ANALISIS POR EMISION DE RAYOS X Anomalies in the internal friction and sound velocity in the high-temperature superconductor La1.8Sr0.2CuO4 Bulk density CONDUCTIVIDAD ELECTRICA DENSIDAD VOLUMICA APARENTE Electric conductivity FRICCION INTERNA High-Tc superconductors IMANTACION Indicador automático de deformación Internal friction MODULO DE YOUNG Magnetization SUPERCONDUCTIVIDAD SUPERCONDUCTORES SUPERCONDUCTORES DE TC ALTO Softening of the flux-line structure in La1.8Sr0.2CuO4 measured by a vibrating reed Specific heat of La1.8Sr0.2CuO4: Anomaly at the superconducting transition Superconductivity Superconductors X-ray emission analysis Young modulus