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Processing ZnS based electroluminescent precursor powder mixtures with
Processing ZnS based electroluminescent precursor powder mixtures with
Outline
Outline
Display Technology
Display Technology
Electroluminescence
Electroluminescence
Electroluminescent material search
Electroluminescent material search
Patent Application Information US patent application pub#
Patent Application Information US patent application pub#
Explosive Chamber (patent info)
Explosive Chamber (patent info)
Concerns due to limited information in the Patent
Concerns due to limited information in the Patent
Final Material Processing
Final Material Processing
Increased Luminosity
Increased Luminosity
Zinc Sulfide
Zinc Sulfide
Photoluminescence of Zinc Sulfide after Dynamic Compression
Photoluminescence of Zinc Sulfide after Dynamic Compression
Shock Assisted Doping
Shock Assisted Doping
Explosive Doping
Explosive Doping
Explosive Doping Literature
Explosive Doping Literature
Hypothesis of patent mechanism
Hypothesis of patent mechanism
Experimental Procedure
Experimental Procedure
Heating the TNT
Heating the TNT
Video of TNT burning
Video of TNT burning
Frame 1
Frame 1
Frame 2
Frame 2
Mixing of TNT and ZnS
Mixing of TNT and ZnS
Conclusions
Conclusions
Future Work
Future Work
Starting Materials (patent info)
Starting Materials (patent info)
Comparative Sample A
Comparative Sample A
Luminance
Luminance
EL Element
EL Element

Презентация на тему: «Processing ZnS based electroluminescent precursor powder mixtures with TNT». Автор: Greg Kennedy. Файл: «Processing ZnS based electroluminescent precursor powder mixtures with TNT.ppt». Размер zip-архива: 1161 КБ.

Processing ZnS based electroluminescent precursor powder mixtures with TNT

содержание презентации «Processing ZnS based electroluminescent precursor powder mixtures with TNT.ppt»
СлайдТекст
1 Processing ZnS based electroluminescent precursor powder mixtures with

Processing ZnS based electroluminescent precursor powder mixtures with

TNT

5/9/2008

Greg Kennedy and S. Itoh

2 Outline

Outline

Introduction Electroluminescence Summary of patent application US patent application pub# (20070080327) European Union Patent (WO2007043676) Investigation of the process ZnS explosive processing literature Preliminary experiments Conclusions and Future Work

3 Display Technology

Display Technology

EL-11 inch 3mm $2500

LCD

Plasma

4 Electroluminescence

Electroluminescence

Examples of different wavelengths obtained by doping

5 Electroluminescent material search

Electroluminescent material search

The research has been financed by companies in a very competitive and fast growing field Most publicly available information is found in patents and patent applications Look at one recent patent and some older published works

6 Patent Application Information US patent application pub#

Patent Application Information US patent application pub#

(20070080327)

Starting Materials Primarily ZnS, (Zinc Sulfide) Mn and Ir (activators, emission centers) Ba and Mg Explosive Chamber discussion Final heat treatment Gallium Arsenide compound semiconductor Standard manufacturing of EL element

7 Explosive Chamber (patent info)

Explosive Chamber (patent info)

0.01mmHg vacuum (~1Pa) 32g TNT selected for 50MPa in one liter chamber TNT is exploded by heater (4) upon heating to 450?C ~109g Sample mixture(8) is placed under TNT Produced “calcined cake”

8 Concerns due to limited information in the Patent

Concerns due to limited information in the Patent

Is the explosive separated from the sample? Does the TNT detonate by heating? Does the TNT melt, boil before detonation? How does the vacuum change the detonation process? What is heating rate? Controls temperature of the powder And detonation of TNT Maybe electric detonator is ok, but heating of powder might be necessary for desired final performance

9 Final Material Processing

Final Material Processing

(patent info)

Sample B

Sample C

Explosive Loading “Calcined cake” is allowed to cool Washed with deionized water, Dried Pulverizer/Separator powder (5-20µm) 0.005g GaAs mixed with 15g of powder in mechanical stirrer 8 hours Calcining in nitrogen atmosphere at 700?C in a silica tube Washed with glacial acetic acid Remove excessive compounds, flux and impurities Rinsed with deionized water

Explosive loading “Calcined cake” is allowed to cool Washed with deionized water, Dried Pulverizer/Separator powder (5-20µm) 8 hours Calcining in nitrogen atmosphere at 700?C in a silica tube Washed with glacial acetic acid Remove excessive compounds, flux and impurities Rinsed with deionized water

10 Increased Luminosity

Increased Luminosity

Increased from 400 to 4000 cd/m^2 “The reason for the excellent properties … is due to instantaneous high temperature, light emission and/or shock wave produced by the explosion. However, particulars of the mechanism for the development of such favorable properties are still unknown.”

*Patent application US2007/0080327A1

11 Zinc Sulfide

Zinc Sulfide

Sphalerite Cubic Band Gap 3.54eV

Wurtzite Hexagonal Band Gap 3.67eV

Phase Change ---> 1019?C

High pressure phase change to a different Rock Salt type structure 15GPa Mashimo (1999)

12 Photoluminescence of Zinc Sulfide after Dynamic Compression

Photoluminescence of Zinc Sulfide after Dynamic Compression

Pure ZnS does not exhibit photoluminescence, but after dynamic compaction bright photoluminescence occurs due to microdefects created by shock loading Phase change from sphalerite to wurtzite Fluorescence microscopic observation showed blue particles and green particles Blue particle concentration can be increased by adding sulphur The increase in Zn vacancies from the increase in sulphur causes an increase in photoluminescence intensity Photoluminscence is reduced after roasting shock loaded sample *Batsonov, Fizika Goreniya I Vzryva, Vol. 3, No. 3, pp441-448 1967

13 Shock Assisted Doping

Shock Assisted Doping

Efficient process Vacancies and interstitials Heterogeneous distribution of defects Heterovalent doping is possible Eu2+ in NaCl type systems (example) Create charge defects

Lapshin and Kurnikova, ZPS, Vol 28. No1, 95-100, Jan. 1978

14 Explosive Doping

Explosive Doping

*Lapshin, et. al, ZPS, vol 14, no 6, 1020-1026, June 1971

Emission bands are shifted to longer wavelengths compared to thermally processed materials Same occurs in thermally produced material after shock loading The chemical form of the can change the wavelength MnS emission band at 589µm Mn(NO3)2 demission at 570µm Inhomogeneous phase transformation of cubic and hexagonal phase generates large number of defects Emission bands are wider than thermally produced ZnS:Cu Traps are formed, causing long time phosphorescence

15 Explosive Doping Literature

Explosive Doping Literature

Pre-shock starting material before firing 8GPa Detonating pressure from tetryl Fired for 2hrs at 1250oC The pre-shocked sample had 40% increased intensity with slight shift to shorter wavelengths under excitation by 254µm source

*Horiguchi - Pre-shock Treatment for Preparation of Zn2SiO4(Mn) Phosphor having High Luminescence Intensity, Naturwissenschaften (1966)

16 Hypothesis of patent mechanism

Hypothesis of patent mechanism

The TNT is heated to 450oC Melting point 80.9oC Boiling Point 295oC Location for Temperature not described TNT Melts, then boils The boiling tnt mixes with EL powder Vapor evolves and is ignited by the hot nichrome heater wire Localized heating causes deflagration in the TNT

17 Experimental Procedure

Experimental Procedure

Heat the TNT to 450 and test for deflagration or detonation Examine mixing of liquid TNT and precursor powder Test the powder for exothermic reaction upon heating to 450 (thermal analyzer) Duplicate the patent experiment Initiation of deflagration by heated wire Heating from the base by heater external to the powder container

18 Heating the TNT

Heating the TNT

19 Video of TNT burning

Video of TNT burning

20 Frame 1

Frame 1

21 Frame 2

Frame 2

22 Mixing of TNT and ZnS

Mixing of TNT and ZnS

Examine the possibility of mixing of the TNT and precursor powders Nichrome wire heater in plaster 10grams of ZnS 20grams TNT Glass container video

23 Conclusions

Conclusions

TNT deflagrates upon heating There is no explosion as described in the patent Heating the TNT and the powder can lead to extensive mixing This would allow good heat transfer to the precursor powder and promote localized doping

24 Future Work

Future Work

Using the observations from this work Proceed to examine the powder mixture described in the Chatani Patent

25 Starting Materials (patent info)

Starting Materials (patent info)

Sample A -conventional method Sample B ZnS 100g MnSO4 0.27g ZnO 0.5g BaF2 3g MgCl2 3g IrCl3 0.012g NaCl 2g Sample C 15g of Sample B after explosive processing and pulverizing 0.005g Gallium Arsenide (1-3µm) compound Semiconductor Mechanical stirrer in plastic bottle (20 minutes)

26 Comparative Sample A

Comparative Sample A

7g ZnSO4 0.5g CuCl 0.5g CuSO4 800oC for 40 minutes From JP-A No. 2005-126465

27 Luminance

Luminance

Example 1 and 2 ,Measurement is at 280V at 8 KHz Example 3 voltage was increased to maintain constant luminance , 315 V after 24hrs, and 330 after 100 hours, stable 120 hours to 1000 hours

28 EL Element

EL Element

Silk screen of sample A, B, C onto BaTiO3 Greater than 80% of particles 12 to 18µm Barium titanate is deposited on the emitting layer Electrode is deposited on the BaTiO3

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