Design, Synthesis And Characterization Of Borate Andcarbonate NLO Material

Nonlinear optical(NLO) material is one of the important part of solid-state lasers. It is largely uses in laser frequency conversion, optical parameter oscillators, other optical and photonic devices. To understand the relationship between the composition/structure and NLO properties will be guide us designing new NLO crystals. The BO3 group possess π-conjugated molecular orbital which can produce large second-order susceptibility. Analogous to BO3 group, the CO3 structural units possess a number of unique advantages. So carbonate NLO materials becoming more and more popular. However until now, there is not reported about NLO material which including both of BO3 and CO3 groups.There were three effective strategy has been discussed.(1) To choose favorable structural units like BO3, CO3 anionic groups and have them parallel aligned.(2) To combine second-order Jahn-Teller distorted cations into the same compound;(3) To increase the density of the active asymmetric NLO structural units. Guided by this idea, we synthesized a new compound of borate carbonate NLO material Pb7O(OH)3(CO3)3(BO3) by hydrothermal reactions. Interestingly this compound shows much stronger SHG response, of 4.5 times that of KH2PO4(KDP) and also phase matchable. To make clear the relationship between the structure and NLO properties, the direction and magnitude of the local dipole moments in Pb On polyhedra and BO3, CO3 triangles of Pb7O(OH)3(CO3)3(BO3) have been quantified using a bond-valence method. Furthermore, the electronic properties, the band structure, density of states, electron location function are calculated on the basis of the density functional theory(DFT). It shows that the SHG response of Pb7O(OH)3(CO3)3(BO3) mainly originates from the cooperation of Pb On polyhedra and BO3, CO3 triangles. UV-Vis-NIR Diffuse Reflectance Spectrum shows the cutoff edge is below 340 nm. These indicate that to combine the π-conjugated BO3, CO3 active ionic groups at the same time may be product a very promising NLO crystal for practical application.Two kind of lead borate Pb6B11O18(OH)9 and Pb6B4O11(OH)2 was sysnthesised by hydrothermal reactions. Single-crystal X-ray diffraction analysis, XRD, IR, EDS and elemental analysis also determined the including element and crystal structure. Pb6B11O18(OH)9 crystalized in assemetric space group P32. The crystal data wasa = b = 11.7612(10) ?, c = 13.2822(3) ?, γ = 120°, V = 1591.12(18) ?3. The structure contain chains built up from BO4 and BO3 units. The SHG response of compound Pb6B11O18(OH)9 was 0.24 times that of KDP. Single-crystal X-ray diffraction analysis shows the crystal data was a = 13.7784(10) ?,b = 12.5433(9) ?,c = 7.7112(6) ?,V = 1332.70(17) for compound Pb6B4O11(OH)2. The crystal structure including B3O8 group and Pb6O4 cluster. They sharing O atoms and gives 3D net work.Lead borate or lead borate – carbonate compound indicating that they have potential application in UV Spectrum.