Simultaneous dynamic electrical and structural measurements of functional materials

A new materials characterization system developed at the XMaS beamline, located at the European Synchrotron Radiation Facility in France, is presented. We show that this new capability allows to measure the atomic structural evolution (crystallography) of piezoelectric materials whilst simultaneously measuring the overall strain characteristics and electrical response to dynamically (ac) applied external stimuli

SrHf0.67Ti0.33O3 high-k films deposited on Si by pulsed laser deposition

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Optimal growth and thermal stability of crystalline Be 0.25Zn0.75O alloy films on Al2O 3(0001)

The influence of growth temperature on the synthesis of Be xZn1-xO alloy films, grown on highly-mismatched Al2O3(0001) substrates, was studied by synchrotron x-ray scattering, high-resolution transmission electron microscopy and photoluminescence measurements. A single-phase BexZn 1-xO alloy with a Be concentration of x = 0.25, was obtained at the growth temperature, Tg = 400 °C, and verified by high-resolution transmission electron microscopy. It was found that high-temperature growth, Tg≥600 °C, caused phase separation, resulting in a random distribution of intermixed alloy phases. The inhomogeneity and structural fluctuations observed in the BexZn1-xO films grown at high temperatures are attributed to a variation in Be composition and mosaic distribution via atomic displacement and strain relaxation. © 2014 AIP Publishing LLC

Pinning effect on the band gap modulation of crystalline Be xZn1-xO alloy films grown on Al2O 3(0001)

We have investigated the influence of Be concentration on the microstructure of BexZn1-xO ternary films (from x = 0 to 0.77), grown on Al2O3(0001) substrates using radio-frequency co-sputtering. With increasing Be concentration, the (0002) X-ray diffraction peak shows a systematic shift from 33.86° to 39.39°, and optical spectroscopy shows a blue-shift of the band gap from 3.24 to beyond 4.62 eV towards the deep UV regime, indicating that Be atoms are incorporated into the host ZnO lattice. During the band-gap modulation, structural fluctuations (e.g. phase separation and compositional fluctuation of Be) in the ternary films were observed along with a significant change in the mean grain size. X-ray photoelectron spectroscopy indicates higher concentrations of metallic Be states found in the film with the smaller grain size. Correlation between these two observations indicates that Be segregates to near grain boundaries. A model structure is proposed through simulation, where an increase in grain growth driving force dominates over the Be particle pinning effect. This leads to further coalescence of grains, reactivation of grain growth, and the uniform distribution of Be composition in the BexZn 1-xO alloy films. © 2014 The Royal Society of Chemistry

Simultaneous dynamic electrical and structural measurements of functional materials

A new materials characterization system developed at the XMaS beamline, located at the European Synchrotron Radiation Facility in France, is presented. We show that this new capability allows to measure the atomic structural evolution (crystallography) of piezoelectric materials whilst simultaneously measuring the overall strain characteristics and electrical response to dynamically (ac) applied external stimuli

A polar corundum oxide displaying weak ferromagnetism at room temperature

Combining long-range magnetic order with polarity in the same structure is a prerequisite for the design of (magnetoelectric) multiferroic materials. There are now several demonstrated strategies to achieve this goal, but retaining magnetic order above room temperature remains a difficult target. Iron oxides in the +3 oxidation state have high magnetic ordering temperatures due to the size of the coupled moments. Here we prepare and characterize ScFeO(3) (SFO), which under pressure and in strain-stabilized thin films adopts a polar variant of the corundum structure, one of the archetypal binary oxide structures. Polar corundum ScFeO(3) has a weak ferromagnetic ground state below 356 K-this is in contrast to the purely antiferromagnetic ground state adopted by the well-studied ferroelectric BiFeO(3)