US2911376A - Activating material for electrodes in electric discharge devices - Google Patents

Activating material for electrodes in electric discharge devices Download PDF

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Publication number
US2911376A
US2911376A US316359A US31635952A US2911376A US 2911376 A US2911376 A US 2911376A US 316359 A US316359 A US 316359A US 31635952 A US31635952 A US 31635952A US 2911376 A US2911376 A US 2911376A
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United States
Prior art keywords
electrodes
mole
baceo
firing
cerate
Prior art date
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Expired - Lifetime
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US316359A
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English (en)
Inventor
Rudolph Joseph
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.)
Osram GmbH
Original Assignee
Patent Treuhand Gesellschaft fuer Elektrische Gluehlampen mbH
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J61/00—Gas-discharge or vapour-discharge lamps
    • H01J61/02—Details
    • H01J61/04—Electrodes; Screens; Shields
    • H01J61/06—Main electrodes
    • H01J61/067—Main electrodes for low-pressure discharge lamps
    • H01J61/0675—Main electrodes for low-pressure discharge lamps characterised by the material of the electrode
    • H01J61/0677—Main electrodes for low-pressure discharge lamps characterised by the material of the electrode characterised by the electron emissive material
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J1/00—Details of electrodes, of magnetic control means, of screens, or of the mounting or spacing thereof, common to two or more basic types of discharge tubes or lamps
    • H01J1/02—Main electrodes
    • H01J1/13—Solid thermionic cathodes
    • H01J1/14—Solid thermionic cathodes characterised by the material
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J17/00—Gas-filled discharge tubes with solid cathode
    • H01J17/02—Details
    • H01J17/04—Electrodes; Screens
    • H01J17/06—Cathodes
    • H01J17/066—Cold cathodes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J61/00—Gas-discharge or vapour-discharge lamps
    • H01J61/02—Details
    • H01J61/04—Electrodes; Screens; Shields
    • H01J61/06—Main electrodes
    • H01J61/067—Main electrodes for low-pressure discharge lamps
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J9/00—Apparatus or processes specially adapted for the manufacture, installation, removal, maintenance of electric discharge tubes, discharge lamps, or parts thereof; Recovery of material from discharge tubes or lamps
    • H01J9/02—Manufacture of electrodes or electrode systems
    • H01J9/04—Manufacture of electrodes or electrode systems of thermionic cathodes
    • H01J9/042—Manufacture, activation of the emissive part
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J2893/00—Discharge tubes and lamps
    • H01J2893/0064—Tubes with cold main electrodes (including cold cathodes)
    • H01J2893/0065—Electrode systems
    • H01J2893/0066—Construction, material, support, protection and temperature regulation of electrodes; Electrode cups

Definitions

  • the oxides of the activating metals as barium oxide and strontium oxide are produced by thermic treatment from other compounds of the alkaline earths, for instance from carbonates or from the super oxides after their introduction into the discharge devices.
  • thermic treatment of the carbonates takes place 'by increased discharge currents on the electrodes, e.g. on the iron cylinders.
  • the required glow temperature of more than 1000 C. cannot be reached in consequence of the easy vaporizibility and danger of sputtering so that, therefore, often a complete decomposition of the carbonates and an unsufiicient activation result.
  • Carbonates being uncompletely decomposed may cause during the burning hours of a lamp the already mentioned gas development of the electrodes, spotting and darkening of the luminescent coating, e.g. because mercury compounds are formed.
  • an object of this invention is that activating materials and methods of their manufacture have been discovered which do not have the above described disadvantages, but have a durable partly reduced conductive form in the air and a good ability to adhere.
  • the activating material according to this invention consists completely or partly in a partly reduced chemical compound of an oxide of an alkaline earth metal with an oxide of rare earths, especially Ce, or of Sn or Ti respectively or of a mixture of the oxides of the said elements.
  • the activating material contains preferably barium-cerate, BaCeO which particularly has a perovskite structure.
  • the activating material is suitably produced as a semi-conductor by thermic reducing treatment, preferably in hydrogen outside the discharge device.
  • Reduced BaCeO has a durable, partly reduced conductive form in the air, similar to titanates crystallizing in perovskite lattice too.
  • activated BaO is not stable in the air because it is able to react with oxygen or carbonic acid respectively or with water vapour, whereas for instance activated BaCeO does not change its stability in the air at normal temperatures.
  • the activated state maybe impressed to the material by reducing firing from the ited States Patent 0 trodes will be very much facilitated because these additions of getter metals are gettering away any oxygen adhering to the material.
  • themethod of manufacture of the activating material according to this invention will be in such manner that the oxide of an alkaline earth metal is mixed well together with an oxide of rare earths, especially Ce, or of Sn or Ti respectively, or with.
  • an activating material Will be used which consists only of the partly reduced Ba-cerate according to this invention.
  • the idea of this invention is also used when employing any activating material according to this invention containing also other activating substances already known though the above mentioned bad influences are present partly.
  • the fluorine-containing Ba-cerates will be produced most suitably by firing a compound of 1 mol BaCeO produced according to the above mentioned method, with x mol CeO and x mol BaF whereby x may be 0.01 to 1, preferably 0.1 to 0.3, for 2 to 3 hours in H at 1350 to 1400 C.
  • x may be 0.01 to 1, preferably 0.1 to 0.3, for 2 to 3 hours in H at 1350 to 1400 C.
  • a good mixing of the materials is necessary which will be reached in the best way by grinding in the ball mill.
  • a further method of manufacture is to fire 2 mol BaCeO with x mol BaCO and x mol CeF under the same conditions whereby x may again vary within the above mentioned limits. According to both the methods a dark coloured crystalline material with perovskite lattice structure will be obtained.
  • An activating material is suitably used in the form of an emulsion of the finest ground activating powder in alcohol, acetone, butylacetate or other suitable organic liquids without or with organic binders as coating paste for cold cathodes or hot cathodes inlow pressure discharge lamps.
  • barium cerate especially for cold cathodes because the firing process by means of discharge current heating is omitted which only is to be regulated with difficulties.
  • the reduction of the cathode drop to be obtained is as great with the BaCeO and with the 13210203 1 as with the best oxide pastes.
  • the cathode drop amounts in both cases to about 85 to 95 volts.
  • the BaCeO has real advantages. For instance the ability of the cerate to adhere on the metallic bases, e.g. tungsten coils, is greater than that of the BaO which is very much loosened in consequence of the gas development during the thermic decomposition of the carbonates.
  • the cathode drop of the cerate in the hot cathode is also of the same size as that in the best oxide hot cathodes. It lies between and volts.
  • the barium cerate may be used also in the form of sintered compact pieces (rods) with or without metallic enclosure as hot cathode (supply cathode) in discharge devices.
  • This form proved very suitable for cold starting slimline lamps because the material hardly sputters and as shown by tests can endure more than 400,000 cold startings.
  • no binders e.g. nitrocellulose etc., are to be employed which always would involve impurities by coal residues or carbon compounds at decomposition.
  • a thermic decomposition is not necessary so that a generation of gas will be avoided in the discharge device. Therefore, no loosening of the layers arises caused by the generation of gas, as in the case of BaO.
  • the life of the cerate cathode is very good because the stability of the BaCeO and especially that of the BaCe(O ,F,) is great and because the speed of evaporation is reduced in consequence of forming compounds. Owing to the fact that no decomposing gases are generated when using Ba-cerate the spotting, caused often by uncomplete decomposition when using BaCo or E210 and the darkening of the luminescent layer, because a mercury compound is formed, are prevented. The decrease in the brightness during life, especially in luminiscent tubes, is much lower than in tubes having otherwise activated electrodes.
  • Figure 1 is an elevational view, with parts in axial section, of a discharge device embodying my invention.
  • Figure 2 is a view similar to Figure 1, but showing a modification.
  • Figure 3 is a much enlarged axial sectional view of a modified form of electrode, which may be used in a discharge device such as shown in Figure 1 or Figure 2.
  • Fig. 1 shows a discharge tube 1 of glass on each end of which an electrode 2 is provided consisting of an iron sheet metal cylinder closed as usual on the one side.
  • the leading-in wires 3 of the electrode cylinders 2, serving likewise as supports for them, are also sealed-in in the stems of the discharge tube in a well-known manner.
  • the inner wall of the electrode cylinder is coated with an activating material 4 according to this invention, e.g. barium-cerate (BaCeO which is applied to the wall of the electrode in the form of an emulsion in alcohol.
  • the discharge tube 1 is filled with rare gas, e.g.
  • the inner wall of the discharge tube is still provided with a luminescent layer 5, e.g. of Mg-wolframate, Zn-Be-silicate or of any mixture of luminescent materials, to obtain the color radiation desired.
  • the gas pressure may be about 4 to 8 millimeters and the current intensity of the surface of the electrodes about 20 ma./cm. and more.
  • a hollow cylinder electrode may be loaded with about 200 ma. and more if it is closed at the one end and having a diameter of 10 mm. at a length of 30 mm. and an activating material according to this invention, e.g. BaCeO on the inner wall.
  • Fig. 2 shows a discharge tube 6 with hot cathodes 7 (one of them in sectional view) consisting of little hollow metal cylinders 8, e.g. of molybdenum or nickel, in the inner space of which is to be found the activating ma terial 9 according to this invention, eg., barium-cerate, in the form of strong compressed powder or in the form of a suitable sintered cerate pill.
  • the metallic cylinders 8 may have for instance a length of 10 mm., an inner -diameter of 1 mm. and a wall thickness of 0.1 mm.
  • the current loading power of these electrodes operating already at small surges (of about ma.) as hot cathodes may vary within the limits of about to 500 ma.
  • the discharge moves completely into the inner space of the electrodes.
  • the metallic cylinder itself does not glow or only a little during operation.
  • the current loading power of the electrode towards smaller or greater currents over the above mentioned current loading may be still increased by changing the diameter and the wall thickness of the metallic cylinder towards smaller or greater values than stated.
  • the cathode drop lies at 16 volts at currents of 150 ma., at about 12 volts at currents of 500 ma.
  • the gas filling of the discharge tube may here also amount to about 4 to 8 millimeters and the inner wall may be provided with a luminescent coating 5 according to the example given in Fig. 1.
  • Fig. 3 shows a further modified form of a cathode with the activating material according to this invention in a very much enlarged scale of 20:1.
  • the fluorinecontaining barium-cerate body 12 according to this invention is provided in a metallic electrode cap 11. in our example the barium-cerate body 12 fits into a groove of the electrode cap 11 and is held by a metallic holding body 13.
  • the electrode cap 11 suitably fits with the opening towards the stem of the lamp which is not shown in the drawing.
  • the dimensions and accommodations of the activating material of the form of the electrodes etc. may be similar to those as shown in the examples of the Figs. 1 and 2.
  • the electrode cap 11 may have for instance a diameter of 5 mm., a length of 4 mm., and a height of 1 mm.
  • the loading power of these electrodes operating also as hot cathodes already at small currents (of about 150 ma.), may vary within the limits of about 150 to 500 ma.
  • the discharge moves completely into the inner space of the electrodes.
  • the metallic cylinder itself will not glow or only a little during operation.
  • the metallic holding body 13 may favourably consist of thin molybdenum sheet because it rises to higher temperatures.
  • the inner wall of the discharge tube not shown in the drawing may be provided with a luminescent layer, e.g.
  • the method of preparing an electron-emissive material for electric-discharge devices comprising thoroughly admixing together the following constituents in the indicated molar ratios: two moles BaCeO x mole BaCO and x mole CeF where x is from 0.1 to 0.3; then firing said admixture in an air atmosphere at from 1200 to 1400 C. for about two to three hours; and thereafter firing said admixture at from 1350 to 1400 C. in a hydrogen atmosphere for from two to three hours.

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Discharge Lamp (AREA)
  • Vibration Dampers (AREA)
US316359A 1951-11-01 1952-10-23 Activating material for electrodes in electric discharge devices Expired - Lifetime US2911376A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE314128X 1951-11-01
DE111052X 1952-10-11

Publications (1)

Publication Number Publication Date
US2911376A true US2911376A (en) 1959-11-03

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US316359A Expired - Lifetime US2911376A (en) 1951-11-01 1952-10-23 Activating material for electrodes in electric discharge devices

Country Status (7)

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US (1) US2911376A (en(2012))
BE (1) BE515205A (en(2012))
CH (2) CH111052A (en(2012))
DE (1) DE944621C (en(2012))
FR (1) FR1065061A (en(2012))
GB (1) GB740456A (en(2012))
NL (2) NL91686C (en(2012))

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4158153A (en) * 1978-01-23 1979-06-12 Eckberg Edwin E Low voltage fluorescent lamp having a plurality of cathode means
US4321503A (en) * 1978-11-06 1982-03-23 Westinghouse Electric Corp. HID Lamp electrode comprising barium-calcium niobate or tantalate
US5744905A (en) * 1994-12-23 1998-04-28 Philips Electronics North America Corporation Emission materials for discharge lamps and method for manufacturing electrode structures with such materials
US5905339A (en) * 1995-12-29 1999-05-18 Philips Electronics North America Corporation Gas discharge lamp having an electrode with a low heat capacity tip
US5982097A (en) * 1995-12-29 1999-11-09 Philips Electronics North America Corporation Hollow electrodes for low pressure discharge lamps, particularly narrow diameter fluorescent and neon lamps and lamps containing the same
US6037714A (en) * 1995-09-19 2000-03-14 Philips Electronics North America Corporation Hollow electrodes for low pressure discharge lamps, particularly narrow diameter fluorescent and neon lamps and lamps containing the same
US20030122109A1 (en) * 2001-12-26 2003-07-03 Seung-Youl Kang Blue phosphor for fluorescent display and method for synthesizing the same
WO2008151670A1 (de) * 2007-06-14 2008-12-18 Osram Gesellschaft mit beschränkter Haftung Verfahren zur herstellung eines elektrisch leitenden hohlkörpers für den lampenbau und zugehörige lampe

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2980617A (en) * 1956-03-13 1961-04-18 Indiana General Corp Ferrite compositions and method of making same
DE1157411B (de) * 1959-10-22 1963-11-14 Leybolds Nachfolger E Luftbestaendige Gluehkathode fuer Ionisationsmanometerroehren

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2147447A (en) * 1936-09-21 1939-02-14 Siemens Ag Glow cathode
US2249672A (en) * 1936-12-10 1941-07-15 Gen Electric Discharge device
US2447038A (en) * 1945-10-31 1948-08-17 Raytheon Mfg Co Cathode structure
US2477279A (en) * 1946-09-11 1949-07-26 Hanovia Chemical & Mfg Co Electrical discharge device
US2586768A (en) * 1949-02-24 1952-02-26 Driver Harris Co Vacuum tube electrode element
US2661336A (en) * 1948-11-17 1953-12-01 Rca Corp Getter material for electron discharge devices
US2663816A (en) * 1949-09-28 1953-12-22 Sylvania Electric Prod Electric discharge lamp

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE858738C (de) * 1941-03-24 1952-12-08 Telefunken Gmbh Pulverfoermiger, nicht verdampfender Fangstoff fuer elektrische Entladungsgefaesse
DE875695C (de) * 1945-02-03 1953-05-04 Lorenz C Ag Mischgetter fuer die Hochvakuumtechnik
DE823909C (de) * 1950-05-28 1951-12-06 Hoerner Fa Eugen Elektrode fuer Entladungsroehren
CH301568A (de) * 1951-09-06 1954-09-15 Izzolampa Egysult Getterstoff und Verfahren zu dessen Herstellung.

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2147447A (en) * 1936-09-21 1939-02-14 Siemens Ag Glow cathode
US2249672A (en) * 1936-12-10 1941-07-15 Gen Electric Discharge device
US2447038A (en) * 1945-10-31 1948-08-17 Raytheon Mfg Co Cathode structure
US2477279A (en) * 1946-09-11 1949-07-26 Hanovia Chemical & Mfg Co Electrical discharge device
US2661336A (en) * 1948-11-17 1953-12-01 Rca Corp Getter material for electron discharge devices
US2586768A (en) * 1949-02-24 1952-02-26 Driver Harris Co Vacuum tube electrode element
US2663816A (en) * 1949-09-28 1953-12-22 Sylvania Electric Prod Electric discharge lamp

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4158153A (en) * 1978-01-23 1979-06-12 Eckberg Edwin E Low voltage fluorescent lamp having a plurality of cathode means
US4321503A (en) * 1978-11-06 1982-03-23 Westinghouse Electric Corp. HID Lamp electrode comprising barium-calcium niobate or tantalate
US5744905A (en) * 1994-12-23 1998-04-28 Philips Electronics North America Corporation Emission materials for discharge lamps and method for manufacturing electrode structures with such materials
US6037714A (en) * 1995-09-19 2000-03-14 Philips Electronics North America Corporation Hollow electrodes for low pressure discharge lamps, particularly narrow diameter fluorescent and neon lamps and lamps containing the same
US5905339A (en) * 1995-12-29 1999-05-18 Philips Electronics North America Corporation Gas discharge lamp having an electrode with a low heat capacity tip
US5982097A (en) * 1995-12-29 1999-11-09 Philips Electronics North America Corporation Hollow electrodes for low pressure discharge lamps, particularly narrow diameter fluorescent and neon lamps and lamps containing the same
US20030122109A1 (en) * 2001-12-26 2003-07-03 Seung-Youl Kang Blue phosphor for fluorescent display and method for synthesizing the same
US6866796B2 (en) * 2001-12-26 2005-03-15 Electronics And Telecommunications Research Institute Blue phosphor for fluorescent display and method for synthesizing the same
WO2008151670A1 (de) * 2007-06-14 2008-12-18 Osram Gesellschaft mit beschränkter Haftung Verfahren zur herstellung eines elektrisch leitenden hohlkörpers für den lampenbau und zugehörige lampe

Also Published As

Publication number Publication date
FR1065061A (fr) 1954-05-20
GB740456A (en) 1955-11-16
DE944621C (de) 1956-06-28
NL91686C (en(2012))
NL173358B (nl)
BE515205A (en(2012))
CH314128A (de) 1956-05-31
CH111052A (de) 1925-07-16

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