Large temperature coefficient of resistivity (TCR) of La1-xCaxMnO3 films prepared by spin-coating method
La 1- x A x MnO 3 (A = alkaline-earth or alkali metal) perovskites with large temperature coefficient of resistivity ( TCR ) offer immense opportunity for the application in high-performance infrared bolometer. However, numerous studies have revealed that the manganite films with large TCR values are not easily obtained by various fabrication technologies. Herein, a facile sol-gel spin-coating technique was used to prepare La 1- x Ca x MnO 3 (LCMO, 0.280 ≤ x ≤ 0.375) films. All the samples were highly oriented along the out-of-plane direction of La 0.3 Sr 0.7 Al 0.65 Ta 0.35 O 3 (001) substrates. With the rise in Ca doping amount, the resistivity of the films first decreased, and then, increased. This change can be attributed to the competition between the carrier concentration and lattice distortion. The LCMO films displayed large TCR and low-field magnetoresistance ( MR ) values, which exceeded those of previously reported thin films. The maximum TCR and low-field MR values were observed at x = 0.330, reaching 30.13% K −1 (266.43 K) and 68.6% (270.08 K), respectively. The La 0.67 Ca 0.33 MnO 3 film with large TCR and MR values presents potential for the applications in high-sensitivity infrared bolometers and magnetic sensors.
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