Browsing by Author "Juan, Yung-Hsiang"

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Epitaxial Yttria-Stabilized Zirconia on Muscovite for Flexible Transparent Ionic Conductors
(2018-12-01)
Wu, Ping-Chun
;
Lin, Yu-Pin
;
Juan, Yung-Hsiang
;
Wang, Yao-Ming
;
Do Thi-Hien
The advantages of ionic conductors have attracted great interest worldwide because they can fit the requirements that standard electrical conductors struggle to meet. Yttria-stabilized zirconia (YSZ) is the most common ionic conductor for various practical applications. In this study, in order to bring ionic conductors into the field of soft technology, transparent YSZ films with superior mechanical flexibility were epitaxially grown on a muscovite substrate by pulsed-laser deposition. The epitaxial relationship between YSZ and muscovite has been well established, indicating a high-crystallinity thin film. The heterostructure of YSZ/muscovite exhibits excellent ionic conductivity with great mechanical flexibility. The smallest bending radius of this heterostructure that can be achieved is similar to 10 mm with excellent mechanical cyclabilty (>800 cycles) and stability (>10(5) s), serving as a new platform to fabricate highly flexible ionic conductors.
Manipulate the Electronic and Magnetic States in NiCo2O4 Films through Electric-Field-Induced Protonation at Elevated Temperature
(2019-04-19)
Wang, Meng
;
Sui, Xuelei
;
Wang, Yujia
;
Juan, Yung-Hsiang
;
Lyu, Yingjie
Ionic-liquid-gating- (ILG-) induced proton evolution has emerged as a novel strategy to realize electron doping and manipulate the electronic and magnetic ground states in complex oxides. While the study of a wide range of systems (e.g., SrCoO2.5, VO2, WO3, etc.) has demonstrated important opportunities to incorporate protons through ILG, protonation remains a big challenge for many others. Furthermore, the mechanism of proton intercalation from the ionic liquid/solid interface to whole film has not yet been revealed. Here, with a model system of inverse spinel NiCo2O4, an increase in system temperature during ILG forms a single but effective method to efficiently achieve protonation. Moreover, the ILG induces a novel phase transformation in NiCo2O4 from ferrimagnetic metallic into antiferromagnetic insulating with protonation at elevated temperatures. This study shows that environmental temperature is an efficient tuning knob to manipulate ILG-induced ionic evolution.