Nanosized a-Al2O3 and CrN powders were mixed in calculated proportion and homogenized by ball milling. Cr2N reinforced Al2O3 composites were prepared by hot pressing of nano CrN–Al2O3 powders. Dense sintered bodies were obtained by hot pressing at 1400-1550 8C and 30 MPa for 60 min. X-ray diffraction (XRD) analysis indicated that the CrN converted to Cr2N during the sintering process. Microstructures of the composites were studied by field emission scanning electron microscopy (FE-SEM). It was found that Cr2N particles were uniformly dispersed in the Al2O3 matrix. The bending strength of the Al2O3–Cr2N composite with the addition of 12.97 vol% Cr2N hot pressed at 1400 8C reached 848 MPa, and the fracture toughness of samples was over 4 MPa m1/2.

Nanocrystallind CrN powder was synthesized by the direct nitridation of nanosized Cr2O3 powder. Puwder X-ray diffractometry patterns indicated that pure cubi-phase CrN powder could be obtained by nitridation at 800 C for 8h. Transmicsion electron microscopy images showed that the particle sizes were 40-80nm. The effect of the nitridation temperature and holdig time on the powder properties was studied.

A new method was used to prepare the TeO2 powders with high purity. Acousto-optic paratellurite (TeO2) crystals were grown by the modified Bridgman method using the high purity TeO2 powders. The highly perfect TeO2 single crystal (bubble-free, twin-free, and crack-free) up to 52_52_80mm3 was obtained. The crack reason of the single crystal was discussed. The optimum conditions of growing high quality and large size TeO2 single crystals were obtained, which included a growth rate of less than 0.6 mm/h, a temperature gradient in solid–liquid interface of about 45 K/cm and a growth direction of /1 10S.

A magnetic composite of multiwalls carbon nanotubes (MWNTs) decorated with iron oxide nanoparticles was synthesized successfully by a simple and effective chemistry precipitation method. The composite was characterized by X-ray diffraction analysis (XRD), Mo¨ ssbauer spectrum (MS), transmission electron microscopy (TEM), and Fourier transform spectroscopy (FTIR) techniques. The patterns of XRD and MS indicated that MWNTs, g-Fe2O3, and Fe3O4 coexisted in the composite. The TEM observation indicated that the nanoparticles of iron oxide were attached on the surface of the MWNTs, and the sizes of the particles ranged from 25 to 80 nm. FTIR spectra showed that SO4_ functional groups existed on the surface of MWNTs after modification by sodium dodecylbenzene sulfonic acid (SDBS), which could immobilize Fe3+ ions onto the MWNTs. The hysteresis loops of the MWNTs and decorated MWNTs were measured by vibrating sample magnetometer (VSM), and the results showed that the composite was ferromagnetism with the saturated magnetization of 20.07 emu/g, and the coercive of 163.44 Oe.

A novel magnetic nanocomposite of g-Fe2O3 nanoparticles decorated multiwalls carbon nanotubes (MWNTs) was synthesized for the first time by a simple chemistry precipitation method. The structure and morphology of the composite was characterized by X-ray powder diffractometer (XRD), TEM and EDS. The results of XRD and TEM show that g-Fe2O3 nanoparticles is immobilized on the side wall of the MWNTs, the size of most of the particle is o5 nm.The EDS analysis shows that the atomic ratio of Fe to O is 2:3. The magnetization curves of the MWNTs and g-Fe2O3 decorated MWNTs were measured by VSM at room temperature, which indicate that the saturated magnetization (Ms), remanence (Mr) and coercivity (Hc) of the decorated MWNTs are much larger than those of MWNTs, and the decorated MWNTs exhibit well magnetic properties.