Effect of A-site ionic size variation on TCR and electrical transport properties of (Nd sub(0.7-x) La sub(x)) sub(0.7) Sr sub(0.3) MnO sub(3) with x = 0, 0.1 and 0.2

• Published in: IOP conference series. Materials Science and Engineering 2015-01, Vol.73
• Main Authors: Vadnala, Sudarshan, Asthana, Saket, Pal, Prem, Srinath, S
• Format: Article
• Language: English
• Subjects: Crystallization; Insulators; Manganites; Parents; Semiconductors; Transition temperature; Transport; Transport properties
• ISSN: 1757-8981; 1757-899X
• DOI: 10.1088/1757-899X/73/1/012047

In this work, the structural and transport properties of (Nd sub(0.7-x) La sub(x)) sub(0.7) Sr sub(0.3) MnO sub(3) manganites with x = 0, 0.1 and 0.2 prepared by solid state reaction route are studied. These compounds are found to be crystallized in orthorhombic structural form. Experimental results showing a shift in the metal to semiconductor/insulator transition temperature (T sub(MI)) towards room temperature (289 K) with the substitution of Nd by La, as the value of x is varied in the sequence (0,0.1,0.2), have been provided. The shift in the T sub(MI), from 239 K (for x= 0) to near the room temperature 289 K (for x=0.2), is attributed to the fact that the average radius of site-A increases with the percentage of La. The maximum temperature coefficients of resistance (TCR) of (Nd sub(0.7-x) La sub(x)) sub(0.7) Sr sub(0.3) MnO sub(3)(x = 0.1 and 0.2) are found to be higher compared to its parent compound Nd sub(0.7) Sr sub(0.3) MnO sub(3). The electrical transport mechanisms for (Nd sub(0.7-x) La sub(x)) sub(0.7) Sr sub(0.3) MnO sub(3)(x = 0 to 0.2) are explored by using different theoretical models, for temperatures below and above T sub(MI). An appropriate enlightenment for the observed behavior is discussed in detail.