Optical Ceramics Group
STAFF
SUZUKI, Tohru; KOBAYASHI, Kiyoshi; HIROTA, Noriyuki; NAKANE, Takayuki; ESTILI, Mehdi; FURUSE, Hiroaki（Staff Tabs）
AIM and GOAL
Recently, fabrication and usage of transparent polycrystalline sintered ceramics are required because easily composition control and upsizing. Optical ceramics, which possess harsh-environment resistance such as heat resistance and chemical resistance, can be used as materials for lasers, phosphor matrix and scintillators, etc., and can be applied for sensors and medical field. We aim to fabricate advanced ceramics that not only possess optical functions but also have other functions such as electrical conductivity, mechanical properties, etc. that take advantage of the feature of ceramics.
APPROACH
In order to make transparency in polycrystalline ceramics, it is necessary to achieve densification by ultimately eliminating defects, and it is necessary to understand each of the ceramics processing such as powder synthesis, forming and sintering. It is important to design the process for precisely controlling the microstructure in sintered ceramics. We also focus on the processing using the external fields such as magnetic field and electric field, and in order to clarify their effectiveness, we also use in-situ observations in a magnetic field to elucidate the phenomena that occur during the processing. Furthermore, we are improving the method of the ionic conductivity measurement in addition to measuring optical properties.
FIG １ Transparent alumina fabricated by Spark Plasma Sintering. (a) is prepared from the powder directly, (b) is prepared by colloidal processing in a magnetic field for controlling the c-axis orientation.
FIG 2 n-situ observation of particle deposition process under high magnetic fields in HGMS (high gradient magnetic separation) (an example of the in-situ observation of behavior of materials under high magnetic fields)
Page top /Organization / Staff / Materials / Methods
SUZUKI, Tohru：Group Leader
locale=enEmail: SUZUKI.Tohru@nims.go.jp
Page top /Organization / Staff / Materials / Methods
KOBAYASHI, Kiyoshi
locale=enEmail: KOBAYASHI.Kiyoshi@nims.go.jp
Page top /Organization / Staff / Materials / Methods
HIROTA, Noriyuki
locale=enEmail: HIROTA.Noriyuki@nims.go.jp
Page top /Organization / Staff / Materials / Methods
NAKANE, Takayuki
locale=enEmail: NAKANE.Takayuki@nims.go.jp
Page top /Organization / Staff / Materials / Methods
ESTILI, Mehdi
locale=enEmail: ESTILI.Mehdi@nims.go.jp
Interest：CNT-MXene membranes for electrochemical energy storage applications
Outline：
- Superior prospect of 2D MXenes for electrochemical energy storage applications.
- Restacking and agglomeration of MXenes considerably limit their true potential for fast ion transport.
- CNTs were dispersed to control the structure and porosity of MXene membranes.
- CNT–MXene hybrid membranes show dramatically improved Li-ion transport properties.
Features：
- A scalable method to fabricate ultralight yet continuous CNT–MXene membranes with uniform/3D CNTs dispersion.
- Correlation among CNTs content, surface microstructure, MXenes’ stacking structure and ion transport properties of the films.
- Li-ion transport mechanisms in the CNT–MXene membranes.
- MXene membranes with tunable 2D and 3D structures with improved ion-transport performances.
- Potential application of selected CNT–MXene ultralight membranes as interlayers for Li-O2 batteries.
Feasible study：
- The compact surface microstructure of MXene membranes is dramatically changed as CNTs occupy MXene/MXene edge interfaces.
- The 2D stacking order of MXenes is preserved up to 30 wt% CNTs.
- The 2D alignment is completely disrupted at 40 wt% CNTs, and a more pronounced surface opening and internal expansion of ~770% are realized.
- Both 30 wt% and 40 wt% membranes show stable cycling performance under a significantly higher current density due to faster transport channels.
- Notably, for the 3D 40 wt% membrane, over-potential during repeated Li deposition/dissolution reactions is further reduced by another ~50%.
- Ultralight yet continuous hybrid films comprising up to ~0.027 mg/cm2 Ti3C2 MXene can be prepared using aqueous colloidal dispersions and vacuum filtration for specific applications
Summary：
- A method to fabricate ultralight yet continuous CNT–MXene membranes for electrochemical energy storage applications.
- Inexpensive multi-walled CNTs control the structure of MXene membranes and improve their ion-transport properties.
Page top /Organization / Staff / Materials / Methods
FURUSE, Hiroaki
locale=enEmail: FURUSE.Hiroaki@nims.go.jp
Page top /Organization / Staff / Materials / Methods