Synthsis, structure and physical property of vanadate garnets

1实验合成了以下5种类型的钒酸盐石榴石：类型3：{A^_2A^；2；2；>}[M^_2A^；2；3；>；]-(V_3)O_>；12；>，类型4：{A^A^；2；>2}[M^M^；3；>2；](V_3)O_&lt；12；类型5：{A^A^；_2](V_3)O_&lt；12&gt；类型6：{A^&lt；2&>t；_3}[M^M^&lt；2&>；](V_3)O_&lt；12&gt；和类型7：{-_&lt；0.5&gt；A^&lt；2&gt；_&lt；}[M^&lt；2&>t；_2](V_3)O_&lt；12&gt；，其中A^=Li^、Cu^、Na^、Ag^和K^；；A^&lt；2&>=Cd^&lt；2&>，Ca^&lt；2&>；和Pb^&lt；2&>；和Pb^&lt；2&>；M^=Li^；M^&lt；2&>；=Ni^；lt；2&>，2&>，Co^&lt；2；，Cu^&lt；2；；2&>；和Cd^&lt；2&>t；和Cd^&lt；2&>；3&gt；和Fe^&lt；3&gt；。{Na_2Ca}[Nife^&lt；3&>；](V_3)O_&lt；12&>，{A^Ca_2}[LICR^&lt；3&>；](V_3)O_&lt；12&>，其中A^=Li^和Na^，{A^Ca_2}[Life^；3&>；](V_3)O_&t；12&>，其中A^=Li^，Cu^，Na^和Ag^，{LICA_2}[M^&lt；2&>t；(V_3)[LiCd](V_3)O_&lt；12&>，其中M^&lt；2&>；和Mn^&lt；2&>t；，{KCa_2}[Mn_2](V_3)O_&lt；12&>，{Ca_3}[LiCd](V_3)O_&lt；12&>，其中M^&lt；2&gt；=mg^&lt；2&gt；，Co^&lt；2&gt；，Zn^&lt；2&gt；，Mn^&lt；2&gt；和Cd^&lt；2&gt；是首次合成的纯相石榴石。石榴石在类型3和类型4中都只形成了少量的石榴石。在类型5，6中，…虽然Pb2&gt；的有效离子半径比Sr^&lt；2&gt；的有效离子半径大，但与Pb2&gt；取代Ca^&lt；2&gt；相比，Sr^&lt；2&gt；形成的石榴石的种类受到很大的限制。这归因于“软硬酸碱原理”。在5，6和7型中，在M^&lt；2&gt；=Cu^&lt；2&gt；的情况下，由于“Cu^&lt；2&gt；2的Jahn-Teller效应”，形成的石榴石的种类相当有限。2用钒酸盐熔剂生长良好的晶体，研究了钒酸石榴石(NACA_2M_2V_3O_(12))的形态。通过在低过饱和度下生长晶体确定了第一级F面，发现在较低温度下为{110}面，在较高温度下为{211}面。这种变化归因于八面体位置的键长与十二面体位置的键长之比随着温度的升高而变化。当晶体在低温区长大时，除了出现{110}面外，还出现了主要的{211}面，而在高温区，晶体以{110}面为主。产生这些现象的原因是由于随着晶体尺寸的增大，矿物营养物质向晶体表面的运移速率增加而引起的表面动力学。较少

1 Experiments were conducted to synthesize vanadate garnets of the following 5 types ; Type3:{A^+_2A^<2+>}[M^<2+>M^<3+>]-(V_3)O_<12>, Type 4:{A^+A^<2+>_2}[M^+M^<3+>](V_3)O_<12>, Type 5:{A^+A^<2+>_2}[M^<2+>_2](V_3)O_<12>, Type 6:{A^<2+>_3}[M^+M^<2+>](V_3)O_<12> and Type 7:{□_<0.5>A^<2+>_<2.5>}[M^<2+>_2](V_3)O_<12>, where A^+=Li^+,Cu^+,Na^+,Ag^+ and K^+;A^<2+>=Cd^<2+>,Ca^<2+>,Sr^<2+> and Pb^<2+>;M^+=Li^+;M^<2+>=Ni^<2+>,Mg^<2+>,Co^<2+>,Cu^<2+>,Zn^<2+>,Mn^<2+> and Cd^<2+>;M^<3+>=Cr^<3+> and Fe^<3+>. New variations of {Na_2Ca}[NiFe^<3+>](V_3)O_<12>,{A^+Ca_2}[LiCr^<3+>](V_3)O_<12>, where A^+=Li^+ and Na^+,{A^+Ca_2}[LiFe^<3+>](V_3)O_<12>, where A^+=Li^+,Cu^+,Na^+ and Ag^+,{LiCa_2}[M^<2+>_2](V_3)O_<12>, where M^<2+>=Co^<2+> and Mn^<2+>,{KCa_2}[Mn_2](V_3)O_<12>,{Ca_3}[LiCd](V_3)O_<12> and {Pb_3}[LiM^<2+>](V_3)O_<12>, where M^<2+>=Mg^<2+>,Co^<2+>,Zn^<2+>,Mn^<2+> and Cd^<2+> were prepared as phase-pure garnets for the first time. Garnets were formed only a few in both types 3 and 4. In types 5,6 … More and 7, the variety of garnets formed was greatly limited by the replacement of Ca^<2+> by Sr^<2+> as compared with that being not so much limited by the replacement of Ca^<2+> by Pb^<2+>, though the effective ionic radius of Pb^<2+> is larger than that of Sr^<2+>. This is ascribed to "the hard and soft acids and bases principle". In types 5,6 and 7, in the case of M^<2+>=Cu^<2+>, the variety of garnets formed was fairly limited due to the "the Jahn-Teller effect of Cu^<2+>".2 The morphologies of vanadate garnets (NaCa_2M_2V_3O_<12>,M=Ni,Mg or Co) were studied by growing well-formed crystals from sodium vanadate flux. The first rank F-faces were determined by growing crystals at low supersaturation levels and were found to be the {110} face at lower temperature and the {211} face at higher temperature. This change was ascribed to a change in the ratio of the bond lengths at the octahedral site to that of the dodecahedral site with increasing temperature. When crystals grew larger in the lower temperature region, predominantly {211} faces appeared in addition to {110} faces, whereas in the higher temperature region, {110} faces were predominant over {211} faces. The reason for these phenomena was ascribed to the surface kinetics caused by an increase in the rate of mineral nutrient transport to the surface of the crystal with increasing crystal size. Less