Ultrasonic studies on sodium-doped LaMnO3 perovskite material

摘要

La_(1?x )Na_(x )MnO_(3) perovskite manganite in the form of circular pellets was prepared with the composition of x ?=?0.10, 0.15 and 0.20 by the solid-state reaction technique. To confirm the crystalline nature of the samples, X-ray diffraction patterns of the samples were obtained. It is found that the samples have a rhombohedral structure with R3c space group. Particle size was determined from the obtained scanning electron microscope images. Ultrasonic velocity and the attenuation measurements were carried out on the samples employing the transmission technique in the temperature range from 300 to 400?K. The anomalous behaviour obtained in the ultrasonic measurements was used to explore the transition temperature of the prepared La_(1?x )Na_(x )MnO_(3) perovskite samples. The temperatures 320, 328 and 334?K are the ferromagnetic to paramagnetic phase transition temperatures of the samples x ?=?0.10, 0.15 and 0.20, respectively.