The self-assembly of a three-dimensional strontium-based metal-organic framework [Sr(Hbtc)(H2O)]n (1) was achieved through the reaction of Sr(NO3)2 with a 1,2,4-benzenetricarboxylic acid (1,2,4-H3btc) ligand under hydrothermal conditions. This Sr-based metal-organic framework exhibits remarkable semiconducting behavior, as evidenced by theoretical calculations and experimental measurements. Temperature-dependent DC conductivity, near-room-temperature AC conductivity, diffuse reflection spectra, and photoluminescence spectra provide strong proof that compound 1 shows a band gap of 2.3 eV, which is comparable to that for other commonly available semiconducting materials (e.g., CdSe, CdTe, ZnTe, GaP, etc.). The optimized molecular structure and electronic properties (density of states and band gap energy) of 1 were calculated using density functional theory, and the results are consistent with experimental findings. This is the first report on the semiconducting properties of a strontium-based MOF, which will pave the way for further studies in semiconducting MOFs with interesting potential applications in optoelectronic devices.
The moderately heavy-electron compound URu&Si2 is known to exhibit two electronic phase transitions at low temperatures, one to an antiferromagnetically ordered state at TN =17.5 K followed by another to a superconducting state at T, -1.5 K. The shape of the specific-heat anomaly at TN, which is reminiscent of a second-order BCS-type mean-field transition, suggests the formation of a spin-or charge-density wave opening a gap over part of the Fermi surface. The efFect of chemical substitution of the transition metals M =Re, Tc, Os, Rh, and Ir for Ru in URuzSi2 has been investigated by means of electrical resistivity, magnetic susceptibility, and specific-heat measurements in URu2 "M"Si2for x 0.2. The anomaly associated with the 17.5 K transition involves a very small magnetic entropy and is smeared out by very small concentrations of the M substituent. An inverse correlation between T, and TN in the Rhand Ir-doped materials for x &0.01 and in the Os-doped series for x & 0. 1 is consistent with the picture of two electronic transitions competing for states at the Fermi level.
High-energy scattering processes, such as deep inelastic scattering (DIS) and quasielastic (QE) scattering provide a wealth of information about the structure of atomic nuclei. The remarkable discovery of the empirical linear relationship between the slope of the EMC effect in DIS and the short-range-correlation (SRC) scaling factors a2 in QE kinematics is naturally explained in terms of scale separation in effective field theory. This explanation has powerful consequences, allowing us to calculate and predict SRC scaling factors from ab initio low-energy nuclear theory. We present ab initio calculations of SRC scaling factors for a nucleus A relative to the deuteron a2(A/d) and relative to 3 He a2(A/ 3 He) in light and medium-mass nuclei. Our framework further predicts that the EMC effect and SRC scaling factors have minimal or negligible isovector corrections.
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