ZnO nanocrystals are receiving renewed attraction due to their multifunctional properties. Selective enhancement and tuning of its optical and electrical properties are essential for achieving novel devices with accurate sensing...

Photovoltaic phenomena are widely exploited not only for primary energy generation but also in photocatalytic, photoelectrochemistry, or optoelectronic applications. In contrast to the interface-based photovoltaic effect of semiconductors, the anomalous or bulk photovoltaic effect in ferroelectrics is not bound by the Shockley-Queisser limit and, thus, can potentially reach high efficiencies. Here, we observe in the example of an Fe-doped LiNbO3 bulk single crystal the existence of a purely intrinsic “piezophotovoltaic” effect that leads to a linear increase in photovoltaic current density. The increase reaches 75% under a low uniaxial compressive stress of 10 MPa, corresponding to a strain of only 0.005%. The physical origin and symmetry properties of the effect are investigated, and its potential for strain-tuned efficiency increase in nonconventional photovoltaic materials is presented.

Dilute magnetic semiconductors such as transitionmetal-doped ZnO are potential candidates for spintronic applications. Transition metals such as Mn, Fe, and Cu when doped in ZnO enable spin magnetic properties to conventional semiconductors. Although several techniques such as wet chemical and vapor deposition methods are employed to achieve homogeneous doping in ZnO, these methods have limits pertaining to solubility levels of dopant ion, morphology, competition between intrinsic and extrinsic defects and localization of the defect species. This manuscript is an addition to the vast knowledge of methods and protocols that present the synthesis of transition-metal-doped ZnO. In this report, manganese-doped ZnO is synthesized via a microwave-assisted hydrolysis technique. The defect structure of Mn-doped ZnO wires is investigated via electron paramagnetic resonance and photoluminescence techniques. The analysis indicates that Mn 2+ substitutes the Zn ion and dominates the intrinsic defect species in ZnO.

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The low-temperature phase transitions observed in magnetoelectric bismuth ferrite (BiFeO 3 , BFO) have recently been a topic of interest to several researchers. This communication focuses on connecting recent structural revelations, such as the existence of a "skin" layer in BFO, the lattice contraction, and subsequent expansions in the skin layers with X-band electron paramagnetic resonance (EPR) spectra. A closer look at Lande's g-factor and the EPR asymmetry parameters reveal vital information about the origin of the phase transitions at 140, 200, and 280 K. Correlating the EPR results with existing theoretical calculations indicates that oxygen vacancies (V O ) accumulate at the skin layer, causing lattice contraction. This contraction causes local changes in the spin magnetic moment and translates to an anomaly in the resonant lines. The discussions imply that the phase transition at 140 K is due to spin reorientation caused by changes of interatomic distances and angles between the Fe Fe 3+ 2+ −V O •• − Fe Fe 3+ 2+ sites. Transition at 200 K is observed to occur due to elastic distortion of the oxygen octahedra. The transition at 280 K is thought to be due to the freezing of spins in the lattice.