Hot sputtering of barium strontium titanate on nickel foils

Abstract

The relationships linking temperature and voltage dependent dielectric response, grain size, and thermal budget during synthesis are illustrated. In doing so, it was found that maximizing thermal budgets within experimental bounds leads to electrical properties comparable to the best literature reports irrespective of the processing technique or microstructure. The optimal film properties include a bulk transition temperature, a room temperature permittivity of 1800, a voltage tuning ratio of 10:1 at 450 kV/cm, and a loss tangent less than 1.5% at 450 kV/cm. The sample set illustrates the well-known relationship between permittivity and crystal dimension, and the onset of a transition temperature shifts at very fine grain sizes. A brick wall model incorporating a high permittivity grain and a low permittivity grain boundary is used to interpret the dielectric data. However, the data show that high permittivity and tunability values can be achieved at grain sizes or film thicknesses that many reports associate with dramatic reductions in the dielectric response. These differences are discussed in terms of crystal quality and maximum processing temperature. The results collectively suggest that scaling effects in ferroelectric thin films are in many cases the result of low thermal budgets and the consequently high degree of structural imperfection and are not from the existence of low permittivity phases at the dielectric-electrode interface.

Magnetoelectric properties of flexible BiFeO3/Ni tapes

“…In previous reports, ferroelectric BaTiO 3 , (Ba,Sr)TiO 3 , Pb(Zr,Ti)O 3 and (Pb,La)(Zr,Ti)O 3 films were directly grown on nickel and copper substrates using pulsed laser deposition (PLD), [9][10][11] chemical solution deposition (CSD), 2,12-16 and sputtering. 17,18 Most of the reports show the expected structural properties of the films but with limited demonstration of desired dielectric properties. 2,[13][14][15][16][17][18] In fact, only one report illustrated the ability to deposit Pb(Zr,Ti)O 3 film directly on copper foil with satisfied polarization hysteresis loop.…”

“…17,18 Most of the reports show the expected structural properties of the films but with limited demonstration of desired dielectric properties. 2,[13][14][15][16][17][18] In fact, only one report illustrated the ability to deposit Pb(Zr,Ti)O 3 film directly on copper foil with satisfied polarization hysteresis loop. 2 There is no report at all on the ME properties even though these ferroelectric films are directly deposited on magnetic substrates such as Ni foils.…”

Processing of 0.7BaTiO3–0.3BiScO3 Solid‐Solution Coatings

“…). The grain morphology and size were similar to (Ba,Sr)TiO 3 coatings on Ni foils and BaTiO 3 coatings on Cu foils heat‐treated at 900°C for 1 and 0.5 h, respectively . SEM observations show intergranular pores for coatings made with undoped precursor (Fig.…”

“…To mitigate substrate oxidation, several groups have used heat treatments in inert or reducing environments with a subsequent re‐oxidation heat treatment to form the correct phases in dielectric coatings. Formation of (Ba,Sr)TiO 3 and other barium titanate‐based coatings by heat treatment up to 400°C in low pO 2 (~10 −18 atm) on nickel and copper substrates has been demonstrated . Formation of a 600‐nm‐thick BaTiO 3 coating on copper was shown by firing at 900°C in an oxygen partial pressure of 10 −13 atm …”

Piezoelectric properties of lead-free (Na0.5Bi0.5)0.95Ba0.05TiO3 thin films on polycrystalline nickel foils

“…has been attempted. Not only the cost can be greatly reduced, but also it can be widely adopted to design lots of devices, such as structural health monitoring systems, supercapacitors, energy harvester, operating under extreme conditions [22][23][24][25][26][27][28]. For the structural health monitoring systems, the integration of ferroelectric/piezoelectric films on metal substrates can increase the safety and reliability and reduce the cost of assembly.…”