Caesium iodide (CsI) thin films have attracted much attention due to good electron transport and emission properties in the soft X-ray and extreme ultraviolet range. With the rapid development of nuclear physics, high energy physics and astrophysics, the requirements for CsI film photocathodes become increasingly severe, and it is therefore of considerable interest to develop CsI photocathodes with high quantum efficiency (QE) and stable performance. However, the internal mechanisms of QE variation and photocathode aging are not entirely clear or certain up to date. In this paper, the recent progress on CsI film photocathodes is reviewed and some controversial issues are introduced. Several perspectives are also proposed in the end.

The electronic structures and optoelectronic properties of C/Ge-doped single-walled armchair silicon nanotubes were determined by using first-principles calculations in the framework of density-functional theory. In particular, the calculated results indicate that both pure and C/Ge-doped silicon nanotubes display a direct band gap. The band gap is decreased firstly and then increased for the silicon nanotubes doped with C and Ge, respectively. Moreover, the upper of valence band is mainly contributed by the Si-3p states and the lower of conduction band is primarily occupied by the Si-3p states. The state dielectric constant is improved and the optical absorption shows a red-shifted for the C-doped silicon nanotubes, whereas the state dielectric constant is reduced and the optical absorption shows a blue-shifted for the Ge-doped silicon nanotubes. The results provide an useful theoretical guidance for the applications of single-walled armchair silicon nanotubes in optical detectors.

The effect of impurity such as Fe and Cu ions on the optical loss and laser performance of N31-type Nd-doped phosphate laser glass was studied. It was found that the laser slope efficiency decreased in accordance with an e exponential function, and the laser threshold increased in quadratic with the increase of Fe concentration. Moreover, the empirical equations between concentration of Fe with laser slope efficiency and laser threshold were obtained. It also showed that laser efficiency was seriously influenced by Cu ion compared with that by Fe ion at the same concentration. The results are useful for improving the gain performance of laser glass and quantitatively control of the impurity in raw materials in the future.

Er³⁺ doped Ge-Ga-S-CsBr chalcohalide glasses were fabricated by melt-quenching method. The properties of upconversion luminescence under the excitation of 1550 nm laser were investigated. Strong green emissions centered at 525 nm and 545 nm, and weak red emission centered at 660 nm, were observed, along with near infrared emission bands centered at 810 nm and 980 nm. The up-conversion fluorescence was contributed to multi-photon involved process. The Si solar cell efficiency slightly increased from 7.28% (without upconversion layer) to 7.32% (using Er³⁺ doped 0.9(Ge₂₅Ga₁₀S₆₅)-0.1CsBr glass as upconversion layer). The results show that the investigated Er³⁺-doped chalcohalide glasses has a potential application for the enhancement of Si solar cell efficiency.

Polycrystalline In₄Se₃ thermoelectric materials were synthesized in the processing sequence of vacuum melting, annealing and spark plasma sintering. The effect(s) of melting and annealing duration periods on the phase, composition, microstructure, and thermoelectric properties of polycrystalline In₄Se₃ were investigated. After the melting process, both In and InSe phase were detected in the ingots. With increasing melting duration time, an increase in Se deficiency was observed, leading to an increase of carrier concentration, which contributed to the observed improvement of electrical conductivity. The specimen melted for 48 h showed relatively higher ZT. Thus on the basis of 48 h melting process, the ingots were then annealed for different periods of time, which eliminated the presence of InSe phase. After annealing, scattered large step-like structures were observed in the matrix, which favored the reduction of thermal conductivity but had no significant influence on the electrical conductivity. The ZT was significantly enhanced to 0.83 at 702 K by extending melting and annealing duration time to 48 h and 96 h, respectively, which is 32% higher than that reported in literature. It was concluded that both the extension of melting and annealing duration periods could improve the thermoelectric performance of polycrystalline In₄Se₃.

The barrier layer of Ti-Al and the contact layer of Ni were joined to Yb_0.3Co₄Sb₁₂ simultaneously by using spark plasma sintering (SPS) technique. The Mo-Cu electrode was then welded to thermoelectric element Yb_0.3Co₄Sb₁₂/Ti-Al/Ni by using Ag-Cu-Zn alloy as solder. SEM results show that there are no cracks at the interfaces of Yb_0.3Co₄Sb₁₂/Ti-Al/Ni/Ag-Cu-Zn/Mo-Cu thermoelectric joints. The EDS analysis shows that intermetallic compounds (IMCs) layer containing AlCo, TiCoSb and TiSb₂ phases are formed at the interface between Yb_0.3Co₄Sb₁₂ and Ti-Al. After thermal aging at 500℃ for 30 d, the inter-diffusions at both Yb_0.3Co₄Sb₁₂/Ti-Al interface and Ag-Cu-Zn/Ni interface tend to be steady. The contact electrical resistivity of the Yb_0.3Co₄Sb₁₂/ Ti-Al/Ni/Ag-Cu-Zn/Mo-Cu thermoelectric joints are about 6.1 μΩ·cm² after welding, and it maintained as low as 10 μΩ·cm² even after thermal aged for 30 d.

A series of Ba₈Ga₁₅XSi₃₀ (X=Ga、Zn、Cu) clathrate samples were prepared by combining arc melting, ball milling and spark plasma sintering (SPS) techniques. The crystal structure and thermoelectric properties of all samples were studied. Compared with Ba₈Ga₁₆Si₃₀, the lattice constant a decreases as one Ga is replaced by Zn or Cu. What’s more, thermal conductivity decreases and magnitude of Seebeck coefficient increases with Zn or Cu doping. Consequently, thermoelectric figure of merit ZT increases significantly.

AlN ceramics doped with rare earth oxide (Sm₂O₃, Y₂O₃) were prepared by Spark Plasma Sintering (SPS) in nitrogen atmosphere using AlN powder as raw materials. The effect of rare earth oxide on the phase composition, microstructure and electrical resistivity of AlN ceramics were investigated. The results showed that those sintering additives promoted densification through liquid-phase sintering. AlN ceramics with electrical resistivity values of 1×10¹⁰-1×10¹² Ω•cm were obtained by precipitating rare earth aluminates as a conducting pathway at the grain boundaries. With the increasing of Sm₂O₃ doping, the phase of samarium aluminate gradually changed from Sm₄Al₂O₉ to SmAlO₃ which had a higher resistivity than Sm₄Al₂O₉. 3wt% Sm₂O₃ doped AlN ceramics had the minimum resistivity of 1.32×10¹⁰ Ω•cm with the relative density of 99.33%. The yttrium aluminate phase gradually changed from Y₃Al₅O₁₂ to Y₄Al₂O₉ with the increase of Y₂O₃-doping. The electrical resistivity of different yttrium aluminates were about 1×10⁸ Ω•cm. Y₂O₃- doped AlN sample with over 3wt% Y₂O₃ had an electrical resistivity about 1×10¹⁰ Ω•cm. 4wt% Y₂O₃ doped AlN ceramic had the electrical resistivity of 1.60×10¹⁰ Ω•cm with the maximum relative density of 99.08%.

TiC powders were prepared at low temperature from the Ti-C system with polytetrafluoroethylene (PTFE) as a chemical activator. The reaction temperature, phase composition and morphology were determined via differential scanning calorimetry (DSC), X-ray diffraction (XRD) and field emission scanning electron microscope (FESEM) to explore the reaction mechanism, respectively. The FESEM result shows that TiC powders with average particle size less than 100 nm are synthesized via low-temperature combustion synthesis at 530 ℃ by adding 3wt% PTFE into Ti-C system. Based on the most intensive diffraction peak (200) of the XRD pattern, the crystallite size of prepared TiC powders is calculated to be about 81 nm by the Scherrer formula, which is close to the average particle size observed from the FESEM image. It indicates that TiC particles consist of a single crystal as the result of fast, low-temperature, solid-state synthesis process. According to DSC results, the combustion synthesis mainly includes two reaction processes. Firstly, the initial reaction between titanium and PTFE particles releases a great amount of heat, and subsequently, the heat induced combustion reaction between titanium and carbon particles.

The co-continuous β-Si₃N₄ reinforced Al matrix composites were fabricated through squeeze casting of porous β-Si₃N₄ preforms with porosity of 53.43% which obtained by pressureless sintering. The influences of heat-treatment temperature on the microstructures and mechanical properties of co-continuous β-Si₃N₄ reinforced Al matrix composites were investigated. With the heat-treatment temperature increase, the degree of interfacial reaction, dislocation density increase, and vickers hardness increases, while fracture toughness decreases, accompanied by flexural strength increasing until 850℃ and then decreasing. The fracture mode of composites changes gradually from ductile intergranular rupture to brittle intergranular rupture. When being heat-treated at 850℃, the composites obtain the optimum mechanical properties with the reaction layer of about 20-50 nm.

Agglomerated ZrB₂-MoSi₂ composite powders with different contents of MoSi₂ were successfully prepared by spray drying and vacuum sintering. Then ZrB₂-MoSi₂ composite coatings were deposited on C/C composites by atmospheric plasma spraying (APS) using ZrB₂-MoSi₂ composite powders with average size of 30 μm as raw material. The microstructure and anti-oxidation performance of coatings were characterized by XRD, SEM, etc. It could be found out that the microstructure of ZrB₂-MoSi₂ composite coatings was dense with bonding strength up to 7.2 MPa. And oxidation-resistance of composite coating at high temperature could be improved by appropriate addition of MoSi₂. The weight loss of C/C composites coated by ZrB₂-40wt%MoSi₂ coating was only 1.7% after 9 h in air at 1500℃. The coating exhibited good self-sealing performance and excellent anti-oxidation ability.

Using agglomerated and sintered ZrO₂-7wt%Y₂O₃ (7YSZ) powders as raw materials, columnar thermal barrier coatings (TBCs) were prepared by plasma spray-physical vapor deposition (PS-PVD) at substrate temperature of 850 ℃. The microstructures of columnar coating were analyzed by field emission-scanning electron microscope (FE-SEM). Based on the theory of atoms together, the formation and growth process of 7YSZ nucleus were investigated and the deposition mechanism of columnar coating was also analyzed. Besides, under the temperature of 1200 ℃, the CMAS (CaO-MgO-Al₂O₃-SiO₂) corrosion of columnar 7YSZ coating was examined and its failure mechanism was also discussed. During the deposition process of columnar 7YSZ coating, the 7YSZ gas molecules were firstly absorbed on substrate, then through diffusion and migration, the critical nucleus formed rapidly. Besides, the critical nucleus further grew up forming crystal island by absorbing other molecules. Then after following four steps of island formation, union formation, channel formation and continuation, the columnar coating formed eventually. When above melting temperature, the CMAS could penetrate into porous columnar coating by capillary force and react with the 7YSZ coating. Finally, the cracks appeared in the coating due to thermochemical and thermomechanical interaction.

A new seeding method, the steam-assisted conversion seeding, was used to prepare the high-quality SAPO-34 molecular sieve membranes by secondary growth method on the low cost macroporous α-Al₂O₃ supports. The seeds with different sizes of 2 μm, 1 μm, 500 nm, and 100 nm were mixed in the synthesis solution to prepare the seeds-containing pastes which was coated on the surface of the support. The effects of the particle size on the paste layers, seed layers and membranes were investigated. A perfect seed layer was formed and effectively modified the defects of the macroporous α-Al₂O₃ support and then, induced a continuous, compact and unconspicuousl pinholes SAPO-34 membrane. The SAPO-34 membrane displayed high performance in the pervaporation dehydration of 90wt% IPA/water mixtures at 348 K, showing water ?ux up to 1.396 kg/(m²·h) and separation factor at 973.

A simple two-step process was developed in this study to render aluminum with lower friction and superhydrophobicity. Alumina film was firstly fabricated on aluminum by Sol-Gel technology. Fatty acid was then deposited on alumina film to endow superhydrophobicity. The surface morphology of alumina film after treatment using boiling water or hydrazine solution was evaluated. The effect of molecular structure of fatty acid on the wettability of the composite film was investigated. Friction-reducing behavior of the superhydrophobic films on aluminum was determined in a ball-on-plate configuration. It was found that the stearic acid film on alumina film treated by hydrazine solution showed superhydrophobicity and low friction, leading to significantly extending lifespan of the alumina film.

By using carbon spheres as a template, precursor Ni(OH)₂/C were prepared by a hydrothermal synthesis technology with the reaction of hexahydrate nickel chloride and urea. And then the precursor was calcinated in pure nitrogen to obtain core-shelled NiO/C microspheres. Scanning electron microscope (SEM), X-ray diffraction (XRD), X-ray energy dispersive (EDX), and the thermo gravimetric analyzer (TGA) were used to characterize morphology and structure of the samples. Results show that the NiO/C microspheres have core-shell structure with diameter around 1.4 μm, carbon sphere as the core, and cubic NiO nanoplates with thickness of 50 nm as the shell. Electrochemical behavior and sensing property of core-shelled NiO/C microspheres were studied via cyclic voltammetry and amperometric method. The results displayed that glucose sensitivity of the NiO/C is 31.37 mA/(mmol·L^-1·cm²) better than that of NiO, among the linear range of 2-1279 μmol/L with detecting limit at 2 μmol/L. Furthermore, the core-shelled NiO/C microspheres exhibit good stability and anti-interference ability.

Hydroxyapatite (HA) nanorods with uniform morphology and high aspect ratio were prepared by hydrothermal method using alginate (SA) as controlling agent. The samples were characterized by XRD, FTIR, SEM, TEM and TG/DSC to detect the effects of temperature and time on the crystallinity, composition and morphology of the final products. Meanwhile, the growth mechanism of HA nanorods was explored. Experiments showed that uniform HA nanorods with low organic composition could be well synthesized via hydrothermal method at 80°C after 24 h. Investigations on the microstructures of nanorods revealed that their growth could be divided into four stages: initial nucleation, surface regulation, continuous growth and oriented attachment.

The aim of this study is to investigate the effect of nanocrystalline cellulose (NCC) with favorable mechanical properties on the compressive strength of calcium phosphate cement (CPC). Compressive test, Gilmore needle test, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) were used to analyze the physicochemical properties of CPC influenced by different contents of NCC. Scanning electron microscope (SEM) and fluorescence microscope were used to observe the morphologies of CPC and the dispersity of labeled-NCC in CPC, respectively. NCC significantly increased the compressive strength of CPC up to about 27 MPa when the content of NCC was 2%. Setting times of CPC were prolonged with increased NCC, but still met the clinical requirements when the content of NCC was not more than 2%. XRD and XPS indicated that the combination of NCC with Ca²⁺ could form unstable coordination compound and NCC promoted the dissolution and conversion of dicalcium phosphate dehydrate (DCPD) and CaCO₃. SEM showed that CPC became denser with fewer pores and cracks by addition of NCC. Fluorescence microscope demonstrated the homogeneous dispersion of labeled-NCC in CPC.

CeO₂ nanorods were synthesized by a hydrothermal method at 160℃ from CeCl₆·6H₂O and NH₃·H₂O in the presence of an ionic liquid 1-butyl-3-methyl-imidazolium chloride ([Bmim]Cl). The phase and morphology of the resulting products were characterized by X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM), respectively. The results reveal that morphology of CeO₂ prepared in the presence of the ionic liquid is nanorod while it changes to irregular nanoparticle without ionic liquid. The resulting nanorods are about 13-25 nm in diameter and 200-500 nm in length. With the increase of ionic concentration, nanorods were disappeared gradually and nanoparticles were obtained. Moreover, increasing the hydrothermal temperature to 180℃, nanospheres at size of 19-24 nm could be synthesized by aggregation of ~2 nm nanocrystals.

Eu²⁺-doped Ba₃Si₆O₁₂N₂ green phosphors were prepared by microwave assisted sintering method at 1275℃ for 4 h, while the counterparts using conventional solid-state reaction method were synthesized at temperature higher than 1300℃ and for to 10 h. Microwave assisted sintering could reduce the activation energy and enhance the diffusion rate, thus greatly improved the sintering. Moreover, the influence of Si₃N₄ content on phase formation, morphology, absorption, and quantum efficiency, and photoluminescence properties of phosphors were studied. As a result, the Ba₃Si₆O₁₂N₂:Eu²⁺ samples sintered by microwave assisted sintering method have a higher phase purity and photoluminescence intensity under ultraviolet excitation as compared with samples sintered in the conventional tube furnace. The proposed method is a potential preparation method for the oxynitride phosphors with strong photoluminescence and high phase purity.