Y3NbO7 transparent ceramic series for high refractive index optical lenses

A₂B₂O₇ and A₃BO₇ transparent ceramic families are potential materials for optical lenses because of their high refractive index. Although nonstoichiometry is widely present in these material families, its effect on refractive index and optical properties has not yet been fully studied. In this study, optical properties are reported for the Y₃NbO₇ transparent ceramic series, Y_1−xNb_xO_1.5+x (x = 0.20, 0.22, 0.24, 0.25, 0.26), which were fabricated by a pressureless pre-sintering and a hot isostatic pressing post-sintering treatment. The refractive index increases from 2.04 to 2.10 (at 587.6 nm) as the Nb content x increases, which is mainly attributed to the variation in the oxygen ion/vacancy ratio. The Abbe number is larger than 40, showing a decreasing trend as the Nb content x increases. The specimen with x = 0.24 has the highest inline transmittance, which were 62% and 76% at 587.6 and 2000 nm, respectively, for a 1-mm-thick specimen. Through the approach of nonstoichiometry, Y_1−xNb_xO_1.5+x series exhibit balanced properties of refractive index, Abbe number, and transmittance, which can be considered as a promising candidate for high refractive index optical lenses.     

Electrical and thermophysical properties of mechanochemically obtained lanthanide hafnates

This contribution presents the synthesis and thermophysical characterization of seven lanthanide hafnates Ln₂Hf₂O₇ (Ln=Sm³⁺, Eu³⁺, Gd³⁺, Dy³⁺, Y³⁺, Ho³⁺, Yb³⁺); the title samples were prepared at room temperature by mechanically milling stoichiometric mixtures of the corresponding elemental oxides. Irrespective of the lanthanide ion involved, milling promotes the formation of highly disordered fluoritelike materials. Postmilling thermal treatments facilitate the formation of the fluorite ordered derivative, the pyrochlore structure, but only for the larger lanthanides (Sm³⁺, Eu³⁺, Gd³⁺). Impedance spectroscopy measurements revealed that these materials show a moderate‐to‐good oxygen ion conductivity at high temperatures; furthermore, those adopting the pyrochlore structure give higher σ_dc and lower E_dc than their fluorite analogues (σ_dc at 750°C>10^?3 S·cm^?1 vs <5·10^?4 S·cm^?1, respectively). The same trend also holds for the thermal resistivity at high temperatures; the highest thermal resistivity and thus, lowest κ was obtained for Eu₂Hf₂O₇ (κ~1.3·W·m^?1·K^?1 at 800°C). Therefore, Ln₂Hf₂O₇ phases might be attractive component materials for electrochemical devices and thermal insulating coatings.     

高炉炉缸中心温度偏低的操作

达钢5号高炉一代炉龄后期,高炉冷却系统严重损坏,导致冷却不均匀,高炉加风到一定量时,高炉就会出现管道气流,严重影响高炉的正常生产。通过采用调节风口面积来保证风速活跃炉缸、在原燃料较好的情况下取消中心加焦、在矿石之后或矿石中间加萤石从而保护高炉冷却壁和适当扩大风口进风面积保证风量等方法,使炉缸中心温度逐步回升,高炉抗干扰能力明显增强,高炉各种指标明显好转,从而保证了高炉的稳定顺行,同时也保护了高炉炉衬。     

河南陈楼萤石矿床M3-I矿体原生晕特征及深部找矿预测

为探究河南陈楼萤石矿床M3-I矿体原生晕特征及深部成矿潜力,对矿体189件样品测试数据进行分析研究。结果表明,M3-I矿体有效的原生晕指示元素组合为F、Ca、Y、Ag、As、Sb、Mo、Ba、Ce;矿体原生晕轴向分带序列为Mo-Sb-Ca-F-Ag-Ce-As-Ba-Y,具明显的"反向分带"特征,矿体剥蚀系数具振动波状变化趋势,矿体向深部有较大延伸或存在盲矿体。文章建立了矿体原生晕叠加理想模型,在484 m中段至364 m中段存在一个矿体B的头部叠加在矿体A的下部,矿体B在334 m中段以下仍有较大延伸。     

常温浮选萤石研究

研究采用一种新型捕收剂XJD—01实现了在常温条件下的萤石浮选。浮选效果明显优于油酸加温浮选；采用粗磨浮选抛尾-粗精再磨精选-中矿单独精选的流程．获得了CaF2回收率为49．20％的二级萤石精矿和CaF2回收率为37．94％的四级萤石精矿两种精矿产品。在精选循环中还通过添加硫化钠有效地降低了精矿中的杂质含量。     

熊耳山地区铁炉坪银铅矿床成矿时代——来自萤石Sm-Nd测年证据

铁炉坪矿床的矿石特征及围岩蚀变分带均反映了矿床热液成因特点。近年来,萤石Sm-Nd同位素体系已经被成功地应用于热液矿床中的成矿事件年龄。该项研究在铁炉坪矿区切穿矿脉的萤石脉中选取萤石进行Sm-Nd年龄测定,获得等时线年龄为(125±18)Ma,该数据与熊耳山矿田内有关岩体和矿床的近矿蚀变岩同位素年龄结合,不仅对铁炉坪矿床主成矿时代具有一定的限制作用,对于研究熊耳山矿田内岩浆—热液活动演化或成矿持续时间亦具有重要的参考价值。     

High-entropy fluorite oxides: Atomic stabiliser effects on thermal-mechanical properties

High-entropy oxides Hf_0.25Zr_0.25Ce_0.25Gd_0.125X_0.125O_2-δ (X = Ca, Ti or Si) have been fabricated via solid-state reactions, in which the co-stabiliser X was intentionally chosen for its significant atomic mass and size difference from Gd. The single phase of these cubic fluorite oxides with dense microstructures has been confirmed by XRD, EDS and TEM characterizations. These phases are thermally stable without the appearance of secondary phase and phase separation within the temperature range studied (up to 1200 °C). Compared to yttria-stabilised zirconia (YSZ), which is used in the current commercial thermal barrier coatings, these fluorite oxides have higher coefficients of thermal expansion and lower thermal conductivities. They also exhibit comparable Young’s modulus and hardness with other reported high-entropy fluorite oxides. The fluorite oxides reported in this study are promising to improve the thermal expansion matching between ceramic topcoat and metal substrates for thermal barrier coating applications.     

大别山地区萤石矿床控矿因素及成矿规律

文章通过对河南省大别山地区萤石矿床的综合研究,系统地总结了矿床(点)成矿规律,认为该区域矿床类型多属产于酸性—中酸性岩浆岩接触带的热液充填型。脆性岩石更利于断裂构造的形成且易于热液充填形成萤石矿床,构造线的走向对矿床形成起控制作用。这些研究为该区今后开展萤石矿成矿预测及地质找矿工作提供了参考。     

贵州某萤石矿地质特征及矿床成因

贵州贞丰县新近开发的某萤石矿具有较大规模,萤石矿体形态呈现为层状、似层状,局部呈透镜状产出,矿体走向北西,长约3200 m,倾向与背斜轴两翼近似平行,沿倾向延深约200 m,矿体厚度2.00～6.90 m。文章通过对区域地质、矿区地质、矿体地质特征的研究和分析,认为该萤石矿的主要成矿要素为沉积盆地、灰岩、火山喷发活动、褶皱,在各成矿要素的共同作用下,形成了二叠系上统龙潭组第一段(P_3l~1)和二叠系中统茅口组(P_2m)之间的构造蚀变体(Sbt),发育出了多种矿物的矿体,含萤石矿、锑矿、金矿等,是一处沉积改造型萤石矿。这些矿体的共同特点是沿断裂、背斜平行分布,以背斜轴部为中心,两侧延伸,为矿山的找矿工作指明了方向。     

稀相高温萤石粉气力输送技术的应用

为证实稀相正压气力输送系统用于高温萤石粉输送的可行性 ,进行了小流量、短距离输送的工程设计和实践 ,通过调试分析了运行中出现的问题 ,提出了解决方案 ,推荐了料气混合比、输送气流流速等几个重要的设计参数。实践表明 :该技术用于小型输送系统 ,具有很高的性价比 ,并且操作简单 ,具有推广应用价值