Big Single Crystals Research Articles

Large Titanium-Oxo Clusters as Precursors to Synthesize the Single Crystals of Ti-MOFs

Titanium(IV)-based metal-organic frameworks (Ti-MOFs) have received significant attention in recent years because of their numerous photocatalytic applications; however, the synthesis of new Ti-MOFs with precise crystal structures is still challenging. Herein, three new Ti-MOFs with single-crystal structures (denoted as FIR-125–FIR-127) are rationally synthesized by employing a large Ti44-oxo cluster as the precursor to assembly with the organic ligand. Big single-crystals can be successfully obtained and structurally determined by single-crystal X-ray diffraction. During the synthesis, the large Ti44-oxo cluster is transferred to small Ti8O8(CO2)16 building units in the Ti-MOF. In addition, FIR-125 exhibit high stability, permanent porosity, and photocatalytic activity. This work provides a new strategy toward the big crystal growth of Ti-MOFs through the slow transformation of large titanium-oxo clusters.

A pure organic nanocomposite of DIPAB/EP with strong ferroelectricity

Organic materials are light, flexible, easy to process and compatible with organic substrate. Unfortunately, there are no strong ferroelectric organics to apply in practice until now. Diisopropylammonium halide is a kind of organic salts with strong ferroelectricity. However, it is difficult to apply to the electrical devices because the big single crystal of them is rather difficult to prepare and is low mechanic strength, meanwhile it easily absorbs moisture to deteriorate the dielectricities due to its high solubility in both water and ethanol. In this study, a new organic composite, diisopropylammonium bromide (DIPAB)/epoxy resin (EP), where DIPAB is filled in bisphenol-A EP matrix, is prepared to smooth away the shortcoming of DIPAB. At the same time, a new approach to nanoparticles for very soluble salts is developed by re-crystalization of them from viscous liquid. Re-crystallization of DIPAB from EP solution results in a kind of nanocomposite as hybrid material and keeps the strong ferroelectricty.

New progress on FeSe-based superconductors: high-quality and high-critical-parameter (Li, Fe)OHFeSe thin film

High-quality superconducting thin films play an important role in the application and basic research of high-Tc superconductivity. In these aspects, iron-based superconductors feature the merits of rich physical phenomena and high superconducting critical parameters (including the transition temperature Tc, the upper critical field Hc2 and the critical current density Jc). The recently discovered high-Tc (Li,Fe)OHFeSe superconductor proves to be an important material for the studies of the mechanism and application of unconventional high-Tc superconductivity. However, due to the hydroxyl ion inherent in the compound, none of the conventional high-temperature synthesis methods is applicable for (Li,Fe)OHFeSe materials in bulk and thin film forms. Recently, by developing a hydrothermal ion-exchange technique, we have synthesized for the first time big and high-quality single crystals of (Li,Fe)OHFeSe (2015 Phys. Rev. B 92 064515). Here in this paper, we brief our most recent progress on growing a high-quality single-crystalline superconducting film of (Li,Fe)OHFeSe (2017 Chin. Phys. Lett. 34 077404). The film has been prepared on a LaAlO3 substrate by a hydrothermal epitaxial method. The high crystalline quality of the film is verified by X-ray diffraction (XRD). The XRD measurements show a single (001) orientation with a small crystal mosaic of 0.22 in terms of the full width at half maximum of the rocking curve, as well as an excellent in-plane orientation revealed by the -scan of (101) plane. Its bulk superconducting transition temperature Tc of 42.4 K is determined by both zero electrical resistance and diamagnetism measurements. Based on systematic magnetoresistance measurements, the upper critical field Hc2 is estimated to be 79.5 T and 443 T for the magnetic field perpendicular and parallel to the ab plane, respectively. Moreover, a large critical current density Jc of a value over 0.5 MA/cm2 is achieved at ~20 K. Such a (Li,Fe)OHFeSe film therefore is not only important for the fundamental research for understanding the high-Tc mechanism, but also promising for the applications in high-performance electronic devices and large scientific facilities such as superconducting accelerator.

Large-scale grain growth in the solid-state process: From “Abnormal” to “Normal”

Abnormal grain growth (AGG) has been a common phenomenon during the ceramic or metallurgy processing since prehistoric times. However, usually it had been very difficult to grow big single crystal (centimeter scale over) by using the AGG method due to its so-called occasionality. Based on the AGG, a solid-state crystal growth (SSCG) method was developed. The greatest advantages of the SSCG technology are the simplicity and cost-effectiveness of the technique. But the traditional SSCG technology is still uncontrollable. This article first summarizes the history and current status of AGG, and then reports recent technical developments from AGG to SSCG, and further introduces a new seed-free, solid-state crystal growth (SFSSCG) technology. This SFSSCG method allows us to repeatedly and controllably fabricate large-scale single crystals with appreciable high quality and relatively stable chemical composition at a relatively low temperature, at least in (K0.5Na0.5)NbO3(KNN) and Cu-Al-Mn systems. In this sense, the exaggerated grain growth is no longer 'Abnormal' but 'Normal' since it is able to be artificially controllable and repeated now. This article also provides a crystal growth model to qualitatively explain the mechanism of SFSSCG for KNN system. Compared with the traditional melt and high temperature solution growth methods, the SFSSCG method has the advantages of low energy consumption, low investment, simple technique, composition homogeneity overcoming the issues with incongruent melting and high volatility. This SFSSCG could be helpful for improving the mechanical and physical properties of single crystals, which should be promising for industrial applications.

Synthesis of zeolite NaX at 25 °C and 95 °C: Characterization, cobalt exchange and catalytic performance in epoxidation of styrene

Zeolites NaX were synthesized with the crystallization temperatures of 25°C and 95°C and converted into cobalt-exchanged catalysts (Co2+–NaX) by an ion-exchange method. The results indicated that zeolites synthesized at 25°C were composed of many closely packed nanocrystals with the average size of around 30nm, while the samples obtained at 95°C were big single crystals. Zeolite NaX before and after the cobalt exchange kept pure faujasite structure, however, the introduction of cobalt ions into zeolite would lead to a decrease in the intensity of all crystallographic reflexes. Moreover, Co2+–NaX (25°C zeolite sample) exhibited higher catalytic performances in epoxidation of styrene as compared with that of Co2+–NaX (95°C zeolite sample) catalysts, which may be attributed to their short diffusion path and enhanced physical transport of reactants and products.

Silicon Float Zone Single Crystal Automatic Growth

As basis of the big diameter crystal development, the single crystal automatic growth is the most important technique for system standardization and mass production. In this article, author introduced a new useful way for the single crystal automatic growth of float zone. By setting the growth interval and controlling parameter, PLC controller could automatically control the single crystal growth when the single crystal’s diameter is greater than 50mm. This method applied to the machine system can greatly reduce the fault of manual operation as well as labor intensity. Also it improved the single crystal quality which increases the ability to develop big diameter single crystal in the future.

Synthesis and properties of mullite-type (Bi 1− xSr x) 2(M 11− yM 2y) 4O 9− x (M = Al, Ga, Fe)

Mullite-type A 2M 4O 9 phases (M = Al, Ga, Fe), representing promising oxygen conducting materials for solid oxide fuel cells (SOFCs), were synthesized using the glycerine- and the EDTA/citric acid synthesis method. For strontium-doped material pure phases could be obtained only by washing the samples after the heating in both synthesis methods. Temperature dependent investigations were carried out to show the influence of the metal atoms on the structural stability and thermal expansion coefficients. Whereas the Sr-free phases show a quasi linear thermal expansion behavior in all three directions up to their incongruent melting points, a discontinuity in the measured range is observed for the investigated strontium doped dibismuth-nonaoxotetrametallate(III) caused by the decomposition into Bi 2M 4O 9, strontium metallates and bismuthoxide. Big single crystals were only observed for the Sr-free compound, of which the structure of Bi 2(Ga 0.45Fe 0.55) 4O 9 will be presented here in the Bärnighausen tree corresponding mullite-type setting.

Single crystal growth and characterizations of iron arsenide superconductor BaFe2−xNixAs2 (0.0 ≤ x ≤ 0.12)

A series of big single crystals of BaFe2−xNixAs2 have been prepared by the FeAs self-flux method, with nominal nickel doping x = 0–0.12. The dimensions of the cleaved crystals are over 10 mm along ab plane and ∼2 mm in maximum along the c direction. The measurements of x-ray diffraction, electrical resistance and magnetic property are carried out on the crystals. For the undoped parent compound BaFe2As2, both resistance and magnetization data display an anomaly associated with spin density wave and/or structural phase transition, with the transition temperatures at ∼138 K. For Ni-doped BaFe2−xNixAs2 crystals, the superconducting critical temperature Tc ranges from 4.3 K for x = 0.06 sample to 20 K for the optimally doped x = 0.10 crystal.

Study on the Reaction of Polymeric Zinc Ferrocenyl Carboxylate with Pb(II) or Cd(II)

In this paper, the reaction of polymeric zinc ferrocenyl carboxylate, {[Zn(OOCClH3C6Fc)2(H2O)3](CH3OH)}n (1; FcC6H3ClCOONa = sodium 2-chloro-4-ferrocenylbenzoic), with Pb(NO3)2 or Cd(NO3)2 was investigated. By immersion of selected big single crystals of 1 into aqueous solutions of Pb(NO3)2 and Cd(NO3)2, respectively, two central metal ion exchange induced single-crystal to single-crystal (SCTSC) transformation products, {[Zn0.74Pb0.26(OOCClH3C6Fc)2(H2O)3](H2O)}n (2) and {[Zn0.82Cd0.18(OOCClH3C6Fc)2(H2O)3](H2O)}n (3), could be obtained. In contrast to above-mentioned SCTSC products, 1 can dissolve well in THF solution, and the reaction of the solution containing 1 with Pb(NO3)2 or Cd(NO3)2 results in a 1-D Pb(II) polymer, [Pb(μ2-η2-OOCClH3C6Fc)2(CH3OH)2]n (4), and a mononuclear Cd(II) complex, {[Cd(η2-OOCClH3C6Fc)2(H2O)3](CH3OH)2} (5). Our results indicate that metal ion exchange can be implemented through heterogeneous or homogeneous pathways and suggest an easy means to remove lead and cadmium ions. At ...

Polymeric Zinc Ferrocenyl Sulfonate as a Molecular Aspirator for the Removal of Toxic Metal Ions

A porous bilayered open coordination polymer [Zn(4,4'-bpy)(2)(FcphSO(3))(2)](n) (1; FcphSO(3)Na=m-ferrocenyl benzenesulfonate), has been assembled from Zn(NO(3))(2), m-ferrocenyl benzenesulfonate, and the bridging ligand 4,4'-bipyridine (4,4'-bpy). Ion-exchange induced products [Cd(0.6)Zn(0.4)(4,4'-bpy)(2)(FcphSO(3))(2)](n) (2), [Zn(0.75)Pb(0.25)(4,4'-bpy)(2)(FcphSO(3))(2)](n) (3), and [Cu(0.5)Zn(0.5)(4,4'-bpy)(2)(FcphSO(3))(2)](n) (4) could be obtained directly by suspending a big single crystal of 1 into concentrated solutions of Cd(NO(3))(2), Pb(NO(3))(2), and Cu(NO(3))(2), respectively. Most importantly, the big single crystal of 1 could be partly regenerated after immersion into concentrated aqueous solutions of Zn(NO(3))(2). On the other hand, powdered 1 could also be used as a metal ion adsorbent because of the well-defined pore size and pore shape. Ion exchange takes place along with the process of ion sorption. The big single crystal of 1 removes harmful metal ions by means of ion exchange, whereas powdered 1 removes toxic metal ions mainly through ion sorption. Also, compound 1 could be employed as a multi-ion analysis fluorescent probe to detect dangerous metal ions, such as Pb(2+), Cd(2+), Ag(+), and Cu(2+). The compounds described in this study may have potential applications in the design of new molecular devices.

Crystal structure and vibrational spectra of piperazinium bis(4-hydroxybenzenesulphonate) molecular–ionic crystal

The piperazinium bis(4-hydroxybenzenesulphonate) crystallizes from water solution at room temperature in P2 1/ c space group of monoclinic system. The crystals are built up of doubly protonated piperazinium cations and ionized 4-hydroxybenzenesulphonate anions that interact through weak hydrogen bonds of O–H⋯O and N–H⋯O type. Mutual orientation of anions is determined by non-conventional hydrogen bonds of C–H⋯π type. Room temperature powder FT IR and FT Raman measurements were carried out. The vibrational spectra are in full agreement with the structure obtained from X-ray crystallography. The big single crystals of the title salt can be grown.

Growth of big single crystals of Sr2YRu1-xCuxO6 from high temperature solutions

Single crystals of Sr2YRu1-xCuxO6 (x = 0 - 0.4) have been grown from PbO-PbF2 based solutions in the temperature range 1150 – 1350°C. A silicon carbide heating element furnace (with a recrystallized alumina tube lining) in a vertical configuration was used to grow the crystals in platinum crucibles. Conditions for the stable growth of big crystals have been investigated. The morphology of the crystals containing Cu was found to change from octahedral to cube octahedral as the growth temperature is increased from 1150 to 1350°C. Crystals measuring up to 4.5 mm across and 2.5 mm thick have been grown from 1250°C. The incorporation of Cu into the crystals was ascertained by EDS and x-ray diffraction analysis. A diamagnetic transition which increased in magnitude and temperature with x was observed. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Eine neue Verbindung im System Ba/Ln/Zn/Pt/O: Ba4Sm4Zn3PtO15/On a New Com pound in the System Ba/Ln/Zn/Pt/O : Ba4Sm4Zn3PtO15

Abstract Reactions of mixtures of BaCO3, ZnO, Sm2O3 (3:5:1) heated in platinum crucibles up to 1250 °C led to big black single crystals of Ba4Sm4Zn3PtO15. The new compound crystallizes with hexagonal symmetry, space group C6v 4mc, a = 11.657, c = 6,789 Å , Z = 2. It is isotypic with Ba6Nd2Al4O15 but shows an ordered Pt4+ and Zn2+ distribution over the aluminium positions. The octahedrally coordinated barium sites of the Ba6Nd2Al4O15 type are occupied by Sm3+. In comparison to compounds of the composition Ba6Ln2M4O15 (M = Al, Fe, Co), Ba4Sm4Zn3PtO15 is the first example containing different oxidation states at the M3+ positions.

Magnetic and Magneto-Optical Properties of Bi3Fe5O12 Thin Films Deposited on Garnet-Layered Glass.

Structural, magnetic and magneto-optical properties of polycrystalline bismuth iron garnet Bi3Fe5O12 (p-BIG) films were prepared on Bi1.7Y1.2Fe5.1O12 coated glass. The p-BIG layers were formed on vitreous SiO2 and Coming 0317 glass substrates by rf-sputtering in the wide range of substrate temperature from 475°C to 700°C. BIG single crystal (s-BIG) films were also prepared on gadolinium gallium garnet (GGG) single crystals in the temperature range from 500°C to 600°C. It is found that p-BIG layers could be obtained by sputtering with Ar gas alone as well as mixed gases of Ar and O2, and that they show higher figures of merit than s-BIG layers because of small absorption of light for the wavelength of around 540nm. The effect of glass substrates on the crystallinity, magnetic and magneto-optical properties of the p-BIG films were also investigated.

Electronic and magnetic properties of heavy rare-earth hexaboride single crystals

Big single crystals of heavy rare-earth (Tb, Dy and Ho) hexaborides have been grown by the crucible-free vertical floating zone method. Temperature and magnetic field dependence of the electrical resistivity, the specific heat and the magnetic susceptibility have been reported and discussed. The experimental results indicate the complex magnetic behavior of heavy rare-earth hexaborides at low temperatures.

NEUTRON DIFFRACTION STUDY OF MUNGINDI IRON NICKEL METEORITE

The Mungindi Iron Nickel Meteorite was investigated by neutron diffraction. All layers of the γ‐phase (separated from each other by α‐phase bars) form, from the crystallographic point of view, the same, big single crystal. The perfection of this single crystal is very high. In the kamacite phase each individual “single crystal” is broken into a group of crystals.

Correlation of the oxygen and carbon isotope ratios of calcite samples from a hydrothermal ore vein.

The variation of the carbon isotope ratio of calcite samples collected from the micro crystalline main body of a hydrothermal ore vein has been found to follow a trend opposite to that shown by the oxygen isotope ratio of the same samples. This anomalous behaviour is explained by the presumable mechanism of the formation of the vein. The “oxygen-carbon isotopic behaviour” has been found normal in the case of big single crystals of calcite from the same vein.

The crystal growth kinetics of ammonium dideuterium arsenate ND 4D 2AsO 4

The growth rate of ND 4D 2AsO 4 single crystals has been measured as a function of temperature and the supersaturation of the solution. A method which allows the growth of big single crystals has been developed. The largest crystals had dimensions of 15×10×70 mm.

Kristallachsenlagen in Hagelkörnern

The big single crystals of a shell of a hailstone are mostly arranged in palisades, directed to a certain point. This preferred orientation of shape of single crystals is identical to the direction of growth of the hailstone at the place of the crystallite refered to. If we look at the statistical deviation of the direction of thec-axis — determined by a Replica method — of the crystallites of a whole shell from the local direction of growth, we find that thec-axis looks mainly in the direction of growth (Figures 7, 10, 12) but the relative height of the maximum of the distribution may vary from one shell to another (Figures 7 and 10). Although in one case no rule of orientation could be found (Figures 14 and 15) and in another thec-axis was perpendicular to the direction of growth (Figure 16). Results of some primary investigations, based upon experiments in the hail tunnel, leed us to the conclusion that the arrangement of the crystallographic axis of the different single crystals depends very much on the growing conditions of the ice deposits. Therefore one may expect, that in the near future an interpretation of the icing conditions of natural hailstones is possible on behalf of their crystallographic structure. Icing experiments in the hail tunnels will give us the rules one has to observe for this procedure.