Abstract Quaternary pyrochlore phases of the general formula Bi2-xCaxM2-yM'yO7-x/2+y/2 (M = Ti, Hf, Sn; M' = Sb, Nb, Ta) were prepared by solid state reactions and characterized via structural and dielectric properties. The cubic a-lattice parameters show an expected linear relationship with the ionic radii of the substituted M cations. The solid solution Bi2-xCaxSn2-ySbyO7-x/2+y/2 was analyzed by X-ray and neutron diffractions. The solubility limit is close to x = 1.3, and for x > 1.3, the reaction products contain a mixture of the pyrochlore phase and the Ca2Sb2O7 weberite phase. The refined formulas for compositions with nominal calcium content x = 0.5, 1.0, and 1.5 are Bi1.36Ca0.64Sn1.60Sb0.40O6.88, Bi0.82Ca1.18Sn1.10Sb0.90O6.86, and Bi0.76Ca1.24Sn1.06Sb0.94O6.85 respectively, indicating slight oxygen deficiencies. Temperature and frequency independent dielectric constants and low loss are observed at 1 MHz. The dielectric constants vary from 16 to 98 depending on the composition. We have also prepared new cubic quaternary pyrochlores with the formula BiCdMTeO7, where M = Al, Cr, Ga, In, Fe, Mn, and Sc. Magnetic property measurement shows paramagnetism in the M = Cr and Mn phases but antiferromagnetism with short-range correlations in the M = Fe phase. All these compositions are insulating. The measured dielectric constants and dielectric loss are independent of temperature and frequency.

中文翻译：

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基于四元烧绿石氧化物的与温度无关的低损耗电介质

摘要 通过固态反应制备了通式 Bi2-xCaxM2-yM'yO7-x/2+y/2 (M = Ti, Hf, Sn; M' = Sb, Nb, Ta) 的四元烧绿石相，并通过结构和介电特性。立方 a 晶格参数与取代的 M 阳离子的离子半径显示出预期的线性关系。固溶体 Bi2-xCaxSn2-ySbyO7-x/2+y/2 通过 X 射线和中子衍射进行分析。溶解度极限接近 x = 1.3，对于 x > 1.3，反应产物包含烧绿石相和 Ca2Sb2O7 韦伯石相的混合物。标称钙含量 x = 0.5、1.0 和 1.5 的组成的精炼公式为 Bi1.36Ca0.64Sn1.60Sb0.40O6.88、Bi0.82Ca1.18Sn1.10Sb0.90O6.86 和 Bi0.76Ca1.24Sb06.86。 .94O6.85 分别表示轻度缺氧。在 1 MHz 下观察到与温度和频率无关的介电常数和低损耗。介电常数根据成分的不同在 16 到 98 之间变化。我们还制备了新的立方四元烧绿石，其分子式为 BiCdMTeO7，其中 M = Al、Cr、Ga、In、Fe、Mn 和 Sc。磁性测量显示 M = Cr 和 Mn 相中的顺磁性，但 M = Fe 相中具有短程相关性的反铁磁性。所有这些组合物都是绝缘的。测得的介电常数和介电损耗与温度和频率无关。磁性测量显示 M = Cr 和 Mn 相中的顺磁性，但 M = Fe 相中具有短程相关性的反铁磁性。所有这些组合物都是绝缘的。测得的介电常数和介电损耗与温度和频率无关。磁性测量显示 M = Cr 和 Mn 相中的顺磁性，但 M = Fe 相中具有短程相关性的反铁磁性。所有这些组合物都是绝缘的。测得的介电常数和介电损耗与温度和频率无关。