Intrinsic structure and thermal stability of YBCO thin film

Abstract

The melting behaviours of two kinds of c-axis oriented YBa2Cu3Ox (YBCO) films with different four-symmetry in-plane orientations were observed in situ by using high temperature optical microscopy. The in-plane orientation was detected by pole figures and the atomic configuration in the vicinity of the interface of one sample was evaluated by electron diffraction and high-resolution transmission electron microscopy. It is found that the melting mode and the thermal stability of the YBCO thin films with different in-plane orientations differ completely from each other. Such a phenomenon is considerably influenced by the geometrical lattice matching between the YBCO thin films and the MgO substrate, as well as the terminal plane of the YBCO thin films.

Peritectic melting of thin films, superheating and applications in growth of REBCO superconductors

“…(2) Different intrinsic structures Secondly, two kinds of c-axis oriented YBCO/MgO films with different four-symmetry in-plane orientations were in-situ investigated under 0.21 and 1 atm. oxygen partial pressures [47,48]. The films were denoted as film E (0°orientated grains) and film F (45°orientated grains), respectively, according to the pole figure results shown in Fig.…”

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

“…Among the first types of substrates, MgO is most widely adopted for investigations on LPE processed REBCO films, due to the low wettability and chemical stability of MgO with respect to the Ba–Cu–O solvent. − More importantly, due to its suitable thermal expansion coefficient during growth, the MgO substrate is a unique material in preparing uncracked high-quality REBCO LPE thick films. ,,− However, due to the aforementioned misfit issue, REBCO can only be epitaxially grown after the deposition of the template layer.…”

Melting behavior and superheating capacity of REBa2Cu3Oy films with nano‐layer buffered structures

“…Nowadays, deep investigation on the superheating mechanism, searching novel structures possessing the high superheating capability, and realizing its practical application attract great attention in the scientific world . In recent years, experimental evidences have clearly proved that the c ‐axis oriented RE123 (REBa 2 Cu 3 O y , RE = Nd, Sm and Y) films on the MgO substrate (shortly, RE123/MgO), as a quasi‐2D structure possesses a superheating capacity, i.e., the RE123 film may remain in its metastable solid phase above its peritectic melting temperature over several tens degrees . Like most functional oxide materials, RE123 features anisotropic surface energy in the crystalline plane (equivalent to anisotropic melting temperature) and the a‐b plane is characterized by the low surface energy, which is the intrinsic reason why this quasi‐2D nanocrystalline film does not easily melt.…”

“…Further, Cai presented the variations of the thermal stability of Y123 films with different crystallinities. Wang, Tang and Cheng et al found different melting behaviors and thermal stabilities of films derived from different orientations (in‐plane and out‐of‐plane). Moreover, Yan et al pointed out that the Nd123 thin film has low thermal stability than the Y123 film due to its higher growth rate of Nd 4 Ba 2 Cu 2 O 10 than that of Y 2 BaCuO 5 , which are derived from the RE123 decomposition.…”