus 0.25V to minus 0.4V.

Description

Preparation of Lead Telluride The present invention is concerned with a method of preparation of lead telluride.
Single phase lead telluride has a very narrow stoichiometric range (Te: 49.994 to 50.013 at 700"C) and co-existence of a second phase is easily caused by deviation from this stoichiometry. Biphasic lead telluride however has inferior mechanical and semiconductive properties compared to single phase lead telluride.
In order to try to avoid the unwanted effect of segregation on solidification, various complex methods have been suggested for the production of single phase lead telluride, such methods include melting the lead and tellurium in a sealed atmosphere, single crystal growth or rapid solidification, mechanical pulverisation, cold pressing, and sintering in a hydrogen atmosphere.
Direct alloy formation methods such as molecular beam epitaxy or chemical vapour deposition have also been suggested, but the cost of the manufacturing equipment remains expensive and the methods are therefore impractical for commercial production.
It has also been tried to electrochemically deposit tellurium alloys from aqueous solutions containing two or more metal elements. However, reports of such methods are limited, because lead readily reacts with typical electrolytes such as sulphuric acid to form insoluble compounds such as lead sulphate.
We have developed a method of electrochemically producing single phase lead telluride which alleviates the above problems.
According to the present invention, therefore, there is provided a method of preparing substantially single phase lead telluride, which method comprises:a) arranging electrodes in contact with a reaction medium comprising substantially free sulphamate ions, electrical contact being provided between said electrodes; b) contacting electrochemically reactive species comprising lead and tellurium in said reaction medium; and c) maintaining a deposition electrode at a potential in the range of about -0.25V to -0.4V (referenced to a calomel electrode) so as to produce a deposit of lead telluride.
Preferably the free sulphamate ions are initially present in the reaction medium as sulphamic acid, the concentration of the latter in the reaction medium being preferably in the range of about 0.1 to 0.4 mole/litre. It is beneficial that the above concentration range is achieved because at higher concentrations the hydrolysis of lead sulphamate becomes significant whereas at lower concentrations the product deposition rate becomes unacceptably low. The use of sulphamic acid as the electrolyte alleviates the problem of lead compound precipitation experienced with previously used electrolytes such as sulphuric acid.
It is preferred that the precursors for the reactive species comprising lead and tellurium are lead sulphamate and tellurium dioxide respectively. The lead sulphamate itself may however be produced in situ from the reaction of a suitable lead-containing reagent (such as lead carbonate) and sulphamic acid.
Preferably the lead sulphamate is included in the reaction medium at a concentration in the range of about 0.03 to 0.5 mole/litre; at higher concentrations the hydrolysis of lead sulphamate becomes significant, whereas at lower concentrations the composition uniformity of the lead telluride may be unacceptable. Preferably the tellurium dioxide is present at a concentration in the range of 0.002 to 0.05 mole/litre, in which range the reaction medium is essentially saturated with the tellurium dioxide; additional tellurium dioxide may however be added as tellurium is consumed during the reaction with lead.
Although it is generally preferred that the lead telluride is produced by the reaction of separate compounds such as lead sulphamate and tellurium dioxide as described above, it is of course envisaged that the lead telluride may be obtained from a single complex containing both lead and tellurium. In the latter case, the electrochemically reactive leaN2nd tellurium could be generated resulting from discharge and decomposition of the complex.
The deposition electrode is preferably the cathode which is typically in the form of a metal sheet; the anode is typically an insoluble anode formed from a suitable material such as graphite or platinum. As previously described the potential of the deposition electrode is maintained in the range of about -0.25V to -0.4V, because at higher potentials the concentration of lead in the deposit becomes unacceptably high, whereas at lower potentials the concentration of lead in the deposit becomes unacceptably low.
Preferably the reaction medium is maintained at a temperature in the range of about 20 to 50"C; above this temperature range the hydrolysis of lead sulphamate again becomes significant whereas below this range the deposition rate may become unacceptably slow.
It is further preferred that the reaction medium should be substantially agitated during operation of the method so as to increase the rate of deposition of the lead telluride on the electrode.
In some embodiments, it is preferred that a dopant should be added to the reaction medium so as to improve the resulting semi-conductive properties of the product.
Typical dopants include oxides of silver, tin, indium, or bismuth. The semi-conductive properties of the product may alternatively or additionally be modified by controlling the lead/telluride ratio present in the product. Tertiary or quaternary lead telluride may also be deposited by controlling the concentration of ions present in the reaction medium.
The invention will now be further illustrated by the following example which does not limit the scope of the invention in any way.
Example The following components were mixed together in the order specified:a) 7.5g of sulphamic acid dissolved in 150ml of distilled water; b) lOg of lead carbonate; and c) 7.5g of sulphamic acid.
The mixture was then filtered and 100mg of tellurium dioxide was then added.
The resultant mixture contained 0.26 mole/litre of free sulphamic acid, 0.26 mole/litre of lead sulphamate and 0.002 mole/litre of tellurium.
A finely polished copper sheet exposing 2x2cm area for deposition was used as the cathode, and a graphite plate was used as the insoluble anode. The cathode potential was kept at - 0.35V (referenced to a saturated calomel electrode) and the temperature was maintained at 350C.
A cathode current density of 0.6mA/cm2 was measured and maintained at this value for about 30 minutes until a deposit analysed to be 50% lead, 50% telluride was obtained.

Claims (15)

Claims:
1. A method of preparing substantially single phase lead telluride, which method comprises: a) arranging electrodes in contact with a reaction medium comprising substantially free sulphamate ions, electrical contact being provided between said electrodes; b) contacting electrochemically reactive species comprising lead and tellurium in said reaction medium; and c) maintaining a deposition electrode at a potential in the range of minus 0.25V to minus 0.4V so as to produce a deposit of lead telluride.
2. A method according to claim 1, wherein the free sulphamate ions are initially present in the reaction medium as sulphamic acid.
3. A method according to claim 2, wherein the sulphamic acid concentration in the reaction medium is in the range of 0.1 to 0.4 mole/litre.
4. A method according to any of claims 1 to 3, wherein the reactive species comprising lead is lead sulphamate, or precursor reagents therefor.
5. A method according to claim 4, wherein the lead sulphamate is included in the reaction medium at a concentration in the range of 0.03 to 0.5 mole/litre.
6. A method according to claim 4, wherein said precursor reagents comprise lead carbonate and sulphamic acid.
7. A method according to any of claims 1 to 6, wherein said reactive species comprising tellurium is tellurium dioxide.
8. A method according to claim 7, wherein said tellurium dioxide is present at a concentration in the range of 0.002 to 0.05 mole/litre.
9. A method according to any of claims 1 to 8, wherein said deposition electrode is the cathode.
10. A method according to any of claims 1 to 9, wherein the anode comprises graphite or platinum.
11. A method according to any of claims 1 to 10, wherein said reaction medium is maintained at a temperature in the range of 20 to SOOC.
12. A method according to any of claims 1 to 11, wherein said reaction medium is substantially agitated.
13. A method according to any of claims 1 to 12, wherein a dopant is added to the reaction medium.
14. A method according to claim 13, wherein said dopant includes one or more oxide of silver, tin, indium or bismuth.
15. A method substantially as described herein, as illustrated by the Example.
GB9118659A 1991-08-30 1991-08-30 Preparation of lead telluride Expired - Fee Related GB2259098B (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
GB9118659A GB2259098B (en) 1991-08-30 1991-08-30 Preparation of lead telluride
JP29896791A JP3152976B2 (en) 1991-08-30 1991-11-14 Method for manufacturing lead telluride semiconductor

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB9118659A GB2259098B (en) 1991-08-30 1991-08-30 Preparation of lead telluride

Publications (3)

Publication Number Publication Date
GB9118659D0 GB9118659D0 (en) 1991-10-16
GB2259098A true GB2259098A (en) 1993-03-03
GB2259098B GB2259098B (en) 1995-01-18

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Family Applications (1)

Application Number Title Priority Date Filing Date
GB9118659A Expired - Fee Related GB2259098B (en) 1991-08-30 1991-08-30 Preparation of lead telluride

Country Status (2)

Country Link
JP (1) JP3152976B2 (en)
GB (1) GB2259098B (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2005114755A3 (en) * 2004-05-18 2006-05-11 Basf Ag Tellurides having novel property combinations

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6603173B1 (en) 1991-07-26 2003-08-05 Denso Corporation Vertical type MOSFET

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3887446A (en) * 1974-07-26 1975-06-03 Us Navy Electrochemical preparation of metallic tellurides
JPS50122892A (en) * 1974-03-14 1975-09-26
GB2006268A (en) * 1977-10-14 1979-05-02 Univ Queensland Preparation of semiconductor films on electrically conductive substrates
SU1516929A1 (en) * 1988-01-29 1989-10-23 Московский химико-технологический институт им.Д.И.Менделеева Method of producing semiconductor sensitive elements for gas analysis

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS50122892A (en) * 1974-03-14 1975-09-26
US3887446A (en) * 1974-07-26 1975-06-03 Us Navy Electrochemical preparation of metallic tellurides
GB2006268A (en) * 1977-10-14 1979-05-02 Univ Queensland Preparation of semiconductor films on electrically conductive substrates
SU1516929A1 (en) * 1988-01-29 1989-10-23 Московский химико-технологический институт им.Д.И.Менделеева Method of producing semiconductor sensitive elements for gas analysis

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2005114755A3 (en) * 2004-05-18 2006-05-11 Basf Ag Tellurides having novel property combinations

Also Published As

Publication number Publication date
GB9118659D0 (en) 1991-10-16
GB2259098B (en) 1995-01-18
JPH0558796A (en) 1993-03-09
JP3152976B2 (en) 2001-04-03

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PCNP Patent ceased through non-payment of renewal fee

Effective date: 19990830