B2O3添加宝石级金刚石单晶的生长特性

利用温度梯度法, 在5.3-5.7 GPa压力、1200-1600 ℃的温度条件下, 将B₂O₃粉添加到FeNiMnCo+C合成体系内, 进行B₂O₃添加宝石级金刚石单晶的合成. 研究得到了FeNiMnCo触媒生长B₂O₃添加宝石级金刚石单晶的相图分布规律. 结果表明B₂O₃添加会使晶体生长的“V”形区上移和低温六面体单晶生长区间变宽. 通过晶体生长实验, 研究合成了不同形貌的B₂O₃添加宝石级金刚石单晶. 研究同时证实, B₂O₃的过量添加会对宝石级金刚石单晶生长带来不利影响. 当B₂O₃的添加量高于约3 wt‰、生长时间超过20 h时, 很难实现优质B₂O₃添加宝石级金刚石单晶的生长. 但B₂O₃的适量添加(不超过1 wt‰), 有助于提高低温板状六面体宝石级金刚石单晶的成品率. 通过对晶体生长速度的研究发现, B₂O₃的添加使得优质晶体的生长速度明显降低, 随着晶体生长时间的延长, B₂O₃添加剂对晶体生长的抑制作用会越发明显. 扫描电镜测试结果表明, 合成体系内B₂O₃添加剂的引入, 导致晶体表面的平整度明显下降.     

Synthesis and characterizations of boron and nitrogen co-doped high pressure and high temperature large single-crystal diamonds with increased mobility

We synthesized and investigated the boron-doped and boron/nitrogen co-doped large single-crystal diamonds grown under high pressure and high temperature (HPHT) conditions (5.9 GPa and 1290℃). The optical and electrical properties and surface characterization of the synthetic diamonds were observed and studied. Incorporation of nitrogen significantly changed the growth trace on surface of boron-containing diamonds. X-ray photoelectron spectroscopy (XPS) measurements showed good evident that nitrogen atoms successfully incorporate into the boron-rich diamond lattice and bond with carbon atoms. Raman spectra showed differences on the as-grown surfaces and interior between boron-doped and boron/nitrogen co-doped diamonds. Fourier transform infrared spectroscopy (FTIR) measurements indicated that the nitrogen incorporation significantly decreases the boron acceptor concentration in diamonds. Hall measurements at room temperature showed that the carriers concentration of the co-doped diamonds decreases, and the mobility increases obviously. The highest hole mobility of sample BNDD-1 reached 980 cm²·V^-1·s^-1, possible reasons were discussed in the paper.     

高温高压下氮氢协同掺杂对{100}晶面生长宝石级金刚石的影响

在压力为5.5–6.2 GPa, 温度为1280–1450 ℃的条件下, 利用温度梯度法详细考察了氮氢协同掺杂对100晶面生长宝石级金刚石的影响. 实验结果表明伴随合成腔体内氮、氢浓度的升高, 合成条件明显升高, 金刚石生长V形区间上移; 晶体的红外光谱中与氮相关的吸收峰急剧增强, 氮含量可达2000 ppm, 同时位于2850 cm^-1和2920 cm^-1对应于 sp³杂化 C–H 键的对称伸缩振动和反对称伸缩振动的红外特征峰逐渐增强, 表明晶体中既有高的氮含量, 同时又含有氢. 对晶体进行电镜扫描发现, 氮氢协同掺杂对晶体形貌影响明显, 出现拉长的{111}面, 且晶体表面上有三角形生长纹理. 拉曼测试表明, 晶体的峰位向高频偏移、半峰宽变大, 说明氮、氢杂质的进入对晶体内部产生了应力. 本文成功地以{100}晶面为生长面合成出高氮含氢宝石级金刚石单晶, 在探究氮氢共存环境下金刚石生长特性的同时, 也可为理解天然金刚石的形成机理提供帮助.     

Li2B4O7晶体及其熔体结构的拉曼光谱研究

采用高温原位拉曼光谱技术,研究了Li₂B₄O₇从常温至1 373 K温度范围内的拉曼光谱。在升温过程中,晶体的拉曼光谱出现展宽和红移现象,且强度降低。晶体熔化时,由2个[BO₄]和2个[BO₃]组成的[B₄O₉]环状结构转变成(B₃O₆)3- 六元环和[BO₃]结构,[BO₄]结构减少直至消失。基于密度泛函理论,计算了Li₂B₄O₇晶体的拉曼光谱,对其振动模式进行了分析归属。利用量子化学从头计算法计算了由[B₃O₆-BO₃]为基础相互连接形成的x(Li₂B₄O₇)(x=2, 3, …, 9)的环状团簇模型的拉曼光谱,对Li₂B₄O₇熔体的结构进行了模拟分析。计算结果表明Li₂B₄O₇熔体的阴离子基元为三个(B₃O₆-BO₃)组成的大三元环超级结构。     

添加Fe(C5H5)2合成氢掺杂金刚石大单晶及其表征

在Ni₇₀Mn₂₅Co₅-C体系中添加含氢化合物Fe(C₅H₅)₂作为新型氢源, 利用温度梯度法, 在压力为5.5-6.0 GPa、温度为1280-1400 ℃的条件下, 成功合成出氢掺杂的宝石级金刚石大单晶. 通过傅里叶显微红外光谱发现, 随着Fe(C₅H₅)₂添加量的增加, 合成晶体中与氢相关的对应于sp³杂化C-H键的对称伸缩振动和反对称伸缩振动的红外特征峰2850和2920 cm^-1逐渐增强, 而晶体中氮含量却逐渐减少. 通过合成晶体的拉曼光谱分析发现, 金刚石的拉曼峰伴随Fe(C₅H₅)₂的添加向高频偏移, 这表明氢的进入在金刚石内部产生了压应力. 观察扫描电子显微镜图像发现, 在低含量Fe(C₅H₅)₂添加时晶体表面平滑, 而高含量添加时晶体表面缺陷增多, 且呈现出气孔状. 使用新的添加剂Fe(C₅H₅)₂作为氢源, 合成出含氢宝石级金刚石单晶, 丰富了金刚石单晶中对氢的研究内容, 也可为理解天然金刚石的形成机理提供帮助.     

Different effect of NiMnCo or FeNiCo on the growth of type-Ⅱa large diamonds with Ti/Cu as nitrogen getter

In order to synthesize high-quality type-Ⅱa large diamond, the selection of catalyst is very important, in addition to the nitrogen getter. In this paper, type-IIa large diamonds are grown under high pressure and high temperature(HPHT) by using the temperature gradient method(TGM), with adopting Ti/Cu as the nitrogen getter in Ni_(70)Mn_(25)Co_5(abbreviated as NiMnCo) or Fe_(55)Ni_(29)Co_(16)(abbreviated FeNiCo) catalyst. The values of nitrogen concentration(N_c) in both synthesized high-quality diamonds are less than 1 ppm, when Ti/Cu(1.6 wt%) is added in the FeNiCo or Ti/Cu(1.8 wt%) is added in the NiMnCo. The difference in solubility of nitrogen between both catalysts at HPHT is the basic reason for the different effect of Ti/Cu on eliminating nitrogen. The nitrogen-removal efficiency of Ti/Cu in the NiMnCo catalyst is less than in the FeNiCo catalyst. Additionally, a high-quality type-Ⅱa large diamond size of 5.0 mm is obtained by reducing the growth rate and keeping the nitrogen concentration of the diamond to be less than 1 ppm, when Ti/Cu(1.6 wt%) is added in the FeNiCo catalyst.     

The role of Sb(5+) in the structure of Sb(2)O(3)-B(2)O(3) binary glasses--an NMR and Mössbauer spectroscopy study

Glasses of general formula xSb₂O₃ (1−x)B₂O₃ (0x0.8) have been prepared by conventional melt- quenching. Mössbauer spectroscopy shows that a fraction of the Sb³⁺ is converted to Sb⁵⁺ and this fraction increases with x. High-field ¹¹B MAS NMR gives well-resolved resonances from boron atoms which are 3- and 4-coordinated to oxygen. The fraction of 4-coordinated boron, N₄, goes through a maximum value of 0.12±0.01 at x=0.5. The position of the maximum in N₄ is consistent with the cation potential for Sb³⁺, as observed for other systems. However, the low value of N₄ at this maximum is not so readily explained. The values are similar to those predicted if [BO₄]⁻ were stabilised by [SbO₄]⁺ but the trends with composition are different.     

Mn-Mg共掺杂AlON荧光粉制备及荧光性质

采用固相反应法成功合成了一系列Mn-Mg共掺的Al₂₃O₂₇N₅荧光粉。结果显示煅烧条件和Mn的掺杂浓度对Mn-Mg共掺的AlON荧光粉的制备和发光性质都有重要影响。获得纯相AlON的温度从未掺杂的1 900 ℃下降到10% Mn和10% Mg(摩尔分数)共掺杂的1 800 ℃。晶格参数随着Mn掺杂浓度升高而增加,说明Mn进入了AlON晶格中。未掺杂和Mg单掺以及10% Mn和10% Mg共掺杂样品的发射光谱都含有一个350～600 nm之间的宽带发射。绿光发射归属于Mn的3d电子之间的传输。蓝光发射可能与杂质或Al空位相关。     

Nonmetallic crystals with high thermal conductivity

Nonmetallic crystals transport heat primarily by phonons at room temperature and below. There are only a few nonmetallic crystals which can be classed as high thermal conductivity solids, in the sense of having a thermal conductivity of > 1 W/cmK at 300K. Thermal conductivity measurements on natural and synthetic diamond, cubic BN, BP and AIN confirm that all of them are high thermal conductivity solids. Studies have been made of the effect on the thermal conductivity of nitrogen impurities in diamond, and oxygen impurities in AIN. The nitrogen impurities scatter phonons mostly from the strain field, the oxygen impurities scatter phonons mostly from the mass defects caused by aluminum vacancies. Pure A1N as well as pure SiC, BeO, BP and BeS conduct heat almost as well as does copper at room temperature, while pure natural and synthetic diamonds conduct heat five times better than copper.All of the nonmetallic solids that are known to possess high thermal conductivity have either the diamond-like, boron carbide, or graphite crystal structure. There are twelve different diamond-like crystals, a few boron carbide-type crystals, and two graphite structure crystals that have high thermal conductivity. Analyses of the rock-salt, fluorite, quartz, corundum and other structures show no candidates for this class. The four rules for finding crystals with high thermal conductivity are that the crystal should have (1) low atomic mass, (2) strong bonding, (3) simple crystal structure, and (4) low anharmonicity. The prime example of such a solid is diamond, which has the highest known thermal conductivity at 300K.     

B掺杂ZnO透明导电薄膜的实验及理论研究

采用脉冲直流磁控溅射技术与基于密度泛函理论的平面波赝势方法对B掺杂ZnO （BZO）薄膜进行了研究. 以B₂O₃：ZnO陶瓷靶为溅射靶材,制备了低电阻率、可见和近红外光区高透过率的BZO薄膜. 系统地研究了衬底温度对BZO薄膜的结构、光电特性的影响. 结果表明：适当的增加衬底温度可以促进BZO薄膜结晶质量改善,晶粒尺寸增加,迁移率增大,电阻率降低. 在200 ℃时制备了电阻率为7.03×10^-4 Ω·cm,400–1100 nm平均透过率为89%的BZO薄膜. 理论模拟结果表明：在BZO薄膜中,以替位方式掺入的B （B_Zn）的形成能最低,B主要以替位形式掺入ZnO,其次分别为八面体间隙（B_IO）和四面体间隙（B_IT）的掺杂方式. B 掺入后,费米能级穿过导带,材料表现出n型半导体特性,光学带隙展宽,导电电子主要来源于B 2p,O 2p及Zn 4s电子轨道. 关键词： BZO薄膜 第一性原理计算 磁控溅射 太阳电池     

Synthesis of N-type semiconductor diamonds with sulfur,boron co-doping in FeNiMnCo-C system at high pressure and high temperature

A series of diamonds with boron and sulfur co-doping were synthesized in the Fe Ni Mn Co-C system by temperature gradient growth(TGG) under high pressure and high temperature(HPHT). Because of differences in additives, the resulting diamond crystals were colorless, blue-black, or yellow. Their morphologies were slab, tower, or minaret-like. Analysis of the x-ray photoelectron spectra(XPS) of these diamonds shows the presence of B, S, and N in samples from which N was not eliminated. But only the B dopant was assuredly incorporated in the samples from which N was eliminated. Resistivity and Hall mobility were 8.510 ?·cm and 760.870 cm~2/V·s, respectively, for a P-type diamond sample from which nitrogen was eliminated. Correspondingly, resistivity and Hall mobility were 4.211×10~5 ?·cm and 76.300 cm~2/V·s for an N-type diamond sample from which nitrogen was not eliminated. Large N-type diamonds of type Ib with B–S doping were acquired.     

考虑Stefan影响的单颗粒硼着火过程研究

针对含硼推进剂固体火箭冲压发动机内单颗粒硼的着火过程展开了系统研究. 考虑硼颗粒周围气相流动以及硼颗粒与周围环境间的传热传质过程, 建立了考虑Stefan流作用的一维硼颗粒着火模型, 研究了硼颗粒实现着火和未能实现着火两种典型情形下硼颗粒及周围气相的参数变化规律, 对两种情形下Stefan流的变化规律及其成因展开了详细分析. 研究表明, 在硼颗粒实现着火的过程中, 液态B₂O₃的蒸发及硼的 氧化均能在硼颗粒的反应自加热作用下急剧加速, 硼颗粒表面附近的氧气和气相B₂O₃分布变化剧烈; 在未能实现着火的过程中, 液态B₂O₃的蒸发和氧气消耗的质量流率相对较小, 并逐渐趋于稳定, 硼颗粒表面附近的氧气和气相B₂O₃分布相对变化很小.在两种典型情形下, 硼颗粒外表面的Stefan流都会经历先由周围空间流向颗粒表面, 而后变为由颗粒表面流向周围空间的过程. 关键词： 固体火箭冲压发动机 硼颗粒 着火过程 Stefan流     

Electrical and structural properties of diamond films implanted by various doses of oxygen ions

Oxygen-doped diamond films are prepared by implanting various dose oxygen ions into the diamond films synthesized by hot filament chemical vapour deposition, and their electrical and structural properties are investigated. Hall effect measurements show that lower dose oxygen ion implantation is beneficial to preparing n-type diamonds. The carrier concentration increases with the dose increasing, indicating that oxygen ions supply electrons to the diamonds. The results of AES spectrum indicate that oxygen ions are doped into the diamond films, and the O-implanted depth is around 0.1μm. Raman spectrum measurements indicate that the lower dose oxygen ion implantation at 10¹⁴cm^-2 or 10¹⁵cm^-2 is favourable for producing less damaged O-doped diamond films.     

Magnli相亚氧化钛Ti8O15的电子结构和光学性能的第一性原理研究

采用基于密度泛函理论的平面波超软赝势法研究了Magneli相亚氧化钛Ti8O15的电子结构和光学性能.计算出的能带结构显示Ti₈O₁₅相比锐钛型TiO₂禁带宽度大幅度降低.态密度分析表明,其原因在于Ti₈O₁₅的O原子的2p轨道以及Ti原子的3p,3d轨道相对于TiO₂的相应轨道向左产生了偏移,同时由于O原子的缺失使得Ti原子的3d,3p轨道多余电子在Fermi能级附近聚集形成新的电子能级.态密度分析结果还显示,相对于TiO₂,Ti₈O₁₅Fermi能级附近电子格局发生了如下变化:O原子的2p轨道电子贡献减少,Ti原子的3d轨道的电子对Fermi能级贡献增大.光吸收计算图谱表明,TiO₂仅在紫外光区有较高的光吸收能力,而Ti₈O₁₅由于禁带宽度变窄引起光吸收范围红移到可见光区,从而在紫外光区和可见光区都有较高的光吸收能力,计算结果与实验得到的紫外-可见漫反射吸收光谱结果一致.     

5d过渡金属原子掺杂氮化硼纳米管的第一性原理计算

采用基于密度泛函理论的第一性原理计算方法,研究了当氮化硼纳米管（BNNT）中的B原子和N原子被5d过渡金属原子（Lu,Hf,Ta,W,Re,Os,Ir,Pt,Au,Hg）取代时BNNT的几何结构、电子结构和磁性性质. 作为对比,给出了理想BNNT,B缺陷体系（V_B）和N缺陷体系（V_N）的相应结果. 研究发现：5d原子取代B（B_5d）时体系的局域对称性接近于C_3v,但是取代N（N_5d）时体系的局域对称性偏离C_3v对称性较大;利用相同的5d原子进行掺杂时,B_5d的成键能比N_5d的成键能大;对于B_5d或者N_5d,其成键能基本上随着5d原子的原子序数的增大而降低;掺杂体系中出现了明显的杂质能级,给出了态密度等结果;不同掺杂情况的磁矩不同,取代B 时体系的总磁矩呈现出较强的规律性. 利用对称性和分子轨道理论解释了5d原子取代B时杂质能级的产生和磁性的变化规律. 关键词： 第一性原理计算 5d过渡金属原子 氮化硼纳米管 密度泛函理论     

碱金属阳离子对[B3O7]型非线性光学晶体结晶习性的影响

本文利用高温拉曼光谱技术和从头计算的方法, 研究了LiB₃O₅和CsB₃O₅晶体高温熔融体的结构, 分析了碱金属阳离子对熔体结构的影响, 以及熔体结构的差异与LiB₃O₅和CsB₃O₅晶体结晶习性的联系. 结果表明: LiB₃O₅和CsB₃O₅晶体高温熔融体中的结构基团 主要为B₃Ø₇和B₃Ø₆两种不同类型的硼氧六元环; 环内BØ₄ 四面体的数量影响了六元环呼吸振动峰的拉曼频率, 随BØ₄四面体数量的增加六元环呼吸振动峰向低频移动; LiB₃O₅晶体高温熔融体中, BØ₄四面体含量相对较多; 然而, 离子半径相对较大的Cs⁺离子却阻碍了熔体中BØ₄四面体的形成, 造成CsB₃O₅晶体高温熔融体中BØ₄/BØ₃比值的降低. 结合LiB₃O₅和CsB₃O₅晶体生长动力学过程的分析 (Wang D, Wan S M et al. 2011 Cryst. Eng. Comm. 13 5239), 阳离子的不同导致高温熔体中BØ₄四面体数量的差异, 被认为是影响LiB₃O₅和CsB₃O₅晶体结晶习性的重要因素, 有效降低高温熔体中BØ₄四面体的数量, 将是实现LiB₃O₅晶体生长的关键条件. 关键词： 硼酸盐晶体 熔体结构 拉曼光谱 结晶习性     

Measurement of X-ray transmission factors of some boron compounds

Measurements have been made to determine X-ray transmission factors of some boron compounds (H₃BO₃,Na₂B₄O₇ and B₃Al₂O₃) by using an extremely narrow-collimated-beam transmission method in the energy range 15.746–40.930 keV. The characteristic K and Kβ X-rays of the different elements (Zr, Mo, Ag, In, Sb, Ba and Pr) passed through boron compounds were detected with a high-resolution Si(Li) detector. Results are presented and discussed in this paper.     

偏硼酸钡低温相的晶体结构

本文报道了新型信频材料——偏硼酸钡[Ba₃(B₃O₆)₂]低温相的晶体结构。晶体属三方晶系,空间群为C₃⁴-R3,取六方坐标系,晶胞参数为a=b=12.532?,c=12.717?,z=6。在PhilipsPW-1100四圆衍射仪上收集到独立衍射693个。采用重原子法通过三维帕特逊和三维傅里叶合成测定结构,并用对角矩阵最小二乘法修正至R=0.046。该晶体是一个由Ba²⁺和(B₃O₆)^3-环交错组成的层状阶梯式结构。其阴离子(B₃O₆)^3-环基本上是平面状的。基团平面垂直于三次轴;Ba²⁺近邻有7个氧原子。将此结构与偏硼酸钡高温相比较表明,由于钡阳离子的非中心对称分布改变了阴离子硼氧环共轭基团的电子云密度,这一结构上的变化对该晶体的倍频效应做了主要贡献。 关键词：     

Effect of oxygen on regulation of properties of moderately boron-doped diamond films

Regulation of oxygen on properties of moderately boron-doped diamond films is fully investigated. Results show that, with adding a small amount of oxygen (oxygen-to-carbon ratio < 5.0%), the crystal quality of diamond is improved, and a suppression effect of residual nitrogen is observed. With increasing ratio of O/C from 2.5% to 20.0%, the hole concentration is firstly increased then reduced. This change of hole concentration is also explained. Moreover, the results of Hall effect measurement with temperatures from 300 K to 825 K show that, with adding a small amount of oxygen, boron and oxygen complex structures (especially B₃O and B₄O) are formed and exhibit as shallow donor in diamond, which results in increase of donor concentration. With further increase of ratio of O/C, the inhibitory behaviors of oxygen on boron leads to decrease of acceptor concentration (the optical emission spectroscopy has shown that it is decreased with ratio of O/C more than 10.0%). This work demonstrates that oxygen-doping induced increasement of the crystalline and surface quality could be restored by the co-doping with oxygen. The technique could achieve boron-doped diamond films with both high quality and acceptable hole concentration, which is applicable to electronic level of usage.     

Eu掺杂的高Gd玻璃荧光及闪烁发光性能研究

分别在空气和还原气氛下,采用高温熔融法制备了Eu 掺杂(1 wt%) 的15SiO₂-25B₂O₃-30Al₂O₃-30Gd₂O₃ 氧化物玻璃,对二者的光致发光和闪烁发光性能进行测试. 结果显示：还原气氛下制得的玻璃在395 nm 紫光和X 射线激发下,均可以得到450–550 nm 的Eu²⁺ 蓝绿发光和615 nm 的Eu³⁺ 红光;然而在不同的激发光源下,Eu²⁺ 和Eu³⁺发光强度比存在明显不同,395 nm 紫光激发下,Eu³⁺ 发光强度仅为Eu²⁺ 的0.02 倍,X 射线激发下,Eu³⁺ 发光强度变为Eu²⁺ 强度的1.37 倍. 通过声子边带谱分析,还原后玻璃中Si 形成体附近的Eu³⁺ 全部被还原为Eu²⁺,B 和Al形成体周围的Eu³⁺ 部分被还原为Eu²⁺. 进一步分析闪烁发光的机理表明：Gd 的敏化剂作用以及B 和Al 形成体周围Eu²⁺→Eu³⁺ 的能量传递都增强了还原玻璃中Eu³⁺ 的闪烁发光性能. 关键词： 高Gd玻璃 2+')" href="#">Eu²⁺ 闪烁发光 声子边带谱