LiMn2O4 thin films prepared on a Pt/Ti/SiO 2/Si(100) substrate by pulsed laser deposition were studied with focusing on the effects of different processing conditions and Sn substitution on phase evolvement and surface microstructure. Major experimental parameters include substrate temperature up to 770 °C and working oxygen pressure of 50-250 mTorr. LiMn2O4 thin films became highly crystallized with increased grain sizes as the substrate temperature increased. Second phases such as LiMnO2 and Li2Mn2O 4 were found at the temperature of 300 and 770 °C, respectively. As an optimum condition, films grown at 450 °C showed a homogeneous spinel phase with well-defined crystallinity and smooth surface. A high pressure of oxygen tended to promote crystallization and grain growth. Working pressure did not affect significantly the phase formation of the thin films except that unexpected LiMn3O4 phase formed at the lowest oxygen pressure of 50 mTorr. Tin-substituted thin films showed lower Mn-O stretching vibrations, which suggests that more Li-ions can be inserted into vacant octahedral sites of the spinel structure.
Bibliographical noteFunding Information:
This work was supported by a National Research Foundation of Korea (NRF) grant funded by the Korean government ( MEST ) (Grant No. NRF-2018M3C1B7021994 and 2019R1A2C2084965 ).
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Ceramics and Composites
- Condensed Matter Physics
- Mechanics of Materials
- Materials Chemistry
- Electrical and Electronic Engineering