Synthesis and Crystal Structures of Alkali Lithium Molybdates and Alkali Lithium Tungstates

,; ,

J. Korean Ceram. Soc. > Volume 22(3); 1985 > Article

Journal of the Korean Ceramic Society 1985;22(3): 72.

알칼리 리치움 몰리브덴산염과 알칼리 리치움 텅그스텐산염의 합성과 결정구조

정수진

서울대학교 무기재료공학과

Synthesis and Crystal Structures of Alkali Lithium Molybdates and Alkali Lithium Tungstates

ABSTRACT

Single crystals of the compound MeI $(LiMoO_4)$ and $Me^I(LiWO_4)$ ($Me^I=K$, Rb, Cs) were synthesized by slow evaporation from aqueous solution and bycooling from melt. The compounds of potassium or rubidium are hygroscopic and they form easily hydrated crystals $Me^I LiMoO_4$.$H_2O$ or $Me^ILiMoO_4$.$H_2O$ or $Me^ILiWO_4$.$H_2O$ from aqueous solution. The structures of these hydrated crystals are each other isotypic and they are built up of distorted layers of $(LiMoO_5)$ or $(LiWO_5)$. There exist two types of tetrahedral framework structures in this group of anhydrous molybdates and tung-states ; tridymite-type and cristobalite-type. $KLiMoO_4$ and $KLiWO_4$ have two types of polymorphic structures where as only the cristobalite-type is found in the Rb-and Cs-compounds. The system $KLiSO_4-KLiMoO_4$ was studied. Two components are almost immiscible but there eixst a narrow area of solid solution on the side of sulfate in the system.