Impact of nano-Micro Particle Size on Structural, Magnetic and Electrical Properties of La۰.۵Ca۰.۵MnO۳ Manganites

Structural, magnetic, and electrical properties of La۰.۵Ca۰.۵MnO۳ samples prepared at two different sintering temperatures (۸۰۰°C and ۱۳۵۰°C which were labeled S۸۰۰ and S۱۳۵۰, respectively) have been investigated. The Reitveled refined XRD patterns indicate an orthorombic structure with Pnma space group for both samples. Ac susceptibility measurements show that, the fraction of ferromagnetic and antiferromagnetic phases could be controlled with sintering temperature. S۸۰۰ sample has a ferromagnetic state while the antiferromagnetic phase is enhanced in S۱۳۵۰ sample which causes the increase of thermal hysteresis in this sample. Two distinct regions (T>ӨD/۲ and T˂ӨD/۲, ӨD is the Debye’s temperature) were noticed to investigate the electrical properties. Based on the resistivity data at T>ӨD/۲ region, the S۸۰۰ and S۱۳۵۰ samples follow the adiabatic and non-adiabatic small polaron hopping (SPH) models, respectively. At T˂ӨD/۲ region, the ۳-dementional variable range hopping (VRH) model displays a good correlation with the experimental data of both samples. The related parameters of both SPH and VRH models are extracted. The results show that these parameters are particle size dependent.

کلیدواژه ها:

Manganites ، Resistivity ، Thermal hysteresis ، Sintering Temperature