Thieme Christian, Rüssel Christian
Otto-Schott-Institut für Materialforschung, Jena University, Fraunhoferstr. 6, Jena 07743, Germany.
Materials (Basel). 2016 Jul 27;9(8):631. doi: 10.3390/ma9080631.
Solid solutions with the composition BaSrZn₂SiGeO₇ and BaZn₂SiGeO₇ were prepared with different values of x using a conventional mixed oxide route. Both compounds exhibit very different thermal expansion, which is due to the different crystal structures. BaSrZn₂SiGeO₇ solid solutions exhibit the structure of high-temperature BaZn₂Si₂O₇ and show negative thermal expansion, which was proven via high-temperature X-ray diffraction. Up to around x = 1, the crystal structure remains the same. Above this value, the low-temperature phase becomes stable. The Sr-free solid solutions have the crystal structure of low-temperature BaZn₂Si₂O₇ and show also a limited solubility of Ge. These Sr-free compositions show transitions of low- to high-temperature phases, which are shifted to higher temperatures with increasing Ge-concentration.
采用传统的混合氧化物路线，制备了具有不同x值的BaSrZn₂SiGeO₇和BaZn₂SiGeO₇组成的固溶体。这两种化合物表现出非常不同的热膨胀，这是由于不同的晶体结构所致。BaSrZn₂SiGeO₇固溶体呈现高温BaZn₂Si₂O₇的结构，并表现出负热膨胀，这已通过高温X射线衍射得到证实。直至x约为1时，晶体结构保持不变。高于此值时，低温相变得稳定。无Sr的固溶体具有低温BaZn₂Si₂O₇的晶体结构，并且Ge的溶解度也有限。这些无Sr的组合物显示出低温到高温相的转变，随着Ge浓度的增加，转变温度向更高温度移动。
