Synthesis and properties of nonstoichiometric samples of $\mathrm{Y}{\mathrm{Ba}}_2{\mathrm{Cu}}_3{\mathrm{O}}_{7-x}$; $0.04\le x\le 1.00$

A simple and accurately reproducible route was previously described for the synthesis of $\mathrm{Y}{\mathrm{Ba}}_2{\mathrm{Cu}}_3{\mathrm{O}}_{7-x}$ with intermediate compositions, $0.0<x<\mathrm{}1.0\mathrm{}$, that involves equilibration of appropriate proportions of compounds with $x=0.0\mathrm{}$ and $x=1.0\mathrm{}$ in sealed tubes. This synthetic procedure has been further explored and products studied by powder diffraction, thermogravimetric analysis, and magnetization measurements. The temperature required for such equilibrations has been studied at three representative compositions, by using sealed H tubes to physically separate the two components. For $0.0<x<\mathrm{}0.4\mathrm{}$, in contrast to earlier suggestions of phase separation, powder x-ray diffraction and the superconducting properties indicate that single-phase orthorhombic materials (on a length scale greater than about 60 Å) are obtained on quenching from temperatures above 350°C. In particular, the superconducting transition temperature varies in a smooth, S-shaped fashion over the $0.04<x<\mathrm{}0.40\mathrm{}$ composition field, the observed variation of the transition width with $x$ is as expected from the variation of $\frac{d{T}_c}{\mathrm{dx}}$ in this range, and there are no indications of multiple superconducting transitions in the dc magnetization data.