Journal of the Korean Crystal Growth and Crystal Technology (한국결정성장학회지)

The Korea Association of Crystal Growth (한국결정성장학회)
권호 표지
DOI QR코드

DOI QR Code

Crystal structure of Mn-Co-Ni thermistor

Mn-Co-Ni 서미스터의 결정구조 분석

  • Lee, Jung-Il (Department of Materials Science and Engineering, Korea National University of Transportation) ;
  • Mhin, Sungwook (Heat Treatment R&D Group, Korea Institute of Industrial Technology) ;
  • Ryu, Jeong Ho (Department of Materials Science and Engineering, Korea National University of Transportation)
  • 이정일 (한국교통대학교 신소재공학과) ;
  • 민성욱 (한국생산기술연구원, 열처리연구실용화그룹) ;
  • 류정호 (한국교통대학교 신소재공학과)
  • Received : 2015.09.25
  • Accepted : 2015.10.08
  • Published : 2015.10.31
Download PDF
⟨ Previous Next ⟩

Abstract

This study was performed to investigate crystal structure of cubic spinel-type monophase oxide composed of the Mn-Co-Ni ternary system. Starting material was prepared by mixing Mn, Co, Ni oxides then evaporation to dryness. The XRD patterns were analyzed by in-situ XRD as increasing temperature from room temperature to $1400^{\circ}C$ in air atmosphere. The cubic spinel phase was existed in a temperature range from $900^{\circ}C$. However, separation of NiO phase was detected from $1300^{\circ}C$, which was the origin of deterioration in the crytallinity. The surface morphology of the manufactured NTC thermistors were analyzed by FE-SEM for comparison of good and bad samples.

본 연구에서는 Mn-Co-Ni 삼성분계로 이루어진 NTC 서미스터의 cubic 스핀넬 결정구조의 변화를 고찰하고자 하였다. Mn, Co, Ni로 이루어진 산화물 원재료 분말들을 혼합하고 건조한 후 In-situ XRD 장비를 이용하여 공기분위기에서 상온부터 $1400^{\circ}C$까지 가열하면서 발생하는 결정구조 변화를 분석하였다. In-situ XRD 분석 결과 cubic 스핀넬 구조는 $900^{\circ}C$부터 존재하는 것을 확인할 수 있었으나, 온도가 $1300^{\circ}C$ 이상으로 올라갔을 때는 스핀넬 결정구조로부터 NiO의 상분리 현상이 발생하기 시작함을 관찰할 수 있었다. 이러한 NiO 상의 분리가 고온에서의 NTC 서미스터의 결정성 감소의 원인임을 알 수 있었으며, 제작된 NTC 서미스터의 표면을 FE-SEM을 이용하여 관찰하여 양품과 불량품의 차이를 분석하였다.

Keywords

References

  1. K. Uh, C.S. Kim and S.M. Shin, "Properties and applications of NTC thermistor", J. Electronic Engineering Soc. 21 (1994) 19.
  2. K. Kato, T. Ota, Y. Hikichi, H. Unuma, M. Takahashi and H. Suzuki, "A new class of NTC thermistors", Kor. J. Ceram. 6 (2000) 168.
  3. R. Metselaar, R.E.J. Van Tol and P. Piercy, "The electrical conductivity and thermoelectirc power of $Mn_3O_4$ at high temperature", J. Solid State Chem. 38 (1981) 335. https://doi.org/10.1016/0022-4596(81)90064-5
  4. K. Park, "Fabrication and electrical properties of Mn-Ni-Co-Cu-Si oxides nagative temperature coefficient thermistors", J. Am. Ceram. Soc. 88 (2005) 862. https://doi.org/10.1111/j.1551-2916.2004.00170.x
  5. W. Wang, X. Liu, F. Cao and C. Tian, "Synthesis of nanocrystalline $Ni_{1}Co_{0.2}Mn_{1.8}O_{4}$ powders for NTC thermistor by a gel auto-combustion process", Ceram. Int. 33 (2007) 459. https://doi.org/10.1016/j.ceramint.2005.10.010
  6. M. Suzuki, "AC hopping condcution in Mn-Co-Ni-Cu complex oxide semiconductors with spinel structure", J. Phys. Chem. Solids 41 (1980) 1253. https://doi.org/10.1016/0022-3697(80)90160-2
  7. E.G. Larson, R.J. Arnott and D.G. Wickham, "Preparation, semiconduction and low temperature magnetization of the system $Ni_{1-x}Mn_{2+x}O_{4}$", J. Phys. Chem. Solids 23 (1962) 1771. https://doi.org/10.1016/0022-3697(62)90216-0
  8. B. Gillot, J.L. Baudour, F. Bouree, R. Metz, R. Legros and A. Rousset, "Ionic configuration and cation distribution in cubic nickel manganite spinels $Ni_{x}Mn_{3-x}O_{4}$ (0.57 < x < 1) in relation with thermal histories", Solid State Ionics 58 (1992) 155 https://doi.org/10.1016/0167-2738(92)90022-H
  9. J.-I. Lee, T.W. Kim, J.Y. Shin and J.H. Ryu, "Preparation and characterization of Mn-Co-Ni NTC thermistor", J. Korean Cryst. Growth Cryst. Technol. 25 (2015) 80. https://doi.org/10.6111/JKCGCT.2015.25.2.080
  10. Y. Abe, T. Meguro, S. Oyamatsu, T. Yokoyama and K. Komeya, "Formation region of monophase with cubic spinel-type oxides in Mn-Co-Ni thernary system", J. Mater. Sci. 34 (1999) 4639. https://doi.org/10.1023/A:1004633610231