chemical physics of discharges - Argonne National Laboratory
chemical physics of discharges - Argonne National Laboratory chemical physics of discharges - Argonne National Laboratory
-4:c~rciiny to recent studies o ;i42 flame mechanisms, hydrogen atoms are m>zs?Iit i_n the methane-air flame as well as in the hydrogen flame (15). This it aypna!-eC! reasonable to search for phosphors that candoluminesce in th3 :?,t!isnL7-air flame. This search and the study of the characteristl-s of this phmonenon were the objectives of our investigation. ?.!-I; c pial s R-rc zarthc: vere obtaineci as ?..?.'?:I pure oxides from Lindsay i Ci?c.:-:iccl Pivision of Amrican lotash and Chemical Corporation. Other zhmi. :?-ls vert rcsearch grade. Ca1ci.w OxiSe Phosphors I Calcium and rare .earth nitrate solutions were prepared and mixed in the required amounts. The mixed nitrate solution was slowly poured intc hot mionium carbonate solution with stirring. The precipitate vas Cilt:?md, mshed vitli hot ammonium carbonate solution, dried at 13C)°C, and ignited at 900°C for 30 minutes. -The pure rare earth oxides :wr? prcpared by precipitation from the nitrate in the same manner. ! Yttrium Europium Tunastate - (YO. ~Euo. I)PO~WO~ - and Gadolinium Europ.i.um Molybdate - ( Gdo. &uo. 1 >Os. Mooa T!ie required amounts of the oxides (tungstic acid in the case of tjqsten) wme mixed, heated in a platinum crucible at 1000°C for 2 hours, :-round with mortar and pestle, and reheated at 1000°C for 2 hours. The X-ray patterns of the two-products showed that in both a new phase had been .formed. Screcninp; Tests I Mounting strips about 2 cm wide and 10 em long were made of insulating fire brick and of copper sheet. Phosphor powder, thick enough to hide ' the surface of the strip, was pressed on to it with a spatula. The ' nearl:i vertical face of the strip was observed as it was passed through a methane-air flame (bunsen burner) and a hydrogen diffusion flame in a dark room. ( Spectra Thrne different methods of mounting the phosphors were used in obtainiw the spectra. When we wished to observe the effect of temperature, the phosphor was applied as a paste to a silicon carbide rod. Pastes made with monomethyl ester of ethylene glycol seemed to adhere after drying somewhat better than those made with other liquids. The silicon carbide rod, about 6 mm in diameter, was held between two vater-cooled electrical terminals to allow the electrical current passing between the terminals to heat the silicon carbide rod and the phosphor. iYhen hydrogen was used as a fuel, the phosphor could be coated dry on the fritted disk of a Gas-dispersion tube. The fritted disk was operated as a porous-plat€ burner (Figure 1) without p-imary air. Knoiin ai-,o~ints of other gases could be added to the hydrogen. I I \ I ,( I 1 I b
I I 1 543 - , The phosphor ijas coated on a water-cooled eo r plate when a methane-air flame was to be used. The plate was 1 in. square x l/$ in. thick wit!i trro l/k-in. copper tubes soldered to the back for cooling water. Plating the face with silver was found to be necessary to prevent slow Poisoiling of the phosphor by the copper. The phosphor vas settled onto the plate from a water suspension. The plate was mounted facing upwards at about 45' to the horizontal and the flame of a 1 National Welding Equipment Go. Type-3A blowpipe was d3,rected downward jonto it. I A Beckmail DK-2 spectrophotometer with an IP 28 photomultiplier was used to record spectra. The backplate of the lamp housing was removed to al1o:s direct entrance of the radiation from the excited phosphor into the spectrophotometer. A slit opening of 0.4 mm without an aux- iliary light-gathering system gave sufficient enera. Varying light intensity Prom the flickering of the flame was troublesome and made it necessary to use the highest time constant and the slowest recording rete of the instrument. The porous-plate burner gave the steadiest radiation. RZSULTS Screening tests to discover phosphors that candoluminesce in methaneair flames or in hydrogen flames were run on a number of commercial phosphors and on others prepared in our laboratories. The latter were principally rare earths - pure and in calcium oxide. The phosphors were spread on fire-brick slabs and on copper strips - the latter to hold down the temperature of the phosphor at least momentarily - and , tested by impi,agement in both hydrogen and methane-air flames. Sev- , eral phosphors that candolumenesce in both flames irere found. Detailed results are shown in Tables 1 and 2. These results should be regarded as tentatlve rather than conclusive. A few additional phosphors not listed in the tables were tested. ' Three General Electric silver-activated zinc sulfides (NOS. 118-2-3, 118-2-11, and 118-3-1) showed emission in the blue. Their spectra, abtained with a hydrogen diffusion flame on a fritted glass disk, showed that the emission was the band spectrum of S2 and that no cando- )luminescence was present (6). The S2 was undoubtedly formed by decom- position of the phosphor. Zinc sulfide activated by silver and cop er showed both candoluminescence and the band spectrum of S2 (Figure 27. A boron nitride sample from Carborundum' Co., Electronics Division showed weak, green luminescence in hydrogen and methane flames. Two recently developed rare earth phosphors, (YO. s EUO. 1)203-W03 and ( Gdo. eEuo. 2) 203- MOOS were prepared and tested (4) . Both luminesced red in hydrogen and metharle flames on the fire-brick strip. , Light emission in some of the screening tests may have had a source other than candoluminescence. The emission from magnesium germanate ,was probably thermal. This is indicated by the color of the emission (vhite to yellowish white), by the absence of a maximum of emission intensity vith increasing temperature of the phosphor, and by equal mission \?hen the phosphor is heated to the same temperature with or eithout the flame. For this test, the phosphor was mounted on the electrically neated silicon carbide rod, and temperature equivalence 'was indicated by the emission of the phosphor at 2.25 microns. Light J ! I
- Page 496 and 497: 492 found at 5.7 and 4.9& for the W
- Page 498 and 499: 494 mechanisms. However, the voltad
- Page 500 and 501: For pure polynuclcar arom.i;ic hydr
- Page 502 and 503: - '-'. . ' . . values are listed in
- Page 504 and 505: 500 (1;) Ten, T. 17.: a;1d,Dic;
- Page 506 and 507: - ~ Resistivity Czlculation 2: 1 j:
- Page 508 and 509: 504 o ' C 0s 2 0 v x i 8 2 0 ! P -
- Page 510 and 511: 506 i
- Page 512 and 513: d 601 L P LL
- Page 516 and 517: I I I I I I I I m W N W N 0 (D ? 0
- Page 518 and 519: 514 was heated under nitrogen in a
- Page 520 and 521: The line broadening at 79OK of the
- Page 522 and 523: 13. 14. 15. 16. 17. 18. 19. 20. 21.
- Page 524 and 525: W L, Z 6 m (1: 0 6 d j o 2 ' 1 0.0
- Page 526 and 527: Coals 522 Studies of the 1600 cm-l
- Page 528 and 529: L in ole i c a c id - 0' Two sample
- Page 530 and 531: 526 Table 1.- Ultimate analyses of
- Page 532 and 533: 528 6. Friedel, R. A., and H. Retco
- Page 534 and 535: egeneration. The system can be seen
- Page 536 and 537: 532 and can be expressed in terms o
- Page 538 and 539: 534 in the vapor increases with inc
- Page 540 and 541: NH3 NH3 NH3 NH3 Pyridine Pyridine P
- Page 542 and 543: Mole Ratio of Test No. Quinoline to
- Page 544 and 545: IXPROFJCTION D; M. Mason Institute
- Page 548 and 549: 544 Table 1. LIGHT EMISSION OF Y"TR
- Page 550 and 551: emission in a few cases may be by d
- Page 552 and 553: LITERATUR2 CITED i. C. -. .' * il.
- Page 554 and 555: co, CH,,OR 1 - OTHER ADDITIVE FRITT
- Page 556 and 557: FRIT 'TED CO, CH,.OR 4 ___ OTHER AD
- Page 558 and 559: 340 350 300 400 4 50 500 600 700 80
- Page 560 and 561: 0 554 WITH COOLING (PLATE AT 40°C)
- Page 562 and 563: 5 56 then t = to when e = 0 2) the
- Page 564 and 565: 5 58 The surface heat transfer coef
- Page 566 and 567: Discussion and Results 560 Three br
- Page 568 and 569: __- ._ 562 Table I THERMAL AND PHYS
- Page 570: ln 4 I 0 4J v \ 1.0 0.8 0.6 L - 0.4
-4:c~rciiny to recent studies o ;i42 flame mechanisms, hydrogen atoms are<br />
m>zs?Iit i_n the methane-air flame as well as in the hydrogen flame (15).<br />
This it aypna!-eC! reasonable to search for phosphors that candoluminesce<br />
in th3 :?,t!isnL7-air flame. This search and the study <strong>of</strong> the characteristl-s<br />
<strong>of</strong> this phmonenon were the objectives <strong>of</strong> our investigation.<br />
?.!-I; c pial s<br />
R-rc zarthc: vere obtaineci as ?..?.'?:I pure oxides from Lindsay i<br />
Ci?c.:-:iccl Pivision <strong>of</strong> Amrican lotash and Chemical Corporation. Other<br />
zhmi. :?-ls vert rcsearch grade.<br />
Ca1ci.w OxiSe Phosphors<br />
I Calcium and rare .earth nitrate solutions were prepared and mixed<br />
in the required amounts. The mixed nitrate solution was slowly poured<br />
intc hot mionium carbonate solution with stirring. The precipitate<br />
vas Cilt:?md, mshed vitli hot ammonium carbonate solution, dried at<br />
13C)°C, and ignited at 900°C for 30 minutes. -The pure rare earth oxides<br />
:wr? prcpared by precipitation from the nitrate in the same manner. !<br />
Yttrium Europium Tunastate - (YO. ~Euo. I)PO~WO~ - and Gadolinium<br />
Europ.i.um Molybdate - ( Gdo. &uo. 1 >Os. Mooa<br />
T!ie required amounts <strong>of</strong> the oxides (tungstic acid in the case <strong>of</strong><br />
tjqsten) wme mixed, heated in a platinum crucible at 1000°C for 2<br />
hours, :-round with mortar and pestle, and reheated at 1000°C for 2<br />
hours. The X-ray patterns <strong>of</strong> the two-products showed that in both a<br />
new phase had been .formed.<br />
Screcninp; Tests<br />
I<br />
Mounting strips about 2 cm wide and 10 em long were made <strong>of</strong> insulating<br />
fire brick and <strong>of</strong> copper sheet. Phosphor powder, thick enough to hide '<br />
the surface <strong>of</strong> the strip, was pressed on to it with a spatula. The '<br />
nearl:i vertical face <strong>of</strong> the strip was observed as it was passed through<br />
a methane-air flame (bunsen burner) and a hydrogen diffusion flame in<br />
a dark room. (<br />
Spectra<br />
Thrne different methods <strong>of</strong> mounting the phosphors were used in<br />
obtainiw the spectra. When we wished to observe the effect <strong>of</strong> temperature,<br />
the phosphor was applied as a paste to a silicon carbide rod.<br />
Pastes made with monomethyl ester <strong>of</strong> ethylene glycol seemed to adhere<br />
after drying somewhat better than those made with other liquids. The<br />
silicon carbide rod, about 6 mm in diameter, was held between two<br />
vater-cooled electrical terminals to allow the electrical current<br />
passing between the terminals to heat the silicon carbide rod and the<br />
phosphor.<br />
iYhen hydrogen was used as a fuel, the phosphor could be coated dry<br />
on the fritted disk <strong>of</strong> a Gas-dispersion tube. The fritted disk was<br />
operated as a porous-plat€ burner (Figure 1) without p-imary air.<br />
Knoiin ai-,o~ints <strong>of</strong> other gases could be added to the hydrogen.<br />
I<br />
I<br />
\<br />
I<br />
,(<br />
I<br />
1<br />
I<br />
b
Change language