温度传感器(2)

4.利用磁特性的温度传感器在随温度不同磁性能发生很大变化的材料中有热敏铁氧体和磁补偿合金,这里仅就第一种材料来谈一谈。热敏铁氧体的实用温度范围中包括居里温度Tc,即产生磁体二次相变的温度。改变铁氧体的成份可自由     

Lepidocrocite-like TiO2 and TiO2(110)–(1 × 2) supported on W(100)

Ultrathin films of TiO₂ were grown on a W(100)–O(2?×?1) substrate and characterised with a combination of scanning tunneling microscopy (STM) and low energy electron diffraction. In addition to islands of rutile TiO₂(110) with (1?×?1) termination that were reported previously, we also observed rutile TiO₂(110) islands with a (1?×?2) film termination. A lepidocrocite-like TiO₂ nanosheet was also observed on the W(100) surface. High resolution STM images show that the nanosheet grows in the principal orthogonal directions of the W(100) substrate and forms a commensurate (1?×?7) coincident cell.     

大块致密[(Ca_(1-x)Sr_x)_(2-2y)](Ti_(2-2y)Li_2y)Si_(2y)O_(6-y)在CO_2减排及资源化利用方面的应用

介绍大块的、致密的、用作介电材料的非化学计量比化合物(“掺杂材料“)的合成及其应用。介质阻挡放电(DBD)是指在两金属电极之间插入一层绝缘材料的等离子放电装置。从放电物理学角度来讲,这层材料的介电常数越高,所产生的等离子能量就越高,这样,如果应用到等离子化学领域,就会提高化学反应能力。目前商业化生产的高介电常数材料的强度都较低,如BaTiO_3,在等离子发生的瞬间就会被击穿。所以要在DBD中使用高介电常数的材料,就必须进行新型介电材料的研发。介绍了高强度、高密度、高介电常数的非化学计量比化合物[(Ca_(1-x)Sr_x)_(2-2y)](Ti_(2-2y)Li_(2y))Si_(2y)O_(6-y)的合成理论、工艺方法及其在CO_2减排、资源化利用方面的应用。     

二氯硅烷(SiH_2Cl_2)

半导体级,纯度妇8.7%物理I性质分子量蒸汽压(ZoOC)沸点(1大气压)冰点(1大气压)无色1 01。OO。63巴(表压)8。2“C一122“C液态密度(20OC)1.261克/毫升气态密度(沸点,1大气压)4.94克/升在空气中燃烧界限4.1一98.8体积%气态比重(空气=1)3.93有刺激性和窒息性气味安全 警告:易燃、有毒和腐蚀物质。 危害性 八小时工作时间内空气中最大允许含量值未定气但毒性类似于四氯化硅。在空气中易燃,可燃范围极宽。在钢瓶中蒸汽压力约为0.6巴(表压)时呈液态。蒸汽比空气重得多。即使与少量卤素和其它氧化剂接触也会发生激烈反应,与水能发生激烈反应。…     

Crystal Structure of Neptunium(V) Phthalate (NpO2)2(OOC)2C6H4·4H2O

The crystal structure of (NpO₂)₂(OOC)₂C₆H₄·4H₂O [rhombic cell: a = 15.937(3), b = 26.922(5), c = 8.020(2) Å, space group Pbcn, Z = 8, V = 3441.0(12) ų, d _calc = 2.988 g cm^{- 3}, CAD4, MoK , graphite monochromator, 2934 independent reflections; R ₁ = 0.0352, wR ₂ = 0.0951] was studied. The structure consists of NpO₂ ⁺ cations, H₄C₆(COO)₂ ^{2 -} anions, and molecules of coordinated and crystallization water. The crystal lattice involves neutral layers [(NpO₂)₂(OOC)₂C₆H₄(H₂O)₃] _n parallel to the {101} plane. The dioxocations in these layers are bonded to each other to form cationic networks [the Np···Np distance is 3.911(1)-4.202(1) Å]. The coordination polyhedra of Np(1) and Np(2) are pentagonal bipyramids (CN 7). The point group of the neptunyl(V) groups is close to D _h. These groups are bidentate ligands in the cation-cation interaction. The Np = O bond lengths are 1.852(6) [Np(1)-O(1)], 1.849(7) [Np(1)-O(2)], 1.845(7) [Np(2)-O(3)], and 1.841(7) Å [Np(2)-O(4)]; the O = Np = O bond angles are 178.6(3)° [O(2)-Np(1)-O(1)] and 177.4(3)° [O(3)-Np(2)-O(4)]. The equatorial plane of the Np(1) bipyramid consists of two oxygen atoms of adjacent Np(2)O₂ ⁺ dioxocations, two water molecules, and a single oxygen atom of the phthalate anion. The equatorial plane of the Np(2) bipyramid consists of two oxygen atoms of adjacent Np(1)O₂ ⁺ dioxocations, two oxygen atom of the phthalate anion, and a single water molecule. The bond lengths in the equatorial plane of the bipyramid lie in the following ranges: Np-Oyl 2.373(7)-2.437(7) Å (average 2.397 Å) , Np-Ophth 2.360(7)-2.474(7) Å (average 2.431 Å), and Np-Owater 2.534(8)-2.558(9) Å (average 2.544 Å). The phthalate anions are tridentate bridging ligands binding neptunium atoms only within a single cationic network.     

照相有机物讲座(七) 成色剂(2)

成色剂的类别和应用特点现代彩色多层感光材料应用减色法原理形成彩色影象。在每一个乳剂层中成色剂与显影剂氧化物分别生成黄、品红和青等三补色。根据成色剂所能形成的颜色不同,在化学结构上把它分为三种类型,即黄、品红和青成色剂(实例见表2、表3和表4) 。人们对彩色感光材料在清晰度、颗粒性、彩色还原、影象色牢度等质量特性方面不断提出的改进要求,促进了成色剂的研制工作。在     

橡胶知识浅说(2)

1.比重各类生胶的比重,以乙丙橡胶最小,为0.86～0.87;氟橡胶最大,为1.8～2.0。硫化胶的比重因配方不同而异,炭黑、硫黄的比重为2,氧化锌等金属化合物为5～6,但由于有机系的配合剂比重多为1,因此通常橡胶的比重在1～2的范围内。也有例外,如填充铅粉的隔音板是重质材料,但它也比金     

Interaction of An(VI) (An = U, Np, Pu) and Np(V) with 2,3-pyridinedicarboxylic (quinolinic) acid (H2Quin): Complexation in aqueous solutions, synthesis and structure of the complexes [UO2(HQuin)2], [(NpO2)2(HQuin)2(C6H4NO3)2]·2H2O, and [PuO2Quin(H2O)]

Complexation of An(VI) (An = U, Np, Pu), and Np(V) with 2,3-pyridinedicarboxylic (quinolinic, H₂Quin) acid in aqueous solutions was studied. Np(V) can form 1: 1 and 1: 2 complexes, and An(VI), also 1: 3 complexes (at pH ? 6 and [H₂Quin] ? 0.1 M). Quinolinate ion can coordinate to actinide(VI) and (V) ions in solutions in different modes. The apparent stability constants of the complexes in a wide pH range and the concentration stability constants of the An(VI) complexes were measured. In the series from Pu(VI) to U(VI), the stability of the complexes slightly increases. Crystalline complexes [UO₂(HQuin)₂], [(NpO₂)₂(HQuin)₂(HL)₂]·2H₂O (HL is N-protonated 2-hydroxypyridine-3-carboxylic acid anion), and [PuO₂Quin(H₂O)] were synthesized, and their structures were determined by single crystal X-ray diffraction. Different types of coordination of quinolinate ions to actinide ions are also observed in the crystalline complexes.     

有奖自测问答(2)

为了帮助读者学习音响知识，本刊采用有奖问答的形式，使学习形式更为灵活，寓学习于活动之中，并以微薄奖励活跃活动的气氛。读者通过回答问题可以自行检测自己的学习进步情况，同时所列问题尽量能给读者的学习以提示，便于读者发现问题和解决问题。读者按回答问题的分数高低得奖，若数名并列则采取抽奖的方式确定获奖者。全年问题都答对者将公布性名，并给予荣誉称号。问题中分为发烧音响和专业音响两种体裁，读者可任选一种，共答题必答。本期奖品由惠威公司和安润公司提供：一等奖1名：天鹅MI音箱一对二等奖3名：美国舒尔话筒一只（12…     

录像机的灵活运用(2)

6、一盘磁带能使用无数次,为了防止消磁,可把控制录像用的爪弄断 录了像的磁带能够原封不动地保存。如果不需要它的时候,可以把它倒回去重新录像,这时,以前的影像和声音完全消掉,换上了新的内容。这就是说,一条磁带能够使用无数次。     

色彩的魅力(2)

传统彩色摄影为何用减色法? 大家知道,白光可分解成红、绿、蓝三色光,而红、绿、蓝三色光又可混合叠加成白光。我们称红、绿、蓝三色光为加色法三原色。 与色光不同,我们的照片和反转片,却是由黄、品、青三种染料来表达千变万化的色彩,我们称黄、品、青三色为减色法三原色。     

工业膜分离法(2)

(续第 5期 )3　毫微滤孔径介于反渗透膜和超滤膜 (平均 2ｎｍ )的膜称为毫微滤膜。与水分离的溶质的粒径和操作压力的范围也介于反渗透和超滤之间。毫微滤有时亦称为“松散反渗透” ,特别适用于因粒径排拒作用截留无电荷的分子或因静电相互作用截留荷电成分的用途。毫微滤膜极适用于截留分子量 >2 0 0的有机物(例如乳糖、蔗糖和葡萄糖 )和多价离子。这类膜比反渗膜通量更高 ,操作压力低得多。例如前者在70 ｐｓｉｇ压力下的通量为 2 5ｇａｌ/ｆｔ2 ｄａｙ ,后者在2 2 5ｐｓｉｇ压力下通量亦为 2 5ｇａｌ/ｆｔ2 ｄａｙ。3 1　毫微滤膜目前…     

硫化氢(H_2S)

样本)品洲化学纯级典垫分析,二氧化碳二硫化碳二氧化硫’甲硫醇氧硫化碳甲烷平衡气规格(查阅现行产 纯度”二,重量%(液相)COZCS:50:CH:SHCOSCH40 .13%0。09%0。05%0。02%0。01%量气痕空物理性质分子量34.08蒸汽压(20OC)17.38巴(表压)比容(20OC,l大气压)701毫升/克沸点(i大气压)一6o.33oC气态密度(ooC,1大气压)1。539克/升液态密度(沸点)。.993克/毫升临界温度ioo.4oC在空气中的燃烧界限4.3~45%(体积)气态比重(空气=1)’1.189无色,含量超过Ivpm时,有令人不快的臭鸡蛋味。安全 替告:有毒、腐蚀、可燃。 危害性 有毒,空气中允许最大浓…     

Ti(acac)2Cl2/AlEt2Cl(或AlEt2Cl-ZnCl2)催化剂催化丙烯腈聚合反应

研究了Ti(acac)2Cl2／AlEt2Cl催化丙烯腈聚合反应,分析了加入第三组分ZnCl2对聚合反应的影响,用^13C—NMR对聚合产物进行了表征,并探讨了聚合反应机理。结果表明,随着聚合温度的提高和聚合反应时间的增加,单体转化率增大,聚丙烯腈的分子量提高。当体系中n(AN)／n(Cat)超过一定量时,则得不到高聚物。体系中加入ZnCl2能明显提高单体转化率和产物分子量,并且产物的三单元规整结构含量明显增加。     

并流共沉淀法合成Dy_(2)O_(3)-ZrO_(2)纳米粉体EI北大核心CSCD

采用并流化学共沉淀法合成了Dy_(2)O_(3)掺杂ZrO_(2)(DySZ)纳米粉体材料,系统研究稳定剂掺杂量、阳离子浓度、反应系统pH值和煅烧温度对粉体材料物相组成、晶体结构和微观形貌的影响。结果表明:不同合成工艺条件下,DySZ粉体材料均具有纳米尺度特征,球形颗粒尺寸为10~30 nm,Dy_(2)O_(3)的掺杂可以起到稳定晶型的作用;稳定剂掺杂量对DySZ粉体的物相组成具有明显影响,掺杂量为10%(质量分数)时可合成单一四方相结构的DySZ粉体;DySZ粉体材料的四方度和微观形貌对稳定剂掺杂量、阳离子浓度、反应体系pH值和煅烧温度均不敏感,但其平均晶粒尺寸随稳定剂掺杂量、阳离子浓度和反应体系pH值的升高略有降低,随煅烧温度的提高而显著增加。     

Electromechanical properties of Pb(In(1∕2)Nb(1∕2))O(3)-Pb(Mg(1∕3)Nb(2∕3))O(3)-PbTiO(3) single crystals

The Pb(In(1∕2)Nb(1∕2))O(3)-Pb(Mg(1∕3)Nb(2∕3))O(3)-PbTiO(3) (PIN-PMN-PT) crystals were studied as function of phase and orientation. The properties, including the Curie temperature T(C), ferroelectric-ferroelectric phase transition temperature T(R∕O-T), coercive field, and piezoelectric∕dielectric responses, were systematically investigated with respect to the composition of PIN-PMN-PT crystals. The Curie temperature T(C) was found to increase from 160 to 220 °C with ferroelectric-ferroelectric phase transition temperature T(R-T) and T(O-T) being in the range of 120-105 °C and105-50 °C, respectively. The piezoelectric activity of PIN-PMN-PT crystals was analyzed by Rayleigh approach. The ultrahigh piezoelectric response for domain engineered [001] (1600-2200 pC∕N) and [011] (830-1550 pC∕N) crystals was believed to be mainly from the intrinsic contribution, whereas the enhanced level of piezoelectric and dielectric losses at the compositions around morphotropic phase boundaries (MPBs) was attributed to the phase boundaries motion.