Shadowgraphic imaging of material removal during laser drilling with a long pulse excimer laser

After the development of a novel XeCl excimer laser with a nearly diffraction-limited beam and 175 ns pulse length, research was done on different industrial applications of this laser. Hole drilling, one of these applications, was studied extensively. A better understanding of the drilling process is necessary to optimise the drilling efficiency and to control the quality of the holes. A shadowgraphic imaging technique was used for studying the removal of material from the hole and the absorption of the laser beam by this removed material. Images were made at successive times both during and after the laser pulse.In drilling of thin foils, it was shown that the material was ejected mainly after the laser pulse. A comparison of different materials showed that the drilling process should be optimised for each material independently. Furthermore, the plume was found to be not fully transparent for processing materials with a strong absorption line at or near the laser wavelength. The correlation between material and drilling speed suggests improved energy transfer and improved melt ejection for the materials with this absorption. PACS 42.62.Cf; 52.38.Dx; 52.38.Mf     

Eine Cr2As-Phase mit Fe2P-Typ

Ohne ZusammenfassungMit 2 Abbildungen     

The magnetic properties and anisotropy of the linear chain compound TlFe3Te3

The magnetic properties of TlFe₃Te₃ are studied on powdered samples and single crystals. Below 220 K TlFe₃Te₃, is a very anisotropic ferromagnet, the crystallographic c axis being the easy axis of magnetization. While in the easy direction saturation is achieved below 0.5 kOe, in the hard direction saturation is reached at 64 kOe. The angular dependence of the magnetization follows closely a cos ¦?¦ law. The magnetic transition is very abrupt at low external fields, suggesting a first order phase transition. It is accompanied by a small anomaly in the thermal dilatation of the c axis. The magnetization shows an anomalous increase below 50 K suggesting a phase transition.     

Faserförmige Erdalkali-thioferrate

Potassium in KFeS₂ is easily substituted by Ca²⁺, Sr²⁺ and Ba²⁺ in aqueous solution. During this topochemical reaction the (FeS₂)-chains existing in KFeS₂ remain unchanged. The following phases have been prepared: Ca(FeS₂)₂·xH₂O, Sr(FeS₂)₂·xH₂O, Sr(FeS₂)₂, -Ba(FeS₂)₂, -Ba(FeS₂)₂, Ba₁₉(FeS₂)₃₆, and Ba₁₂(FeS₂)₁₁. The crystal structures of Sr(FeS₂)₂ (a=7.91₇,c=5.50₅ Å, P4b2, partially ordered defect TlSe type) -Ba(FeS₂)₂ (a=8.11₁,c=5.59₀Å, I4/mcm, disordered defect TlSe type), and -Ba(FeS₂)₂ (a=7.71₆,c=5.35₇ Å, I4/m) are determined from fibre diagrams. -Ba(FeS₂)₂ is the parent phase of the quasi continuous series of phases Ba _p (FeS₂)_2q .     

Röntgenographische Untersuchungen im System: Vanadin-Arsen-Kohlenstoff

Zusammenfassung Zwei neue binäre Vanadinarsenide werden identifiziert: V₅As₃ mit W₅Si₃-Struktur (T1) und V_1,5As, dessen Elementarzelle bestimmt wird. Im Dreistoff V–As–C werden zwei ternäre Phasen sichergestellt: V₅As₃C_0,7 mit teilweise aufgefüllter Mn₅Si₃-Struktur und V₂AsC mit Cr₂AlC-Struktur (H-Phase).

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Two new binary vanadium arsenides have been identified: V₅As₃ with W₅Si₃-structure (T1) and V_1,5As, of which the unit cell is determined. Two ternary phases were found in the ternary system V–As–C: V₅As₃C_0·7 having partially filled Mn₅Si₃-structure; V₂AsC cristallizes with the Cr₂AlC-type (H-phase).

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Die Kristallstruktur einiger Hafnium-haltiger Phasen

Zusammenfassung Im System Hafnium-Aluminium werden neben derLaves-Phase HfAl₂ die Kristallarten HfAl₃, Hf_0,75Al und Hf₄Al₃ nachgewiesen. Ein beobachtetes Hf₅Al₃ dürfte wieder eine metalloidstabilisierte Phase sein. Ferner wird im Bereich um 60 At.% Hafnium eine weitere, metastabile Phase festgestellt. Bei Hf₃Al scheint eine Ordnungsphase vorzuliegen. Hafnium löst Aluminium. HfAl₃ kristallisiert sowohl im TiAl₃- als auch im ZrAl₃-Typ. Hf₄Al₃ ist isotyp mit Zr₄Al₃. Hf₅Al₃ tritt als D 8₈-Typ auf.Im System Hafnium-Zinn wird neben Hf₅Sn₃ noch HfSn₂ nachgewiesen. Außerdem läßt sich im Mittelbereich eine Phase beobachten, welche der analogen Hf-Al-Phase strukturell ähnlich ist. Die Struktur des HfSn₂ gehört zum CrSi₂-Typ.     

Zum Dreistoff: Vanadin-Arsen-Kohlenstoff

Zusammenfassung Die Aufteilung der Phasenfelder (1100° C) im Dreistoff: V–As–C wird ermittelt. Die Phase mit Cr₃Si-Typ (A15) und die T1-Phase (W₅Si₃-Typ) besitzen eine von der Stöchiometrie abweichende Zusammensetzung. Neben den schon beschriebenen Phasen V₅As₃C_0,7 (aufgefüllter D8₈-Typ) und V₂AsC (H-Phase) existiert noch eine weitere ternäre Phase der Formel V₃AsC. Die Struktur derselben wird mittels Einkristallmethoden bestimmt; Raumgruppe D _2h ¹⁷ , die Gitterparameter sind:a=3,128 Å,b=10,140 Å,c=7,699 Å. Die Struktur kann durch Auffüllung der Oktaederlücken im Re₃B-Typ abgeleitet werden.

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The equilibria for the ternary system: V–As–C are investigated for 1100°C. The respective compositions of the phase having Cr₃Si-type (A15) and the T1-phase (W₅Si₃-type) differ from stoichiometry. Besides V₅As₃C_0,7 (filled D8₈-type) and V₂AsC (H-phase) already described there is another ternary phase of formula V₃AsC. The crystal structure of V₃AsC has been determined by single crystal methods: Space group D _2h ¹⁷ ; the lattice parameters are found to be:a=3.128 Å,b=10.140 Å,c=7.699 Å. The crystal structure of V₃AsC can be derived by filling of the octahedral voids of the Re₃B-type.

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20, 21-Azirdin-Steroide: Reaktion von Derivaten der Oxime von 5-Pregnen-20-on,9β,10α-5-Pregnen-20-on und 9β,10α-5,7-Pregnadien-20-on mit Lithiumaluminiumhydrid und von 3β-Hydroxy-5-pregnen-20-on-oxim mit Grignard-Verbindungen

20, 21-Aziridine Steroids: Reaction of Derivatives of the Oximes of 5-Pregnen-20-one, 9β, 10α-5-Pregnen-20-one and 9β, 10α-5,7-Pregnadiene-20-one with Lithium Aluminium Hydride, and of 3β-Hydroxy-5-pregnen-20-one Oxime with Grignard Reagents. Reduction of 3β-hydroxy-5-pregnen-20-one oxime ( 2 ) with LiAlH₄ in tetrahydrofuran yielded 20α-amino-5-pregnen-3β-ol ( 1 ), 20β-amino-5-pregnen-3β-ol ( 3 ), 20β, 21-imino-5-pregnen-3β-ol ( 6 ) and 20β, 21-imino-5-pregnen-3β-ol ( 9 ). The aziridines 6 and 9 were separated via the acetyl derivatives 7 and 10 . The reaction of 6 and 9 with CS₂ gave 5-(3β-hydroxy-5-androsten-17β-yl)-thiazolidine-2-thione ( 8 ). Treatment of the 20-oximes 12 and 15 of the corresponding 9β,10α(retro)-pregnane derivatives with LiAlH₄ gave the aziridines 13 and 16 , respectively. Their deamination led to the diene 14 and triene 17 , respectively. Reduction of isobutyl methyl ketone-oxime with LiAlH₄ in tetrahydrofuran yielded 2-amino-4-methyl-pentane ( 19 ) as main product, 1, 2-imino-4-methyl-pentane ( 22 ) as second product and the epimeric 2,3-imino-4-methyl-pentanes 20 and 21 as minor products. – 3β-Hydroxy-5-pregnen-20-one oxime ( 2 ) was transformed by methylmagnesium iodide in toluene to 20α, 21-imino-20-methyl-5-pregnen-3β-ol ( 23 ) and 20β, 21-imino-20-methyl-5-pregnen-3β-ol ( 26 ). Acetylation of these aziridines was accompanied by elimination reactions leading to 3β-acetoxy-20-methylidene-21-N-acetylamino-5-pregnene ( 30 ) and 3β-acetoxy-20-methyl-21-N-acetylamino-5,17-pregnadiene ( 32 ). The reaction of oxime 2 with ethylmagnesium bromide in toluene gave 20α, 21-imino-20-ethyl-5-pregnen-3β-ol ( 24 ) and 20α,21-imino-20-ethyl-5-pregnen-3β-ol ( 27 ). Acetylation of 24 and 27 led to 3β-acetoxy-20-ethylidene-21-N-acetylamino-5-pregnene ( 31 ), 3β-acetoxy-20-ethyl-21-N-acetylamino-5,17-pregnadiene 33 and 3β, 20-diacetoxy-20-ethyl-21-N-acetylamino-5-pregnene ( 37 ). With phenylmagnesium bromide in toluene the oxime 2 was transformed to 20β, 21-imino-20-phenyl-5-pregnen-3β-ol ( 25 ) and 20β,21-imino-20-phenyl-5-pregnen-3β-ol ( 28 ). Acetylation of 25 and 28 yielded 3β-acetoxy-20-phenyl-21-N-acetylamino-5, 17-pregnadiene ( 34 ) and 3β,20-diacetoxy-20-phenyl-21-N-acetylamino-5-pregnene ( 39 ). LiAlH₄-reduction of 39 gave 3β, 20-dihydroxy-20-phenyl-21-N-ethylamino-5-pregnene ( 41 ). – The 20, 21-aziridines are stable to LiAlH₄. Consequently they are no intermediates in the formation of the 20-amino derivatives obtained from the oxime 2 .     

Einlagerungsphasen vom TypMe x[Ta2S2C]

Zusammenfassung Ta₂S₂C bildet mit den Übergangsmetallen der ersten langen Periode Einlagerungsphasen. Die Elemente Ti, V, Cr, Mn, Fe, Co und Ni besetzen teilweise die oktaedrischen Lücken in den Schwefeldoppelschichten von 3s-Ta₂S₂C. Kupfer wird in die tetraedrischen Lücken in 1s-Ta₂S₂C eingelagert. Die Temperaturabhängigkeit der paramagnetischen Suszeptibilitäten zeigtCurie-Weiss-Verhalten, das auf ferromagnetische Ordnung in Mn_x[Ta₂S₂C] und Fe_x[Ta₂S₂C] und antiferromagnetische Ordnung in V_x[Ta₂S₂C], Cr_x[Ta₂S₂C], Co_x[Ta₂S₂C] und Cu_x[Ta₂S₂C] bei tiefen Temperaturen hinweist. Die strukturellen und magnetischen Eigenschaften dieser Phasen werden diskutiert.

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Intercalation phases of Me_x[Ta₂S₂C] typ (Me=Ti, V, Cr, Mn, Fe, Co, Ni, Cu)

Ta₂S₂C forms intercalation phases with the transition metals of the first long period. The elements Ti, V, Cr, Mn, Fe, Co and Ni occupy the octahedral voids in the sulphur double layers of 3s-Ta₂S₂C. Copper is intercalated into the tetrahedral voids of 1s-Ta₂S₂C. The temperature dependence of the paramagnetic susceptibilities exhibitsCurie-Weiss behaviour indicating ferromagnetic ordering for Mn_x[Ta₂S₂C] and Fe_x[Ta₂S₂C] and antiferromagnetic ordering for V_x[Ta₂S₂C], Cr_x[Ta₂S₂C], Co_x[Ta₂S₂C], and Cu_x[Ta₂S₂C] at low temperatures. The structural and magnetic properties of these phases are discussed.

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Herrn Prof. Dr.Hans Nowotny in Verehrung gewidmet.     

Intercalation phases of TiS2, 2HNbS2, and 1TTaS2 with ethylenediamine and trimethylenediamine: A crystal chemical and thermogravimetric study

The title compounds were prepared and chemicaly analyzed. Their crystal structures were determined from rotating crystal photographs. 1T-, 2H-, and two different 3R-polymorphs were observed. The thermogravimetric analysis, revealing two to four distinct steps for the phases derived from TiS₂ and 2HNbS₂, and only one to two smeared-out steps for those derived from 1TTaS₂, proves the coexistence of strongly and weakly bound intercalate molecules. The first ones cannot be thermally deintercalated without chemical decomposition. The results are discussed within the framework of an ionic bonding model.