Research output: Contribution to journal › Article › peer-review
Synthesis of nanocrystalline calcium aluminate C12A7 under carbon nanoreactor conditions. / Volodin, Alexander M.; Zaikovskii, Vladimir I.; Kenzhin, Roman M. et al.
In: Materials Letters, Vol. 189, 15.02.2017, p. 210-212.Research output: Contribution to journal › Article › peer-review
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TY - JOUR
T1 - Synthesis of nanocrystalline calcium aluminate C12A7 under carbon nanoreactor conditions
AU - Volodin, Alexander M.
AU - Zaikovskii, Vladimir I.
AU - Kenzhin, Roman M.
AU - Bedilo, Alexander F.
AU - Mishakov, Ilya V.
AU - Vedyagin, Aleksey A.
PY - 2017/2/15
Y1 - 2017/2/15
N2 - Recently we have shown that carbon coating supported on the surface of oxide nanoparticles is able to stabilize their size and prevent sintering at high temperatures. The carbon shell can play the role of a nanoreactor where phase or chemical transformations of nanoparticles take place. In the present study the carbon nanoreactor approach was used to study the C12A7:eˉ electride synthesis in the argon atmosphere. For these systems the appearance of free electrons registered by electron paramagnetic resonance (EPR) was observed at moderate temperatures (starting from 1250 °C). In the presence of the carbon shell the material maintains relatively high dispersity even at 1450 °C, which exceeds the melting temperature for C12A7. The possibility of increasing substitution of oxygen anions with electrons in C12A7@C systems was examined by increasing calcination temperature from 1200 up to 1450 °C. Highly sensitive EPR method for qualitative and quantitative characterization of these systems was proposed. It was shown that in absence of the carbon coating conduction electrons appear only at temperatures close to the melting point (above 1360–1380 °C). The electride formation inside the carbon shell occurs due to carbothermal reduction of C12A7 nanoparticles encapsulated inside the shell.
AB - Recently we have shown that carbon coating supported on the surface of oxide nanoparticles is able to stabilize their size and prevent sintering at high temperatures. The carbon shell can play the role of a nanoreactor where phase or chemical transformations of nanoparticles take place. In the present study the carbon nanoreactor approach was used to study the C12A7:eˉ electride synthesis in the argon atmosphere. For these systems the appearance of free electrons registered by electron paramagnetic resonance (EPR) was observed at moderate temperatures (starting from 1250 °C). In the presence of the carbon shell the material maintains relatively high dispersity even at 1450 °C, which exceeds the melting temperature for C12A7. The possibility of increasing substitution of oxygen anions with electrons in C12A7@C systems was examined by increasing calcination temperature from 1200 up to 1450 °C. Highly sensitive EPR method for qualitative and quantitative characterization of these systems was proposed. It was shown that in absence of the carbon coating conduction electrons appear only at temperatures close to the melting point (above 1360–1380 °C). The electride formation inside the carbon shell occurs due to carbothermal reduction of C12A7 nanoparticles encapsulated inside the shell.
KW - C12A7
KW - Carbon Nanoreactor
KW - Ceramic composites
KW - Electride
KW - EPR
KW - Nanocomposites
KW - OXIDATION
KW - AMMONIA-SYNTHESIS
KW - MECHANISM
KW - STABLE ELECTRIDE
KW - 12CAO-CENTER-DOT-7AL(2)O(3) ELECTRIDE
KW - CATALYST
UR - http://www.scopus.com/inward/record.url?scp=85006375550&partnerID=8YFLogxK
U2 - 10.1016/j.matlet.2016.11.112
DO - 10.1016/j.matlet.2016.11.112
M3 - Article
AN - SCOPUS:85006375550
VL - 189
SP - 210
EP - 212
JO - Materials Letters
JF - Materials Letters
SN - 0167-577X
ER -
ID: 10317574