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We present the current performance of the in situ radiocarbon (14C) extraction line at the University of Bern with an improved extraction and combustion system. After three major steps of improvement, the extraction of sample CO2gas now takes place inside a platinum crucible, supported by an outer quartz-glass crucible. This setup allows us to operate the line as a closed system for several samples without breaking the vacuum. Measurements of procedural blanks and samples from our reference strewn field, Jiddat al Harasis 073, performed in our system all show a good reproducibility and, for the strewn field samples, consistency with published data. We describe each improvement step in detail, discussing the advantages and disadvantages of all tested setups. By sharing our knowledge, we aim to inform and prevent others from making the same or similar detours in establishing14C extraction systems for extraterrestrial samples.

The experimental production of multicomponent crystals with M-type hexaferrite structure, the qualitative and quantitative composition of which reflects the formula AB 12 O 19 , where A is Ba, Pb, Sr, Ca, Zn, and B is Fe, Mn, Ni, Ti, Al, Cu, W is carried out. The resulting material of this composition in the future can provide the ability to smoothly change the frequency of ferromagnetic resonance and throughput. In this way, the properties required by electronic equipment manufacturers can be obtained. In the course of the research, have been studied the possibilities of using different methods for synthesizing experimental samples – solid-phase sintering, melting in a platinum crucible, and melting in a stainless steel crucible. According to SEM and EDX results of the obtained samples, two main types of multicomponent crystalline phases were found: hexagonal crystals having the structure of hexaferrite M-type and octahedral crystals having the structure of spinel AB 2 O 4

We report new aspects of the application of the flux-growth method for the preparation of single crystals of silicates, in particular, mixed-framework (octahedral–tetrahedral) metal-Y silicates, in air. The detailed investigations involve flux-growth syntheses in the system BaO–K2O–Y2O3–SiO2–MoO3, in which various important run parameters have been varied in a systematic way (heating and cooling rates, Tmax and duration of holding step, continuous or stepwise cooling, total duration of run, amount of MoO3 solvent, Y2O3/SiO2 molar ratio, size and filling volume of platinum crucible). The results demonstrate that the crystallization of various silicate structure types are strongly controlled by the Y2O3/SiO2 molar ratios and the amount of MoO3 solvent in the precursor mixtures. A decrease of the Y2O3/SiO2 ratio, i.e., an increasing amount of SiO2, promotes an increasing structural complexity of the silicates; nesosilicates crystallize at comparatively low SiO2 concentrations, sorosilicates at intermediate o...

The new lead strontium germanate PbSrGeO4 was synthesized by a high-temperature solid-state reaction of lead(II) oxide, strontium carbonate, and germanium(IV) oxide at a temperature of 900 °C in a platinum crucible. The compound crystallizes in the orthorhombic space group P212121 (no. 19) being isotypic to the structure of BaNdGaO4 [1]. The primitive cell contains four formula units with lattice parameters of a = 995:40(2), b = 732:44(2), c = 599:42(2) pm, V = 437:02(2)Å3, and residuals of R1 = 0:0385 and wR2 = 0:0997 for all data. The main structural element of PbSrGeO4 is an isolated [GeO4]4- tetrahedron. A circular arrangement of six of these [GeO4]4- tetrahedra leads to the formation of large channels along b in which the strontium cations are eightfold coordinated by oxygen atoms. The lead cations are coordinated by three oxygen atoms, and with a lone pair of electrons they show a pseudo-tetrahedral coordination. Next to the structural investigations, PbSrGeO4 was characterized by Raman-spectroscopic investigations and DFT calculations.

The preparation of platelike NaNbO3 grains via single-step molten salt synthesis using Bi2O3, Na2CO3, Nb2O5, and NaCl as reactants was examined. When a new alumina crucible was used, platelike NaNbO3 grains were obtained, but a repeatedly used alumina crucible resulted in irregularly shaped NaNbO3 grains. When a platinum crucible was used, even NaNbO3 could not be obtained. Addition of alumina substrates and alumina granules to the reaction mixture in the platinum crucible resulted in the formation of platelike NaNbO3 grains and second-phase grains. The second-phase grains, which were composed of Al2O3, Bi2O3, Na2O, and Nb2O5 and had a pyrochlore structure, could be removed by sieving. The second phase acted as a scavenger for Bi2O3 and hence, the possibility of using another scavenger was attempted. The new scavenger was a mixture of Na2CO3 and Nb2O5, and using them, platelike NaNbO3 grains were successfully obtained with NaNb5Bi2O16 as a byproduct, which could then be removed by sieving.

High purity nanoporous silica was fabricated using Shirasu volcanic ash as a starting material. The starting materials were placed into a platinum crucible and were melted at 1400°C. A mother glass was formed by quenching the melt in pure water. Leaching was performed by immersing the mother glass into an HCl solution. Nonsilica phases formed by phase separation in the mother glass were leached out with acid solution. The obtained porous silica was more than 99% pure and had pore size smaller than 2 nm. In order to control the pore size, post heat treatment was performed. The pore size could be controlled from 3.1 to 21.7 nm by changing the post treatment temperature.

By melting a mixture of high-purity oxides in a platinum crucible under flowing purified oxygen, we have prepared (TeO2)0.75(WO3)0.25 glass with a total content of 3d transition metals (Fe, Ni, Co, Cu, Mn, Cr, and V) within 0.4 ppm by weight, a concentration of scattering centers larger than 300 nm in size below 102 cm−3, and an absorption coefficient for OH groups (λ ∼ 3 μm) of 0.008 cm−1. The absorption loss in the glass has been determined to be 115 dB/km at λ = 1.06 μm, 86 dB/km at λ = 1.56 μm, and 100 dB/km at λ = 1.97 μm. From reported specific absorptions of impurities in fluorozirconate glasses and the impurity composition of the glass studied here, the absorption loss at λ ∼ 2 μm has been estimated at ≤100 dB/km. The glass has been drawn into a glass-polymer fiber, and the optical loss spectrum of the fiber has been measured.

The stability of δ-TeO 2 phase was studied in binary TeO 2 –WO 3 , TeO 2 –CdO and ternary TeO 2 –WO 3 –CdO glasses. The samples were prepared by heating high purity powder mixtures of TeO 2 , WO 3 and/or CdO to 800 °C in a platinum crucible with a closed lid, holding for 30 min and quenching in water bath. Differential thermal analysis (DTA), X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques were used to characterize the thermal, phase and microstructural properties of the δ-TeO 2 phase. The addition of CdO into the tellurite glasses increased the stability range of the δ-TeO 2 phase up to higher temperature values and expanded the compositional δ-TeO 2 formation range. The formation of δ-TeO 2 phase in the binary systems was observed for samples containing 5–10 mol% WO 3 and 5–15 mol% CdO. However, for the ternary TeO 2 –WO 3 –CdO system the formation of δ-TeO 2 phase was determined in a wider compositional range.

We present a new method for the decomposition of silicate rocks by flux-free fusion in preparation for whole-rock trace element determination (Sc, Rb, Sr, Y, Zr, Nb, Cs, Ba, rare earth elements and Hf) that is especially applicable to zircon-bearing felsic rocks. The method was verified by analyses of RMs of mafic (JB-1a, JB-2, JGb-1) and felsic rocks (JG-3, JR-3, JSd-1, GSP-2, G-2). Pellets of powdered sample (up to 500 mg) without flux were weighed and placed in a clean platinum crucible. The samples were then fused in a Siliconit® tube furnace and quenched to room temperature. The optimum condition for the fusion of granitic rock was determined to be heating for 2–3 min at 1600 °C. The fused glass in the platinum crucible after heating was decomposed using HF and HClO4 in a Teflon® beaker. Decomposed and diluted sample solutions were analysed using a quadrupole inductively coupled plasma-mass spectrometer. Replicate analyses (n = 4 or 5) of the RMs revealed that analytical uncertainties were generally

A new method has been developed for handling volatile and hygroscopic substances in bomb calorimetry. A platinum crucible, covered with a platinum lid and sealed with vaseline, is used. The lid is opened by a counterweight when the vaseline is ignited. The enthalpy of formation of liquid butanol-1 was measured and compared with literature values.

This article describes a methodology for analyzing zinc in zinc concentrates materials by wavelength-dispersive X-ray fluorescence (WD-XRF) spectrometry with gel for sample preparation. The sample was decomposed with aqua regia. The sample solution mixed with agaron gel was heated to boiling. The mixture became quasi-solid gel under normal temperature. The elements dispersed in gel medium were detected by WD-XRF spectrometry. The method has both advantages of the solution preparation method and the solid preparation method. In addition, this method was adapted in detecting high content ores, because it avoided the risking of using platinum crucible. The method has been applied to the determination of lead, zinc and iron in zinc concentrates successfully.

Two novel alkali(I) borogermanates with noncentrosymmetric structures, namely, CsB 3GeO 7 and K 2B 2Ge 3O 10, have been synthesized by high-temperature solid-state reactions in a platinum crucible. The structure of CsB 3GeO 7 features a novel three-dimensional (3D) framework composed of cyclic B 3O 7 (5-) groups that are interconnected by Ge(IV) cations, whereas the structure of K 2B 2Ge 3O 10 is a new 3D network based on cap-shaped [Ge 3B 2O 14] (10-) clusters that are interconnected via Ge-O-B bridges. CsB 3GeO 7 exhibits a second-harmonic generation (SHG) response that is about 1.5 times that of KDP (KH 2PO 4), whereas the SHG signal of K 2B 2Ge 3O 10 is very weak. Both compounds are insulators and transparent in the range of 300-5000 nm. The electronic structure calculations for both compounds also have been performed.

The presence of an impurity like rhodium in the platinum crucible used for the growth of KTiOPO4 (KTP) single crystals can have severe consequences in the performance of devices made from these crystals. In the present study the effect of rhodium incorporation has been investigated. Rhodium-incorporated KTP crystals have a lower ionic conductivity (1.3 × 10–7 S/cm at 100 kHz) than pure KTP crystals (3.5 × 10–6 S/cm at 100 kHz) along the c-axis. And the optical absorption in the green-wavelength regime leads to a detrimental effect on their SHG performance. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

PbSrGeO4 is prepared by a high-temperature reaction of stoichiometric amounts of PbO, SrCO3, and GeO2 (platinum crucible, 900 °C, 130 h).

The photorefractive crystal, Bi2TeO5, was grown by the modified Bridgman method for the first time. High purity Bi2O3 and TeO2 were used as starting materials and were mixed thoroughly with molar ratio of Bi2O3/TeO2 = 1 ∶ 1. Platinum crucible was fabricated with a seed well of 10 mm in diameter and several folds were pressed so that the spontaneous nuclei could be eliminated through competition. The crucible was sealed during the growth so that the evaporation of TeO2 was controlled effectively. By optimizing growth parameters, transparent and crack-free Bi2TeO5 crystal up to 25 mm in diameter and 40 mm in length was grown successfully.

In attempt to synthesize β-Al2O3 platelets using a novel method, powder mixtures consisting of γ-Al2O3 and NaF were heated in a platinum crucible. The effect of the mixing ratio of the raw materials, heating temperature and duration of heating at the selected temperature on the formation of the β-Al2O3 platelets was investigated. When powder mixtures consisting of γ-Al2O3:NaF=1:X (X=1-4; molar ratio) were heated at 900°C for 3h, β-Al2O3 hexagonal platelets formed. The size of the platelets were 3-8μm in diameter and 10-20 in aspect ratio, independent of the amount of NaF in the starting powders. When a powder mixture consisting of γ-Al2O3:NaF=1:2 was heated at 700 to 1100°C for 3h, β-Al2O3 platelets systematically formed. The size and morphology of the platelets were the same as above, independent of heating temperature. In addition, when the powder mixture consisting of γ-Al2O3:NaF=1:2 was heated at 800°C for 0h, β-Al2O3 platelets with the same size and morphology formed.

Platinum dendrites were found in lithium tetraborate crystals grown by the Czochralski method using a platinum crucible. The mode of occurrence and formation mechanism of platinum dendrite in lithium tetraborate were examined. It is revealed that platinum dendrites developed in the cellular structure that occurred during growth. The formation of platinum dendrite that is discussed is associated with the growth condition leading to cellular growth. The morphology of platinum dendrite is also explained by its specific crystallographic symmetry.

Crystals of cadmium zinc diborate, Cd1.17Zn0.83B2O5, have been obtained by spontaneous nucleation in a platinum crucible at 1072 K. The crystal structure exhibits diborate groups, B2O54−, sharing O atoms with considerably distorted M1O6 octa­hedra and M2O4 tetra­hedra. Both metal centers are disordered in the proportion Cd:Zn = 0.92:0.08 on the M1 site and Cd:Zn = 0.25:0.75 on the M2 site. A strong second-harmonic generation has been observed for the title compound when excited with an Nd:YAG laser (λ = 1064 nm).

Two novel alkali(I) borogermanates with noncentrosymmetric structures, namely, CsB3GeO7 and K2B2Ge3O10, have been synthesized by high-temperature solid-state reactions in a platinum crucible. The structure of CsB3GeO7 features a novel three-dimensional (3D) framework composed of cyclic B3O75− groups that are interconnected by Ge(IV) cations, whereas the structure of K2B2Ge3O10 is a new 3D network based on cap-shaped [Ge3B2O14]10− clusters that are interconnected via Ge−O−B bridges. CsB3GeO7 exhibits a second-harmonic generation (SHG) response that is about 1.5 times that of KDP (KH2PO4), whereas the SHG signal of K2B2Ge3O10 is very weak. Both compounds are insulators and transparent in the range of 300−5000 nm. The electronic structure calculations for both compounds also have been performed.

Large size and high quality single crystals GdCa4O(BO3)3 have been grown from platinum crucible under air atmosphere by the conventional rf-heating Czochralski method. The crystal growth conditions, growth habits, and transmission spectra were investigated. The crystal is transparent in the visible and near-infrared region (320-2600 nm). It has a good second harmonic generation phase-matching condition. The phase-matching experiment result is well consistent with the theoretical one. The frequency-doubling efficiency is 26.7% in the phase-matching angles θ = 45° and = 45.1° direction.

Single crystals of triclinic Pr(2)(B(2)O(5))(MoO(4)) were prepared from an incongruently melting flux in the system Pr(2)O(3)-MoO(3)-B(2)O(3) in a platinum crucible in an atmosphere of air. In the crystal structure, distorted edge-sharing [PrO(8)] square anti-prisms form a three-dimensional framework. These are further linked by isolated [MoO(4)] tetra-hedra and isolated pyroborate groups [B(2)O(5)], the latter consisting of two independent trigonal [BO(3)] groups sharing one O atom. The [MoO(4)] tetra-hedra and the [B(2)O(5)] groups are arranged in alternating layers parallel to the ab plane.

Glasses with the mol% composition 52.6 SiO2·18.7 Al2O3·14.3 MgO·7.7 TiO2·4.7 B2O3·2.0 CaO were crystallized using electrochemically induced nucleation. During this process, a voltage is applied between a platinum wire and a platinum crucible containing the melt heated to 1330 °C. At the platinum wire, which acts as the cathode, Ti4+ is reduced to Ti3+, leading to a local nucleation of mullite crystals which grow in the glass melt. The square needles of 1–50 μm diameter exhibit complex growth structures including very fine tips surrounded by halos and various stages of needle fragmentation. They are surrounded by an Al/Si-diffusion barrier of up to 7 μm thickness and a dark frame where SiO2 is enriched. It is proposed that the stepwise diameter increase of the needles is mainly initiated by dendritic growth localized to tips formed at the edges of the square needles. The presented results provide visual examples on how crystals manipulate their environment during growth which in turn affects the growth of the crystals.

Piezoelectric Pb[(Zn1/3Nb2/3)0.91Ti0.09]O3 (PZNT 91/9) single crystals with diameters of 40 mm were successfully grown from solution by the Bridgman method with a PbO flux supported on the bottom of the crucible. This type of Bridgman method is more suitable for growing large and heavy crystals than the hanging-type Bridgman method. Using a modified supporting method, a PZNT 91/9 single crystal was grown. The crystals were grown in a platinum crucible heated to 1,130°C, and the growth rate was 0.20–0.50 mm/h. The obtained crystals were about 40 mm in diameter×20 mm in length (200 g) and were light brown in color. The Curie temperature, T c, ranged from 170 to 175°C. These results confirm that the Bridgman method using a supported crucible is useful for the mass production of large crystals of PZNT 91/9.

Modification of ASTM C 621 is needed in order to determine the corrosion of the material MoSi 2 by molten glass since this material reacts with the prescribed platinum crucible. The latter was replaced with a fusion-cast alumina-zirconia-silica refractory crucible. A correction for the width of the saw kerf is suggested. The modified method was carried out on a number of cylindrical samples in molten E-glass at 1550°C. The specimen-glass interfacial regions were characterized using SEM, EDS, and XRD

A new modification of the top-seeded growth from high temperature solutions (HTS), allowing simultaneous application of the accelerated crucible rotation technique (ACRT), was developed. The platinum crucible containing the flux was equipped with the platinum reflectors bearing the holder of the seed. A particular interest was devoted to the optimization of the temperature distribution in the flux and to the ACRT program. The apparatus was tested by the growing of YIG: Mn single crystals on the seeds orientated in [111], [110] and [211] directions.

A simple method for the determination of total fluorine in blood plasma and serum (0.5–1 ml) is described. The method involves fixation of fluorine with low-fluoride magnesium acetate, ashing in a platinum crucible at 270°C and 650°C, and direct determination of fluoride in the dissolved ash with a fluoride-selective electrode. The blank value is 0.05 μg of fluoride. The relative accuracy of the method is about 15% for total fluorine contents in the range 0–0.5 μg.

Glycerol-treated montmorillonite gradually loses one layer of the two-layer glycerol complex upon heating to 150–200°C, forming a monolayer complex with a sharp X-ray reflection at about 14 A. This complex is quite stable on further heating to about 230–250°C. Above 250°C the monolayer complex breaks down rapidly. A gravimetric method has been used to determine the weight of the glycerol monolayer. The procedure involves addition of a 10% glycerol solution to a dried and weighed sample of clay in a platinum crucible followed by a heating and weighing procedure in a thermoanalyzer (Mettler). The method was used to calculate the internal and external surface area of different clays.

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Studies of crystal growth of fluorinated perovskites AMe II F 3 and pyrochlores AMe II Me III F 6 (A = K, Rb, Cs; Me II = Fe, Co, Ni, Zn; Me III = Al, V, Cr, Fe) are reported. In order to avoid high temperature hydrolysis of these compounds thus giving MeO or Me 2 O 3 , two techniques of growth have been selected: 1) flux growth from a mixture containing melted chlorides and 2) the Bridgman-Stockbarger method in sealed platinum crucible. Phase diagrams are used in order to obtain maximum yield of crystals and avoid side crystallization.

Es wird die Zuchtung von CaWO4-Einkristallen aus einer LiCl-Schmelze im Pt-Tiegel beschrieben. Die Bildung von Reaktionsprodukten (Li2WO4) und deren Verdampfung kann durch Zugabe von CaCl2 zuruckgedrangt werden, so das eine Ausbeute von 89% erzielt wird. Die Veranderung der Schmelzzusammensetzung in Gegenwart von H2O und CO2 sowie durch partielle Verdampfung wird angegeben. — Em Vergleich zeigt, das die bei tieferen Temperaturen gewonnenen Kristalle (erregende Absorption bei 255 nm) ein einfacheres Fluoreszenzspektrum (Maximum bei 442 nm) gegenuber den Hochtemperaturkristallen (Maxima bei 302, 313, 370, 408, 439 und 479 nm) haben. The growth of CaWO4-monocrystals from melts of LiCl in a platinum crucible is described. The formation of reaction products (Li2WO4) and their evaporation may be reduced by adding CaC12. An output of 89% CaWO4-crystals could be achieved. The change of the composition of the melt in presence of H2O and CO2 as well as by partial evaporation is reported. — Composing high temperature crystals with those from lower temperature shows a more simple fluorescence spectrum for the latter (maximum at 442 nm) and a more complicated spectrum for the former (maxima at 302, 313, 370, 408, 439 and 479 nm) with the excitation band at 255 nm.

Glasses corresponding to mole formulas R2TiO3 and R2Ti2O5 were prepared in 1- to 5-g quantities by quenching in a platinum crucible. K2O, Rb2O, and Cs2O formed fairly stable glasses with TiO2. On heat treatment, these glasses nucleated readily and formed opal-like glasses. Li2O and Na2O, however, did not form glasses with TiO2 in 1-g quantities. Hygroscopicity increased with the alkali content and decreased with the increase in TiO2 concentration. The refractive indices of the glasses ranged from 1.66 to 1.90. These facts indicate that TiO2 is a glass former in its own right and that Ti4+ exists in sixfold coordination in these glasses.

The method to be described is particularly suitable for the quantitative determination of zinc, present in the form of zinc oxide or of zinc salts, in transparent rubber articles. Rubber articles of this type contain very small quantities of zinc compared with the quantities present in non-transparent rubber articles, in fact the lower limit is only 0.05 per cent, i.e., only about one-hundredth as much as the normal content. The analytic determination of the zinc content when present in such extremely low percentages as this is extremely difficult by ordinary, methods, and even with higher but nevertheless small percentages of zinc, the use of relatively large quantities of material is necessary and the analytical results are often far from precise. The ordinary method of incineration in a porcelain crucible does not lend itself to the isolation of small quantities of zinc because the latter is easily fixed by the silica of the crucible. On the other hand incineration in a platinum crucible is not suitable because of the tendency of this metal to form a carbide in contact with the carbonaceous substances in the rubber. The novel feature of the method of analysis to be described is the procedure for obtaining a solution of the inorganic substances in the rubber. This involves destruction of the rubber by concentrated sulfuric acid and subsequent oxidation of the organic residue by concentrated nitric acid. This gives a solution of the zinc in the form of sulfate. It is then isolated as zinc sulfide and is redissolved and determined volumetrically by the already known method of precipitation with a standard solution of potassium ferrocyanide. The most suitable concentration, acidity and temperature to give precise results by this procedure for low percentages of zinc in rubber were established.

The method described below was evolved as a substitute for counting, which is unsatisfactory for epiphytic marine diatoms. It depends upon the estimation of the amount of diatom-silica associated with unit dry weight of the sub-stratum. The sea-weed samples are first freed from sand particles and are then treated with strong nitric acid in the usual way. In order to convert the insoluble silica of the diatoms into a soluble form suitable for chemical estimation, the material is fused in a platinum crucible with a mixture of K2CO3 and Na2CO3 and the fused mass is dissolved in (silica-free) distilled water and filtered. The amount of silica in the filtrate is determined colorimetrically according to the method of Dienért and Wandenbulcke (cf. Atkins, 1926). The method is simple in practice and saves considerable time and labour. The full procedure is illustrated by reference to a study of the periodicity of Grammatophora marina (Lyngb.) Kütz. at Swanage, Dorset.This species (PL. I) is found all the year round on Cladophora rupestris in a pit in one of the reefs at Peverel Point, Swanage. In summer it is the only epiphytic diatom on the Cladophora, while in spring and autumn small numbers of other epiphytes (Cocconeis, Opephora, Rhoicosphenia) are present. In order to obtain a fairly representative picture of the abundance of Grammatophora at different times, samples of the Cladophora were collected monthly from a definite area in the pit, each including 3–4 cm. of the apices of five to ten Cladophora tufts cut at random.

E. Heyn determined the melting points of mixtures of copper and cuprous oxide of compositions varying between 100 per cent. Cu and 88·24 per cent. Cu, 11·76 per cent. Cu 2 O. The results of his experiments are shown by the points marked + in fig. 1. These points fall on two curves intersecting at the eutectic point 1065° C., Cu 2 O 3·5 per cent., Cu 96·5 per cent. Heyn found that all his mixtures showed a halt in the cooling curve at this eutectic temperature, so that within the range of his experiments there is no evidence of the existence of solid solutions. C. N. Otin has lately published some experiments on the melting points of the system cuprous oxide-silica. He attempted to determine the melting point of cuprous oxide, but as some oxidation always took place in his experiments, and as he did not analyse the solid obtained (on account of having to remelt it to get it out of the platinum crucible), there is some doubt as to the actual composition of the substance of which he determined the melting point. The highest temperature at which he found a halt in the cooling curve was 1205° C.

A method is described for filling thin-walled ampullae with volatile liquids with the total exclusion of air and water. In this way it is possible to weigh out accurately the amount of material used for a heat of combustion measurement before the experiment is made. To aid the combustion reaction in proceeding to completion a high platinum crucible is used covered with a platinum shield. In a normal heat of combustion reaction it is impossible to detect the presence of carbon monoxide in the combustion gases. The reproducibility obtained is 0.01-0.02%.