PYROCHLORES .8. STUDIES OF SOME 2-5 PYROCHLORES AND RELATED COMPOUNDS AND MINERALS
PYROCHLORES .8. STUDIES OF SOME 2-5 PYROCHLORES AND RELATED COMPOUNDS AND MINERALS
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DOI：
10.1139/v72-580
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发表时间：
1972-01-01
期刊：
影响因子：
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通讯作者：
KNOP, O
中科院分区：
文献类型：
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作者：
BRISSE, F;STEWART, DJ;KNOP, O
立方辉石为Cd_2Nb_2O_7、Cd_2Ta_2O_7、Sn_2Nb_2O_7、Sn_2Ta_2O_7。制备了Cd_2Sb_7O_7、Ca_2Sb_2O_7、Mn_2Sb_2O_7、Pb_2Sb_2O_7及相关化合物，并通过多种方法对其进行了研究。加热到700度以上。Ca_2Sb_2O_7（烧绿石）转变为Ca_2Sb_2O_7（烧绿石），Pb_2Sb_2O_7（烧绿石）转变为菱方畸变的Pb_2Sb_2O_7烧绿石。根据粉末衍射强度对Cd_2Nb_2 O_7和Cd_2 Ta_2 O_7的晶体结构进行了精修，得到x（O_2）的最佳估计值分别为0.434（2）和0.434（3）。还对自然界中的硼铁矿和辉锑矿进行了研究。墨西哥圣刘易斯波托西辉锑矿的穆斯堡尔~（121）Sb谱表明，Sb（V）和Sb（III）的比值约为0.2。BaCd_2Cl_6·5 H_2 O和BaCd_2Cl_6·2 H_2 O的粉末衍射图均为烧绿石型。Br可部分取代氯，得到BaCd_2Cl_6 −zBrz·5 H_2 O混晶，其z = 2。讨论了2-5氧化物焦绿石的晶体化学及weberite与烧绿石相的关系。
The cubic pyrochlores Cd2Nb2O7, Cd2Ta2O7, Sn2Nb2O7, Sn2Ta2O7. Cd2Sb7O7, Ca2Sb2O7, Mn2Sb2O7, Pb2Sb2O7, and related compounds were prepared and investigated by a number of methods. On heating above 700°. Ca2Sb2O7(pyrochlore) transformed to Ca2Sb2O7(weberite), while Pb2Sb2O7(pyrochlore) changed to a rhombohedrally distorted Pb2Sb2O7pyrochlore. Refinement of the crystal structures of Cd2Nb2O7and Cd2Ta2O7from powder diffractometer intensities yielded 0.434(2) and 0.434(3) respectively as the best estimates ofx(O2). Specimens of natural bindheimite and stibiconite were also examined. Stibiconite from San Luis Potosi (Mexico) was shown, on the evidence of its Mössbauer121Sb spectrum, to contain Sb(V) and Sb(III) in the approximate ratio of 0.2.BaCd2Cl6•5H2O and BaCd2Cl6•2H2O both give powder diffraction patterns of the pyrochlore type. The chlorine could be partially replaced by Br to give mixed crystals BaCd2Cl6−zBrz•5H2O almost up toz= 2.The crystal chemistry of 2–5 oxide pyrochlores and the relationship of the weberite to the pyrochlore phases are discussed.