Self-Propagating High-Temperature Synthesis of Chromium Substituted Lanthanide – Barium – Copper Oxides, LnBa2Cu3-xCrxO7-y (Ln = Y; La; Nd; Sm and Yb)

Maxim V Kuznetsov,Yuri G Morozov,Alexander G Merzhanov,Ivan P Parkin

doi:10.18321/ectj521

Abstract

A series of MBa2Cu3-xCrxO7-y (M = Y; La; Nd; Sm and Yb; x = 0, 0.05, 0.15, 0.25) materials were synthesized in air by self-propagating high-temperature synthesis (SHS) involving reaction of stoichiometric mixtures of rare-earth metal (III) oxide, barium peroxide, copper metal, chromium (III) oxide and sodium perchlorate. All the SHS processes were followed by sintering in oxygen at 950 °C for 2h. The products were characterized by SEM, X-ray powder diffraction, UV, superconductive transition temperatures (Tc) and magnetic susceptibility (χ) measurements. X-ray diffraction data showed that single phase orthorhombic (or tetragonal for M = Nd) materials were produced. All series of materials showed a systematic increase in lattice parameters and unit cell volume with chromium content (M = Y: x = 0, V = 174.25 Å3; x = 0.25, V = 175.10 Å3). Thermal stability of all the SHS prepared materials increased with x. Oxygen content of all the samples increased with x, but did not exceed 7.0. Superconductivity transition temperature decreased with chromium substitution in all systems (98-77 K). Magnetic susceptibility decreased with chromium substitution.

Highlights

The final Y123 product was formed in the SHS step by crystallization of a melt of Y2O3, barium cuprates and copper (II) oxide
High temperature superconducting materials (HTSC) such as LnBa2Cu3O7-y (Ln = Y or rare-earth metal (REM)) are of widespread engineering, academic and industrial interest
Materials with known dopant distributions can be used for the creation of crystalline heterostructures such as HTSC - metal or HTSC dielectrics that can be used for industrial purposes

Summary

Introduction

The final Y123 product was formed in the SHS step by crystallization of a melt of Y2O3, barium cuprates and copper (II) oxide. Lattice parameters for the five series of MBa2Cu3-xCrxO7-y (M = Y; La; Nd; Sm; Yb) HTSC samples obtained following the SHS reaction of BaO2, Cu, M2O3, Cr2O3 and NaClO4. An increase in chromium substitution in the SHS prepared materials results in products with higher thermal stability.

Results

Conclusion