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Smart Materials Congress 2019
Nano Research and Applications
ISSN: 2471-9838
Page 30
August 01-02, 2019
Dublin, Ireland
Smart Materials and
Structures
8
th
International Conference on
Konatsu Kamimoto, Nano Res Appl 2019, Volume 05
Rapid sintering of unique material of LNT (Li
2
O-Nb
2
O
5
-TiO
2
)
with periodical structure by air pressure control
Konatsu Kamimoto
Toyohashi University of Technology, Japan
I
n the Li
2
O-Nb
2
O
5
-TiO
2
system, Li
1+x−y
Nb
1−x−3y
Ti
x+4y
O
3
(0.05
≤ x≤0.3, 0≤y≤ 0.182) (LNT) forms with a superstructure
known as the M-phase, which is formed by the periodical
insertion of an intergrowth layer in a matrix with a
trigonal structure. To apply this unique structure as a
host material of phosphor, new phosphors have been
investigated based on LNT or related structures made by
a conventional electric furnace. However, the synthesis
of a homogeneous M-phase required treatment at 1373
K for over 24 h. The sintering time depended on the Ti
content, and annealing was repeated in an electric
furnace for 24–264 h until a homogeneous structure was
formed by the insertion of periodical intergrowth layers.
Accordingly, a fast sintering technique that uses lower
energy is required for the practical application of this
material as phosphors and electro ceramics. This time,
we pioneered a new rapid sintering technique, which
uses a simpler furnace that only requires the control of
air pressure. The LNT solid solutionmaterial, with various
Ti content of 15-30 mol%, was sintered at 1273 K-1373
K for 30 min-1 h under various air pressures (0.35 MPa–
0.60 MPa) using the newly developed an air-pressure
control atmosphere furnace (FULL-TECH FURNACE
CO., Ltd., Osaka, Japan). To clarify the mechanism of
the rapid sintering, various microscales to nanoscale
characterization techniques were used: X-ray diffraction,
a scanning electron microscope, a transmission
electron microscope (TEM), a Cs-corrected scanning
TEM equipped with electron energy-loss spectroscopy
and X-ray absorption ne structure spectroscopy. As a
result, the biggest grain of LNT with Ti 20 mol% could be
synthesized at 1373 K for 30 min under 0.35 MPa. It was
confirmed that a homogeneous phasewas obtained from
the TEM image and selected area electron diffraction
(SAED) patterns from the [010] axis. We concluded that
through the control of air pressure, the interstitial oxygen
enabled rapid sintering with a combination of vacancies,
and that accordingly, grain growth and the distribution of
Ti ions improved somewhat surprisingly.
Recent Publications
1. H Nakano, K Kamimoto, 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(6):987.
2. H Nakano, K Kamimoto, N Yokoyama and K
Fukuda (2017) The effect of heat treatment
on the emission color of P-doped Ca
2
SiO
4
phosphor. Materials 10(9):1000.