Slide sem t

1
Szczecin
May, 7 2007
RADIATION DEFECTS AND OXIDATION STATE OF nl- IONS
IN NON-STOICHIOMETRICAL OXIDES
Nicolay A. Kulagin
Kharkiv National University for Radio
Electronics, av. Shakespeare 6-48, Kharkiv 61045,
Ukraine. E-mail nkulagin_at_bestnet.kharkov.ua ,
kulagin_at_kture.kharkov.ua
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Outline of the talk

• Radiation stimulated by X rays, gamma, electrons
  and particles charges transfer in
  oxides sapphire, garnets, perovskites
• Optical absorption, luminescence, EPR and
  TSL-TSC spectra of irradiative oxides doped with
  nd- and nf- ions
• - X Ray spectra and oxidation state of component
  and doped nl- ions
• Ab initio energy calculations for doped and
  radiation clusters and unit defects
• Electronic state stability of doped nl- ions
  under radiation of oxides
• Change of oxides surface under plasma treatment
  quasi-ordered nano-scale structures
• Shot summary

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Growth and Treatment

• The main methods of crystallization of the oxide
  single crystals
• Czochralsky - Cz Verneuil - V
• Method of horizontal and vertical crystallization
  - DC
• Stepanov S, etc.
• Mixtures of different quality and different
  concentration - C of accidental impurities were
  used for oxides crystals growth
• super- pure (C lt10-5 wt ),
• pure (C lt10-3 wt ), and
• standard one ((C lt10-2 wt )
• Thermal treatments and co-doping by Ca, Mg
• O2, 1200 ltT lt1800 K
• CO2, 1500 ltT lt1800 K
• vacuum, 10-5 Torr, 1500 ltT lt1900 K

4
Pure Sapphire Al2O3

• Optical absorption of sapphire grown by different
  methods

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Pure Sapphire
Al2O3
TABLE. Spectral parameters of the sapphire grown
by different techniques
Sample Abs.edge nm Optical Bands, nm AA bands nm TL, 320-420 nm TSC peaks T, K TL bands nm
V 195 206, 225, 260, 400 570 206, 225, 280, 475 - 388, 578 690
Vp 142 175, 206, 230, 400 206, 225, 280, 475 4 385, 560 507 320, 690 690
Vsp 142 185,206, 230 No AA 0.1 430, 507 560 420, - 690
DC 145 175, 206 235 206, 230 no TL 398, 507 -
DCr 142 175, 206, 235 206, 230 280, 470 8 373, 506, 565 320, 420 690
Czr 143 180, 206 206, 475 2 430, 580 320, 420 420, 690
Cr 142 198, 225 No AA no TL 387, 426 485 - -
Sr 142 175, 206 230 206, 230 1 390,418, 430, 506 420 -
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Ruby Radiation Effect
Optical absorption of ruby Al2O3Cr
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Structure and Defects
Simplified garnet structure
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Pure Garnet

• Optical absorption of pure YAG crystals grown by
  Chochralsky 1 and HDC methods

9
Optics of Y3Al5O12NdCr Garnets Radiation
Effect
Optical absorption of YAG before and after
irradiation
10
TSL TSC spectra for YAG pure and doped with
CrNd
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ESR of Cr3 ion in Garnet
EPR spectra of Cr3 ions in YAG crystals
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Optics of GSGG and GSAG Garnets doped with Cr
and Ca
OAS of doped garnets before and after thermal
treatment
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Optics of YAGV3 Thermal Treatment
OAS spectra of V3 ions in YAG crystals
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Theoretical Results - Cr3O-26 Cluster under
Pressure

• Table 2. Theoretical values of radial
  integrals for Cr3 ions in
• Cr3O-26 clusters for different R

Integral Free ion / R 2.1 Free ion / R 2.1 1.96 1.9 1.8 1.5
Configuration 3d3 Configuration 3d3 Configuration 3d3 Configuration 3d3 Configuration 3d3 Configuration 3d3 Configuration 3d3
F2(3d,3d), cm-1 87080 72010 58644 50932 45863 44795
F4(3d,3d), cm-1 54582 42380 35644 30881 27796 29599
?(3d), cm-1 290.9 245.1 220.2 194.8 167.5 74.9
(3dr3d ), a.u. 1.093 1.351 1.561 1.721 1.839 2.100
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Theoretical Results - Cr3O-26 Cluster, Ruby
and YAG

• Table1. Dependence of Cr3 ions energy
  levels on R Cr-O (cm-1)

RCr-O(Å)\ Level 2E 2T1 4T2 2T2 4T1(t22e) 4T1(t2e2)
Theory R 2.0 Å 14850 15652 16500 22171 24229 37661
1.96 14220 14969 18100 21538 25811 40324
1.9 12500 13113 20500 19392 27659 44176
Ruby
Experiment 14433 15087 18133 21318 24767 39067
Semiempirical 14354 14989 18108 21355 24843 39362
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Theoretical Results - Cr3O-26

• Table 3. Semiempirical and theoretical data for
  B, C and Dq for Cr3 ions in different crystals
  (cm-1)

Integral ?-Al2O3 Y3Al5O12 Gd3Sc5O12 Gd3Sc2Ga3O12 Cr3O-26
B 682 725 740 740 789
C 3120 3373 3578 3578 2829
Dq 1787 1650 1500 1500 1750
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Theoretical Results - 3d2 configuration of
Cr4O-26
Table 4. Theoretical level scheme for ion Cr4
in ruby (Dq 1990 cm-1, B 1050 cm-1 and C
3873 cm-1)
2S1G(t,e) level Energy, cm-1 2S1G(t,e)- level Energy,cm-1
3T1(t22) 0 1T2(t2e) 34909
1E(t22) 15002 3A2(e2) 38391
1T2(t22) 15618 1T1(t2e) 38391
3T2(t2e) 18045 1E(e2) 54429
1A1(t22) 30962 1A1(e2) 75683
3T1(t2e) 31939
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Optics of Garnets Cr4 Energy Levels Schemes
Y3Al5O12 Y3Al5O12 Gd3Sc2Ga3O12 Gd3Sc2Ga3O12
2S1G ?theor, nm ?exp, nm ?theor, nm ?exp, nm
3A2 - - - -
1E 10950 11000 847 -
3T2 964 964 1052 1052
3T1 640 640 661 600
1A1 627 - 507 504
1T2 517 - 475 504
1T1 453 - 407 410
3T1 410 - 410 410
TABLE 10. Energy levels of Cr4O2-4 cluster
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Perovskites ABO3

• LiNbO3Cr -gt
• A - Li, B Nb5
• YAlO3Cr/Nd -gt
• A Y3, B Al3
• SrTiO3V, Mn, Fe, Co, Ni / Pr, Nd, Sm, Tm
• A Sr2 (RE2, 3),
• B Ti4 (Me2, 3, 4)

• 
  Simplified structure of perovskite

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Perovskite - YAlO3CrNd
OAS spectra of Cr3 ions in YAlO3 crystals
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Perovskite SrTiO3 Optical Absorption

• Optical absorption of SrTiO3 crystals.
• Pure (1) and blue sample (2) a, crystals doped
  with RE b (1 - Sm, 2 Pr, 3 Nd, 4 Tm)

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Dielecrical Properties of SrTiO3
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Dielecrical Properties of SrTiO3
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Structure and Defects in SrTiO3

• Energy zones of a wide band gap crystal with
  different transitions and local levels

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X Ray Lines of nlN Ions

• X Ray lines Ka1 1s1/2 2p3/2
  transition
• nl-1nlN- La1 2p3/2 3d5/2
  transition
• configurations
• nl- level nlJ-
  spin-orbit level
• 3d
  --------------------- 3d5/2
• 
  --------------------- 3d3/2
• --------------------- 2p3/2
• 2p
• 
  --------------------- 2p1/2
• 1s
• 
  1s1/2

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X Ray Microanalysor
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CrKa- Line Valency Shift for Irradiated Ruby
and Garnet
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Perovskite SrTiO3 X Ray
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Energy of X Ray of RE and AC ions
RE E (K?1 ) E(K?1) E(L?1)
Nd 2 37337,290 42250,942 5370,471
Nd 3 37336,610 42248,875 5369,708
Nd 4 37335,741 42246,471 5368,449
Eu2 40071,174 45371,500 5852,357
Eu3 40070,420 45369,567 5848,793
Eu4 40069,405 45367,192 5847,622
Gd2 42921,661 48620,131 6062,622
Gd2 42920,521 48618,235 6063,971
Gd2 42920,118 48615,998 6060,614
Yb2 52156,939 58580,850 7421,563
Yb3 52155,897 58578,564 7426,668
Yb4 52155,007 58576,031 7429,100
U2 95912,345 108809,007 13639,793
U3 95912,037 108808,394 13639,528
U4 95911,663 108807,659 13639,200
Np2 98307,960 111517,588 13970,953
Np3 98307,642 111516,963 13970,674
Np4 98307,262 111516,221 13970,346



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K?1- line K?1- line K?1- line K?1- line L?1- line L?1- line L?1- line
Ion E0 a -b E0 a -b
Ac 88951.080 0.431 0.070 12671,789 0,424 0.052
Th 91233.519 0.467 0.034 12989,542 0,326 0.032
Pa 93553.072 0.540 0.034 13311,565 0,479 0.030
U 95910.145 0.605 0.033 13637,868 0,539 0.029
Np 98305.122 0.659 0.032 13968,481 0,580 0.028
Pu 100738,542 0,691 0,031 14303,356 0,640 0.027
Am 103210,648 0,724 0,030 14641,226 0,682 0.026
Cm 105721,613 0,767 0,028 14986,249 0,711 0.025
Bk 108272,134 0,826 0,026 15334,323 0,728 0.023
Cf 110862,572 0,882 0,025 15686,806 0,740 0.021
Es 113493,397 0,920 0,024 16043,560 0,784 0.021
Fm 116165,234 0,935 0,023 16405,048 0,790 0.020
Md 118877,847 0,977 0,022 16770,396 0,851 0.020
No 124428,762 1,035 0,021 17140,694 0,875 0.019
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SEM Picture after SrTiO3Sm Plasma Treatment
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SEM Picture after SrTiO3Tm Plasma Treatment
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SEM Picture after SrTiO3Nd Plasma Treatment
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3D- AFM Picture after SrTiO3Sm Plasma Treatment
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3D-AFM Picture after SrTiO3 Ni Plasma Treatment
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Energy Levels Scheme Parametrization of nl(f)-
Ions
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Theoretical Foundations
Free Ions HFP approach
Doped Crystals HL-SCF for Clusters
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Theoretical Foundations Ions and Hamiltonians
Ion nlN Me 3dN, RE - 4fN, AC - 5fN gt
ME The main configurations nlN and
nlNnlN Cluster MEn Lk.
Ligand O-2, F-, Cl- etc

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Theoretical Foundations Energy of Cluster



,


,
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Theoretical Foundations Radial Integrals
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Theoretical Results - 3d24p configuration of
Cr3 in Cr3O-26
Integral Free / R(Å) 2.1 Free / R(Å) 2.1 Free / R(Å) 2.1 1.96 1.9 1.8 1.5
Configuration 3d24p Configuration 3d24p Configuration 3d24p Configuration 3d24p Configuration 3d24p Configuration 3d24p Configuration 3d24p Configuration 3d24p
F0(3d,4p), cm-1 F0(3d,4p), cm-1 91284 65490 69606 71629 74294
F2(3d,4p), cm-1 F2(3d,4p), cm-1 22295 9455 12485 14705 21010
G1(3d,4p), cm-1 G1(3d,4p), cm-1 7778 2513 4924 7046 14430
G3(3d,4p),cm-1 G3(3d,4p),cm-1 7193 2001 3838 5471 11135
?(3d), cm-1 ?(3d), cm-1 331.9 322.1 303.8 288.7 238.1
?(4p), cm-1 ?(4p), cm-1 642.0 97.6 129.6 153.3 198.8
(3dr3d) a.u. (3dr3d) a.u. 1.018 1.064 1.148 1.219 1.474
(4pr4p) a.u. (4pr4p) a.u. 2.734 3.538 3.314 3.210 3.045
(4pr4p) a.u. (4pr4p) a.u. 2.734 3.538 3.314 3.210 3.045
?E(3d33d24p), eV ?E(3d33d24p), eV 17.8 21.8 16.1 9.9 11.6
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Self Consistent Field Equations for nl-Ions in
Solids
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Self-Consistent Potential for nl-Ions in Solids
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Self Consistent Field Equations for nl-Ions
in Solids
Boundary conditions P(nlr) r ?8 ? 0 - for
unit center or impurity ion Wigner-Zeits
conditions ?P(nlr)/?r r?R ? 0 for cluster
and crystal
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SCF Potential and Radial Wave Functions for nf-
Ions
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Short Summary

• Ab initio study of the electronic structure
  of MEnLk-clusters and energy of X-ray lines
  is a powerful and effective method of
  investigation of foundations of doped materials.
  This method and optical spectra of nl- ions in
  oxides - on the one hand and study of the
  influence of irradiation or thermal treatment to
  crystals doped with d- or/and f ions on the other
  hand allow to explain of the nature of radiation
  defects into doped oxides and draw the simple
  conclusion that stability of the oxidation state
  of ions in crystals is determined relation of
  energy of ionization of MEn ion I Me and
  Madelung's constant aM - SZi/ri for the cation
  site.

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Concluding Remarks

• Crystals growth method determines the main
  defects of the
• oxides through crystals stoichiometry

• Crystals stoichiometry determines electronic
  state and ions
• valency and properties of the oxide single
  crystals, too

• Relation A/O changes
• for simple oxides up 0.95 to 0.99
• for garnet crystals A/B changes up 0.9 to 0.98
• for perovskites - 0.8 0.98 (A1-xB1-yO3-z)
• Value of A/O and A/B is determined by
  possibility of the
• regular nd and nf ions to change their
  valency.
• We can used non-stoichiometry oxides for
  expansion of area of employment of the pure and
  doped single crystals