Synthesis of bulk lanthanum polyphosphate and other rare earth phosphates through hydrothermal hot-pressing

Bulk samples of lanthanum polyphosphate were synthesized through a hydrothermal hot-pressing(HHP)process.In this process,pressing temperature,pressure and volume of water were varied in order to improve the density and strength of the resulting materials.The strength of the bulk samples was estimated through drilling and ultrasonic treatments.In order to improve the strength of the materials,the use of microwave irradiation was examined.Lanthanum polyphosphate formed porous bulk samples with a filling factor of approximately 70%,which was calculated from real and theoretical densities.With respect to machinable strength,a drilled hole greater than 7.0 mm in diameter was obtained on some bulk samples,and the diameter of the samples was 14 mm.The HHP process is a useful method for obtaining bulk samples of lanthanum polyphosphate.Bulk lanthanum polyphosphate containing water crumbled easily to a powder form upon ultrasonication.However,these bulk samples retained their shape upon ultrasonication,despite containing water,after exposure to microwave irradiation,and also experienced minimal weight loss.Furthermore,to study the effect of microwave heating,bulk lanthanum orthophosphate,yttrium orthophosphate and polyphosphate were also examined.

利用纳米ZnO粉制备厚膜气敏传感器的研究

以ZnO纳米粉(平均粒径30nm)为原料,利用水热热压方法制备了ZnO多孔纳米固体,同时用通常的水热法对ZnO纳米粉进行了预处理(预处理ZnO纳米粉)。然后,分别以ZnO多孔纳米固体和预处理ZnO纳米粉为原料,制备了厚膜气敏传感器。本征电阻的测试结果表明,这两种厚膜气敏传感器的本征电阻比用未经处理的ZnO纳米粉(以下简称“原料ZnO纳米粉”)制备的厚膜气敏传感器大大降低并很快达到稳定状态。有效地改善了器件工作的稳定性。结合对三种传感器的显微结构分析,对出现上述差异的原因进行了讨论。