Characteristics of MOD Bi-2212 Thin Films on r-Cut Sapphire With $\hbox{CeO}_{2}$ Buffer Layer

We have studied
$\hbox{Bi}_{2}\hbox{Sr}_{2}\hbox{CaCu}_{2}\hbox{O}_{8 + \delta}$
(Bi-2212) thin films fabrication by a metal organic decomposition method. When the Bi-2212 thin films were prepared on c-cut sapphire substrates, the maximum critical temperature
$(T_{\rm C})$
was 25 K by 820
$^{\circ}\hbox{C}$
air annealing in an electric furnace for 30 min. When the Bi-2212 thin films were prepared on r-cut sapphire substrates with
$\hbox{CeO}_{2}$
buffer layer, the Bi-2212 thin films were grown epitaxially on the
$ \hbox{CeO}_{2}$
buffer layer. The maximum
$T_{\rm C}$
obtained in the
$\hbox{Bi-2212}/\hbox{CeO}_{2}/\hbox{r-cut}$
sapphire was 62.5 K by 840
$^{\circ}\hbox{C}$
air annealing in an electric furnace for 30 min. To improve the surface morphology, face-to-face annealing process was introduced for the
$\hbox{Bi-2212}/\hbox{CeO}_{2}/\hbox{r-cut}$
sapphire. By face-to-face annealing,
$T_{\rm C}$
was increased up to 65 K, and the critical current density of
$1.03 \times 10^{5}\ \hbox{A/cm}^{2}$
was obtained at 5 K.