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1 PREPARATION OF MONODISPERSED PARTICLES CONTROLLED IN SIZE AND SHAPE 1 [email protected]

2 LaMer ITO Indium Tin Oxides 2

3 3 Basic concept For preparation of monodispersed particles

4 Stöber silica Widely used indutraially 4

5 Monodispersed particles Particles with uniformity in size, shape, structure, composition, etc. Within ca. 10 % in standard deviation of size. Since monodispersed particles have homogeneous character, they have highly function. For example, in the case of hematite α-fe 2 O 3, in spite of dark red for random particle system, it become yellow by μm in size and ellipsoid in shape, in contrast to blight red for platelet-type particles in the same hematite. 5

6 LaMer Model 6

7 For monodispersed particles 7

8 Basic concepts for monodispersed particle formation 1. Separation of nucleation and particle growth 2. Inhibition of aggregation between particles 3. Storing monomers (T. Sugimoto, Adv. Colloid Interface Sci. 28, 65 (1987).) 8

9 Separation of nucleation and particle growth Control for degree of supersaturation In dilute system or reservoir system Generally supersaturation for homogeneous nucleation is larger than that for heterogenous one. Control of nucleation period Period of nucleation should be shortened compare with particle growth. 9

10 Strict inhibition of aggregation Dilute system Electrostatic repulsion, which inhibits aggregation, becomes larger in lower electrolyte concentration. Protective colloids Specific adsorption onto surfaces Fixing particles Blocking Brownian motion by fixing them 10

11 Storing monomers Reservoir Oxide particles O supplied from water as a reservoir, which is uncontrollable. Hence, metallic ion reservoir should be controlled. Metallic particles Metal one has extremely low solubility in any solvent. Some devices are required for the furhter growth Supply from the outside Double-jet method for AgBr, AgCl etc. 11

12 12 Formation mechanism Don t determine growth mechanism, only judging from TEM photos.

13 13

14 Inside of CdS 14

15 15

16 16

17 17

18 18 Sol-gel method Stöber method to prepare silica particles

19 Stöber Silica 19

20 Sol-Gel method Metal alkoxide as a starting material is hydrolyzed to give sol in rather mild conditions. Since gel is finally obtained via sol phase, Gel-Sol is called. For monodispersed particle production, we stop at the sol phase. Si(-O-C 2 H 5 ) 4 + 2H 2 O Ł SiO 2 + 4C 2 H 5 OH 20

21 Stöber silica sol Main preparation conditions TEOS=Tetraethylorthosili cate, Si(-O-C 2 H 5 ) mol/l Solvent = ethanol NH 3 cat. =1 10 mol/l H2O= mol/l Temp.=

22 Sol by Sol-Gel method TiO 2, ZrO 2 etc. Due to lower temperature, particles always show amorphous. For industrial use, thermal treatment at high temp. is sometimes required. Amorphous spherical SiO2: W. Stöber, A. Fink, and E. Bohn: J. Colloid Interface Sci. 26, (1968) 62. TiO2: E.A. Barringer and H.K. Bowen: J. Am. Ceram. Soc. 67 (1984) C-113. E. A. Barringer, N. Jubb, B. Fegley, Jr., R. L. Pober, and H. K. Bowen: in "Ultrastructure Processing of Ceramics, Glasses, and Composites," (L. L. Hench and D. R. Ulrich, Eds.), pp Wiley, New York, B. Fegley, Jr., E. A. Barringer, and H. K. Bowen: J. Am. Ceram. Soc. 67, (1984) C-113. ZrO2: K. Uchiyama, T. Ogihara, T. Ikemoto, N. Mizutani, and M. Kato: J. Mater. Sci. 22, (1987) T. Ogihara, N. Mizutani, and M. Kato: Ceram. Intern. 13, (1987) 35. PZT: T. Ogihara, H. Kaneko, N. Mizutani, and M. Kato: J. Mater. Sci. Lett. 7, (1988) 867. H. Hirashima, E. Onishi, and M. Nakagawa: J. Non- Cryst. Solids 121, (1990)

23 The other monodispersed particle formation system Dilute system Matijevic Colloids Poly-styrene latex Polymerization Emulsion Soap-free Etc. 23

24 LaMer ITO Indium Tin Oxides 24

25 Gel-Sol method 25

26 Monodispersed Hematite prepared by Gel-sol method a) b) c) 26

27 Monodispersed CdS, CdS, and Cu 2 O a) b) c) 27

28 Difference between Sol-gel and Gel-sol method 28

29 Gel-sol method 29

30 Hematite Particle Synthesis 30

31 Gel-sol method for hematite 31

32 Gel-Sol Method Basic concept for the Gel-Sol method. 32

33 LaMer ITO Indium Tin Oxides 33

34 Uniform Titania Particles 34

35 Gel-Sol Process Titanium(IV) isopropoxide (TIPO) [Ti(OC 3 H 7 ) 4 ] Triethanolamine (TEOA) [N(C 2 H 4 OH) 3 ] TIPO:TEOA = 1:2 ([TIPO] 0 = 0.25 mol dm -3 ) C 2 H 4 O OH 4 C 2 Stable complex N C 2 H 4 O Ti OH 4 C 2 N C 2 H 4 O Ti OH 4 C 2 N C 2 H 4 O OH 4 C 2 C 2 H 4 OH H 2 O (+HClO 4 or + NaOH) Ti(OH) 4 gel 1st aging (100, 1 day) 2nd aging (140, 3 days) Shape controller TiO 2 (anatase) 35

36 Titania formation 36

37 Formation Mechanism of Titania 37

38 Concentration changes of TiO 2, Ti(OH) 4, and supernatant Ti 4+ species during the 2nd aging (ph = 10) Concentration (mol dm -3 ) TiO 2 Ti(OH) 4 Supernatant Ti 4+ species Time (h) Phase transformation: Ti(OH) 4 TiO 2 38

39 Effect of ph on the particle size and shape of TiO 2 Ellipsoidal particles No change from gel 39

40 Shape Control Effect of DETA on the shape of TiO 2 particles [DETA] = M DETA CH 2 CH 2 NH 2 NH CH 2 CH 2 NH M 0.25 M [TIPO] 0 = 0.25 M, [TEOA] = 0.50 M; ph nm 40

41 Shape control of TiO 2 particles by the addition of amines Primary Amines Secondary Amines Tertiary Amines (a) ED 0.20M (b) TMD 0.05M (a) (C 2 H 5 ) 2 NH 0.05M (a) (CH 3 ) 3 N 0.50M (c) DETA 0.05M (d) TETA 0.05M (b) (C 2 H 5 ) 2 NH 0.20M (b) (C 2 H 5 ) 3 N 0.20M ED: NH 2 (CH 3 ) 2 NH 2 TMD: NH 2 (CH 2 ) 3 NH 2 DETA: NH 2 (CH 2 ) 2 NH(CH 2 ) 2 NH 2 TETA: NH 2 (CH 2 ) 2 NH(CH 2 ) 2 NH(CH 2 ) 2 NH nm 41

42 Effect of Na oleate on the shape of TiO 2 particles [Na oleate] = M [TIPO] 0 = 0.10 M, [TEOA] = 0.20 M; ph nm Na oleate = CH 3 (CH 2 ) 7 CH=CH(CH 2 ) 7 COONa 42

43 Synthesis of Monodispersed Anisotropic TiO 2 Particles Gel-Sol Method: Particle Preparation Technique by using Metal Hydroxide Gels Synthesis of Monodispersed Anisotropic TiO 2 Particles 100 C 140 C 24 h Ti(OPr i ) 4 Stabilizer (N(CH 2 CH 2 OH) 3 ) Shape Controller (Amine, Amino Acid) ph Controller Gel Formation by H-Bonding Network of Ti(OH) 4 Sol Formation by Crystal Growth T. Sugimoto, Monodispersed Particles, Elsevier, Amsterdam, K. Kanie and T. Sugimoto, Chem. Commun., 2004,

44 Anisotropic TiO 2 Particles Obtained by the Gel-Sol Method Ethylenediamine Init ph: 10.5 Ethylenediamine Init ph: 10.5, Seeds Succinic Acid Init ph: 10.5 Gluconic Acid Init ph: 9.5 Glutamic Acid Init ph: 10.5 Oleic Acid Init ph: 11.5 none Init ph: 10.5 Oleic Acid Init ph: 9.9 T. Sugimoto, X. Zhou, and A. Muramatsu, J. Colloid Interface Sci., 259, 53 (2003). K. Kanie and T. Sugimoto, Chem. Commun., 2004,

45 Shape Control by Amines and Oleate Amines Parallel to C-axis Olate Organic Amines Adsorb on TiO 2 Surfaces Utilization for Organic-Inorganic Hybridization 45

46 1.The uniform anatase-type TiO 2 nanoparticles are formed by phase transformation of Ti(OH) 4 gel matrix. 2.Triethanolamine (TEOA) is adsorbed to growing TiO 2 particles at ph above 11, and change the morphology from cuboidal to ellipsoidal. The shape control can be explained in terms of the specific adsorption of TEOA to the crystal planes parallel to the c-axis of the tetragonal system. 3.Shape controllers modifies the particle shape to desired one. 46

47 LaMer ITO Indium Tin Oxides 47

48 48 Size-controlled hydrothermal synthesis of Bismuth Sodium & Bismuth Potassium titanates fine particles as lead-free piezoelectric ceramics K. Kanie, A. Muramatsu Tohoku Univ.

49 NEDO Project First Stage BaTiO 3, Bi 0.5 Na 0.5 TiO 3 (BNT), Bi 0.5 K 0.5 TiO 3 (BKT) Development of Lead-free Piezoelectric Ceramic Actuators Tohoku Univ., Fuji Ceramics, etc. The first target is BaTiO 3, which has been prepared in liquid-phase to control the size, shape, crystallinity in nano-scale. The second target is BNT and BKT. NEDO = New Energy and Industrial Technology Development Organization [one of independent administrative institutions in Japan] 49

50 Upstream Nanoparticle production NEDO Project Second Stage Nanotechnology Development of High Performance Lead-free Piezoelectric Actuators Actuator technology Practical application Company 1 Company 2 Companies 3, 4 Automobile Company Nanomaterial Different field Ceramics Different field Electronics and optical devices, Automobile Tohoku Univ. Layered ceramics Na x K 1-x NbO 3 (NKN), NaNbO 3 (NN), KNbO 3 (KN) Piezoelectric Devices Down stream Vertical Cooperation is composed of companies with different fields. 50

51 Synthesis method of BaTiO 3 /SrTiO 3 fine particles H) 3 gel-sol method Schematic drawing of reaction vessel (autoclave) Our First Trial! 51

52 1 BaTiO 3 with different shape Typical Example 52

53 Time evolution 0 5 min 30 min Gel Sol This is Gel-Sol method. 200 nm 53

54 54 Experimental The Present Study Synthesis of Bismuth Sodium Titanate (BNT) Particles Reaction conditions: Ti 4+ : Ti(OiPr) 4 /N(CH 2 CH 2 OH) 3 = 1/2 Bi 3+ : Bi(OH) 3 or Bi(NO 3 ) 3 Gel Na + : NaOH or NaClO 4 Ti 4+, Bi 3+ = 0.25 M; Na + = 2.0 M in H 2 O 250 C, 3 h Sol Autoclave for the Hydrothermal Reaction

55 Results and Discussion 55 ph = 7.0 ph = 8.5 (A) ph = 7.0; (B) 8.5: Bi 2 Ti 2 O 7 (C) ph = 13.0; (D) 14.0: BNT ph = 13.0 ph = 14.0 K. Kanie, H. Sakai, J. Tani, H. Takahashi, A. Muramatsu, Mater. Trans., 48, 2174 (2007).

56 Results and Discussion 56 Bi/Ti Molar ratio = 1/2 Bi/Ti Molar ratio = 1/4 (a) BNT particle and the growth direction. (b) ED pattern of BNT shown in (a). (c) the HRTEM image. (d) EDX profile of the BNT.

57 57 BNT and BKT Fine Particle Synthesis using TiO 2 TiO mol/l Bi(OH) mol/L NaOH 1 16 mol/l KOH 1 16 mol/l Experimental Gel Mixed well Aged at 250 C for 3 days Washed by ion-exchanged water and centrifuged in 3 times Dried at 60 C Sol BNT and/or BKT particles Autoclave for the Hydrothermal Reaction

58 Results and Discussion 58 NaOH concentrations: (a) 4.0 (b) 8.0 (c) 10 (d) 12 (e) 14 (f) 16 M

59 Results and Discussion 59 KOH concentrations: (a) 4.0 (b) 8.0 (c) 10 (d) 12 (e) 14 (f) 16 M

60 60 Piezoelectric properties of ceramics prepared by using hydrothermally prepared BNT fine particles. The sintering period was adjusted to 2 hours. Sample Sintering temp. ( C) r (g/cm 3 ) tand (%) e 33 T /e 0 k p (%) d 33 (pc/n) BNT1 1 1, , , BNT2 2 1, , , BNT3 3 1, Cubic-shaped BNT finer particles; 2 Cubicshaped BNT larger particles; 3 BNT powder obtained by solid phase synthesis. The precursor of the solid phase synthesis of the BNT powder was Bi 2 O 3, Na 2 CO 3, and TiO 2. r: density; tand: tangent delta; dielectric constant: e 33T /e 0 ; coupling factor: k p ; piezoelectric constant: d 33. Results and Discussion

61 Preparation of Piezoelectric Ceramics: Utilization of Fine Particles - Problems - Difficulties in Control of the Resulting Crystallite Diameters and the Grain Boundary in Nano-scale Orientation Control of Plate-like NaNbO 3 by the Texture Treatment: Drastic Increase of the Piezoelectricity Y. Saito et al, Nature, 432, 84, (2004). BaTiO 3 Ceramic Obtained by Solid Phase Sintering Control of Nanostructures of Piezoelectric Ceramics Utilization of Shape- and Size-Controlled Fine- and Nano Particles 61

62 Hydrothermal Synthesis of Sodium Niobate NaNbO 3 Reaction conditions: Nb 5+ : Nb(OEt) 5 /N(CH 2 CH 2 OH) 3 = 1/3 Na + or K + : NaOH or KOH Nb 5+ Conc. in H 2 O: 0.25 M; 250 C, 3 h Gel Formation Aging Temperatures: (a) 100 C; (b) 150 C; (c) 200 C; (d) 250 C 100 C 150 C 200 C 250 C Gel-like Fiber 62

63 Hydrothermal Synthesis of Sodium Niobate NaNbO 3 Formation of Gel Intermediates Before Aging 15 min at 250 C 40 min 60 min Gel-like Fiber Gel-like Fiber NN Particle NN and KN Particles were Obtained by Way of Gel Intermediates 63

64 Size Control of Sodium Niobate NaNbO 3 Fine Particles Reaction conditions: Nb 5+ : 0.25 M (Nb 2 O 5 : M) NaOH: 6.0 M in H 2 O NN Seed: 1.25~7.5 mol% (based on Nb 5+ ) Aging: 3 h with Stirring A TEM Image of NN Seeds for the Preparation of Size-Controlled NN Fine Particles with Cubic Shape 64

65 Size Control of Sodium Niobate NaNbO 3 Fine Particles (a) Seed: 1.25%, 250 C; (b) Seed: 2.5%, 250 C; (c) Seed: 5.0%, 200 C; (d) Seed: 5.0%, 200 C; (e) Seed: 1.25%, 150 C; (f) Seed: 7.5%, 150 C Size Control of NN Particle within the Range from 100 nm to 2 mm can be Achieved by Seeding Technique. KN Particles, Gradually Controlled in Size, are also Fabricated by Seeding. 65

66 Direct Hydrothermal Synthesis of Na x K 1-x NbO 3 (NKN) Fine Particle Reaction conditions: Nb 5+ : NbCl 5 in 0.1 M HCl Na +, K + : 12 M NaOH, 24 M KOH Nb 5+ Conc. in H 2 O: 0.25 M; 200 C, 3 h Hierarchical Structure Na and K Ions were Uniformly Existed in Each Particles 66

67 Direct Hydrothermal Synthesis of Na x K 1-x NbO 3 (NKN) Fine Particle Piezoelectric Properties of KN Ceramics No. Sintered Temp. ( C) Density r (g/cm 3 ) tand (%) d 33 (pc/n) KN-1 1, KN-2 1, KN-3 1,

68 68

69 LaMer ITO Indium Tin Oxides 69

70 ITO ( TCO 70

71 1) 2) 3) 4) 6) 2 7) RGB 8) 71

72 72

73 ITO 3 O 2-, Wavelength [nm] = ev ( nm) = 1000 nm O 2- In 3+ O 2- e O 2- Sn 4+ O 2- In 3+ In 3+ In 3+ In 3+ O 2- O 2- O 2- O 2- O 2- e e O 2- Sn 4+ ITO ITO SnO 2 ZnO AZO 73 ITO

74 (2005) Ni 14.0 W Co 28.3 Mo 15.4 Ti 29.4 In 60.0 Pt

75 Base Metal Rare Metal In V Pt-gr. Nb Ta Li Co Re B Mo W Sb Bi Ti Zr Mn REE Th Sn Ni In Cr Cd Se Al Pb Fe Cu Zn China Russia S.A. S.A. Brazil Australia Chile China Congo Australia Cuba Chile U.S.A. Russia Turkey U.S.A. Russia China U.S.A. Chile China Canada Russia China Russia Bolivia China Peru Australia S.A. Norway S.A. Australia Ukraine Ukraine China Australia China Russia U.S.A. Australia India Norway China Malaysia Indonesia Australia Russia Cuba but Canada U.S.A. China Kazakhstan S.A. India Australia China U.S.A. Chile U.S.A. Canada Guinea Australia Jamaica Australia China Russia Australia Ukraine Chile U.S.A. Indonesia Australia China U.S.A Reserves Distribution Russia Brazil 75

76 ITO Ar + ITO 10-5 ~ 10-4 Ω cm ITO ITO 10 % ITO ITO ITO 100 % (ITO + ) 10-3 ~ 10-1 Ω cm 76

77 Ł Ł Ł Ł 77

78 78

79 79

80 / 80

81 nm ITO 81

82 82

83 83

84 84

85 ITO ITO 100nm ITO 85

86 ITO 86

87 ITO ITO 87

88 ITO ITO 100nm ITO 88

89 ITO In M 0.50 M In(NO 3 ) M NaOH 100 C, 24 h In(OH) C, 3 h In(OH) 3 SnCl 4 (In 1-10%) C 3 h In(OH) 3 ITO ITO 89

90 270 1 h Intensity[a.u.] 20 cubic In(OH) 3 cubic In 2 O θ[degree] 90

91 D. Yu, D. Wang, J. Lu, and Y. Qian, Inorganic Chemistry Communications 5, 475 (2002). J. E. Song, D. K. Lee, H. W. Kim, Y. I. Kim, and Y. S. Kang, Colloids and Surfaces A: Physicochem. Eng. Aspects 257, 539 (2005). J. E. Song, H. W. Kim, and Y. S. Kang, Current Applied Physics 6, 791 (2006). H. Xu and A. Yu, Materials Letters 61, 4043 (2007) C.-H. Han, S.-D. Han, J. Gwak, and S.P. Khatkar, Materials Letters 61, 1701 (2007) 91

92 ITO ITO Sn In(OH) 3 InOOH ITO 92

93 Experimental Procedure -Solvothermal synthesis- HO 93 Tetramethylammonium hydroxide (TMAH) (CH 3 ) 4 N OH N OH - ion resource 0.50 M InCl 3 & M SnCl 4 in Ethylene glycol (EG) solution Stirred at 0 o C 1.5 M TMAH in EG solution ([TMAH] = 1.5, 2.0, 2.5) Stirred for 15 min Put 10 ml of suspension into autoclave Aged at 250 o C, 0 ~ 96 h Washed by EtOH, H 2 O and centrifuged Products (Analysis: XRD, TEM)

94 Effect of TMAH concentration 94 Undefined shape Cubic shape coefficient of variation 16.3% 11.4% 10.7%

95 Time dependence of particles growth Reaction condition: TMAH 2.0 M, 250 o C 95

96 Macroscopic change of reaction solution Reaction condition: TMAH 2.0 M, 250 o C Initial reaction solution Yellow colored gel ITO nanoparticles o C 1 h 250 o C, 95 h Gel formation TMAH conc. 2.0, 2.5 M TMAH conc. 1.5 M NaOH system

97 High resolution TEM observation 97 HR-TEM image FT image HR-TEM image No grain boundary FT image Streaks

98 Effect of Sn concentration 98 Reaction condition : TMAH 2.0 M, 250 o C, 96 h InOOH InOOH + ITO ITO

99 Effect of Temperature 99 Reaction condition : TMAH 2.0 M, Sn/In = 0.1, 96 h

100 100 Electrical Resistivity of ITO nanoparticles Reaction condition: Base conc. 2.0 M, 250 o C, 96 h Basic agent: TMAH Basic agent: NaOH 14.0 ± 1.6 nm 11.4% Ω cm 15.1 ± 2.9 nm 19.2% Ω cm 43.5 ± 10.3 nm 23.7% Ω cm

101 101

102 TiO 2 e - ITO I 3 - I - I - I - TiO 2 I 3 - e - e - e - I I - - I - TiO 2 (Voc) 102 Band Gap Energy /ev Voc TiO 2 ZnO SnO 2 ITO ITO TiO 2 ITO = (Sn TiO 2 ITO ITO ITO * I. Hamberg and C. G. windows, J. Appl. Phys., 60 (1986) R123- R159

103 103