Mossbauer Measurements of Iron Atoms Dispersed in Amorphous Glasslike Carbon

Various iron species have been prepared by pyrolyzing acetylferrocene-furfural resins at 400℃ in vacuum, and analysed by means of Mossbauer spectroscopy. The Mossbauer spectra show that the iron species in an amorphous glasslike carbon matrix are free iron atoms, Fe^+ ions, iron clusters, superparamagnetic irons and ferromagnetic irons

J. Am. Ceram. Soc.

Spark plasma sintering (SPS) of Ca1-xSrxTiO3 was conducted with and without an Li2Si2O5 additive at 1170 degrees C for 4 min. A single phase, Ca1-xSrxTiO3 solid solution was formed; moreover, the mechanical and dielectric properties were improved by adding 0.5 wt% Li2Si2O5. Conversely, in the absence of Li2Si2O5, a mixture of Ruddlesden-Popper phases Srn+1TinO3n+1 and rutile TiO2 was formed in addition to Ca1-xSrxTiO3 although a single phase Ca1-xSrxTiO3 could be formed via pressureless sintering at 1200 degrees C for 2 h in air. These results suggested that Li2Si2O5 was useful even via an SPS technique to promote the mass transfer, and its optimum concentration was 0.5 wt%.Spark plasma sintering (SPS) of Ca1-xSrxTiO3 was conducted with and without an Li2Si2O5 additive at 1170 degrees C for 4 min. A single phase, Ca1-xSrxTiO3 solid solution was formed; moreover, the mechanical and dielectric properties were improved by adding 0.5 wt% Li2Si2O5. Conversely, in the absence of Li2Si2O5, a mixture of Ruddlesden-Popper phases Srn+1TinO3n+1 and rutile TiO2 was formed in addition to Ca1-xSrxTiO3 although a single phase Ca1-xSrxTiO3 could be formed via pressureless sintering at 1200 degrees C for 2 h in air. These results suggested that Li2Si2O5 was useful even via an SPS technique to promote the mass transfer, and its optimum concentration was 0.5 wt%

Multiwalled Carbon Nanotube Monoliths prepared by Spark Plasma Sintering (SPS) and their Mechanical Properties

Three types of multiwalled carbon nanotube (MWCNT) monoliths without any binders were obtained by spark plasma sintering (SPS) treatment at 2000℃ under 80MPa sintering pressure. Three MWCNTs with different diameters: thin (20~30nm∅, CNT Co., Ltd., Korea), thick (100nm∅, Nano Carbon Technologies Co., Ltd., Japan) and spherical thin (20~30nm∅, granulated diameter=1~3μm, Shimizu Corporation, Japan)) were employed for SPS. SEM observation confirmed that these materials maintained the nanosized tube microstructure of raw CNT powder after SPS treatment. The densest monolith was prepared with the spherical MWCNTs. The mechanical properties of this material were estimated by the dynamic hardness test. The elastic modulus of the monolith did not depend on the difference of MWCNTs, but the hardness of spherical MWCNTs was higher than that of thick MWCNTs. The high density and hardness of the spherical MWCNTs were caused by the high packing density during the SPS process because of its spherical granulation. Thus, the spherical MWCNTs were most useful for the MWCNT monolith preparation with the SPS process and its application as a bone substitute material and a bone tissue engineering scaffold material was suggested