TECHNICAL FIELD

The present disclosure relates to material for an electric device, in particular to a phase transformation electronic device achieved by regulating a transformation of a hydrogen-containing transition metal oxide via an electric field.

BACKGROUND

A thermology method is adopted to hydrogenate an oxide. For example, the oxide can be reduced by some hydrides such as CaH2and NaH. H ions would substitute O of the oxide to form H-M bonds (M is a transition metal). Since the H-M bond is shorter than M-O, the hydrogenated oxide exhibits a characteristic of reduced lattice volume. The hydrogenation to the transition metal oxide, on one hand, changes the lattice structure of the transition metal oxide, and on the other hand, changes an electrical or magnetic property of the material due to the accompanied doping of electron or hole. In addition, the oxygen of the oxide sometimes may be carried away during the hydrogenation so as to form a structural phase with oxygen vacancy. Some hydrogen-containing oxides, such as hydrogenated LaSrCoO3, BaTiO3, VO2, TiO2, and the like, have been made by a hydrogen thermal reduction method. In addition to the hydrogenation method, a structural transition of an oxide material can also be achieved by a thermal oxidation method. For example, a transformation from SrCoO2.5with a brownmillerite structure to SrCoO3with a perovskite structure can be achieved by a high oxygen pressure oxidation method. Besides, there are also some other methods now, such as an electrochemical method.

The above methods are all restricted to a regulation between two phases. However, previously there is no hydrogen-containing transition metal oxide capable of achieving a tri-state phase transformation and no phase transformation electronic device corresponding to the tri-state phase transformation achieved by regulating the hydrogen-containing transition metal oxide via an electric field.

SUMMARY

In view of this, for the problems as described above, a hydrogen-containing transition metal oxide and a phase transformation electronic device achieving a tri-state phase transformation by regulating the hydrogen-containing transition metal oxide via an electric field are provided.

A phase transformation electronic device includes a phase transformation material layer and an ionic liquid layer stacked with each other. The ionic liquid layer is capable of providing hydrogen ions and oxygen ions. The phase transformation material layer is formed by a hydrogen-containing transition metal oxide having a structural formula of ABOxHy, wherein A is one or more of alkaline earth metal elements and rare-earth metal elements, B is one or more of transition metal elements, x is a numeric value in a range of 1 to 3, and y is a numeric value in a range of 0 to 2.5.

In one embodiment, the phase transformation material layer is covered by the ionic liquid layer.

In one embodiment, the phase transformation electronic device further includes a first conductive layer stacked on a surface of the ionic liquid layer away from the phase transformation material layer.

In one embodiment, the phase transformation electronic device further includes a second conductive layer spaced from the first conductive layer. The phase transformation material layer is disposed between the first conductive layer and the second conductive layer and electrically connected to the second conductive layer.

In one embodiment, the phase transformation electronic device further includes an insulating support disposed between the first conductive layer and the second conductive layer, and the first conductive layer and the second conductive layer are separated from each other by the insulating support.

In one embodiment, the phase transformation electronic device further includes a first substrate and a second substrate. The first substrate and the second substrate are opposite to and spaced from each other. The first conductive layer is disposed on the first substrate, and the second conductive layer is disposed on the second substrate.

In one embodiment, the first substrate, the first conductive layer, the second conductive layer, and the second substrate are made by transparent materials.

In one embodiment, the alkaline earth metal elements include Be, Mg, Ca, Sr, and Ba. The rare-earth metal elements include La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, and Yb. The transition metal elements include Co, Cr, Fe, Mn, Ni, Cu, Ti, Zn, Sc, and V.

In one embodiment, B is transition metal element Co.

In one embodiment, A is alkaline earth metal element Sr.

In one embodiment, x is 2.5 and y is 0 to 2.5.

In one embodiment, the phase transformation material layer performs a phase transformation among a first phase, a second phase, and a third phase under an action of an electric field. A lattice volume of the first phase is larger than a lattice volume of the second phase. The lattice volume of the second phase is larger than a lattice volume of the third phase.

In one embodiment, the first phase is SrCoO2.5H, the second phase is SrCoO2.5, and a third phase is SrCoO3-δ.

In the phase transformation electronic device of the present disclosure, the ionic liquid gating voltage is adopted to regulate the transformation of the hydrogen-containing transition metal oxide at room temperature under a control of an electric field, so that the corresponding electrical, optical, and magnetic properties can be simultaneously regulated. For example, electric field induced effects, such as a metal-insulator transformation, a dual-bands electrochromic effect (visible light and infrared light), and a tri-state magnetoelectric coupling are achieved. Through these results, an understanding to the electric field controlled ionic storage and ionic transportation is deepened, an exploration to the corresponding basic principle and practical application is achieved, and a basis is provided for a design of a novel crystal structure with particular functions.

