Background oxygen effects on pulsed laser deposited Na0.5K0.5NbO3 films: From superparaelectric state to ferroelectricity
2000 (English)In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 87, no 9, 4439-4448 p.Article in journal (Refereed) Published
Ambient oxygen pressure in a pulsed laser deposition process has been observed to have a critical influence on the compositional, crystalline, and electrical properties of Na0.5K0.5NbO3 (NKN) thin films grown onto polycrystalline Pt80Ir20 and SiO2 (native oxide)/Si(111) substrates. Films prepared at high oxygen pressure (similar to 400 mTorr) were found to be single phase and highly c-axis oriented. X-ray diffraction theta-2 theta scans and rocking curve data show a strong effect of NKN film self-assembling along the  direction regardless of the substrate texture. The high dielectric permittivity of 550, low dissipation factor of less than 3%, and high remanent polarization of 12 mu C/cm(2) indicate the high ferroelectric quality of the fabricated film. The role of the high-energy component of the erosion products has been proven to be crucial to film performance. On the other hand, films grown at low oxygen pressure (similar to 10 mTorr) have been found to be mixed phases of ferroelectric NKN and paraelectric potassium niobates. These films have shown superparaelectric behavior: 5% tunability at an electric field of 100 kV/cm, losses as low as 0.3%, and excellent stability to temperature and frequency changes.
Place, publisher, year, edition, pages
2000. Vol. 87, no 9, 4439-4448 p.
lead magnesium niobate, crystal orientation dependence, thin-films, piezoelectric properties, relaxor ferroelectrics, preferred orientation, zirconate-titanate, ambient gas, ablation, dynamics
IdentifiersURN: urn:nbn:se:kth:diva-19716ISI: 000086724100062OAI: oai:DiVA.org:kth-19716DiVA: diva2:338408
QC 201005252010-08-102010-08-10Bibliographically approved