Rapid Thermal Annealing of Pr^(3+) and Eu^(3+) Implanted Silicon

Pr ion implanted silicon has two types of electrical behavior under different condition of rapid thermal annealing(RTA).For Pr3+ implanted epitaxial silicon samples with dose 1×1014cm-2 and energy 350 keV,annealing at 940℃.the sample has electron conductivity, and the implanted ion acts as a donor;and the sample annealing at 1240℃ has hole conductivity,and the implanted ion acts as an acceptor.For high dose(2×1015 cm-2) Eu3+ implanted epitaxial silicon sample undergoing high temperature RTA treatment,enhanced Raman effect was observed.In this paper.reasonable explanations for these two phenomena have been given.

Enhanced electrical properties and Vickers hardness of calcium bismuth niobate ceramics by W/Co substituted at B-site

Calcium bismuth niobate(CBN)ceramic,as a core element of high-temperature piezoelectric sensors,has attracted widespread attention due to its high Curie temperature within the class of Aurivillius compounds.However,CBN usually faces two shortcomings.poor piezoelectric constant and low resistivity.In this work,CBN-based ceramics with donor–acceptor ions(W/Co)co-substituted at B-site were prepared by solid-state reaction method,and structure–property relationship of ceramics was studied in detail.Co-substitution of W/Co ions effectively improved the electrical property and hardness of CBN ceramics.CaBi_(2)Nb_(1.91)(W_(2/3)Co_(1/3)T_(0.09)O_(9))exhibits enhanced electrical and mechanical properties including high resistivity of-10^(7)Ω·cm at 500℃,piezoelectric constant of-15.3 pC/N and hardness value of-3.57 GPa.These values are two orders of magnitude,over two times,and 1.36 times higher than those of pure CBN ceramic,respectively.This work provides a reference for exploring other bismuth-layered structural ceramics.

Hybrid molecular nanostructures with donor-acceptor chains

We have fabricated hybrid molecular chain structures formed by electron acceptor compound 1 and electron donor molecules 2 and 3 at the liquid/solid interface of graphite surface.The structural details of the mono-component and the binary assemblies are revealed by high resolution scanning tunneling microscopy (STM).Compound 1 can form two well-ordered lamellar patterns at different concentrations.In the co-adsorption structures,compounds 2 and 3 can insert into the space between molecular chains of compound 1 and form large area well-ordered nanoscale phase separated lamellar structures.The unit cell parameters for the coassemblies can be "flexibly" adjusted to make the electron donors and acceptors perfectly match along the molecular chains.Scanning tunneling spectroscopy (STS) results indicate that the electronic properties of individual molecular donors and acceptors are preserved in the binary self-assembly.These results provide molecular insight into the nanoscale phase separation of organic electron acceptors and donors on surfaces and are helpful for the fabrication of surface supramolecular structures and molecular devices.

A novel metal-free porous covalent organic polymer for efficient room-temperature photocatalytic CO_(2) reduction via dry-reforming of methane

At room temperature,the conversion of greenhouse gases into valuable chemicals using metal-free catalysts for dry reforming of methane(DRM) is quite promising and challenging.Herein,we developed a novel covalent organic porous polymer (TPE-COP) with rapid charge separation of the electron–hole pairs for DRM driven by visible light at room temperature,which can efficiently generate syngas (CO and H_(2)).Both electron donor (tris(4-aminophenyl)amine,TAPA) and acceptor (4,4',4'',4'''-((1 E,1'E,1''E,1'''E)-(ethene-1,1,2,2-tetrayltetrakis (benzene-4,1-diyl))tetrakis (ethene-2,1-diyl))tetrakis (1-(4-formylbenzyl)quinolin-1-ium),TPE-CHO) were existed in TPE-COP,in which the push–pull effect between them promoted the separation of photogenerated electron–hole,thus greatly improving the photocatalytic activity.Density functional theory (DFT) simulation results show that TPE-COP can form charge-separating species under light irradiation,leading to electrons accumulation in TPE-CHO unit and holes in TAPA,and thus efficiently initiating DRM.After 20 h illumination,the photocatalytic results show that the yields reach 1123.6 and 30.8μmol g^(-1)for CO and H_(2),respectively,which are significantly higher than those of TPE-CHO small molecules.This excellent result is mainly due to the increase of specific surface area,the enhancement of light absorption capacity,and the improvement of photoelectron-generating efficiency after the formation of COP.Overall,this work contributes to understanding the advantages of COP materials for photocatalysis and fundamentally pushes metal-free catalysts into the door of DRM field.