The effect of tin addition on the electrical conductivity of Sn-doped LaBaMnO3

Abstract

Electrical properties of La0.67Ba0.33Mn1−xSnxO3 (0⩽x⩽0.10) (LBMO-Sn) manganites have been investigated using admittance spectroscopy. The samples exhibit metallic behavior at below metal-semiconductor transition temperature (TMS) and semiconductor-like features above TMS. We find that TMS decreases from 300K for x=0 to 240K for x=0.10. Due to the substitution of manganese by tin, a decrease of DC conductance was observed throughout the whole explored temperature range. Such behavior is essentially due to the disorder introduced in the charge transfer mechanism when replacing some links of the Mn–O–Mn network by Mn–O–Sn ones. From dc conductance study, electronic conduction is found to be dominated by thermally activated hopping. The tin content affects strongly the activation energy (Ea). Its value increases from 27meV for x=0 to 170meV for x=0.10. The ac conductance spectrum is found to be sensitive to the tin content. In contrary to free compound, when introducing tin, the material exhibits several features as a function of frequency and temperature. Also, the spectrum is characterized by the appearance of a conductance peaks, which shifts to higher frequencies. Such behavior indicates the presence of relaxation phenomenon in the system. In the high frequency range, ac conductance can be described by the power law G(ω)=Aωs, indicating a hopping conduction process. The variation of the exponent ‘s’ with temperature and tin content, permits us to conclude that hopping model may be the dominating mechanism in the system and confirm that LBMO-Sn system evolves from metallic to semiconductor behavior when increasing tin content.