| 摘要 |
A ternary solid solution of potassium fluoaluminate, rubidium fluoaluminate and potassium fluoborate preferably containing 1-15 moles per cent, more preferably 1-5, of KBF4, 4-90 moles per cent of RbAlF4 and the remaining proportion KAlF4 is prepared by cooling a melt of the constituents in the required composition. Proportions of 2-5% KBF4 and 4-50% RbAlF4 are preferred from a practical standpoint. The KBF4 may be prepared by the method of Borlander, Hollatz and Fisher, i.e. the reaction of H3BO3 and HF in the presence of KOH. KALF4 and RbAlF4 are prepared by Brosser's method, i.e. evaporating to dryness a mixture of (1) an aqueous HF solution of hydrated alumina and (2) K or Rb fluoride, the solid ingredients being in stoichiometric quantity. In an example, 76.5% KAlF4, 8.5% RbAlF4 and 15% KBF4, on a molar basis, was mixed and fused at 650 DEG C. for one hour, then cooled slowly until solid. The product may be used as a dielectric or insulating material, having an electrical conductivity less than 10-6 mhos. per cm. Specifications 903,657 and 984,896 are referred to. |
