As part of our systematic research on the acentric rare earth chalcogenides, the ErAlGeS5/KBr, Er3AgGeS7/KBr and Er6Ge3S14/KBr systems were investigated and three compounds belonging to the R6B2C2Q14 （R = rare earth, B = 6-coordinated element, C = 4-coordinated element, Q = S and Se） family were identified. These compounds crystallize in the P63 space group, and the crystal data are as follows： Er3Ge1/4GeS7, a = 9.6480（14）, c = 5.7920（12） A^°, Z = 2; Er3Ge0.382（8）GeS7, a = 9.6360（14）, c = 5.8460（12） A^°, Z = 2; Er3Ge1/2GeS7, a = 9.6061（13）, c = 5.8346（18）A^°, Z = 2. Single-crystal analysis indicated that the Er3GexGeS7 （x = 1/4, 0.382（8）, 1/2） structures consist of three types of building blocks： ErS7, GeS4 and GeS6 units. Er3MxGeS7 are deficient compounds with the B sites occupied partly by Ge（Ⅳ） and/or Ge（Ⅱ）.
Zinc oxide,a wide band-gap semiconductor,has shown extensive potential applications in high-efficiency semiconductor photoelectronic devices,semiconductor photocatalysis,and diluted magnetic semiconductors.Due to the undisputed lattice integrity,ZnO single crystals are essential for the fabrication of high-quality ZnO-based photoelectronic devices,and also believed to be ideal research subjects for understanding the underlying mechanisms of semiconductor photocatalysis and diluted magnetic semiconductors.This review,which is organized in two main parts,introduces the recent progress in growth,basic characterization,and device development of ZnO single crystals,and some related works in our group.The first part begins from the growth of ZnO single crystal,and summarizes the fundamental and applied investigations based on ZnO single crystals.These works are composed of the fabrication of homoepitaxial ZnO-based photoelectronic devices,the research on the photocatalysis mechanism,and dilute magnetic mechanism.The second part describes the fabrication of highly thermostable n-type ZnO with high mobility and high electron concentration through intentional doping.More importantly,in this part,a conceptual approach for fabricating highly thermostable p-type ZnO materials with high mobility through an integrated three-step treatment is proposed on the basis of the preliminary research.
Doping luminescent lanthanide ions into semiconductor nanocrystals is an ideal approach for developing nanodevices for various applications. Quantum confinement effects are expected for lanthanide ions doped in small semiconductor nanocrystals. The most recent progress on the synthesis and spectroscopy of lanthanide ions in various semiconductor nanocrystals such as Ⅱ -Ⅵ, Ⅲ-Ⅴ and Ⅳ-Ⅵ families were systematically reviewed, focusing on our recent findings on the optical spectroscopy of Eu^3 ＋ doped in ZnO and TiO2 nanocrystals by wet chemical synthesis. The energy transfer from the band-gap excitation to lanthanides further confirmed that lanthanide ions could be successfully incorporated into the lattice sites in spite of the mismatch in ionic radii.
