Journal of Inorganic Materials ›› 2022, Vol. 37 ›› Issue (1): 101-106.DOI: 10.15541/jim20200653

Special Issue: 【能源环境】热电材料

• RESEARCH LETTER • Previous Articles     Next Articles

Metal Sulfide Ag2S: Fabrication via Zone Melting Method and Its Thermoelectric Property

JIN Min1(), BAI Xudong2, ZHANG Rulin1, ZHOU Lina1, LI Rongbin1   

  1. 1. School of Materials Science, Shanghai Dianji University, Shanghai 201306, China
    2. School of Materials Science and Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China
  • Received:2020-11-16 Revised:2020-12-03 Published:2022-01-20 Online:2021-03-01
  • About author:JIN Min (1982–), male, professor. E-mail:
  • Supported by:
    Shanghai Natural Science Foundation(19ZR1419900)


Metal sulfide Ag2S is an attractive semiconductor due to its excellent physical and chemical property that enable it with wide applications in fields of catalysis, sensing, optoelectronics in past years. In present work, ϕ18 mm× 50 mm Ag2S ingot was successfully prepared using zone melting method and its thermoelectric (TE) behavior was investigated. Ag2S has standard monoclinic P21/c space group (α-Ag2S phase) below 450 K and transfer to cubic structure (β-Ag2S phase) over this temperature. Ag2S is a n-type semiconductor as the Seebeck coefficient S is always negative due to the Ag interstitial ions in the material that can provide additional electrons. S is about -1200 µV·K-1near room temperature, declines to -680 µV·K -1 at 440 K and finally decreases to ~-100 µV·K -1at β-Ag2S state. The electrical conductivity (σ) of α-Ag2S is almost zero. However, the value sharply jumps to ~40000.5 S·m -1 as the material just changes to β-Ag2S at 450 K and then gradually deceases to 33256.2 S·m -1 at 650 K. Hall measurement demonstrates that carrier concentration nH of Ag2S is suddenly increased from the level of ~10 17 cm-3 to ~1018 cm-3during phase transition. Total thermal conductivity κ of α-Ag2S is ~0.20 W·m -1·K-1 but is ~0.45 W·m-1·K-1of β-Ag2S. Ultimately, a maximum ZT=0.57 is achieved around 580 K that means Ag2S might be a promising middle-temperature TE material.

Key words: Ag2S, zone melting, thermoelectric material, phase transition

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