Although γ/η-Mo4O11 and Mo2Ta2O11 are used in a variety of industrial applications and can easily be synthesized in a chemical vapour transport (CVT) process or reactions in silica ampoules, respectively, only few data are available concerning their physical properties. In this paper, we further explore the properties of the three compounds with respect to their thermal and magnetic behavior, surface composition, and Raman spectroscopic properties.

The novel potassium nickel borate nitrate K7Ni[B18O24(OH)9](NO3)6 ·(H3BO3) was obtained from a simple hydrothermal synthesis in a stainless-steel autoclave at T = 513 K starting with nickel dichloride hexahydrate, and boric and nitric acid with the pH adjusted to 8 by KOH. Single-crystal X-ray diffraction data provided the basis for the structure analysis and refinement. The compound crystallizes in the trigonal space group R3̅ (no. 148) with the lattice parameters a = 1222.29(8) and c = 5478.4(4) pm. Generally, K7Ni[B18O24(OH)9](NO3)6 ·(H3BO3) is comprised of nitrate layers and complex nickel borate layers surrounded by boric acid, nitrate anions, and potassium cations.

During the reduction of molybdenum trioxide (MoO3) to metallic molybdenum, the first reduction step yielding molybdenum dioxide as an intermediary product is of crucial importance. In this study, we examined the impact of the parameters reduction temperature, water influx, and potassium content on the hydrogen reduction of this first reaction step. Beginning from the same starting material, the chemical vapor transport mechanism was utilized to yield the phase pure MoO2. Analyses including powder X‐ray diffraction, inductively coupled plasma‐mass spectrometry, scanning electron microscopy, and high performance optical microscopy were performed on the product phases. Modulations of the specific surface areas of molybdenum dioxide ranging from 2.28 to 0.41 m2/g were possible. Furthermore, a distinct shift from small plate‐like grains to cuboid‐like forms was achieved.

The novel dysprosium borate DyB 5 O 8 (OH) 2 was synthesized in a Walker-type multianvil apparatus at a pressure of 2.5 GPa and a temperature of 673 K. Single-crystal diffraction data provided the basis for the structure solution and refinement. The compound crystallizes in the acentric monoclinic space group C2 (no. 5) with the lattice parameters a = 7.9288(5), b = 4.4009(3), c = 9.3409(8) Å, and a monoclinic angle of IntroductionRare earth oxoborates include a wide variety of structural motifs with several different structures. One focus of our intensive research is the synthesis of novel rare earth oxoborates possessing anionic backbones as highly condensed as possible. In the case of borate structures exclusively built up from [BO 4 ] 5tetrahedra, an increase in the B/O ratio coincides with a higher degree of condensation. This concept is derived from the general concept of condensation found in silicates. [1] The dominant structural motive found in high-pressure borates are [BO 4 ] 5tetrahedra, which is in contrast to borates synthesized under ambient pressure conditions, where the [BO 3 ] 3group dominates. Our research has already yielded several examples of highly condensed borates like YB 7 O 12 , [2] -Eu(BO 2 ) 3 , [3] or Dy 4 B 6 O 15 . [4] Especially, the dysprosium borates comprise a variety of different structural motifs incorporating [BO 3 ] 3and [BO 4 ] 5groups and the linkage of these groups to a variety of polyanions. With Dy 4 B 6 O 15 , the first oxoborate with edge-sharing [BO 4 ] 5tetrahedra was found under high-pressure/high-temperature conditions, which was one of the most interesting results, because this structural feature was completely unknown, before we started our investigations under such extreme conditions. Subsequently, the research effort in the multianvil apparatus yielded phases like /ν-DyBO 3 , [5][6] α/ -Dy 2 B 4 O 9 , [7][8] [a]

A potassium tetranitratopalladate(II) with the composition K2[Pd(NO3)4] · 2HNO3 was synthesized by a simple solvothermal process in a glass ampoule. The new compound crystallizes in the monoclinic space group P21/c (no. 14) with the lattice parameters a = 1017.15(4), b = 892.94(3), c = 880.55(3) Å, and β = 98.13(1)° (Z = 2). The crystal structure of K2[Pd(NO3)4] · 2HNO3 reveals isolated complex [Pd(NO3)4]2− anions, which are surrounded by eight potassium cations and four HNO3 molecules. The complex anions and the cations are associated in layers which are separated by HNO3 molecules. K2[Pd(NO3)4] · 2HNO3 can thus be regarded as a HNO3 intercalation variant of β-K2[Pd(NO3)4]. The characterization is based on single-crystal X-ray and powder X-ray diffraction.