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Ultrathin two-dimensional In2S3nanocrystals with photoelectrochemical activity were achieved by cation-induced oriented-attachment growth.

Several superconducting transition temperatures in the range of 30–46 K were reported in the recently discovered intercalated FeSe system (A1-xFe2-ySe2, A = K, Rb, Cs, Tl). Although the superconducting phases were not yet conclusively decided, more than one magnetic phase with particular orders of iron vacancy and/or potassium vacancy were identified, and some were argued to be the parent phase. Here we show the discovery of the presence and ordering of iron vacancy in nonintercalated FeSe (PbO-type tetragonal β-Fe1-xSe). Three types of iron-vacancy order were found through analytical electron microscopy, and one was identified to be nonsuperconducting and magnetic at low temperature. This discovery suggests that the rich-phases found in A1-xFe2-ySe2 are not exclusive in Fe-Se and related superconductors. In addition, the magnetic β-Fe1-xSe phases with particular iron-vacancy orders are more likely to be the parent phase of the FeSe superconducting system instead of the previously assigned β-Fe1+δTe.

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LiFePO 4 /C thin films have been deposited on Ti-coated Si and stainless-steel substrates by radio frequency magnetron sputtering. Negative electric bias ͑0,−50,−80 V͒ and postdeposition vacuum annealing ͑150-650°C͒ was applied to modify the film properties. Suitable substrate bias resulted in films with finer grains and pure olivine phase. The films deposited with Ti underlayers exhibited enhanced crystallization, grain sizes, and conductivity, as compared with films deposited without Ti underlayers. Composition depth profiles showed interdiffusion at the film/underlayer interfaces after annealing. Charge-discharge and cyclic voltammetry curves revealed the different electrochemical characteristics of the films. The films with Ti underlayers displayed lower initial capacity than those without underlayers due to heavy doping of Ti. However, the cycling stability is greatly improved, which was attributed to the enhanced adhesion property of the Ti underlayers to the substrates and films.

Specific-heat measurements on ͑Ba 12x K x ͒BiO 3 , x 0.40 and 0.47, 0.7 # T # 35 K, 0 # H # 9 T, have determined the coefficient ͑g͒ of the normal-state conduction electron specific heat, and shown well-defined specific-heat anomalies at T c that are consistent with the value of g and BCS expressions. These results contradict the suggestion in a recent Letter that g is several orders of magnitude greater than these experimental values and that the absence of a correspondingly large specific-heat anomaly constitutes evidence that the transition is an Ehrenfest fourth-order transition.