Structural and superconducting features of Tl-1223 prepared at ambient pressure

Details of bulk preparation of TlBa$_{\mathrm{2}}$Ca$_{\mathrm{2}}$Cu$_{\mathrm{3}}$O$_{\mathrm{9-\delta }}$ (Tl-1223) superconductor at ambient pressure with the critical temperature (T$_{\mathrm{c}})$ features under thermal-annealing conditions will be presented. The as-prepared Tl-1223 (T$_{\mathrm{c}}=$106K) presents a significantly higher T$_{\mathrm{c}}=$125K after annealing the polycrystalline material in either flowing Ar$+$4{\%}H$_{\mathrm{2}}$, or N$_{\mathrm{2}}$. We further refined the average bulk structures using powder XRD data. Although Ar$+$4{\%}H$_{\mathrm{2}}$ annealed Tl-1223 shows an increased 'c' lattice parameter, it shrinks by 0.03{\%} upon annealing under N$_{\mathrm{2}}$. Due to such indeterminate conclusions on the average structural changes, local structures were investigated at using aberration-corrected scanning-transmission electron microscopy technique. Similar compositional changes in the atomic arrangements of both annealed-samples of Tl-1223 were detected in which the plane containing a Ca atomic layer gives a non-uniform contrast, due to substitution of some heavier Tl. We present extensive bulk properties summarized through temperature-dependent resistivity, and shielding and Meissner fractions of magnetic susceptibility results.