Novel bulk ZnO porous nanosolids were prepared by a unique solvothermal hot-press method, using ZnO nanoparticles and several kinds of solvents as the starting materials. It was found from the experiments that ZnO nanoparticles underwent a "self-assembly process" under some specific hydrothermal hot-press conditions. As a result, some "nanoflowers" formed. The results showed that porous nanosolids with uniform pore diameters could be obtained when water distributed uniformly among the ZnO nanoparticles. On the contrary, if the uniformity of the distribution of water was poor, "nanoflowers" would appear in the water-rich region. It was also found that the photoluminescence of ZnO porous nanosolids was affected by the self-assembly phenomenon. In addition, the experimental results also showed that, both the volume and diameters of the pores could be adjusted by changing either the hot-press temperature, pressure or the kinds of solvents.

本文利用AlCl3和Li3N作为前驱物，利用过量Li3N与水反应大量放热现象，引发两种前驱物之间的固相反应合成了AlN纳米粉。X-射线衍射分析、红外吸收光谱以及透射电子显微镜测试结果表明，利用这种新的合成方法制备的氮化铝主要是六方相，而且颗粒细小、粒度分布比较均匀。另外，这种方法反应迅速、操作过程简单，便于降低制备成本和扩大制备规模。

In this paper, the experimental results of synthesizing BN nanocrystals by both solvothermal and hydrothermal routes have been briefly reviewed. At the end of this paper, the results of utilizing BN nanocrystals as the catalyst for the "polymerization" of benzene are also discussed. The full text contains five parts. 1. Introduction to the synthesis of cubic boron nitride. a. Results of synthesizing cBN by high temperature & high pressure route; b. Results of the synthesis of both hexagonal and cubic boron nitride by sovlothermal route. 2. Synthesis of BN nanocrystals by solvothermal route. a. Preparation of hBN nanocrystals by reacting BBr3 with Li3N; b. The reaction of BCl3 with Li3N for the synthesis of hBN and cBN and cBN nanorods; c. The preparation of hBN nanocrystals from BCl3 and NaN3. 3. Application of structural induction effect on controlling the phases in BN nanocrystals. a. Synthesis of cBN nanocrystals at medium temperature by the induction effect of bulk 316L stainless steel plates; b. Synthesis of cBN nanocrystals at 200°C under the structural induction effect of GaP nanocrystals; c. Preliminary comparison of the induction effects of GaP and Ni nanocrystals. 4. Synthesis of cBN nanocrystals by hydrothermal synthesis route. a. Synthesis of oBN and cBN by the reactions of NaN3, H3BO3 and P in aqueous solutions; b. Synthesis of cBN by the reactions of NaN3, H3BO3 and N2H4·H2O in aqueous solutions. 5. Comparison of the catalytic effects of hBN and AlN nanocrystals on the “polymerization” of benzene molecules.

Boron nitride (BN) nanocrystals with high crystalline perfectness and high yield have been successfully prepared by hydrothermal synthesis route. The experimental results show that the addition of N2H4•H2O and NH4Cl into the reaction mixture significantly improved the perfectness and yield of cBN and oBN nanocrystals. Furthermore, the results of powder X-ray diffraction (XRD), transmission electron microscopy (TEM), selective area electron diffraction (SAED) and high-resolution transmission electron microscope (HRTEM) analysis proved that the major phases in the samples are orthorhombic boron nitride (oBN) and cubic boron nitride (cBN).

A novel "in situ phase-selective route" has been developed, and it was used for the synthesis of cubic boron nitride (cBN) under hydrothermal conditions. The results showed that, if H3BO3, NaN3 and N2H4•H2O were mixed at room temperature and ambient pressure, explosion boron nitride (eBN) was the dominant phase in the sample prepared at 300℃ and 10 MPa. On the contrast, if the reactants were separated with each other at room temperature and ambient pressure, and slowly mixed at high temperature and high pressure (namely, 300℃ and 10MPa) conditions, cBN crystals as large as 0.5mm could be synthesized. This method was called "in situ phase-selective route", it should also be an effective method for the synthesis of diamond crystals in solvothermal and hydrothermal solutions.