Based on the cermet double layer structure, Nb-NbN multi-layer fihns for solar selective coatings were deposi-ted by direct current reactive magnetron sputtering. The Nb/Nb-NbN/A12Q trilayered structure was deposited on a stain-less steel (SS) substrate by using a single niobium target. The expected components were adjusted by changing the gas flowing ratios of At: N2. The A120s antireflective layer on the top of the fihn was produced by r. f. magnetron sputtering using A12O3 ceramic target. A solar absorptivity of 0.94 and a normal emissivity of 0.16 at room temperature have been a-chieved for the coating. Thermal vacuum aging to the samples was carried out at 350 and 500℃ for 1h. The results show a good thermal stability. Microstracture and its dependence on temperature of the Nb, NbN and Nb-NbN single layers were investigated, respectively.

综述了近年来国际上兴起的氧化物ZrW2O8, Y2W3O12等新型负热膨胀材料的研究及其进展。对研究此类负热膨胀氧化物的重要性，其优异的负热膨胀性能以及它的结构特点、机制及可能的应用作了论述。建议我国加大此项课题的研究力度。

应用固态化学反应烧结方法，我们合成了纯立方相的、具有较强的各向同性负热膨胀性能的zr(Hf)W2O8氧化物材料，并通过变温X射线粉末衍射技术测量了其晶格常数随温度的变化，精确给出了zr0.5Hf0.5W2O8和zr0.7Hf0.3W2O8分别在低温和高温下的负热膨胀系数。其中zr0.5Hf0.5w2O8的负热膨胀系数高达8.94×10-6，接近最新文献报道的最高值。其负热膨胀效应可用刚性单元模型来解释。

The oxideZrW2O8displays unusual property of isotropic negativethermal expansionin alargewidetemperature range. which makes il have a number of imporlant potential applications The cubic Zr1-χHfχW2O8 (χ=0.03, 0.5, 0.7, and 1.0)weere synthesized by standard solid state reaedon technique The high and low temperature X-ray diffraclion analysis indicate that the substitution of the Hf4+ for Zr4+ only leads to reducing lbo lattice constants. and the chnges of negalive thermal expansion coeflicients are not obvious. The linear expansion toefficients of Zr-χHfχW2O8(χ=0. 03, 0.5, 0.7, and 1.0)ate about-6×10-6 K-1 in the temperature range of 298to973 K, whilethat of Zr0.5Hf0.5W2O8 is-9.6×10-6 K-1from 83 to 298 K The phase transition temperatures fromα-ZrW2OB toβ-ZrW2O8 structure were also determined by x-ray dil-fraction method Tbormogmvimetric analysis(TGA)exhibits thai Zr1-χHfχW2O8 is not hygroscopic in aln