Nb doping effect in VO2 studied by investigations of magnetic behavior

• Published in: Ceramics international Vol. 44; no. 7; pp. 8623 - 8627
• Main Authors: Wang, Zhong-Long, Zhang, Run, Chen, Xing-Han, Fu, Qing-Shan, Li, Cang-Long, Yuan, Song-Liu, Zhao, Xiu-Jian, Tao, Hai-Zheng
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.05.2018
• Subjects: Curie law; Dimers; Metal-insulator transition; Pauli paramagnetic; Dimers; Curie law; Pauli paramagnetic; Metal-insulator transition
• ISSN: 0272-8842; 1873-3956
• DOI: 10.1016/j.ceramint.2018.02.079

It is shown that for samples of V1-xNbxO2 (0 ≤ x ≤ 3%), each undergoes a magnetic transition characterized by an abrupt variation in susceptibility, and the transition temperature Tm,x shifts from 333.4 K to 303 K with x from 0% to 3%. Above Tm,x the susceptibility weakly varies with temperature, while below Tm,x it varies inversely with temperature. Based on quantitative approaches to susceptibility data, it is proposed that Nb doping not only introduces additional electrons, which leads to an enhancement of the whole in susceptibility for the whole temperature range, but also makes part of V4+ ions become paramagnetic V3+ ions, which results in a strong variation of susceptibility inversely with temperature below Tm,x. The doping-induced decrease in Tm,x is explained to be due to the increase in separation between adjacent V4+ ions and the presence of PM V3+ ions, both being unfavorable to the formation of dimers.