Structura and infrared studies of ( La1-xPrx)0.85Zr0.15MnO3 manganites

• Main Authors: tao-yi chang, 張道宜
• Other Authors: P. H. Chang
• Format: Others
• Language: zh-TW
• Published: 2004
• Online Access: http://ndltd.ncl.edu.tw/handle/23315647763740580113

碩士 === 長庚大學 === 電子工程研究所 === 92 === We present the X-ray diffraction and optical reflectivity measurements of Pr doped (La1-xPrx)0.85Zr0.15MnO3 (x = 0.0, 0.01, 0.05, 0.10, 0.15, and 0.20). These materials are interesting on account of the Mn2+ and Mn3+ ferromagnetic-type magnetization behavior. At room temperature, X-ray diffraction data show that the replacement of La ions with smaller Pr ions causes the shrinkage of the unit cell volume. The variations of the peak positions of the infrared-active internal bending and stretching phonon modes of the MnO6 octahedra are consistent with the X-ray diffraction results. With decreasing temperature, the lattice parameters and unit cell volume for all samples show noticeable changes near the Curie temperature (Tc), and a concomitant splitting of the bending mode, and the presence of polaron feature. Upon further lowering temperature, another anomalies of the lattice constants are observed when an additional increase of resistivity proceed by a minimum at Tmin. Our results suggest that the magnetic and electronic phase transitions are strongly coupled with the lattice dynamics in these materials.