| Oxygen nonstoichiometry and electrical properties of La2–xSrxNiO4+δ (0 ≤ x ≤ 0.5) |
Dang‑Hoang Hop2, Roy Byung Kyu Chung1, Young‑Woo Heo1, Jeong‑Joo Kim1, Joon‑Hyung Lee1
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1School of Materials Science and Engineering, Kyungpook National University, Daegu 41566, Korea
2Ministry of Science and Technology of Vietnam, 113 Tran Duy Hung Street, Cau Giay District, Hanoi, Vietnam |
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Received: January 13, 2020; Revised: February 7, 2020 Accepted: March 12, 2020. Published online: April 30, 2020. |
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| ABSTRACT |
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The amount of interstitial oxygen (δ) in Sr-doped lanthanum nickel oxide ( La2–xSrxNiO4+δ) as a function of Sr content has been investigated by the thermogravimetry analysis (TGA) and X-ray photoelectron spectroscopy (XPS). La2–xSrxNiO4+δ (0 ≤ x ≤ 0.5) ceramics were prepared by the general solid-state reaction process and sintered in different ambient of argon, air or oxygen, respectively. An increase in the amount of Sr decreased δ in La2–xSrxNiO4+δ, while the Ni2+/ Ni3+ ratio analyzed by Ni3p XPS decreased indicating that the oxidation state of Ni increased. Particularly when the sample was sintered in a low oxygen partial pressure condition such as in Ar ambient, the hole concentration strongly depended on the Sr content, suggesting that the hole generation seems mostly originated from Sr2+ substitution into the La3+ site. |
| Key words:
Electrical properties · Sintering · Oxygen nonstoichiometry · p-type · Hole concentration |
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