Certification of YBa2Cu3O7−x Single Crystals

A method for evaluation of the critical temperature Tc and the width of the superconducting transition ΔTc in HTSC single crystals has been developed. By this method, the first derivative of the temperature dependence of the resistivity, \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$\frac{\partial \rho (T)}{\partial T}$\end{document}, is constructed. A technique for synthesis of YBa2Cu3O7−x single crystals with highly reproducible physical-mechanical properties has been described. A standard sample with Tc=94 K and ΔTc=0.25 K has been synthesized and certified.