無容器法により合成した超高屈折率ガラスの物性と構造

無容器法により合成した 無容器法により合成した

超高屈折率ガラスの物性と構造

東京大学生産技術研究所 増野敦信

増野敦信

Collaborators

H. Inoue, K. Yoshimoto, Y. Kikuchi, T. Mizoguchi, Y. Watanabe Institute of Industrial Science, The University of Tokyof y f y J, Yu, Y. Arai, M. Kaneko

Japan Aerospace Exploration Agency (JAXA) S K h

S. Kohara

Japan Synchrotron Radiation Research Institute Y Kuroiwa C Moriyoshi

Y. Kuroiwa, C. Moriyoshi Hiroshima University K. Okajimaj

Saga-LS A. C. Hannon

ISIS F ili R h f d A l L b

ISIS Facility, Rutherford Appleton Laboratory E. Bychkov

Université du Littoral Université du Littoral

Introduction

Containerless processing

with container without container

melt melt

crystallization

9suppress heterogeneous nucleation from the container wall

9promote deeper undercooling in molten

crystallization

from the container wall materials

No crystallization

rature

T_m

rature

No crystallization

temper

ΔT~ small ^tempe

r

t₀

time t₀

time

Containerless processing on the ground

Various types of levitation furnace

Electrostatic levitation furnace Aerodynamic levitation furnace Electrostatic levitation furnace Aerodynamic levitation furnace

Electromagnetic levitation furnace Acoustic wave levitation furnace

Aerodynamic levitation furnace

CCD camera

pyrometer monitor

sample nozzle sample

PC

Beam splitter

Mass flow controller

Gas: air, oxygen, nitrogen, argon Pressure: 1 ~ 3 atm

S l i φ 1 5

CO₂laser Mass flow controller Sample size: φ = 1 ~ 5 mm

Sample weight: 10 ~ 200 mg

Ferroelectric BaTi

O

Monoclinic, a = 1.6914 nm, b = 0.3935 nm, c= 0.9412 nm b = 103.11º

Y. Akishigeet al., Jpn. J. Appl. Phys. 42, (2003) L946.

T. Akashi, et al., Mater. Trans. 44, (2003) 1644.

stable region

~10 ºC

~10 C

9High ferroelectric transition temperatureg p 9Large dielectric constant

9Colorless and transparent

N. Zhu and A. R. West, J. Am. Ceram. Soc. 93, (2010) 295.

Glass formation of ferroelectric BaTi

O

XRD, ND XANES

1.5 mm

J.Yu et al., Chem. Mater. 18, (2006) 2169.

The first time glass formation of ferroelectric titanate without any network former oxides.

RMC simulation

, , ( )

9Glass structure

Distorted TiO₅ polyhedra Edge shared polyhedra 9Crystallization process

Metastable phase formation

J.Yu et al., Chem. Mater. 21, (2009) 259.

Giant dielectric response

Metastable phase formation from BaTi

O

glass

λ= 0.4977 Å T_P3

sity

γ phase

β phase

T_g

Intens β phase

T_x1 T_x2

5 10 15 20 25

α phase

2θ(λ=04977A)

Before crystallization at 1150 K of the

bl f l i h

stable ferroelectric γ phase, two

metastable phases α (at T_x1) and β (at T_x2)

appeared in sequence. Paraelectric β phase Ferroelectric γ phase

J.Yu et al., Chem. Mater. 21, (2009) 259.

Paraelectric β phase Ferroelectric γ phase

Giant dielectric response at T

100 Hz

T_p31150 K T_p1

1001 K

T_p2 1038 K T_g

960 K

1038 K

T_cry1994 K

T_cry2 1018 K

cry1 0 8

J.Yu et al., Chem. Mater. 18, (2006) 2169.

Next step

9Optical properties Transmission Transmission Refractive index

Luminescence properties 9Glass forming region

binar (La O TiO ) binary (La₂O₃-TiO₂)

ternary (BaO-TiO₂-MO_x, La₂O₃-TiO₂-MO_x) 9Unusual crystallization process

Optical properties

Optical properties of BaTi

O

glass

100

60 80 100

ance (%)

Transmittance region of oxide glasses

Bi₂O₃

20 40 60

transmitta

Optical bandgap：3.48 eV

TeO₂ Al₂O₃ Ge₂O₃

300 400 500 600 700 800

0 20

wavelength (nm)

p g p _{2 3}

P₂O₅ B₂O₃ SiO

5000 4000 3000 2000 1000

100

wavenumber (cm^-1)

100 1000 10000

W l h ( )

SiO₂ BaTi₂O₅

60 80

ance (%)

B Ti O l f

Wavelength (nm)

20 40

transmitta

BaTi₂O₅ glass: transparent from 350 nm to 7.7 μm

2 3 4 5 6 7 8 9 10

0

wavelength (μm) A. Masuno et al., J. Appl. Phys. 108, (2010) 063520.

Refractive index of BaTi

O

glass

2.25 _2.4

BaTi₂O₅ glass

ndex 2.20 2 0

2.2

dex n D

ractive i 2.15

1.8 2.0

fractive ind

Bi, Pb, Te glasses

2.10

refr

1.4

ref 1.6

400 500 600 700

2.10

wavelength (nm)

70 60 50 40 30 20 10 1.4

Abbe number ν

9Conventional high refractive index

1 n

n_F：H F (487 nm)

Abbe number

g

glasses contain Bi, Pb, Te.

9Larger Abbe number of BaTi₂O₅ glass among high refractive index glasses

5 . 1 20

c F

d =

−

= −

n n

ν n

n_F：H F (487 nm) n_d：He d (587.6 nm)

n_c：H c (656.3 nm) A. Masuno et al., J. Appl. Phys. 108, (2010) 063520.

among high refractive index glasses

Large oxygen polarizability

N_A: Avogadro’s number

(

)

9Lorentz-Lorenz equation ^αO2-

20B₂O₃-80SiO₂ 1.434

A g

α_m: molar polarizability V_m: molar volume

( )

(

)

2O₅ 1.502

B Ti O 2 57

3/ l ^{BaTi2O5 2.57}

Silicate:30 ~ 60 cm₃/mol Borate: 25 45 cm³/mol

V_m = 22.8 cm³/mol

Quite large α_O2-

•High ionicity of oxygen

•Large contribution of electrons

9Oxygen polarizability

Borate: 25 ~ 45 cm³/mol Phosphate: 27 ~ 60 cm³/mol

(

) ( )

O^{2 2}

−

−

− ^{= α −}

∑

α around oxygen to the high

refractive index.

9Oxygen polarizability

N_O2-:number of oxygen α_Ba2+ = 1.595 (ų) α_Ti4+ = 0 184 (ų)

These features are different from conventional oxide glasses.

A. Masuno et al., J. Appl. Phys. 108, (2010) 063520.

α_Ti4+ 0.184 (Å )

∴Σαi = 0.654 (ų)

g

Origin of high refractive index

Elements in BaTi₂O₅ glass are highly ionic.

Weaken covalent bond between cations and oxygen

Larger packing density Larger packing density

Higher refractive index

Functionalization by rare-earth doping

Ba_0.7Ln_0.3Ti₂O_5.15

nit) M i

Raman scattering

nsity (arb. un Maximum

Phonon Energy 829 cm^-1

Raman inten 829 cm ¹

0 200 400 600 800 1000 1200

R

Raman shift (cm^-1)

SiO t 1100 ¹

High concentration of Ln

SiO₂ system 1100 cm^-1 B₂O₃ system 1265

P₂O₅ system 1360

High concentration of Ln ^{2 5 y}

GeO₂ system 880 TeO₂ system 800

BaTi₂O₅ 829

Upconversion of Er

doped BaTi

O

glass

980 nm B E Ti O

20 ⁴F

7/22H_11/2

4S_3/2 980 nm ~ 550 nm

x = 0.50

4S_3/2 ⁴F_9/2

Ba_1-xEr_xTi₂O_5+x/2

10 15

3/2 11/2 4F_9/2

4I_9/2

4I

03 cm-1 ) y (a. u.)

0.20 0.30 0.40

2H_11/2，⁴S_3/2 green

5

10 I_11/2

4I_13/2

Energy (10 intensity

0.05 0.10 0.20

2H_11/2

4F_9/2 red

0

E

4I_15/2

400 500 600 700 800

wavelength (nm)

0.01

Energy diagram of Er³⁺

ity (a. u.)

2H_11/2

4S_3/2

4F

Different composition

dependence Energy diagram of Er

mission intensi ^F_9/2

Different Strong upconversion luminescence ^{0.0 0.1 0.2 0.3 0.4 0.5}

em

x

process

Luminescent process of Er

doped BaTi

O

glass

9Green

ET: 2 ⁴I_11/2 → ⁴I_15/2 + ⁴F_7/2 ESA: ⁴I_11/2 +hν → ⁴F_7/2

and then

4F_7/27/2 → ²H_11/211/2 → ⁴S_3/23/2 strong luminescence in low concentration

→main process is ESA.main process is ESA.

9Red

Green process + ⁴S → ⁴F Green process + S_3/2 → F_9/2 ET: ⁴I_13/2 + ⁴I_11/2 → ⁴I_15/2 + ⁴F_9/2 ESA: ⁴I_13/2 + hν → ⁴F_9/2

t l i i hi h

strong luminescence in high concentration

→main: ⁴S_3/2 → ⁴F_9/2 and ET

ET: Energy Transfer ET: Energy Transfer

ESA: Excited State Absorption

Glass forming region

Glass forming region of Ba

A

Ti

O

Mg A = Mg，Sr: x ≤ 0.05

A = Ca: x ≤ 0.90

Ca Exceptionally large glass-forming region

of Ba_1-xCa_xTi₂O₅.

0 0 0 2 0 4 0 6 0 8 1 0

Sr

0.0 0.2 0.4 0.6 0.8 1.0

x

xAO-(1-x)B₂O₃ xAO-(1-x)P₂O₅

M xAO (1 x)B₂O₃ M xAO (1 x)P₂O₅

Almost the same regardless of the

Gl f i i

Mg

Ca Ca

Mg

Sr Sr

0.1 0.2 0.3 0.4 0.5 0.0 0.2 0.4 0.6

regardless of the alkali-earth ion substituted

Glass forming region： Mg < Ca < Sr < Ba

Sr Sr

Ba Ba

x x

O. V. Mazurin, M. V. Streltsina, T. P. Shvaiko-Shvaikovskaya (Eds.), Handbook of Glass Data, Physical Science Data 15, Part B (single-component and binary non-silicate oxide glasses), Elsevier, Amsterdam, 1985.

Thermal properties of Ba

Ca

Ti

O

glasses

0.80 x =

b. unit) 0.70

0.60 0.50

TA (arb _0.40

0.30 0.200 15

DT

0.10 0.15 0.12

T and T increased with x

600 800 1000

0.050.03

0.01

T_g and T_x1 increased with x.

ΔT = T_x1 –T_g increased with x.

600 800 1000

Temperature (°C) A. Masuno et al., J. Mater. Chem. 21, 17441 (2011).

Refractive index of Ba

Ca

Ti

O

glasses

n_d：587.6 nm n_F：486.1 nm n_C：656.3 nm C

F d

d n n

n

−

= −1 ν

Refractive index

increases with increase increases with increase of Ca content.

ν_dd decreases.

Unexpected result Unexpected result

A. Masuno et al., J. Mater. Chem. 21, 17441 (2011).

Transmittance of Ba

Ca

Ti

O

glasses

Optical bandgap E

(

)

A

hν = ν − α

Optical bandgap E_opt

α: the absorption coefficient h: the Planck constant

ν: the frequency of light

A: an energy independent constant A: an energy-independent constant

E_opt decreases with

C l l d

increase of Ca content.p

Colorless and transparent

The absorption edge shifted to longer wavelength

Unexpected result wavelength.

A. Masuno et al., J. Mater. Chem. 21, 17441 (2011).

Refractive index dispersion and optical bandgap

Ca substitution

? ?

i d

E d d

? ?

○

Smaller E_opt leads to larger n_d.

n_d increased E_opt decreased

The problem:

Why does Ca substitution decrease E_opt?

Raman scattering spectra of Ba

Ca

Ti

O

glasses

The bands at 636 cm^-1 and 829 cm^-1:

one long Ti O bond and four short Ti O bonds one long Ti–O bond and four short Ti–O bonds The band at 636 cm^-1 does not shift.

l Ti O b d i

→one long Ti–O bond remains.

The peak intensity of the band at 829 cm^-1 decreases and that of the band at 780 cm^-1 increases.

→the lengths of some of the four short bonds g increase

→a narrow distribution of the Ti–O bond length and relaxing the distorted Ti–O polyhedra.

and relaxing the distorted Ti O polyhedra.

A. Masuno et al., J. Mater. Chem. 21, 17441 (2011).

Bandgap decrease by local structure change

Ti 3d

Ti–O bonding state strongly affects the b d

O 2p

band gap.

a narrow distribution of the Ti–O bond length and relaxing the di t t dTi O l h d b l th i h t Ti O b d

→the degree of hybridization of O 2p and Ti 3d orbitals decreases distortedTi–O polyhedra by lengthening some short Ti-O bonds

g y p

→the difference between the bond and anti-bond levels becomes smaller

→bandgap decreases f ti i d i

→refractive index increases

Structural-relaxation-induced high refractive indexg

A. Masuno et al., J. Mater. Chem. 21, 17441 (2011).

The impact of Ca substitution

2 0 2.2

ex nd

Gl th ll t bili d

as the Ca²⁺ content increases,…

1.8 2.0

ctive ind

•Glass are thermally stabilized.

•Optical band gap decreases.

•The refractive index increases

1 4 1.6

Refrac The refractive index increases.

•The Abbe number decreases.

100 80 60 40 20

1.4

Abbe number ν^d

The changes in the physical properties caused by Ca²⁺

substitution are mainly due to the local structure relaxation caused by their different ionic radii.

Structural relaxation induced high refractive index Structural-relaxation-induced high refractive index

A. Masuno et al., J. Mater. Chem. 21, 17441 (2011).

Future work for Ba

A

Ti

O

glasses

Ca Mg

Sr Ca

0.0 0.2 0.4 0.6 0.8 1.0

x

12

Aerodynamic levitation furnace at SPring-8 BL04B2 for in-situ XRD

Sr is the neighboring element of Ba

8

10 T_m-100℃

g g

in the periodic table, and Ca is the second neighbor of Ba. Why glass

f i i i i

4 6

BaTi₂O₅ Ba Sr Ti O

T(r)

forming region is narrow in Sr substitution but wide in Ca

0 2

Ba_0.5Sr_0.5Ti₂O₅ Ba_0.5Ca_0.5Ti₂O₅ SrTi₂O₅ CaTi₂O₅

Structural analysis of undercooling

0 2 4 6 8 10

r (Å)

melt is necessary.

La

O

-TiO

-MO

system

ZrO

La₂O₃-TiO₂ La₂O₃-TiO₂-ZrO₂

ZrO₂

TiO₂ LaO_3/2

H. Inoue et al., Opt. Mater. 33, (2011) 1853.

Y. Arai et al., J. Appl. Phys. 103, (2008) 094905.

M. Kaneko et al., J. Am. Ceram. Soc. 95, (2011) 79.

Abbe diagram

2.4 La₂O₃-TiO₂-MO_x

2.2

dex n

Ba_1-xCa_xTi₂O₅ 2.0

ve in d

1 6 1.8

fracti v

1.4

Re f

100 80 60 40 20

1.4

Abbe number ν

Abbe number ν

BaTi

O

glass

Unusual crystallization process

Metastable phase formation from BaTi

O

glass

λ= 0.4977 Å T_P3

sity

γ phase

β phase

T_g

Intens β phase

T_x1 T_x2

5 10 15 20 25

α phase

2θ(λ=04977A)

Before crystallization at 1150 K of the

bl f l i h

stable ferroelectric γ phase, two

metastable phases α (at T_x1) and β (at T_x2)

appeared in sequence. Paraelectric β phase Ferroelectric γ phase

J.Yu et al., Chem. Mater. 21, (2009) 259.

Paraelectric β phase Ferroelectric γ phase

Giant dielectric response at T

100 Hz

T_p31150 K T_p1

1001 K

T_p2 1038 K T_g

960 K

1038 K

T_cry1994 K

T_cry2 1018 K

cry1 0 8

Measurement of Second harmonic generation

Nd/YAG Laser

IR filter

mirror Nd/YAG Laser

1064 nm

lens harmonic

separator

Monochro meter

Digital PM

oscillometer 532 nm

PC Thermometer

TC

temperature controller heater

Giant Second harmonic generation at T

SHG appeared at T_x1 and disappeared at T_x2.

increasing temp and disappeared at T_x2.

Thi b h i t t ll

SH intensity is 5 times larger

increasing temp.

decreasing temp.

Tc

This behavior totally corresponds to that of dielectric constant.

y g

than g phase

Direct evidence of l i b

correlation between α phase crystal structure and giant dielectric

glass α β γ

a d g a d e ec c response

γ (paraelectric) γ (ferroelectric)

A. Masuno et al., Appl. Phys. Express 4, (2011) 042601.

Mechanism of giant response at T

10 glass

100 kHz

5 10

×10-6

glass

α phase crystallization

0

ε' 5

Grain boundary y

Polar nanocrystals are ordered by an electric field.

9600 980 1000 1020 1040 temperature (K)

Grain boundary

(Maxwell-Wagner effect)

9Giant SHG response at T_x1: α-BaTi₂O₅ has non-centrosymmetric (polar) structure.

9The instant dielectric jump at T_x1 was caused by the alignment of polar nanocrystals of α phase.

9Th l di l t i t t f T t T l i d b th M ll W

9The large dielectric constant from T_x1 to T_x2 was explained by the Maxwell–Wagner effect at the grain boundaries between the glass and the partially crystallized α phase.

By in-situ SHG observation during crystallization process, we obtained the first direct

A. Masuno et al., Appl. Phys. Express 4, (2011) 042601.

evidence that the alignment of polar nanocrystals caused the giant dielectric response.

Ba

Ca

Ti

O

glass

Crystallization of ferroelectric phase

Single phase crystallization from BaTi

O

glass

We found that crystallization from the glass was useful for single phase

preparation of BaTi₂O₅. preparation of BaTi₂O₅. stable

region

~10 ºC

Control of ferroelectric properties by

substitution for Ba as well as BaTiO₃ system.

S B S Ti O ( 0 12) Previous reports;

N. Zhu and A. R. West, J. Am. Ceram. Soc. 93, (2010) 295.

Sr：Ba_1-xSr_xTi₂O₅ (x < 0.12)

→ arc-melt method

X. Yan et al., J. Ceram. Soc. Jpn. 115, (2007) 648.

, , ( )

b c

a _{I l 0 54 /Å}³

KF：Ba_1-xK_xTi₂O_5-xF_x (x < 0.05)

→ sol-gel + SPS

J. Xu and Y. Akishige, Appl. Phys. Lett. 92, (2008) 052902.

a Iso value = 0.54e/ų

C. Moriyoshiet al., Jpn. J. Appl. Phys.48, (2009) 09KF06 .

Results: heat treatment condition

1000 ºC 1000 ºC 1100 ºC 1200 ºC

Ba_1-xCa_xTi₂O₅

○：single phase 1000 C

10 min.

1000 C 12h.

1100 C 10 min.

1200 C 12 h.

0 ○

○：single phase

△：slight impurity of BaTiO₃

×：almost no BaTi₂O₅ phase

0.05 ○

0.07 ○

0 10 ○ ○ ○ ×

0 < x < 0.07

as stable as BaTi₂O₅

0.10 ○ ○ ○ ×

0.12 ○ △ ○

0.15 ○ △

0.10 < x < 0.12 2 5

decreasing stability 0 15 < x < 0 30

0.15 ○ △

0.20 ○ △

0.30 ○ △

0.15 < x < 0.30 metastable phase 0.40 < x

no Ba Ca Ti O phase

0.40 ×

Heating rate: 20 ºC/min.

(5 ºC/ i f 1200 ºC )

no Ba_1-xCa_xTi₂O₅ phase

(5 ºC/min. for 1200 ºC )

Results: dielectric constant

3000

x = 0

tant ε'

1 MHz Ferroelectric transition temperatures were

observed in all Ba_1-xCa_xTi₂O₅ phases (x ≤ 0.30)

1000

2000 ^0.01 0.05 0.07

ectric const

500

The peaks were broaden with increase of x.

0 200 400 600

0 1000

diele 500

temperature (℃)

2500 ^{0.10 0.12}

ε'

400

(℃)

2000

0.15 0.20 0.30

c constant

T P 300

dielectric 1500

0.0 0.1 0.2 0.3 200

0 100 200 300 400 500 600 temperature (℃)

x

T_P dropped 250 ºC.

Results: lattice constants

16 90

)

Change ratio of lattice constants

( )

Ba_1-xCa_xTi₂O₅

16.853.95 16.90

a (Å)

0 0

( )

0 0

0 l

l l

ll = − ^x

Δ ^l0：lattice constant at x = 0 l_x：lattice constant at x

9 45

b (Å) 3.90

-0.4 -0.2 0.0

(%)

9.40 9.45

c (Å)

1 0 -0.8 -0.6

a b

Δl/l 0 (

102.5 103.0

β (°) ^{0.0 0.1 0.2 0.3 0.4}

-1.2

-1.0 b

c

x

605 610

V (Å3 )

Decrease ratio of b axis is larger than other x

axes.

→affect ferroelectric properties

0.0 0.1 0.2 0.3 0.4

V 600

x

→affect ferroelectric properties effectively

Results: Correlation between T

and b axis length

500 Ti2O₆ Ti1O₆ Ti3O₆

400

℃)

T (℃ P 300 _Ba1

Ba2

3.94 3.92 3.90 200

Ba1-O₁₂ Ba2-O₁₂

3.94 3.92 3.90 b-axis length (Å)

Strong correlation between T_P and Strong correlation between T_P and b axis length

Ba-O bond length distribution in BaO₁₂ polyhedra

Site selectivity of Ca in Ba

Ca

Ti

O

Atom g x y z U [10^-2Ų]

Ba_0.95Ca_0.05Ti₂O₅

Ba1 0.944(1) 0.36858(3) -0.002(1) 0.01753(6) 0.647(7) Ca1 0.056(1) 0.36858(3) -0.002(1) 0.01753(6) 0.647(7)

Ba2 1 0 0.5 0.5 0.67(2)

Ti1 1 0 0390(1) 0 024(1) 0 2096(2) 0 83(6)

Ti1 1 0.0390(1) -0.024(1) 0.2096(2) 0.83(6)

Ti2 1 0.2073(1) 0.003(3) 0.3724(2) 0.70(4)

Ti3 1 0.3337(1) 0.504(3) 0.3044(2) 0.77(5)

O1 1 0.0356(3) 0.529(3) 0.2102(5) 0.3(2)

O2 1 0.1108(3) 0.028(3) 0.4271(5) 0.2(2)

O3 1 0.1510(3) 0.025(4) 0.1836(5) 0.2(2)

O4 1 0.1749(3) 0.510(8) 0.6608(5) 0.2(2)

O5 1 0.2344(3) 0.518(5) 0.3953(5) 0.2(2)

O6 1 0.2892(3) 0.518(6) 0.1249(6) 0.6(2)

O7 1 0.4424(3) 0.508(8) 0.2884(5) 0.3(2)

O8 1 0 0.01545 0 0.3(2)

R_WP = 0.0290, R_I = 0.0173, R_F = 0.0104.

( )

b a c

C2, a = 16.9036(1) Å, b = 3.93030(2) Å, c = 9.40715(6) Å, β = 102.9640(4)°.

Ba/Ca Ba _{WP 0.0 90, I 0.0 73,}

F 0.0 0 .

Ca ions occupy only the distorted Ba1 site.

Ba/Ca

C. Moriyoshi et al., J. Phys. Soc. Jpn. 81, (2011) 014706.

XANES spectra of Ca in Ba

Ca

Ti

O

Ba_1-xCa_xTi₂O₅ calculation

CaTiO₃ x = 0.40 _unit)

2c

b. unit)

0.30

0.20 ensity (arb. 4c

nsity (arb

0.10

4050 4060 4070 4080 4090

Int

Inten _0.05 Energy (eV)

Ca site selectivity is realized only at

4020 4040 4060 4080

E ( V)

0.01 Ca site selectivity is realized only at low Ca concentration.

In metastable ferroelectric phase, Ca occupies both 2c and 4c sites

Energy (eV)

Fluorescence method at SAGA-LS

occupies both 2c and 4c sites.

Crystallization of ferroelectric phase

Ferroelectric phase crystallized from Ba_{1 x}Ca_xTi₂O₅ glass.

Ferroelectric phase crystallized from Ba_1-xCa_xTi₂O₅ glass.

Ferroelectric properties depend on b-axis bond length.

0 ≤ x ≤ 0.07: stable phase

site selective Ca doping site selective Ca doping 0.10 ≤≤ x ≤≤ 0.30: metastable phasep

random site doping of Ca

Ba_{1-x1 x}Ca_xxTi_{22 5}O₅ glass is useful as a precursor of ferroelectric phase.g p p

Summary: TiO

glass system

9Optical properties

Colorless and transparent in visible and near IR region Colorless and transparent in visible and near IR region

High refractive index > 2.1 and low wavelength dispersion Strong upconversion luminescence due to low phonon energyg p p gy 9Glass forming region

bi ( i ) d ( i i

binary (La₂O₃-TiO₂) and ternary (BaO-TiO₂-MO_x, La₂O₃-TiO₂- MO_x) systems were determined.

Ca doping caused characteristic changes in physical and Ca doping caused characteristic changes in physical and structural properties.

9Unusual crystallization process

Giant SHG response at a phase crystallization temperature.

M bl f l i h lli d f C d d l

Metastable ferroelectric phase crystallized from Ca doped glasses.

Nb

O

system

dex 2.6

2.4

active ind

1

Refra 2.2

0 30L O 0 70Nb O

1 mm _{400 600 800 1000}

Wavelength (nm)

C l l d t t

0.30La₂O₃-0.70Nb₂O₅

spherical glass was prepared by containerless processing

Colorless and transparent

High refractive index over 2.2 by containerless processing.

φ = 2 ~ 3 mm suitable for small optics used in visible and infrared region

A. Masuno and H. Inoue,

Appl. Phys. Express 3, 10261 (2010). e.g. lens, endoscope, fiber collimator

New glass system ~ frontier in glass science ~

9Without networkformer

TiO₂, Nb₂O₅ glasses prepared by containerless processing 9Large oxygen packing density

9Large oxygen polarizability

Deviation from the classic glass forming rules

Through investigating physical and structural properties, new and extended glass forming rules should be made.

l i i / i i b f i i d di i i l i d

Refferences

1. Glass Formation in LaO3/2–TiO2 Binary System by Containerless Processing

M. Kaneko, J. Yu, A. Masuno, H. Inoue, M. S. V. Kumar, O.

Odawara, S. Yoda

J Am Ceram Soc 95(2012) 79

8. Refractive index dispersion, optical transmittance, and Raman scattering of BaTi₂O₅ glass

A. Masuno, H. inoue, J. Yu, Y. Arai J. Appl. Phys. 108, (2010) 063520.

9 Charge Density Study of Metastable State in BaTi O with J. Am. Ceram. Soc. 95(2012) 79.

2. Site-selective Calcium Substitution in BaTi2O5: Effect on the Crystal Structure and the Ferroelectric Phase Transition

C. Moriyoshi, Y. Kuroiwa, A. Masuno, H. Inoue J. Phys. Soc. Jpn. 81, (2011) 014706.

9. Charge Density Study of Metastable State in BaTi₂O₅with Fivefold Coordinated Ti

C. Moriyoshi, S. Miyoshi, Y. Kuroiwa, J. Yu, Y. Arai, A.

Masuno

Jpn. J. Appl. Phys. 49, (2010) 09ME10.

y p , ( )

3. Structural-relaxation-induced high refractive indices of Ba_1-

xCa_xTi₂O₅glasses

A. Masuno, H. Inoue, Y. Arai, J. Yu, Y. Watanabe J. Mater. Chem. 21, (2011) 17441.

p pp y , ( )

10. Charge Density Study on Phase Transition in BaTi₂O₅ Ferroelectric

C. Moriyoshi, N. Okizaki, Y. Kuroiwa, J. Yu, Y. Arai, A.

Masuno 4. Effect of substituting Al₂O₃and ZrO₂on thermal and optical

properties of high refractive index La₂O₃-TiO₂glass system prepared by containerless processing

H. Inoue, Y. Watanabe, A. Masuno, M. Kaneko, J. Yu Opt Mater 33 (2011) 1853

Jpn. J. Appl. Phys. 48, (2009) 09KF06

11. Comprehensive Structural Study of Glassy and Metastable Crystalline BaTi₂O₅

J. Yu, S. Kohara, K. Itoh, S. Nozawa, S. Miyoshi, Y. Arai, A.

Masuno H Taniguchi M Itoh M Takata T Fukunaga S Opt. Mater. 33, (2011) 1853.

5. Giant second harmonic generation from metastable BaTi₂O₅ A. Masuno, Y. Kikuchi, H. Inoue, J. Yu, Y. Arai

Appl. Phys. Express 4, (2011) 042601.

6. Structure of Glassy and Metastable Crystalline BaTi2O5

Masuno, H. Taniguchi, M. Itoh, M. Takata, T. Fukunaga, S.

Koshihara, Y. Kuroiwa, S. Yoda

Chemistry of Materials 21, (2009) 259.

12. Thermal stability and optical properties of Er³⁺doped BaTi₂O₅ glasses

y y

Fabricated using Containerless Processing

J. Yu, S. Yoda, A. Masuno, H. Natsui, M. Kaneko Ferroelectrics 402, (2010) 130.

7. High Refractive Index of 0.30La₂O₃-0.70Nb₂O₅Glass

g

A. Masuno, H. Inoue, J. Yu, Y. Arai, F. Otsubo Adv. Mater. Res. 39-40(2008) 243.

Prepared by Containerless Processing A. Masunoand H. Inoue

Appl. Phys. Express 3, (2010) 102601.