access icon openaccess Revisiting the effects of Co2O3 on multiscale defect structures and relevant electrical properties in ZnO varistors

This is an open access article published by the IET and CEPRI under the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0/)
Received 30/12/2019, Accepted 06/03/2020, Revised 27/02/2020, Published 10/03/2020

Element doping is an effective method to improve the performance of ZnO varistors. Previous studies mainly focused on the variation of microstructures and Schottky barriers. In this study, the effects of Co dopant on electrical properties are investigated from the aspect of multiscale defect structures, including intrinsic point defects, the heterogeneous interface of depletion/intergranular layers, and interface states at grain boundaries. Combining with analysis of phase composition and energy dispersive spectroscopy, it is found that Co tends to dissolve into ZnO grains when slightly doped. It substitutes Zn2+ with the same valence and affects little on densities of donors. Segregation of Co at grain boundaries would result in the formation of spinel phase Co(Co4/3Sb2/3)O4 and transformation of the intergranular phase from α-Bi2O3 to δ-Bi2O3. Meanwhile, densities of point defects are indirectly affected by oxygen ambient during sintering, resulting in abnormal variation of grain resistivity. And interface states are enhanced, leading to improved barriers at grain boundaries. Therefore, reduced leakage current, enhanced grain resistivity, and improved non-linear coefficient in Co-doped ZnO varistor blocks are understood from the underlying multiple defect structures. This presents a potential approach to explore short-term performance and long-term stability of ZnO varistors from the aspect of defect responses.

Inspec keywords: segregation; semiconductor doping; II-VI semiconductors; interface states; sintering; doping profiles; zinc compounds; varistors; leakage currents; grain boundaries; point defects; grain boundary segregation; wide band gap semiconductors; Schottky barriers

Other keywords: energy dispersive spectroscopy; zinc oxide varistors; dissolving; grain boundaries; element doping; electrical properties; defect responses; phase composition; multiscale defect structures; interface states; intrinsic point defects; depletion-intergranular layers; intergranular phase; ZnO:Co; enhanced grain resistivity; varistor blocks; cobalt dopant effects; Schottky barriers; heterogeneous interface

Subjects: Impurity concentration, distribution, and gradients; Surface diffusion, segregation and interfacial compound formation; Resistors; Other semiconductor devices; Semiconductor-metal interfaces; Microstructure; Semiconductor doping; Grain and twin boundaries; II-VI and III-V semiconductors; Electrical properties of metal-nonmetal contacts; Doping and implantation of impurities

References

    1. 1)
      • 18. Long, W., Hu, J., Liu, J., et al: ‘Effects of cobalt doping on the electrical characteristics of Al-doped ZnO varistors’, Mater. Lett., 2010, 64, (9), pp. 1081–1084.
    2. 2)
      • 8. Li, S., Yu, S., Feng, Y.: ‘Progress in and prospects for electrical insulating materials’, High Voltage, 2016, 1, (3), pp. 122–129.
    3. 3)
      • 35. Shen, C., Wu, L., Chen, Y.: ‘Effect of additions on conduction properties of ZnO varistors’, Jpn. J. Appl. Phys., 1993, 19, (32), pp. 2043–2046.
    4. 4)
      • 2. Li, S., Li, J., Liu, W., et al: ‘Advances in ZnO varistors in China during the past 30 years – fundamentals, processing, and applications’, IEEE Electr. Insul. Mag., 2015, 31, (4), pp. 35–44.
    5. 5)
      • 24. Cheng, P., Song, J., Wang, Q., et al: ‘Fine representation of dielectric properties by impedance spectroscopy’, J. Alloys Compd., 2018, 740, pp. 36–41.
    6. 6)
      • 9. Zeng, R., Zhuang, C., Zhou, X., et al: ‘Survey of recent progress on lightning and lightning protection research’, High Voltage, 2016, 1, (1), pp. 2–10.
    7. 7)
      • 28. Jonscher, A.K.: ‘Universal relaxation law’ (Chelsea Dielectrics Press, London, 1996, 1st edn.).
    8. 8)
      • 15. Pike, G.E., Seager, C.H., Dosch, R.G.: ‘A study of Co and Mn in ZnO varistors’. MRS Proc., 1985, 46, pp. 409–414.
    9. 9)
      • 21. Liu, W., Zhang, L., Kong, F., et al: ‘Enhanced voltage gradient and energy absorption capability in ZnO varistor ceramics by using nano-sized ZnO powders’, J. Alloys. Compd., 2020, 828, p. 154252.
    10. 10)
      • 16. Kim, E.D., Kim, C.H., Oh, M.H.: ‘Role and effect of Co2O3 additive on the upturn characteristics of ZnO varistors’, J. Appl. Phys., 1985, 58, (8), pp. 3231–3235.
    11. 11)
      • 20. Zhang, L., Yu, C., Zhang, L., et al: ‘A statistical approach for effectively analyzing the grain size distribution along the thickness direction in commercial ZnO-based varistor ceramics’. 2018 Condition Monitoring and Diagnosis (CMD), Perth, Australia, 2018, pp. 1–6.
    12. 12)
      • 14. Anderson, R.S.: ‘Lattice-vibration effects in the spectra of ZnO: Ni and ZnO: Co’, Phys. Rev., 1967, 164, (2), pp. 398–405.
    13. 13)
      • 25. Huang, Y., Wu, K., Xing, Z., et al: ‘Understanding the validity of impedance and modulus spectroscopy on exploring electrical heterogeneity in dielectric ceramics’, J. Appl. Phys., 2019, 125, (8), p. 084103.
    14. 14)
      • 11. He, J., Cheng, C., Hu, J.: ‘Electrical degradation of double-Schottky barrier in ZnO varistors’, AIP Adv., 2016, 6, (3), p. 030701.
    15. 15)
      • 29. Cheng, P., Li, S., Zhang, L., et al: ‘Characterization of intrinsic donor defects in ZnO ceramics by dielectric spectroscopy’, Appl. Phys. Lett., 2008, 93, (1), p. 012902.
    16. 16)
      • 36. Hong, Y.W., Kim, J.: ‘Impedance and admittance spectroscopy of Mn3O4-doped ZnO incorporated with Sb2O3 and Bi2O3’, Ceram. Int., 2004, 30, (7), pp. 1307–1311.
    17. 17)
      • 38. Shuk, P., Wiemhofer, H.-D., Guth, U., et al: ‘Oxide ion conducting solid electrolytes based on Bi2O3’, Solid State Ion., 1996, 89, (3–4), pp. 179–196.
    18. 18)
      • 17. Yano, Y., Takai, Y., Morooka, H.: ‘Interface states in ZnO varistor with Mn, Co and Cu impurities’, J. Mater. Res., 1994, 9, (1), pp. 112–118.
    19. 19)
      • 13. Yang, X., Hu, J., He, J.: ‘Effect of interfacial charge relaxation on conducting behavior of ZnO varistors under time varying electric fields’, Appl. Phys. Lett., 2017, 110, (18), p. 182104.
    20. 20)
      • 32. Grosse, C.: ‘A program for the fitting of Debye, Cole–Cole, Cole–Davidson, and Havriliak–Negami dispersions to dielectric data’, J. Colloid Interface Sci., 2014, 419, pp. 102–106.
    21. 21)
      • 34. Han, J., Senos, A.M.R., Mantas, P.Q., et al: ‘Dielectric relaxation of shallow donor in polycrystalline Mn-doped ZnO’, J. Appl. Phys., 2003, 93, (7), pp. 4097–4103.
    22. 22)
      • 31. Lin, J., Li, S., He, J., et al: ‘Zinc interstitial as a universal microscopic origin for the electrical degradation of ZnO-based varistors under the combined DC and temperature condition’, J. Eur. Ceram. Soc., 2017, 37, (11), pp. 3535–3540.
    23. 23)
      • 37. Brankovic, Z., Brankovic, G., Poleti, D., et al: ‘Structural and electrical properties of ZnO varistors containing different spinel phases’, Ceram. Int., 2001, 27, (1), pp. 115–122.
    24. 24)
      • 30. Lin, J., Li, S., He, J., et al: ‘Effect of Al addition on electrical properties of ZnO-based varistor ceramics’, J. Inorg. Mater., 2016, 31, (9), pp. 981–986.
    25. 25)
      • 23. Zhao, X., Liao, R., Liang, N., et al: ‘Role of defects in determining the electrical properties of ZnO ceramics’, J. Appl. Phys., 2014, 116, (1), p. 526.
    26. 26)
      • 1. Li, J., Li, S., Cheng, P., et al: ‘Advances in ZnO-Bi2O3 based varistors’, J. Mater. Sci., Mater. Electron., 2015, 26, (7), pp. 4782–4809.
    27. 27)
      • 7. Shirakawa, S., Kobayashi, T., Matsushita, Y., et al: ‘Zinc oxide surge arresters and HVDC 125kV-upgrade 500 kV converter stations’, IEE J. Trans. Power Energy, 2009, 129, (10), pp. 1194–1200.
    28. 28)
      • 22. Zhao, X., Li, J., Li, H., et al: ‘Intrinsic and extrinsic defect relaxation behavior of ZnO ceramics’, J. Appl. Phys., 2012, 111, (12), p. 6132.
    29. 29)
      • 5. Kobayashi, M.: ‘Development of gapless surge arresters and application of them to power system facilities’. IEEE 33rd Int. Conf. on Lightning Protection (ICLP), Estoril, Portugal, 2016, pp. 1–6.
    30. 30)
      • 6. Kannadasan, R., Valsalal, P.: ‘Modelling and validation of metal oxide surge arrester for very fast transients’, High Voltage, 2018, 3, (2), pp. 147–153.
    31. 31)
      • 4. Matsuoka, M.: ‘Nonohmic properties of zinc oxide ceramics’, Jpn. J. Appl. Phys., 1971, 10, (6), pp. 736–746.
    32. 32)
      • 12. He, J., Cheng, C., Hu, J.: ‘An analytic approach to the degradation of double-Schottky barrier: theoretical prediction of VO0−Zni2+:Zni2+ as dominant mobile ion in ZnO electroceramic’, Scr. Mater., 2015, 104, pp. 25–28.
    33. 33)
      • 10. Zhao, X., Zhao, X., Xu, C., et al: ‘Recent research progress of relaxation performances of defects in ZnO-Bi2O3 varistor ceamics’, Acta Phys. Sin., 2017, 66, (2), pp. 11–24.
    34. 34)
      • 33. Evgenij, B., Ross Macdonald, J.: ‘Impedance spectroscopy: theory, experiment, and applications’ (John Wiley & Sons, Inc., New Jersey, 2018, 3rd edn.).
    35. 35)
      • 26. Wu, K., Huang, Y., Li, J., et al: ‘Space charge polarization modulated instability of low frequency permittivity in CaCu3Ti4O12 ceramics’, Appl. Phys. Lett., 2017, 111, (4), p. 042902.
    36. 36)
      • 39. Huang, Y., Wu, K., Tang, Z., et al: ‘Investigation of electrical inhomogeneity in ZnO varistor ceramics based on electronic relaxations’, Ceram. Int., 2019, 45, (1), pp. 1110–1114.
    37. 37)
      • 19. He, J., Li, S., Lin, J., et al: ‘Reverse manipulation of intrinsic point defects in ZnO-based varistor ceramics through Zr-stabilized high ionic conducting βIII-Bi2O3 intergranular phase’, J. Eur. Ceram. Soc., 2018, 38, (4), pp. 1614–1620.
    38. 38)
      • 27. Wu, K., Huang, Y., Wang, Z., et al: ‘Application of extended derivative method in analyzing dielectric responses of dielectrics’, High Voltage Eng., 2020, 46, (2), pp. 640–647.
    39. 39)
      • 3. He, J.: ‘Metal oxide varistors’ (TsingHua University Press, Beijing, 2019, 1st edn.).
http://iet.metastore.ingenta.com/content/journals/10.1049/hve.2019.0419
Loading

Related content

content/journals/10.1049/hve.2019.0419
pub_keyword,iet_inspecKeyword,pub_concept
6
6
Loading