Temperature stable (1-x)NaCa4V5O17-xBaV(2)O(6) microwave dielectric ceramics for ULTCC applications
CERAMICS INTERNATIONAL
Authors: Pei, Cuijin; Li, Yang; Tan, Jingjing; Yao, Guoguang; Jia, Yanmin; Liu, Weihong; Liu, Peng; Zhang, Huaiwu
Abstract
Novel temperature stable (1-x)NaCa4V5O17-xBaV(2)O(6) (0.8 <= x <= 0.9, (1-x)NCV-xBV) ceramics were successfully synthesized through a high-temperature solid phase reaction route. XRD and SEM-EDS analysis demonstrated that only NaCa4V5O17 and BaV2O6 phases were formed without any extra phase. The introduction of BaV2O6 not only effectively improved the tf of NaCa4V5O17 matrix but also considerably lowered its sintering temperature to 550 degrees C. Typically, an approximate-zero tau(f) value around -1.0 ppm/degrees C was achieved for 550 degrees C sintered 0.12NCV0.88BV ceramics with low epsilon(r) of 10.9 and Qxf of 15,500 GHz (at 10.3 GHz). Its good compatibility with Al electrode furthermore made 0.12NCV-0.88BV composites suitable for ULTCC applications.
First lunar occultations results from the Trebur observatory
NEW ASTRONOMY
Authors: Richichi, A.; Ohlert, J. M.
Abstract
A program of routine observations of lunar occultations has been initiated at the Michael Adrian Observatorium using a 1.2 m telescope equipped with a commercial CMOS camera. The goal is mainly the direct measurement of the angular diameter of late-type stars, as well as of binary stars with small separations. Among the results reported in this first paper, we discuss a measurement of Aldebaran (a Tau), of the two cool, chemically peculiar giant stars R Gem and T Cnc, and of the two newly detected binary stars SAO 139528 and SAO 119489. This work demonstrates the capability to carry out milliarcsecond-level investigations at this relatively small facility on sources down to approximate to 10 mag. We plan to continue this routine program in the coming years, also in coordination with other similar efforts at various observatories with comparable instrumentation.
COA
Publication 
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