13:45 〜 14:00
▲ [15p-A35-2] Thermoelectric properties of super-saturated Cr-doped MnSiy
キーワード：Sigher manganese silicide, Thermoelectric, Super saturated solid solution
The higher manganese silicide (HMS) is one of the promising thermoelectric materials, as it is nontoxic, cheap and it possess large Seebeck coefficient 200mVK-1 with metallic electrical connectivity 2 mWcm. The carrier concentration can be tuned by element substitution, where hole was generally introduced by Cr substitution for Mn. [1,2] The enhancement in power factor Cr substitution was reported, but it was limited by the solubility limit of Cr in HMS. In this work, we attempted rapid quenching technique to increase the solubility limit of Cr in HMS [3,4].
We prepared Mn1-xCrxSiy samples (0 < x < 0.3) by melting high purity Mn (99.9%), Si (99.999%), and Cr (99.9%) elements in arc-melting furnace. The mother ingots were melted again and rapidly quenched by being injected on a copper wheel of 200 mm in diameter and rotating at ~4500 rpm. All the above processes were carried out under pressurized argon atmosphere.
The structural and transport properties were analyzed for both the LQ ribbons and the sintered pellet. The powder XRD and the calculated lattice constants confirmed that the solubility limit (7 at.%) of Cr in HMS was increased into 11 at.% by the liquid quenching technique. We also realized that the grain size of HMS in the quenched ribbons was reduced less than 500 nm, which is much smaller than ~2000 nm of the quenched HMS containing no Cr atoms. The significant reduction in grain size suggested that the Cr atoms assisted the formation of nucleation sites.
We measured the thermoelectric properties of these ribbon samples, and the results will be presented together with the detailed information about the microstructure of present samples.
1. Y. Kikuchi et al., J. J. Appl. Phy. 51 (2012) 085801
2. Ponnambalam et al. J. Electr. Mat., Vol. 41, No. 6, 2012
3. A. Yamamoto, S. Ghodke et al. Jpn. J. Appl. Phys. (2016)
4. S. Ghodke et al. J. Electr. Mat, DOI: 10.1007/s11664-016-4688-x
We prepared Mn1-xCrxSiy samples (0 < x < 0.3) by melting high purity Mn (99.9%), Si (99.999%), and Cr (99.9%) elements in arc-melting furnace. The mother ingots were melted again and rapidly quenched by being injected on a copper wheel of 200 mm in diameter and rotating at ~4500 rpm. All the above processes were carried out under pressurized argon atmosphere.
The structural and transport properties were analyzed for both the LQ ribbons and the sintered pellet. The powder XRD and the calculated lattice constants confirmed that the solubility limit (7 at.%) of Cr in HMS was increased into 11 at.% by the liquid quenching technique. We also realized that the grain size of HMS in the quenched ribbons was reduced less than 500 nm, which is much smaller than ~2000 nm of the quenched HMS containing no Cr atoms. The significant reduction in grain size suggested that the Cr atoms assisted the formation of nucleation sites.
We measured the thermoelectric properties of these ribbon samples, and the results will be presented together with the detailed information about the microstructure of present samples.
1. Y. Kikuchi et al., J. J. Appl. Phy. 51 (2012) 085801
2. Ponnambalam et al. J. Electr. Mat., Vol. 41, No. 6, 2012
3. A. Yamamoto, S. Ghodke et al. Jpn. J. Appl. Phys. (2016)
4. S. Ghodke et al. J. Electr. Mat, DOI: 10.1007/s11664-016-4688-x