Nitridhalogenide des Thoriums

Abstract

Durch Ammonolyse des ThF4 im Ammoniakstrom bei 850°C wurde ThNF hergestellt. Die Verbindung ist hydrolysebeständig, sie kristallisiert in einem rhomboedrischen Schichtengitter, isotyp dem LaOF. ThNF kann man auch aus Th3N4 und ThF4 herstellen. Dieses Verfahren führt ferner zu zwei weiteren Phasen ThNxF4−3x, von denen die Phase mit 0,94 ≥ x ≥ 0,88 tetragonal, die mit 0,87 ≥ x ≥ 0,79 orthorhombisch kristallisiert. Die entsprechenden präparativen Verfahren führten bei etwa 650°C zu ThNCl, ThNBr und ThNJ. Die Stoffe sind in dieser Reihenfolge zunehmend hydrolyseempfindlich, sie kristallisieren isotyp dem BiOCl.

Preparation and crystal structures of novel LaOAgS-type copper and silver fluoride chalcogenides

“…Using relatively soft [Ae 2 F 2 ] 2+ fluorite layers together with [T 2 Ch 2 ] 2− counterparts results in larger number of representatives, as well as significant softening of synthesis conditions, as compared to related series involving more rigid [Ln 2 O 2 ] 2+ moieties. The situation should become even more restricted if one would turn to [M 2 N 2 ] 2+ layers (observed for M = Th [33], U [34], and Ce [35]). The accuracy of geometrical approaches to structure stability based on bond lengths is estimated to be about 2-3%.…”

Optical conductivity of iron-based superconductors

“…At first glance, this observation might lead one to conclude that, similarly to Ba(Fe 1−x Co x ) 2 As 2 and FeTe 1−x Se x , impurity scattering rate is relatively high. However, even taking into account the well-known difficulty to control the lithium stoichiometry in LiFeAs [20,199], recent scanning tunneling microscopy studies have shown that in the best samples the concentration of impurities can be very low [200]. Therefore, it is more likely that in the case of LiFeAs (assuming that the samples investigated by the authors of Ref.…”

Superconducting nitride halides MNX (M = Ti, Zr, Hf; X = Cl, Br, I)

“…a) The [76], only the trend of the caxis in dependence to the inter-halogen distances in [001] direction is the same as in UNX (X ¼ Cl, Br, I) and in the a-polymorphs of MNX (M ¼ Ti, Zr, Hf; X ¼ Cl, Br, I). Black CeNCl [77] as another example for a nitride halide is isostructural to the thorium representative and the only characterized cerium(IV) nitride halide so far.…”