Crystallographic Axis Transition of Sm_1+xBa_2−xCu₃O_7−δ Film Prepared by Liquid Phase Epitaxy (LPE)

Abstract

The effect of two significant factors, flux composition and growth atmosphere, on the crystallographic axis orientation of the Sm1+x Ba2−x Cu3O7−δ “SmBCO” film was studied. We succeeded in achieving a pure a-axis SmBCO LPE film by applying Cu-rich Ba−Cu−O flux (Ba/Cu ratio 3:7) and 1 atm oxygen atmosphere. Compared to YBCO, it is more difficult to grow SmBCO along a-axis. Several possible reasons were considered, especially the mutual substitution of Sm3+ and Ba2+, which may prefer c-axis growth. Significant features of the LPE process, like nucleation, supersaturation, and growth rate, manifest tendency to prevent a-axis growth.

Growth condition related orientation transition for YBa2Cu3O7−δ films on NdGaO3 substrate

“…At high temperatures, owing to the NGO etch-back, the system changes from YBCO to Nd-YBCO and the effective s instantly increases as the substrate is dipped into solution. Similarly to the SmBCO system, NdBCO has a gradual slope of its liquidus, and the growth window of a-axis films is proved to be quite small [3,[28][29]. Both the enhancement of the effective s and the system shift to Nd-YBCO, facilitate the growth of c-axis phase.…”

Evolution of Oriented Structures in YBa2Cu3O7−δ Films by Liquid Phase Epitaxy through Manipulating Supersaturation

“…Figure schematically illustrates the relationship between the supersaturation and the growth rates ( R ) of the a - and c -films, where σ a , σ a 2 , and σ c are critical supersaturations for nucleation of 0° a- grain, 90° a- grain, and c -grain, respectively. Furthermore, it is noticeable that two R ∼ σ curves cross each other at σ cross , where R a equals R c .…”

The Orientation Transition and Control of REBaCu3Oy Films Grown by Liquid Phase Epitaxy

“…(c) Optical polarization micrograph of the a -film. In the yellow ellipse, typical a -axis twinning can be seen …”

“…However, compared to YBCO, the control of the film orientation in SmBCO is far more difficult, especially for the preparation of the a -axis SmBCO film. In this respect, to further explore the a- , c- axis oriented growth mode in REBCO families, the control of crystallographic orientation in the SmBCO film was investigated …”