“…This is confirmed by a good agreement of their experimental diffractograms with the PXRD patterns calculated from the structural data (see the ESI†) despite a strong texture and X-ray absorption of the powder samples. The cation–oxygen distances in the average structures are generally in agreement with the corresponding bond lengths in other polytungstates and oxides, 5,9,18,21,26,27,31,67 excluding some shortened distances K–O and Rb–O (Table 3). It should be noted that these data confirm the compositions and idealized structural models of the compounds proposed by us in ref.…”
Section: Resultssupporting
confidence: 79%
“…The latter was also observed in the HTB-like structures of A 2 W 4 O 13 (A = K, Tl). 5,31 As can be seen from Table 4, the polytungstate superstructure cells found from PXRD data differ in doubling one or two subcell parameters taken in our work. The doubling seems to be caused by both out-of-center displacements of the W atoms in their oxygen octahedra due to the second-order Jahn-Teller (SOJT) effect for the d 0 cations 68 and tilting the cornersharing octahedra along the doubled axis, which are often observed in HTB and related tungsten oxides.…”
Section: Crystal Chemistry and A Homologous Series Of Layered Htb-lik...mentioning
confidence: 59%
“…Later, the formation of these compounds together with K 2 W 4 O 13 was confirmed, and data on potassium polytungstates or their solid solutions in the range of K 2 W 6 O 19 -K 2 W 8 O 25 were obtained. [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] In the system Rb 2 WO 4 -WO 3 , a phase with a formula close to Rb 2 W 3 O 10 together with Rb 2 W 2 O 7 and Rb 2 W 7−x O 22−3x (0 ≤ x ≤ 2.7) was found. 6,7,16,17,[19][20][21][22][23] Cesium polytungstates of similar compositions were also revealed along with Cs 6 W 11 O 36 .…”
60-year-old problem with the atomic arrangements and exact compositions of the alkali polytungstates related to the hexagonal tungsten bronze (HTB) was solved. The systems A2WO4−WO3 (A = K, Rb) were...
“…This is confirmed by a good agreement of their experimental diffractograms with the PXRD patterns calculated from the structural data (see the ESI†) despite a strong texture and X-ray absorption of the powder samples. The cation–oxygen distances in the average structures are generally in agreement with the corresponding bond lengths in other polytungstates and oxides, 5,9,18,21,26,27,31,67 excluding some shortened distances K–O and Rb–O (Table 3). It should be noted that these data confirm the compositions and idealized structural models of the compounds proposed by us in ref.…”
Section: Resultssupporting
confidence: 79%
“…The latter was also observed in the HTB-like structures of A 2 W 4 O 13 (A = K, Tl). 5,31 As can be seen from Table 4, the polytungstate superstructure cells found from PXRD data differ in doubling one or two subcell parameters taken in our work. The doubling seems to be caused by both out-of-center displacements of the W atoms in their oxygen octahedra due to the second-order Jahn-Teller (SOJT) effect for the d 0 cations 68 and tilting the cornersharing octahedra along the doubled axis, which are often observed in HTB and related tungsten oxides.…”
Section: Crystal Chemistry and A Homologous Series Of Layered Htb-lik...mentioning
confidence: 59%
“…Later, the formation of these compounds together with K 2 W 4 O 13 was confirmed, and data on potassium polytungstates or their solid solutions in the range of K 2 W 6 O 19 -K 2 W 8 O 25 were obtained. [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] In the system Rb 2 WO 4 -WO 3 , a phase with a formula close to Rb 2 W 3 O 10 together with Rb 2 W 2 O 7 and Rb 2 W 7−x O 22−3x (0 ≤ x ≤ 2.7) was found. 6,7,16,17,[19][20][21][22][23] Cesium polytungstates of similar compositions were also revealed along with Cs 6 W 11 O 36 .…”
60-year-old problem with the atomic arrangements and exact compositions of the alkali polytungstates related to the hexagonal tungsten bronze (HTB) was solved. The systems A2WO4−WO3 (A = K, Rb) were...
“…(1)(2)(3)(4) Each member of the series is a distinct phase and has a peritectic point in the phase diagram (1) for (K 2 WO 4 + WO 3 ). These compounds can be used to prepare tungsten bronze.…”
“…After thermal treatment up to 600 °C, the XRD powder pattern leads to the identification of only a K 2 W 4 O 13 -like compound . To fit our initial stoichiometry, we must suggest a deficient character for potassium already described in this structure and the possible substitution of vanadium for tungsten. 3 a- Arrangement of the HPAs, showing large nanoporous channels occupied by water molecules and the triangular channels gilled by K + .…”
Single crystals of the potassium salt K3(H2O)4[H2SiVW11O40](H2O)8+x of the vanadium monosubstituted alpha-Keggin dodecatunsgstosilicate were grown from an aqueous solution and analyzed by EDS, XRD, vibration and electronic spectroscopy, and 1H, 51V, and 29Si solid-state NMR spectroscopy. Results indicate the formation of a nanoporous-like compound of hexagonal symmetry (space group P62) with large, water-filled channels running along the c axis. A uniform distribution of vanadium over the 12 metal sites of the alpha-Keggin anion is observed by XRD. Two different neighborhoods were characterized by 51V NMR in a 2:1 ratio (deltaiso=-546.3 and -536.2 ppm), in accordance with a difference in the number of potassium ions in the second coordination shell of vanadium.
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