The bulk crystal of LiSrBO3 （8.39 g） with a size of 21mm × 20mm × 15mm was grown by high temperature solution growth method. The relationship between growth habit and crystal structure was discussed. The transmission spectrum shows an UV absorption edge at about 300 nm. The melting temperature of this crystal was detemained to be 942 ℃ by DTA-TG measurement. The band structure of the LiSrBO3 crystal was studied by means of the first principle method. An indirect band gap was found to be about 4.0 eV, and a low dielectric constant was estimated to be about 1.9 in terms of theoretical results.
In this paper, we investigate the length dependence of linear and nonlinear optical properties of finite-length BN nanotubes. The recently predicted smallest BN（5,0） nanotube with configuration stabilization is selected as an example. The energy gap and optical gap show the obvious length dependence with the increase of nanotube length. When the length reaches about 24 /~, the energy gap will saturate at about 3.2 eV, which agrees well with the corrected quasi- particle energy gap. The third-order polarizabilities increase with the increase of tube length. Two-photon allowed excited states have significant contributions to the third-order polarizabilities of BN（5,0） nanotube.
A novel complex [Ce(NO3)5(H2O)2]2(Hphen)(H2O) (phen =1,10-phenanthro-line) with formula C24H24CeN9O18 and Mr = 866.64 has been synthesized and structurally characterized by X-ray diffraction. It crystallizes in triclinic, space group P with a = 7.5534(2), b = 8.083(2), c = 25.8377(6) , = 86.847(1), = 89.937(1), = 86.981(1), V = 1572.94(6) 3, Dc = 1.830 g/cm3, F(000) = 866, m = 1.545 cm-1 and Z = 2. The final refinement gave R = 0.0486 and wR = 0.1278 for 4852 observed reflections with I > 2s(I). It consists of discrete [Ce-(NO3)5(H2O)2]2- anion, two Hphen+ cations and a lattice water molecule. In the compound, all of the five nitrates are bidentate, and the coordination of Ce(III) is 12. The photo-luminescence of this compound was also investigated.
The single crystal and crystallized powder of triphosphate CeP3O9 have been synthesized, and the space group of CeP3O9has been determined to be C2221 with the cell parameters ofa = 8.6059, b = 11.2437, c = 7.3518 A, V= 711.4（3） A^3, Z= 4, D,. = 3.520 g/cm^3, F（000） = 700, R = 0.0377 and wR = 0.0930. The absorption and emission spectra have been measured, for which the strongest absorption and emission peaks are located at 280 and 320 nm, respectively. The density of state （DOS） and dielectric function have been calculated by the DFT method. The crystal is transparent provided the wavelength is larger than 341 nm, and the observed ultraviolet cut-off edge is at about 350 nm for a polycrystalline power sample. It is possible that the triphosphate CeP3O9 will become an ultraviolet emission material.
TONG Hua-Nan ZHANG Hao CHENG Wen-Dan WU Dong-Sheng GONG Ya-Jing ZHU Jing HUANG Shu-Ping ZHAO Dan
