Research & Reviews: Journal of Material Sciences
MenuISSN:2321-6212
ISSN:2321-6212
S. Ono, H. Kuwahara, H. Kuroe and K. Itatani
Department of Materials and Life Sciences, Sophia University, Japan
Department of Engineering and Applied Sciences, Sophia University, Japan
Posters & Accepted Abstracts: Res. Rev. J Mat. Sci.
The morphologically-controlled preparations of Eu2+-doped calcium silicon nitride (Ca2-xEuxSi5N8: x = 0.05) particles, i.e., the spherical and columnar particles, were conducted by combined techniques of ultrasonic spray pyrolysis and carbothermal reduction/ nitridation. Relating to the ultrasonic spray pyrolysis, the precursor oxides for Ca2-xEuxSi5N8 particles were prepared by this technique at 600�ºC in air, using Ca(NO3)2/Eu(NO3)3 solution (total concentration: 2.86 �� 10-2 mol��dm-3) with suspended Si3N4 particles. The spray-pyrolyzed powder was further mixed with carbon, and carbothermally reduced in N2 atmosphere. The spherical and columnar Ca1.95Eu0.05Si5N8 particles could be prepared by controlling the heating rate and temperature for carbothermal reduction/ nitridation. The spherical Ca1.95Eu0.05Si5N8 particles could be obtained when the spray-pyrolyzed powder (or precursor oxides) was heated to 1000�ºC at the rate of 30�ºCâ�¢min-1and then to 1400�ºC for 2 h at the rate of 10�ºCâ�¢min-1. On the other hand, the columnar Ca1.95Eu0.05Si5N8 particles could be obtained when the spray-pyrolyzed powder was heated to 1100�ºC at the rate of 30�ºCâ�¢min-1 and then to 1500�ºC for 2 h at the rate of 10�ºCâ�¢min-1. The morphological control was conducted by the kinds of liquid phases formed during the heating process. The morphological control of Ca1.95Eu0.05Si5N8 particles could be achieved by the nitridation of spherical and columnar particles formed at 1000�ºC or 1100�ºC. The emission peaks of spherical and columnar Ca1.95Eu0.05Si5N8 particles appeared at 622 nm and 618 nm, respectively, under the excitation at 375 nm. Overall, the spherical and columnar Ca1.95Eu0.05Si5N8 particles could be formed by controlling the heating rate and temperatures for the carbothermal reduction/nitridation of spray pyrolyzed oxide powders. The spherical and columnar particles emitted the lights with the peak wavelength at 622 and 618 nm under excitation at 375 nm.
Satoshi Ono is a student of Sophia graduate school. His research interest is preparation and characterization of Si3N4-containing nitride ceramics.