Investigation of electronic,elastic,and optical properties of topological electride Ca3Pb via first-principles calculations

Electrides are unique materials with the anionic electrons confined to the interstitial sites,expecting important applications in various areas.In this work,the electronic structure and detailed physical properties of topological electride Ca_(3)Pb are studied theoretically.By comparing the crystal structures and band structures of Ca_(3)Pb and Ca_(3)PbO,we find that after removing O^(2-)ions from Ca_(3)PbO,the remaining electrons are confined in the vacancies of the Ca6 octahedra centers,playing the role as anions and forming an additional energy band compared with that of Ca_(3)Pb.These interstitial electrons partially result in the low work function of Ca_(3)Pb.Moreover,the calculated mechanic properties imply that Ca_(3)Pb has a strong brittleness.In addition,the dielectric functions and optical properties of Ca_(3)Pb are also analyzed.

Surface states modulated exchange interaction in Bi2Se3/thulium iron garnet heterostructures

We investigate the modulation of magnetic anisotropy of thulium iron garnet(TmIG)films by interfaced Bi2Se3 thin films.High quality epitaxial growth of Bi2Se3 films has been achieved by molecular beam epitaxy on TmIG films.By the method of ferromagnetic resonance,we find that the perpendicular magnetic anisotropy(PMA)of TmIG can be greatly strengthened by the adjacent Bi2Se3 layer.Moreover,the competition between topological surface states and thickness dependent bulk states of Bi2Se3 gives rise to the modulation of PMA of the Bi2Se3/TmIG heterostructures.The interfacial interaction can be attributed to the enhanced exchange coupling between Fe^3+ions of TmIG mediated by topological surface electrons of Bi2Se3.

Direct-writing Structure Color Patterns on the Electrospun Colloidal Fibers toward Wearable Materials

This study presents a direct-writing structure color patterns on electrospun colloidal fibers by inkjet printing. The colloidal fiber was obtained by electrospinning the aqueous mixture of colloidal particles of poly(styrene-methyl methacrylate-acrylic acid) and poly(vinyl alcohol). The pattern was obtained by directly inkjet printing water onto the electrospun colloidal fiber. The pattern formation was attributed to the morphological transition of the colloidal fiber from the fiber aggregation to latex aggregation and the corresponding color change due to the dissolution of poly(vinyl alcohol) by water. Interestingly, a clear and clean image was successfully obtained on the ethanol-treated colloidal fibers film in comparison to a confused and blur image onto the freshly-made film. It is because the treatment process can compact the fiber structure and lower the spreading/wetting behavior of ink on the fiber structure, contributing to the formation of high-quality pattern. Various letters or quick response code were flexibly designed and printed on to colloidal fibers.Furthermore, the pattern can be easily transferred onto flexible substrate, i.e., a flexible printed bracelet. This work will be of great significance for the development of novel wearable functional materials/devices based on electrospun colloidal fibers.

The Influence of Rare Earth Ions on the Rheological Behavior of Polyamide

The polyamide 66 （PA66）/lanthanum acetate blends with small amounts of salt loadings （≤ 1 wt% of PA） have been prepared in a twin-screw extruder. The rheology of PA66 and its blends has been investigated by a rotational rheometer. The results suggested that with the salt loading in excess of 0.2 wt% the typical Newtonian viscosity plateau disappeared and both the low-frequency complex viscosities η^＊ and storage modulus G＇ of blends were much higher than those of neat PA66, the storage modulus was higher than the loss modulus at low frequencies （tanδ〈 1）, i.e., the melt changed from a viscoelastic liquid for unfilled polymer to a viscoelastic solid （G′ 〉 G″）. While the viscosity followed a strong shear thinning with increasing frequency, the η^＊ and G′ decreased significantly even lower than those of neat PA66 at high frequencies. The combination of dynamic mechanical analysis （DMA） and X-ray photoelectron spectroscopy （XPS） analysis has revealed that coordination effect occurred between lanthanum and carbonyl oxygen atoms in amide groups of the polymer to form pseudo- crosslinked network structure, which makes the glass transition temperatures （Tg） and storage modulus （E′） of blends enhanced. The network structure formation-destruction and chains entanglement-disentanglement processes at different frequencies are responsible for the above rheological behaviors of blends.