摘要
The conclusion has been made that mono- and tri-vacant Dawson phosphotungstates (shown as P<sub>2</sub>W<sub>17</sub> and P<sub>2</sub>W<sub>15</sub>)exist. The bi-vacant Dawson phosphotungstate (P<sub>2</sub>W<sub>16</sub>) which was synthesized by hydrolyzing P<sub>2</sub>W<sub>18</sub> with Na<sub>2</sub>CO<sub>3</sub> soluti on, has been reported by Contant et al., however this was soon rejected by themselves. It has also
