【作者】 刘希涛；

【导师】 许东； 王新强； 张光辉；

【作者基本信息】 山东大学 ， 材料学， 2014， 博士

【摘要】 学科的交叉和融合大大推动了科学的发展,为世界科学家探索未知的奥秘和发现潜在的应用不断注入强大的活力,使新的研究领域不断出现。氨基酸分子是组成生物体蛋白质的基本结构单元,同时氨基酸盐晶体也是一类具有特色的新型非线性光学材料。L-精氨酸磷酸盐(LAP)晶体是山东大学创造性地运用分子工程和晶体结构的理论在国际上首创与研制的一种性能全面优异的生物氨基酸盐非线性光学晶体,并受到了国内外同行高度重视和认同。LAP晶体得到了国内外科学家的广泛研究,诸多独特的性能和特点相继被发现。日本科学家研究表明在激光波长为1053nm、脉冲宽度为1ns时,LAP晶体的激光损伤阈值可达到63GW/cm2,其氘化后的晶体(DLAP)损伤阈值更是高达87GW/cm2。1997年日本科学家发现了LAP和DLAP晶体优异的受激布里渊散射(SBS)性能,它们具有较低的SBS阈值和较高的SBS增益系数,作为SBS介质在相位共轭镜等方面具有重要的应用价值。同时磷酸精氨酸(PA)是无脊椎动物体内能量存储和传输的介质。LAP晶体独特的性能和特点引起了科学家们浓厚的兴趣,国内外都曾开展了一些研究工作,但一直没有找到这些独特性能和特点产生的本征原因及它们之间的关联。本论文首先通过分析生物体内能量存储和传递物质PA与LAP晶体的共性与差异,寻找精氨酸与磷酸之间的相互作用及精氨酸分子构象变化的规律,探索LAP晶体在各种能量(光、热、磁场等)作用下的性能及其与能量存储之间的关联。并在此基础上合成和制备新型功能晶体并对其性能进行研究。主要内容包括：1.通过分析生物体能量存储过程中PA的特性及LAP晶体能量作用下的独特的性能,探讨PA与LAP晶体的共性与差异。生物能量存储和传递过程中,生物体内的磷酸原物质发挥了重要的作用,如PA和磷酸肌酸(PC)。它们都具有高能的磷酸胍键,能够存储和传递大量的生物能量。同时精氨酸分子还具有构象易变和多样性的特点。LAP晶体是由天然碱性氨基酸之一的L-精氨酸分子和无机酸磷酸分子有序排列组成。在不同的结晶态下L-精氨酸分子的构象和空间结构不同。虽然PA在生物体中和LAP晶体所处的环境不同,但两者具有相同的结构基元及能量作用下的相关性能。2.探索研究LAP晶体在光能、热能及磁场作用下的性能。(1)通过光谱学和激光损伤实验研究LAP晶体在寻常光与强激光作用下的性能。在强激光作用下LAP晶体表现出极高的损伤阈值,损伤区域的结构变化很小,LAP晶体可以在结构变化很小的前提下抵御很高的激光能量。(2)通过热学性能、变温X射线及高温单晶衍射研究在热能作用下LAP晶体的性能。变温X射线衍射研究发现：温度升高至90℃过程中有8条新的衍射峰出现,而当温度降到室温时,新的衍射峰会慢慢消失至恢复到原样。高温单晶衍射发现在热能影响下L-精氨酸的构象由弯曲状逐渐向伸展状转变。(3)用核磁共振实验研究LAP晶体在磁场作用下的性能。发现LAP晶体在结晶态具有超长的纵向弛豫时间(1HTl为184s)。溶液核磁共振实验表明,随着磷酸量的增多,L-精氨酸由伸展状的高能态构象转化为折叠状的稳定态构象。(4)利用基于密度泛函理论(DFT)的第一性原理计算方法研究了LAP晶体特异性能产生的根源。从电荷密度得出LAP晶体中L-精氨酸与磷酸形成了强烈的类似共价键的相互作用,这种强烈的相互作用可能是LAP晶体独特性能产生的根源。超极化率计算结果表明LAP晶体的非线性光学响应是L-精氨酸离子内的电荷跃迁转移跟磷酸根与L-精氨酸离子间的电荷跃迁转移共同作用产生的。3.设计、合成和生长新型的胍基磷酸化合物晶体,并对其光电性能进行研究。PC是有脊椎动物体内能量存储和传输的介质,它跟PA具有相似的胍基和磷酸基团,通过高能的磷酸胍键进行能量存储和传递。为了系统研究LAP晶体独特性能与能量存储之间的关联,探索研究了一系列具有肌酸和相同胍基磷酸基团的晶体,并对其中的磷酸胍(G2HP)晶体进行了详细的研究。通过溶液降温法生长出了最大尺寸为55x28x27mm3的G2HP单晶。利用单晶衍射解析了其晶体结构。晶体结构是两个独立的胍基基团、一个独立的磷酸根基团及一个结晶水,通过氢键相互作用连接而成。系统研究了G2HP晶体热学、激光损伤、光学和压电性能。G2HP晶体具有较大的比热和较小的热膨胀各项异性。晶体的热传导性能随着温度的升高而逐渐降低且具有很高的抗激光损伤阈值。该晶体具有较宽的透过波段,紫外截止波长为212nm,相对LAP晶体向紫外移动了8nm。晶体属于光学正单轴晶且具有适当的双折射。通过设计不同的晶体切型,对G2HP晶体介电、弹性和压电的各个系数进行了测量。结果表明晶体具有较好的压电性能,压电系数d14和d36的测量值分别为10.00和4.01pC/N。并结合第一性原理计算对其结构功能关系进行了研究。4.金属硫氰酸盐晶体生长、光电性能及机理研究。金属硫氰酸盐晶体是本课题组在双重基元结构模型理论下探索的一类性能优异的光电功能晶体材料。这类配合物型材料将无机晶体中畸变多面体同有机晶体的共轭体系电荷转移有机地结合起来,使其兼备有机跟无机晶体材料的诸多优点。对此类材料的研究主要集中在其优异的非线性光学性能,对其他的物理性能(如压电性能)及组成、结构与性能之间的关系的研究都比较少,本论文对其中性能优异的MMTC、CMTD、MMTD晶体的生长、形貌、光学和压电性能及光电性能产生机理等做了系统的研究。(1) MMTC晶体的生长与性能研究。利用显微结晶方法探索MMTC晶体最佳生长条件。该晶体生长过程中存在开裂、包裹体和螺位错等缺陷。系统地研究了MMTC晶体的光学性能和压电性能。MMTC晶体具有较宽的透过波段且能够实现位相匹配,其粉末倍频效率与KTP晶体相当。设计不同的晶体切型对MMTC晶体的介电和压电系数进行了测量。结果表明该晶体具有优异的压电性能,最大的压电应变常数d15=22.7pC/N。利用第一性原理分析了其光电性能的起源。MMTC非线性光学响应是由-N=C=S-和畸变的多面体相互作用叠加的结果。晶体的强压电效应主要是由体系中的畸变多面体导致晶体内部的正负电荷不平衡而产生的。(2) CMTD及MMTD晶体的生长与性能研究。用两种方法对CMTD及MMTD晶体原料进行了合成。用降温法生长出了大尺寸晶体,并对其生长形貌进行了研究。由于DMSO的引入使得两个晶体比ABTC晶体更加容易生长。两个晶体结构十分相近,都属于层状结构,主要由畸变的HgS4四面体和CdN4O2或者MnN4O2八面体由-S=C=N-连接而成。系统地对两个晶体的线性及非线性光学性能进行了研究。用V棱镜法测定了CTMD和MMTD晶体的折射率色散方程,并对其位相匹配轨迹进行了计算。两个晶体都属于光学负双轴,都可以实现第1类和II类位相匹配。非线性光学性能测试结果表明它们具有比CMTC及MMTC晶体更加优异的非线性光学性能,其粉末倍频效率都约为KTP晶体的1.2倍。设计了不同的晶体切型,测试了CMTD晶体的压电性能。CMTD晶体具有优异的压电性能,其具有较大压电应变常数436＝20.40pC/N。配体的加入,使得结构的畸变更大,有效增强了其光电性能。更多还原

【Abstract】 Crossover and amalgamation of subjects have greatly promoted the development of science, which injects strong vitality to scientists to explore unknown mysteries and discover potential applications and makes a large number of novel research fields appear constantly.Amino acids are the basic structural units of biological proteins. Meanwhile, the amino acid salt derivate crystals are also a kind of distinctive nonlinear optical (NLO) materials. L-aringine phosphate monohyarate (abbreviated as LAP) was firstly discovered by Shandong University using molecular engineering and crystal structure theory as an excellent biological amino acid salt NLO crystal and obtained a great deal of authorizations. Extensive researches have been carried out to investigate LAP crystal and many unique properties and characteristics of the crystal were found. Research results achieved by Japanese scientists indicated that laser-induced damage threshold of LAP crystal is63GW/cm2with wavelength of1053nm and pulse-width at1ns. Furthermore, the deuterated analogue (DLAP) crystal possesses extremely high threshold of87GW/cm2. In1997, Japanese scientists discovered excellent stimulated brillouin scattering (SBS) performance of LAP and DLAP crystals. They have many important applications as a phase conjugate mirror because of low SBS thresholds and high SBS gain coefficients. Meanwhile, phosphate arginine (abbreviated as PA) works as the medium carrier for bioenergy transport and storage in invertebrates.The unique properties of LAP crystal have attracted much attention of the worldwide scientists. Many investigations have been carried out on this issue. However, it has not obtained the credit reason and correlation for the performance. For exploring the specific performance of LAP under energy interaction (light, heat, magnetic field) and the relation to energy storage, the interactions between arginine and phosphate, and the rule for the changes in molecular conformation of arginine are sought through analyzing the structural similarities and differences between PA as the bioenergy transport carrier and LAP crystal in the dissertation. Meanwhile, a series of novel functional crystals are prepared and characterized. The main contents are as follows:1. The structural similarities and differences between PA as the bioenergy transport carrier and LAP crystal were analyzed and summarized.Phosphagens such as PA and phosphocreatine (PC), play an important role during bioenergy storage and transfer. They all possess high-energy phosphate guanidine bonds which can store and transmit a large amount of bioenergy. Meanwhile, the arginine molecules have conformational variability and diversity. LAP crystal is orderly composed of L-arginine molecules and inorganic phosphate molecules. In different crystalline states, the molecule conformation and spatial structure of L-arginine are different. Although the environment of PA in the organism and LAP in crystalline state are very different, there are many similarities between them, such as the same structural units and energy related properties.2. The specific performances of LAP under energy interaction (light, heat, magnetic field) were explored.(1) The spectroscopy and laser-induced damage threshold measurements were carried out to investigate the specific performance of LAP under light. The crystal exhibits an extremely high laser-induced damage threshold and small structural changes occur in damage area. LAP crystal can resist high laser energy with small structural changes.(2) The thermal behaviors, including thermal properties, temperature dependence X-ray diffraction (XRD) and high temperature single-crystal XRD were investigated to study the specific performance under heat interaction. The G2HP crystal possesses relatively large specific heat and strong anisotropic thermal expansions. There is a reversible specific phase transition as the temperature changed. The conformation of arginine changes from a folded state to an extended one with the increasing of temperature.(3) The nuclear magnetic resonance (NMR) spectra were performed to explore the specific performance and change in conformation of LAP under magnetic field interaction. The saturation recovery experiments have shown that the crystal has a long proton spin-lattice relaxation time (Ti), which may be caused by the strong interaction between guanidine and phosphate groups in the crystal. The solution NMR experiments showed that, with the increase of the phosphoric acid, L-arginine changed from a stretching high-energy conformation to a folded stable conformation.(4) The first-principle calculations based on density functional theory (DFT) were carried out to explore the origin for the specific performance of LAP. From the electric charge density, it was found that there is a strong arginine-phosphate electrostatic interaction which possesses a "covalent-like" stability. The hyperpolarizability results showed that the intramolecular charge transfer of L-aringine and the intermolecular charge transfer between L-arginine and phosphate are all responsible for the NLO response of LAP crystal.3. Novel guanidine phosphate compound crystals were designed, synthesized and grown, and the performance was also carried out.PC, which has the same guanidine and phosphate groups as PA, plays an important role during bioenergy storage and transfer in vertebrate. In order to investigate the correlation between the unique properties of LAP crystal and energy storge, several novel creatine and guanidine phosphate compounds were developed, and detailed researches were carried out for diguanidinium phosphate monohydrate (G2HP) crystal.Bulk single crystals of G2HP with dimensions up to55x28x27mm3have been grown by solution growth method. In the structure, there are two separate guanidyl groups and one phosphate group, which are connected by hydrogen bonds.Thermal properties, laser-induced damage threshold, optical behaviors and piezoelectric properties of G2HP crystal were detailed investigated. The G2HP crystal possesses relatively large specific heat and weak anisotropic thermal expansion. The thermal conductivities are descending as the temperature increases. The crystal also possesses an excellent resistance to laser radiation with a high threshold. G2HP crystal presents a broad transmission range with an ultraviolet transparency cutoff at212nm which shows8nm hypsochromic shift compared with that of LAP crystal. The refractive index measurements show that G2HP is an optically positive uniaxial crystal with suitable birefringence. The complete set of dielectric, elastic and piezoelectric constants of G2HP have been measured through designing different crystal cuts. The results showed that the crystal also has fine piezoelectric properties of d14=10.00,d36=4.01pC/N. Furthermore, the structure-property relationships are discussed on the basis of crystal structure combined with first-principle calculations.4. Crystal growth, photoelectric properties and mechanisms of metallic thiocyanate crystals were studied.Metallic thiocyanate crystals, which were developed under the guidance of the double radical structure model theory by our group, are excellent photoelectric functional crystalline materials. Such materials combine the inorganic distorted polyhedra with asymmetric conjugate organic molecules, which can take both the advantages of organic and inorganic crystal materials. The investigations for these materials are mainly focus on their excellent nonlinear properties. Apart from these studies, the physical properties (such as piezoelectric properties) and the composition-structure-property relationships of these materials have not been carried out to date. Three of them including MMTC, CMTD and MMTD crystals are systemically investigated in the dissertation based on the bulk crystal growth, morphologies, optical properties, piezoelectric properties and mechanisms.(1) Growth and performance of MMTC crystalThe growth habit of MMTC crystal was investigated by means of micro-crystallization method. Bluk crystals of MMTC were grown by the following conditions:pH value ranging from1.5to2.5and NH4Cl concentration ranging from10%to15%. Several kinds of defects including cracks, inclusions and screw dislocation have been found during the crystal growth.The optical and piezoelectric properties of MMTC crystal were detailed investigated. MMTC crystal is a phase matchable NLO material with wide optical transmission range and the SHG efficiency is nearly the same as that of KTP crystal. The complete set of dielectric and piezoelectric constants of MMTC have been measured through design different crystal cuts. The results showed that the crystal possesses excellent piezoelectric properties with the largest piezoelectric constants d15=22.7pC/N. The origin of the photoelectric properties was analyzed using first-principle calculations. The SHG response of MMTC mainly stems from the synergistic effect-N=C=S-ligands and distorted polyhedra. In addition, these distortions destroy the superposition of the positive and negative charge centers in the cell, which leads to the very large piezoelectric effect.(2) Growth and performance of CMTD and MMTD crystalsTwo methods were used to prepare the raw material of CMTD and MMTD in aqueous solutions. A higher purity and yield of crystalline powder was obtained using the two-step reaction compared with the one-step one, but the procedure is somewhat complicated. Bulk single crystals were obtained by the temperature-lowering method and the growth morphologies were also investigated. The introduction of DMSO improved the growth of the two crystals than that of ABTC crystals. The crystal structures of the two crystals are very similarity, which belong to orthorhombic system, P212121space group. The compounds exhibit a neutral layered structure consisting of an asymmetric HgS4tetrahedron and CdN4O2or MnN4O2octahedron which are connected by-S=C=N-ligands.The optical and piezoelectric properties of the two crystals were detailed investigated. Refractive indices of CMTD and MMTD were measured by the V-prism method. On the basis of the Sellmeier equations, the phase-matching angles (0,9) for SHG of1064nm were calculated. The results indicated that the two crystals are optically negative biaxial and Type Ⅰ and Type Ⅱ phase-matchable within limits. The NLO property-measurements indicate that the two crystal exhibits stronger SHG effects than CMTC and MMTC, and both of which are1.2times as high as that of KTiOPO4. The piezoelectric properties of CMTD have been measured through designing different crystal cuts. The crystal possesses excellent piezoelectric properties with the largest piezoelectric constants d36=20.40pC/N, and the electromechanical coupling coefficient k36can reach34.06%. The origin of the photoelectric properties was investigated using first-principle calculations. The introduction of ligands increases the structure distortion and effectively enhances the photoelectric properties of the crystals.更多还原