Structural features and spectroscopic and energy characteristics of alkali metal molybdates and tungstates

Abstract

The gamma-ray blazar 1611+343 was observed with polarization VLBI mode at 5 GHz in February 1999. The total intensity (I) VLBI image of the source shows a core-jet structure. The jet bends eastward at ∼ 3 mas south of the core. Four components have been detected from results of fitting, with apparent speeds estimated at 6.7 ± 0.7, 2.5 ± 0.3, 4.5 ± 0.5 h −1 c for three jet components (taking H 0 = 100 h km s −1 Mpc −1 , q 0 = 0.5). The polarization (P ) VLBI image of 1611+343 displays the polarized configuration in the jet. The mechanism of the curved jet is discussed.

A New Method to Minimize High-Temperature Corrosion Resulting from Alkali Sulfate and Chloride Deposition in Combustion Systems. I. Tungsten Salts

“…As a result of the exact agreement between the four spectra so obtained, the Raman spectrum in Figure 2 is labeled as Na 2 W 4 O 13 with a high degree of confidence. The Raman shift frequencies also closely agree with those tabulated by Fomichev et al 61 It displays two equally strong transitions at 948 and 776 cm -1 , the latter being quite broad and an easily recognized characteristic of this molecule. Because of their thermal instability, salts such as the alkali para-and metatungstates are not expected to play any role in combustion chemistry or deposition.…”

“…The spectral distribution for K 2 W 3 O 10 , K 2 W 4 O 13 , and K 2 W 6 O 19 reflect those illustrated by Becher, but some slight differences are apparent. The crystal structures of the corresponding molybdates also differ and provide no additional insight . Nevertheless, Figure is more than sufficient to clearly illustrate that the nature of the potassium polytungstate spectra is in sharp contrast and readily distinguishable from that of K 2 SO 4 , K 2 WO 4 , or WO 3 .…”

“…However, the molecule has the ability to incorporate additional units of WO 3 into its formulation and form polytungstates. As indicated in the well-characterized phase diagram of Na 2 O/WO 3 mixtures at various temperatures, sodium can form such stable structures as Na 2 WO 4 , Na 2 W 2 O 7 , Na 2 W 4 O 13 , etc. , Potassium behaves similarly but can also produce the 3WO 3 molecule K 2 W 3 O 10 . , The crystal structures of these seven tungstates are characterized by different space groups and so have differing Raman spectral features. , Although not commercially available, these polytungstates are easily synthesized. For example, heating mixtures of Na 2 WO 4 /WO 3 , Na 2 WO 4 /H 2 WO 4 , or Na 2 CO 3 /H 2 WO 4 in the correct proportions ,, each produced an identical Raman spectrum of Na 2 W 2 O 7 (melting point 1019 K).…”

“…59,60 The crystal structures of these seven tungstates are characterized by different space groups and so have differing Raman spectral features. 61,62 Although not commercially available, these polytungstates are easily synthesized. For example, heating mixtures of Na 2 WO 4 /WO 3 , Na 2 WO 4 / H 2 WO 4 , or Na 2 CO 3 /H 2 WO 4 in the correct proportions 60,63,64 each produced an identical Raman spectrum of Na 2 W 2 O 7 (melting point 1019 K).…”

Twinning and incommensurate modulation in baumoite, Ba0.5[(UO2)3O8Mo2(OH)3](H2O)~3, the first natural Ba uranyl molybdate

“…2) of powdered baumoite in the range 4000 to 650 cm −1 was obtained using a Nicolet 5700 FTIR spectrometer equipped with a Nicolet Continuum IR microscope and a diamond-anvil cell. The spectrum was interpreted with regard to the theoretical and experimental papers published by Hardcastle and Wachs (1990), Fomichev et al (1992), Čejka (1999), Fedoseev et al (2001), Sidorenko et al (2005), Frost et al (2008), Mączka et al (2009), Nakamoto (2009), Zhang and Guo (2012) and Barik et al (2014). Moreover, we used data taken from Katscher et al .…”