Heterostrain-enabled ultrahigh electrostrain in lead-free piezoelectric.

Piezoelectric materials provide high strain and large driving forces in actuators and can transform electrical energy into mechanical energy. Although they were discovered over 100 years ago, scientists are still searching for alternative lead-free piezoelectrics to reduce their environmental impact. Developing high-strain piezoelectric materials has been a long-term challenge, particularly challenging for the design of high-strain polycrystalline piezoelectrics containing no toxic lead element.

Tuning the band gap and carrier concentration of titania films grown by spatial atomic layer deposition: a precursor comparison.

Spatial atomic layer deposition retains the advantages of conventional atomic layer deposition: conformal, pinhole-free films and excellent control over thickness. Additionally, it allows higher deposition rates and is well-adapted to depositing metal oxide nanofilms for photovoltaic cells and other devices. This study compares the morphological, electrical and optical properties of titania thin films deposited by spatial atomic layer deposition from titanium isopropoxide (TTIP) and titanium tetrachloride (TiCl) over the temperature range 100-300 °C, using the oxidant HO.

Dielectric films for high performance capacitive energy storage: multiscale engineering.

Dielectric capacitors are fundamental components in electronic and electrical systems due to their high-rate charging/discharging character and ultrahigh power density. Film dielectrics possess larger breakdown strength and higher energy density than their bulk counterparts, holding great promise for compact and efficient power systems. In this article, we review the very recent advances in dielectric films, in the framework of engineering at multiple scales to improve energy storage performance.

Nanoengineering room temperature ferroelectricity into orthorhombic SmMnO films.

Orthorhombic RMnO (R = rare-earth cation) compounds are type-II multiferroics induced by inversion-symmetry-breaking of spin order. They hold promise for magneto-electric devices. However, no spontaneous room-temperature ferroic property has been observed to date in orthorhombic RMnO.

Design of a Vertical Composite Thin Film System with Ultralow Leakage To Yield Large Converse Magnetoelectric Effect.

Electric field control of magnetism is a critical future technology for low-power, ultrahigh density memory. However, despite intensive research efforts, no practical material systems have emerged. Interface-coupled, composite systems containing ferroelectric and ferri-/ferromagnetic elements have been widely explored, but they have a range of problems, for example, substrate clamping, large leakage, and inability to miniaturize.

Very high commutation quality factor and dielectric tunability in nanocomposite SrTiO thin films with T enhanced to >300 °C.

We report on nanoengineered SrTiO-SmO nanocomposite thin films with the highest reported values of commutation quality factor (CQF or K-factor) of >2800 in SrTiO at room temperature. The films also had a large tunability of dielectric constant (49%), low tangent loss (tan δ = 0.01) and a Curie temperature for SrTiO > 300 °C, making them very attractive for tunable RF applications.

Strongly Enhanced Photovoltaic Performance and Defect Physics of Air-Stable Bismuth Oxyiodide (BiOI).

Bismuth-based compounds have recently gained increasing attention as potentially nontoxic and defect-tolerant solar absorbers. However, many of the new materials recently investigated show limited photovoltaic performance. Herein, one such compound is explored in detail through theory and experiment: bismuth oxyiodide (BiOI).

Self-assembled oxide films with tailored nanoscale ionic and electronic channels for controlled resistive switching.

Resistive switches are non-volatile memory cells based on nano-ionic redox processes that offer energy efficient device architectures and open pathways to neuromorphics and cognitive computing. However, channel formation typically requires an irreversible, not well controlled electroforming process, giving difficulty to independently control ionic and electronic properties. The device performance is also limited by the incomplete understanding of the underlying mechanisms.

Room Temperature Ferrimagnetism and Ferroelectricity in Strained, Thin Films of BiFeMnO.

Highly strained films of BiFeMnO (BFMO) grown at very low rates by pulsed laser deposition were demonstrated to exhibit both ferrimagnetism and ferroelectricity at room temperature and above. Magnetisation measurements demonstrated ferrimagnetism ( ∼ 600K), with a room temperature saturation moment ( ) of up to 90 emu/cc (∼ 0.58 /f.

Ferroelectric Sm-doped BiMnO3 thin films with ferromagnetic transition temperature enhanced to 140 K.

A combined chemical pressure and substrate biaxial pressure crystal engineering approach was demonstrated for producing highly epitaxial Sm-doped BiMnO(3) (BSMO) films on SrTiO(3) single crystal substrates, with enhanced magnetic transition temperatures, TC up to as high as 140 K, 40 K higher than that for standard BiMnO(3) (BMO) films. Strong room temperature ferroelectricity with piezoresponse amplitude, d(33) = 10 pm/V, and long-term retention of polarization were also observed. Furthermore, the BSMO films were much easier to grow than pure BMO films, with excellent phase purity over a wide growth window.

Extremely high tunability and low loss in nanoscaffold ferroelectric films.

There are numerous radio frequency and microwave device applications which require materials with high electrical tunability and low dielectric loss. For phased array antenna applications there is also a need for materials which can operate above room temperature and which have a low temperature coefficient of capacitance. We have created a nanoscaffold composite ferroelectric material containing Ba(0.