Millimeter-wave dielectric characteristrics of Sr_1−xCa_xSmAlO₄ ceramics were investigated together with their structures. The solid solution in the space group I4/mmm was determined in the entire composition range, and the excellent microwave dielectric characteristics were not only obtained in the centimeter-wave range but also in the millimeter-wave range. The dielectric constant ε_r indicated a slight decrease from 19.5, and the significantly improved Q×f value was achieved, while the temperature coefficient of resonant frequency τ_f became more negative (from −3.4 to −12 ppm/°C) with increasing x. Q×f value showed apparent increase with increasing frequency, and the Q×f value at 28 GHz was improved from 88 000 to 160000 GHz with increasing x. The best combination of millimeter-wave dielectric characteristics was achieved at x = 0.6: ε_r = 19, Q×f = 143 300 GHz (at 27.3 GHz), and τ_f = −9.3 ppm/°C. The present ceramics could be expected as the promising candidates as millimeter-wave dielectric ceramics.

中文翻译：

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Sr1−xCaxSmAlO4 陶瓷的毫米波介电特性

_{研究了Sr 1− x} Ca _x SmAlO ₄陶瓷的毫米波介电特性及其结构。在整个组成范围内确定了空间群I 4/ mmm中的固溶体，并且不仅在厘米波范围内而且在毫米波范围内都获得了优异的微波介电特性。介电常数ε _r从 19.5 略有下降，Q × f值显着提高，而谐振频率 τ _f的温度系数随着x 的增加而变得更负（从 -3.4 到 -12 ppm/°C）。Q × f值随着频率的增加而呈现明显的增加，并且随着x的增加，28GHz下的Q × f值从88 000 GHz提高到160000 GHz 。毫米波介电特性的最佳组合是在x  = 0.6 时实现的：ε _r  = 19、Q × f  = 143 300 GHz（27.3 GHz 时）和 τ _f  = -9.3 ppm/°C。目前的陶瓷有望成为毫米波介电陶瓷的有希望的候选者。