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1. Ca-repaired BaZrO ₃ nanorods/YBa ₂ Cu ₃ O _7-x interface for enhanced pinning in YBa ₂ Cu ₃ O _7-x nanocomposites with 2-8% BaZrO ₃ doping

   https://doi.org/10.1088/1757-899X/1302/1/012013  

   Wu, Judy; Panth, Mohan; Ogunjimi, Victor; Ann_Sebastian, Mary; Zhang, Di; Haugan, Timothy; Wang, Haiyan (May 2024, IOP Conference Series: Materials Science and Engineering)

   Abstract C-axis aligned BaZrO₃(BZO) nanorods formed via strain-mediated self-assembly in BZO-doped YaBa₂Cu₃O_7-x(BZO/YBCO) nanocomposite films can provide strong pinning to the quantized magnetic vortices. While the strain initiated from the BZO/YBCO lattice mismatch plays a critical role in nucleation and evolution of the BZO nanorods, it also leads to a highly defective BZO/YBCO interface and hence reduced pinning efficiency of BZO nanorods. This work reports a recent study in probing the effect of BZO/YBCO interface on the pinning efficiency of the BZO nanorods as the interface is repaired dynamically during the BZO nanorod growth using Ca doping. Within the BZO doping range of 2-8 vol.%, significantly enhanced pinning efficiency of the BZO nanorods have been observed. A peak enhancement up to five-fold of critical current density at 9.0 T and 65-77 K has been obtained in the 6 vol.% BZO/YBCO nanocomposites after the interface repair. This result not only illustrates the critical importance of the BZO/YBCO interface in the pinning efficiency, but also provides a facile scheme to achieve such an interface to restore the pristine pinning efficiency of the BZO nanorods. 

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2. Disproportionation of Sn(II){CH(SiMe ₃ ) ₂ } ₂ to ·Sn(III){CH(SiMe ₃ ) ₂ } ₃ and ·Sn(I){CH(SiMe ₃ ) ₂ }: Characterization of the Sn(I) Product

   https://doi.org/10.1039/d3cc01542d  

   Mears, Kristian; Nguyen, Gia-Ann; Ruiz, Bronson; Zou, Wenxing; Fettinger, James C; Power, Philip P (May 2023, Chemical Communications)

   Half a century since the photocatalytic disproportionation of Lappert's dialkyl stannylene SnR 2 , R = CH(SiMe 3 ) 2 (1) gave the persistent trivalent radical [·SnR 3 ], the characterization of the corresponding Sn(I) product, ·SnR is now described. It was isolated as the hexastannaprismane Sn 6 R 6 (2), from the reduction of 1 by the Mg(I)-reagent, Mg(BDI Dip ) 2 , (BDI = (DipNCMe) 2 CH, Dip + 2,6-diisopropylphenyl). 

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3. Structural and thermal properties of ultralow thermal conductivity Ba ₃ Cu ₂ Sn ₃ Se ₁₀

   https://doi.org/10.1039/d2dt00309k  

   Ojo, Oluwagbemiga P.; Gunatilleke, Wilarachchige D.; Wang, Hsin; Nolas, George S. (April 2022, Dalton Transactions)

   The thermal properties of Ba 3 Cu 2 Sn 3 Se 10 were investigated by measurement of the thermal conductivity and heat capacity. The chemical bonding in this diamagnetic material was investigated using structural data from Rietveld refinement and calculated electron localization. This quaternary chalcogenide is monoclinic ( P 2 1 / c ), has a large unit cell with 72 atoms in the primitive cell, and a high local coordination environment. The Debye temperature (162 K) and average speed of sound (1666 m s −1 ) are relatively low with a very small electronic contribution to the heat capacity. Ultralow thermal conductivity (0.46 W m −1 K −1 at room temperature) is attributed to the relatively weak chemical bonding and intrinsic anharmonicity, in addition to a large unit cell. This work is part of the continuing effort to explore quaternary chalcogenides with intrinsically low thermal conductivity and identify the features that result in a low thermal conductivity. 

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4. Methane C–H Activation by [Cu ₂ O] ²⁺ and [Cu ₃ O ₃ ] ²⁺ in Copper-Exchanged Zeolites: Computational Analysis of Redox Chemistry and X-ray Absorption Spectroscopy

   https://doi.org/10.1021/acs.inorgchem.0c03693  

   Suleiman, Olabisi; Panthi, Dipak; Adeyiga, Olajumoke; Odoh, Samuel O. (May 2021, Inorganic Chemistry)

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5. The benefit of Ca in improving pinning of BaZrO ₃ -Y ₂ O ₃ doubly-doped YBa ₂ Cu ₃ O _7-x /Ca _0.3 Y _0.7 Ba ₂ Cu ₃ O _7-x multilayer nanocomposite films

   https://doi.org/10.1088/2053-1591/acc7e3  

   Panth, Mohan; Ogunjimi, Victor; Sebastian, Mary Ann; Gautam, Bibek; Haugan, Timothy; Wu, Judy (April 2023, Materials Research Express)

   Abstract This work examines the pinning enhancement in BaZrO 3 (BZO) +Y 2 O 3 doubly-doped (DD) YBa 2 Cu 3 O 7 (YBCO) nanocomposite multilayer (DD-ML) films. The film consists of two 10 nm thin Ca 0.3 Y 0.7 Ba 2 Cu 3 O 7-x (CaY-123) spacers stacking alternatively with three BZO + Y 2 O 3 /YBCO layers of 50 nm each in thickness that contain 3 vol% of Y 2 O 3 and BZO doping in the range of 2–6 vol%. Enhanced magnetic vortex pinning and improved pinning isotropy with respect to the orientation of magnetic field (B) have been achieved in the DD-ML samples at lower BZO doping as compared to that in the single-layer counterparts (DD-SL) without the CaY-123 spacers. For example, the pinning force density ( F p ) of ∼58 GNm −3 in 2 vol.% of DD-ML film is ∼110% higher than in 2 vol% of DD-SL at 65 K and B // c -axis, which is attributed to the improved pinning efficiency by c -axis aligned BZO nanorods through diffusion of Calcium (Ca) along the tensile-strained channels at BZO nanorods/YBCO interface for improvement of the interface microstructure and hence pinning efficiency of BZO nanorods. An additional benefit is in the considerably improved J c ( θ ) and reduced J c anisotropy in the former over the entire range of the B orientations. However, at higher BZO doping, the BZO nanorods become segmented and misoriented, which may change the Ca diffusion pathways and reduce the benefit of Ca in improving the pinning efficiency of BZO nanorods. 

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