Phase equilibria in the BaO–MgO–Ta2O5 system
Phase equilibria in the BaO–MgO–Ta2O5 system
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DOI：
10.1039/b912485c
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发表时间：
2009-10
影响因子：
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通讯作者：
T. Kolodiazhnyi;A. Belik;T. C. Ozawa;E. Takayama-Muromachi
中科院分区：
文献类型：
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作者：
T. Kolodiazhnyi;A. Belik;T. C. Ozawa;E. Takayama-Muromachi
本文报道了BaO-MgO-Ta_2O_5系统在1450 °C平衡时的相关系。发现了与钨青铜结构密切相关的3：1：1钙钛矿型Ba 3 MgTa 2 O 9、9：1：7 TTB型Ba 9 MgTa 14 O 45和4：1：5 Ba 4 MgTa 10 O30三个三元相。在1600 °C平衡后才能得到具有10层六方钙钛矿结构的另一种三元相Ba 10 Mg 0.25 Ta 7.9 O 30。MgO在类TTB的Ba 4 Ta 10 O29、BaTa 4 O 11和Ba6.63Ta34.95O95中的溶解度不超过2.0摩尔%。在Mg 4 Ta 2 O 9-BaTa 2 O 6的结合处发现沿着只有六方相的BaTa 2 O 6。在20 Hz-2 MHz范围内的介电性能的测量表明，Ba 9 MgTa 14 O 45具有99的介电常数，没有频率色散和低介电损耗。我们还澄清了几个矛盾的报告有关的三元和二元相的BaO-MgO-Ta 2 O 5组成字段。
We report on the phase relation in the BaO–MgO–Ta2O5 system equilibrated at 1450 °C. We found three ternary phases, namely 3:1:1 perovskite Ba3MgTa2O9, 9:1:7 TTB (tetragonal tungsten bronze)-type Ba9MgTa14O45 and 4:1:5 Ba4MgTa10O30 closely related to the tungsten bronze structure. Another ternary phase, Ba10Mg0.25Ta7.9O30, with a 10 layer hexagonal perovskite structure can be only obtained after equilibration at 1600 °C. MgO solubility in the TTB-like Ba4Ta10O29, BaTa4O11 and Ba6.63Ta34.95O95 does not exceed 2.0 mol%. Only the hexagonal polymorph of the BaTa2O6 phase was found along the Mg4Ta2O9–BaTa2O6 join. Measurements of dielectric properties in the 20 Hz–2 MHz range revealed that Ba9MgTa14O45 has a dielectric constant of 99 with no frequency dispersion and low dielectric loss. We have also clarified several contradictory reports related to the ternary and binary phases in the BaO–MgO–Ta2O5 composition field.