(JP4506792-W)      New cpds. derived from Bi4V2O11 are claimed and are used electrochemically esp. as oxide-ion-conducting electrolytes. The cpds. must retain the gamma phase of the parent cpd. and the charges must balance. There are three general types; (a) (Bi2-xMxOz) (V1-yM'yOz) where M is substd. for Bi and has an oxidn. no. less than or equal to 3; M' is substd. for V with an oxidn. no. greater than or equal to 5; and x, y and z are appropriate for the nature of the substituents M and M' and additionally where x and y are not zero and additionally where M' is one of the gp. I or II metals, a transition metal, a gp. III to V element or a rare earth; (c) (Bi2-xMxO2) (VO2), where M is as in (a) above with x not zero and additionally where M is a lanthanide.    They are prepd. by heating to 600 deg.C for 10-15 hrs. a mixt. of the oxides of Bi, V, M and M' in the appropriate quantities for the oxidn. states of M and M'; grinding the mixt., then raising the temp. to 700-800 deg.C for a further 10-15 hrs., repeating to obtain the desired phase. Alternatively the oxides can be replaced by cpds. decomposing thermally in situ to form the oxides.    ADVANTAGE -   The gamma phase of Bi4V2O11 is stabilised giving improved conductivity for oxide ion over known oxide electrolytes. Conductivity is about 10 power (-3) ohm-1cm-1 at 200 deg.C., about 100 times greater than currently available materials. The cpds. may be used in fuel cells as sintered ceramics, thin layers or film    (US5227257-A)      The modified bismuth vanadate cpd. has formula (Bi2-xMx02)V1-yM'yOz) where M is one or more metals which can substitute for Bi and with an oxidn. number lower than or equal to 3, M' is one or more elements which may substitute for V and selected from alkali and alkaline earth metals, transition metals, Gp-IIIa to Gp-Va or Gp-IIIb to Gp-Vb metals, and from the rare earth metals, and the limiting values of x, y and z are functions of the substituting elements with the proviso that x+y is greater than zero. Pref. cpds. are (Bi202)(V1-yM'y0z) or (Bi2-xMxO2)(V02) where M is La.    USE/ADVANTAGE -   Used as solid electrolytes using O(2-) anions (claimed). Conductivity is improved and mfr. is easier.    (JP3111422-B2)      New cpds. derived from Bi4V2O11 are claimed and are used electrochemically esp. as oxide-ion-conducting electrolytes. The cpds. must retain the gamma phase of the parent cpd. and the charges must balance. There are three general types: (a) (Bi2-xMxOz) (V1-yM'yOz), where M is substd. for Bi and has an oxidn. no. less than or equal to 3; M' is substd. for V with an oxidn. no. greater than or equal to 5; and x, y and z are appropriate for the nature of the substits. M and M' and additionally where x and y are not zero; (b) (Bi2O2) (V1-yM'yOz), where M' is as in (a) above and y is not zero and additionally where M' is one of the gp. I or II metals, a transition metal, a gp. III to V element or a rare earth; (c) (Bi2-xMxO2) (VO2), where M is as in (a) above with x not zero and additionally where M is a lanthanide. They are prepd. by heating to 600 deg.C for 10-15 hrs. a mixt. of the oxides of Bi, V, M and M' in the appropriate quantities for the oxidn. states of M and M'; grinding the mixt., then raising the temp. to 700-800 deg.C for a further 10-15 hrs., repeating to obtain the desired phase. Alternatively the oxides can be replaced by cpds. decomposing thermally in situ to form the oxides.    ADVANTAGE -   The gamma phase of Bi4V2O11 is stabilised giving improved conductivity for oxide ion over known oxide electrolytes. Conductivity is about 10power(-3) ohm-1cm-1 at 200 deg.C., about 100 times greater than currently available materials. The cpds. may be used in fuel cells as sintered ceramics, thin layers or films. @(26pp Dwg.No.0/4)