Crystallographic phases and transport properties in the superconducting Tm-Ba-Cu-O compound system

The Tm-Ba-Cu-O compound system becomes a superconductor at a critical temperature $T_c$, measured at the midpoint of the resistive transition, of 92 K. From x-ray diffraction techniques, the material seems to be composed of two phases. The dominating (opaque) phase (≳94% in weight) is the superconducting $\mathrm{Tm}{\mathrm{Ba}}_2{\mathrm{Cu}}_3{\mathrm{O}}_{6+x}$ oxide (isostructural with superconducting oxygen-deficient $\mathrm{Y}{\mathrm{Ba}}_2{\mathrm{Cu}}_3{\mathrm{O}}_{6+x}$), which crystallizes in the orthorhombic pmmm space group with $a=3.819\mathrm{}\left(2\right)\mathrm{}$, $b=3.889\mathrm{}\left(2\right)\mathrm{}$, $c=11.669\mathrm{}\left(7\right)\mathrm{}$ Å, and $D_c=7.21\mathrm{}\left(1\right)\mathrm{}$ ${\mathrm{gcm}}^{-3\mathrm{}}$. The other (green) phase is the semiconducting ${\mathrm{Tm}}_2$BaCu${\mathrm{O}}_5$ oxide [space group $\mathrm{Pbnm}$ or $\mathrm{Pbn}{2}_1$; $a=7.079\mathrm{}\left(8\right)\mathrm{}$, $b=12.09\mathrm{}\left(1\right)\mathrm{}$, $c=5.633\mathrm{}\left(2\right)\mathrm{}$ Å, and $D_c=8.53\mathrm{}\left(2\right)\mathrm{}$ ${\mathrm{gcm}}^{-3\mathrm{}}$] isostructural with the series of $L_2\mathrm{BaCu}{\mathrm{O}}_5$ ($L=\mathrm{Y},\mathrm{S}\mathrm{m},\mathrm{E}\mathrm{u},\mathrm{G}\mathrm{d},\mathrm{D}\mathrm{y},\mathrm{H}\mathrm{o},\mathrm{E}\mathrm{r},\mathrm{Y}\mathrm{b}$) oxides.