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Experimental measurements clearly reveal the presence of bulk superconductivity in the CsPb x Bi 4− x Te 6 (0.3≤ x ≤1.0) materials, i.e. the first member of the thermoelectric series of Cs[Pb m Bi 3 Te 5+ m ], these materials have the layered orthorhombic structure containing infinite anionic [PbBi 3 Te 6 ] − slabs separated with Cs + cations. Temperature dependences of electrical resistivity, magnetic susceptibility, and specific heat have consistently demonstrated that the superconducting transition in Cs 0.96 Pb 0.25 Bi 3.75 Te 6.04 occurs at T c =3.1 K, with a superconducting volume fraction close to 100% at 1.8 K. Structural study using aberration-corrected STEM/TEM reveals a rich variety of microstructural phenomena in correlation with the Pb-ordering and chemical inhomogeneity. The superconducting material Cs 0.96 Pb 0.25 Bi 3.75 Te 6.04 with the highest T c shows a clear ordered structure with a modulation wave vector of q ≈ a */2+ c */1.35 on the a – c plane. Our study evidently demonstrates that superconductivity deriving upon doping of narrow-gap semiconductor is a viable approach for exploration of novel superconductors. [ABSTRACT FROM AUTHOR]

Abstract: The transmission electron microscopy observations of the charge ordering (CO) which governs the electronic polarization in clearly show the presence of a remarkable phase separation at low temperatures. Two CO ground states are found to adopt the charge modulations of and , respectively. Our structural study demonstrates that the incommensurately -modulated state is chiefly stable in samples with relatively lower oxygen contents. Data from theoretical simulations of the diffraction suggest that both - and -modulated phases have ferroelectric ordering. The effects of oxygen concentration on the phase separation and electric polarization in this layered system are discussed. [Copyright &y& Elsevier]

Abstract: The structural features of the “5M” martensitic phase in Ni2FeGa alloys have been determined by electron diffraction using the multi-slice least-squares (MSLS) method. The results demonstrate that the “5M” phase contains an evident cooperative effect of monoclinic distortion and sinusoidal modulation along the [110] c direction. Theoretical simulations based on our refined data suggest that the “5M” martensitic phase observed in Ni–Fe–Ga and Ni–Mn–Ga has visible common behaviors in both stacking sequence and local structural distortion. Considering the cooperative effect of monoclinic distortion and sinusoidal modulation, we demonstrate that the “7M” martensitic phase could adopt two equivalent structural phases corresponding with the stacking sequences of and , respectively. [Copyright &y& Elsevier]

Abstract: Transmission electron microscopy (TEM) investigations on Nd2/3− x Li3 x TiO3 with x=0.14 reveal a rich variety of structural features in the samples prepared under different conditions, such as superstructures, anti-phase domains, and nano-chessboard structures. Our careful analysis shows that these structural phenomena can be fundamentally understood as the combination of structural effects of (Nd, Li)-ordering along the 〈001〉p direction and the spinodal decomposition along the 〈100〉p/〈010〉p direction. The coexistence of phase separation and cation ordering can lead to visible nano-structural complexities in many crystals, as the typical results, the regular lamella structure, nano-chessboard structures and anti-phase boundaries have been extensively studied. [Copyright &y& Elsevier]

Abstract: Layered Sr0.35CoO2 has been synthesized by means of an ion exchange reaction from Na0.7CoO2. Resistivity measurements show that this material can be either metallic or semiconducting depending on the annealing conditions. The magnetic susceptibility of the sample increases with decreasing temperature, showing a Curie–Weiss behavior in high temperatures. Transmission electron microscopy observations reveal the presence of two superstructures arising respectively from the intercalated Sr-ordering (a compositional modulation) with q 1 = a*/3+ b*/3 and a periodic structural distortion (a transverse structural modulation) with q 2 = a*/2. [Copyright &y& Elsevier]

Abstract: Transmission electron microscopy (TEM) observations reveal the presence of complex superstructures and remarkable phase separation in association with Na-ordering phenomenon in γ-Na0.5CoO2. Resistivity and magnetization measurements indicate that three phase transitions at the temperatures of 25, 53 and 90K, respectively, appear commonly in γ-Na0.5CoO2 samples. Under a high pressure up to 10kbar, the low-temperature transport properties show certain changes below the charge order transition; under an applied magnetic field of 7T, phase transitions at around 25 and 53K, proposed fundamentally in connection with alternations of magnetic structure and charge ordering maintain almost unchanged. [Copyright &y& Elsevier]