Synthesis, stability and breakdown products of the hydroxyl end member of jeremejevite in the system Al 2 O 3 -B 2 O 3 -H 2 O
Synthesis, stability and breakdown products of the hydroxyl end member of jeremejevite in the system Al 2 O 3 -B 2 O 3 -H 2 O
复制标题
Al 2 O 3 -B 2 O 3 -H 2 O体系中jeremejevite羟基端元的合成、稳定性和分解产物
DOI：
10.1127/ejm/10/5/0875
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发表时间：
1998
影响因子：
2.1
通讯作者：
W. Schreyer
中科院分区：
文献类型：
--
作者：
A. Stachowiak;W. Schreyer
Jeremejevite-OH，Al6 [B03] s (0H) 3，这里缩写为 Jer，是天然氟主导矿物的羟基端元，是在 0.3 GPa 和 400-450 C 的温度下，从 AI2O3-B2O3-H2O 系统中的各种氧化物和氢氧化物混合物中水热合成的。在运行产物中，Jer 通常与痕量 AUB2O9 共存，可能是微小的夹杂物。使用合成的 Jer (60 mol%)+ H2O (40 mol%) 作为起始材料，确定该本体组合物的 Jer 稳定性场高达 5.0 GPa。在 0.3 GPa 和约 575 C Jer 分解为 AI4B2O9 和 H2O-B2O3 流体，而在 3.5 GPa、800 C 和 5 GPa 时，由于 AI4B2O9 在高压下不稳定，形成 750 C AI3BO6+ AIBO3+ 流体。结构中含有平面 B03 基团的 Jer 在高压下非常稳定。在运行含有两种或三种固相的产品中，可以近似估计共存二元流体的组成。在 B2O3/H2O<1 的本体组合物中，与 Jer 和一种或两种其他固体共存的流体随着压力升高和温度降低而变得越来越含水，因此在 5.0 GPa、约 740°C 下，它们的 XB2O3=B2O3/(B2O3+H2O) 接近 0.07，在 0.3 GPa、450°C 接近 0.01。因此，Jer 作为一种高度富含 B 的固体，可以在这种 PT 条件下从 B 含量非常低的流体中结晶出来。在B2O3/H2O>1的本体组合物中，Jer作为唯一的固体可以与XB2O3高达1.0的流体（熔体）共存。 Jer 预计不会作为天然矿物出现，因为与普遍存在的 SiO2 一起，会形成硼硅酸铝。然而，在高氟活性下，以 F 为主的 Jeremejevite 比这些铝硼硅酸盐更稳定，并且与游离 SiO2 共存。
Jeremejevite-OH, Al6 [B03] s (0H) 3, here abbreviated as Jer, the hydroxyl end member of the natural fluorine-dominant mineral, was synthesized hydrothermally at 0.3 GPa and 400-450 C from various oxide and hydroxide mixtures in the system AI2O3-B2O3-H2O. In the run products Jer usually coexisted with traces of AUB2O9, probably as minute inclusions. Using synthetic Jer (60 mol%)+ H2O (40 mol%) as starting material, the stability field of Jer for this bulk composition was determined up to 5.0 GPa. At 0.3 GPa and about 575 C Jer decomposes to AI4B2O9 and H2O-B2O3 fluid, whereas at 3.5 GPa, 800 C and at 5 GPa, 750 C AI3BO6+ AIBO3+ fluid form as a result of the instability of AI4B2O9 at high pressure. Jer containing planar B03-groups in its structure is remarkably stable at high pressure.In run products containing two or three solid phases, the compositions of the coexisting binary fluids could be approximated. In bulk compositions with B2O3/H2O< 1, the fluids coexisting with Jer and one or two other solids become increasingly hydrous with rising pressure and decreasing temperature, so that at 5.0 GPa,~ 740 C their XB2Ο3= B203/(B2O3+ H20) lies near 0.07 and at 0.3 GPa, 450 C near 0.01. Thus Jer as a highly B-rich solid may crystallize under such PT-conditions from very B-poor fluids. In bulk compositions with B2O3/H2O> 1, Jer as the only solid may coexist with fluids (melts) having XB2O3 up to 1.0. Jer is not expected to occur as a natural mineral, because with ubiquitous SiO2 present Al-borosilicates would form. However, at high fluorine activities F-dominant jeremejevite is more stable than these Al-borosilicates and coexists with free SiO2.