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Smart Materials Congress 2019
August 01-02, 2019
Dublin, Ireland
Smart Materials and
Structures
8
th
International Conference on
Nano Research and Applications
ISSN: 2471-9838
Page 16
Photoluminescence- and electric-
properties using a smart material of Li-
(Nb,Ta)-Ti-O system
Hiromi Nakano
Toyohashi University of Technology, Japan
I
n the Li
2
O-M
2
O
5
-TiO
2
system, Li
1+x-y
M
1-x-3y
T
ix+4y
O
3
(M
= Nb, or Ta, 0.06≤x≤0.33, 0≤y≤0.175 (LMT) forms
with a superstructure, and this is known as a smart
material. The superstructure is formed by periodical
insertion of an intergrowth layer of corundum-type
[Ti
2
O
3
]
2+
in a matrix having a trigonal structure during
the grain growth for a long sintering time. To apply
this unique structure as a host material of phosphor,
new phosphors have been investigated based on LMT
or related structures made by a conventional electric
furnace and millimeter-wave heating. Rare earth
(RE
3+
: Eu, Er, Tb, Tm, or Dy) doped LMT phosphors with
various emitted colors were successfully synthesized.
Especially, we synthesized a new red phosphor based
on the quaternary Li
1+x
(Ta
1−z
Nb
z
)
1−x
Ti
x
O
3
(LTNT, 0≤x≤0.25,
0≤ z≤1.0) solid solution. An Eu
3+
-doped LTNT has been
preparedinaconventionalelectricfurnace.Interestingly,
a bright red emission due to the hypersensitive
5
D
0
-
7
F
2
transition in Eu
3+
was observed under direct excitation
of the 4f electron at 400 nm. In the LTNT host material,
the most effective activator was found to be Eu ion and
an internal quantum efficiency of 98% was achieved.
We found that the high PL intensity was closely related
to the polyhedral structure of the [Li (Eu) O
12
] in the
host material. Still more, toward application of the
unique qualities of an electro-ceramic, we fabricated
oriented the solid solution for Nb system (LNT) balk
ceramics by slip casting in a strong magnetic field
of 12 T using various sizes of particles. Anisotropic
electric properties were found along the c-axis, which
were caused by a superstructure. We first clarified the
mechanism showing that the anisotropic
Qf
value was
caused by the anisotropic electron conductivity and the
anisotropic bonding strength in the superstructure.
Recent Publications
1. H Nakano, K Konatsu, T Yamamoto and Y
Furuta (2018) Rapid sintering of Li
2
O-Nb
2
O
5
-
TiO
2
solid solution by air pressure control and
clarification of its mechanism. Materials 11:
987.
Hiromi Nakano, Nano Res Appl 2019, Volume 05