Organic–Inorganic Hybrid Gold Halide Perovskites: Structural Diversity through Cation Size

Crystal structures of a series of organic–inorganic hybrid gold iodide perovskites, formulated as A₂[Au^II₂][Au^IIII₄] [A=methylammonium (MA) ( 1 ) and formamidinium (FA) ( 2 )], A′₂[I₃]_1−x[Au^II₂]_x[Au^IIII₄] [A′=imidazolium (IMD) ( 3 ), guanidinium (GUA) ( 4 ), dimethylammonium (DMA) ( 5 ), pyridinium (PY) ( 6 ), and piperizinium (PIP) ( 7 )], systematically changed depending on the cation size. In addition, triiodide (I₃⁻) ions were partly incorporated into the AuI₂⁻ sites of 3 – 7 , whereas they were not incorporated into those of 1 and 2 . Such a difference comes from the size of the organic cation. Optical absorption spectra showed characteristic intervalence charge-transfer bands from Au^I to Au^III species, and the optical band gap increased as the size of the cation became larger.     

Dicyclopentadienyl complexes of titanium,niobium, and tungsten in the controlled synthesis of poly(methyl methacrylate)

Organometallic compounds Cp₂TiCl₂, (EtC₅H₄)₂NbCl₂, and (PrⁱC₅H₄)₂WCl₂ were assessed as additives that control polymer chain growth in the polymerization of methyl methacrylate. In the presence of compounds mentioned in amounts comparable with that of the initiator, a uniform process with no gel-effect occured and respective linear increase in the molecular weight of the polymer up to high degrees of the monomer conversion was observed.     

Mossbauer investigations of corrosion environment influence on Fe valence states in oxide films of zirconium alloys

Mössbauer investigations about iron atom redistribution in oxide films of zirconium alloys subjected to corrosion at 500°C in pure oxygen and water pair have been analysed. The alloys were also subjected to autoclave conditions at a pressure of 10.0 MPa and autoclave conditions at 350°C and at a pressure of 16.8 MPa, using distilled water and water with additives of lithium and fluorine. It is shown that, depending on the corrosion environment, various compounds of iron, such as α-Fe₂O₃, Fe₃O₄, and FeO, as solid solutions of iron in ZrO₂ are formed in oxide films.     

单粒子势模型下价核子的密度分布

依据实验事实，利用单粒子势模型，计算了一些核态外层价核子的密度分布.计算给出了价核子在核外部分布的概率和贡献，以此作为晕核态的判断标准.通过研究均方根半径随结合能变化的规律，指出了晕核态存在的条件，尤其是质子晕核态存在的条件.这些对判断和寻找晕核态有现实的指导意义. 关键词： 单粒子势模型 价核子 密度分布 中子晕核态 质子晕核态     

Stabilization of valence fluctuations in the cerium solid by the time-dependent collision approach

The collision-generated hybridization which has been found responsible for the on-site mixing of the atomic-likef-state and the band-liked states in mixed valence solids has been studied for the cerium solid. A practical expression which depends on the lattice constant and temperature has been obtained for the collision-generated hybridization. Numerical calculations show that the valence varies continuously with lattice constant and that temperature makes the transition smoother. The collision-generated hybridization is found to be of significant strength in the intermediate valence regime; but over a wide range of the valence near 3.5 it varies rather slowly without preferring a particular valence. Factors which can assist the collision-generated hybridization in stabilizing the mixed valence phase at a particular lattice constant are discussed.     

An observation of electron phase transition in SmB6 at low temperatures

In order to reveal the nature of the ground state of archetypal intermediate-valence compound SmB₆, a comprehensive study of its transport and magnetic properties was carried out on high-quality single crystals at temperatures of 1.8-300 K in magnetic fields up to 7 T. A drastic enhancement of negative magnetoresistance was observed below 14 K, with the maximum absolute value of Δρ/ρB²∼2.2×10⁻³ T⁻² at T≈5.2 K. This effect seems to be attributable to anomalous magnetic scattering of many-body (exciton-polaronic) complexes induced by fast valence fluctuations on Sm sites. The observed anomalies of magnetotransport, thermoelectric and magnetic characteristics are discussed in terms of electron phase transition to the coherent state of interacting many-body complexes occurring at T^*∼5 K.     

Multinuclear magnetic resonance study of some mesoionic oxatriazoles containing nitrogenous exocyclic groups

¹H,¹³C,¹⁴N and¹⁵N NMR measurements are reported for four mesoionic 1-oxa-2, 3, 4-triazoles containing exocyclic nitrogenous groups. The NMR signal assignments are discussed and compared with those previously published for some corresponding oxatriazoles. The results obtained support the proposed cyclic mesoionic structures for the compounds studied. The questions of possible charge delocalization and valence tautomerism are addressed. Compound with N^– H as a exocyclic group (Fig. 1) is found to be relatively unstable, this is attributed to proton migration in the corresponding non-cyclic form of this molecule.Published in Khimiya Geterotsikiicheskikh Soedinenii, No. 9, pp. 1260–1263, September, 1995.     

氟化镁锶中铕和铽的电荷迁移及其平衡解析

在氩气氛中，合成了SrMgF4：xEu，yTb复合组化物磷光体．该体系中Eu3 和Eu2 共存．随共掺入Tb浓度的增加，Eu3 的荧光发射强度降低，Eu2 的发光增强；并且Eu2 的ESR信号增强．认为Eu3 和Tb3 之间存在电荷迁移．即Eu3 ＋Tb3 →Eu2 ＋Tb4 .通过半定量手段研究了这一电荷迁移反应的平衡常数     

混合价聚十五钒酸盐[V_(15)O_(36)Cl](NH_4)_3Na_7·30H_2O的合成与晶体结构

以XRD法确定制得的标题晶体属空间群D_(3A)~3,a=13.111,c=11.130。结构由帕特逊-极小函数法结合差值法解出,经精修得一致性因子R_w=0.0344。晶胞中坐落在6m2特殊位置上的是包合1个Cl~-的聚十五钒酸根[V_(15)O_(36)Cl]~(10-),配合键价法确认这是四价钒占主导地位的一类特种混合价同多酸根。