Thermoluminescence dosimetry of rare earth doped calcium aluminate phosphors

The thermoluminescence (TL) properties of calcium aluminate (CaAl²O⁴) doped with different rare earth ions have been studied and their suitability for radiation dosimetry applications is discussed. It is observed that monocalcium aluminate doped with cerium is a good dosimeter having linear response up to about 4 kGy of radiation doses. Dopant concentration of 0.25 mol% cerium gives maximum TL emission. The well-defined single peak observed at 295°C can be advantageously used for high temperature dosimetry applications.     

钾长石中钾的加压浸取方法

研究了消石灰和钾长石的加压反应条件，获得９０％或更高的提取率。测得浸取反应级数为１．５级，活化能为４５．５ＫＪ／ｍｏｌ。比较了正长石型和微斜长石型两种典型钾长石的预处理条件，指明了浸取残渣的利用途径。     

Multi-scale study of the polishing behaviour of quartz and feldspar on road surfacing aggregate

In this paper, the exact mechanisms as to how petrographic properties of aggregate influence the polishing behaviour quantitatively were identified. Since the aggregate is composed of the different rock-forming minerals, the analyses conducted in this research project focused not only on the aggregate but also on crystals/minerals. The hardest and most abundant rock-forming minerals found on earth – quartz and feldspar – were investigated with polishing tests with the Aachen Polishing Machine on granite aggregates from four sources which exhibit different mineralogical properties. Changes of the aggregate texture and minerals were studied based on texture measurements and skid resistance measurements obtained by means of the Pendulum Test and the Wehner/Schulze device. The influences of mineral composition and crystal size on the changes of the micro-texture and skid resistance of the aggregates were determined by comparing the four granites. The polishing and wearing behaviour of quartz and various feldspars (albite, microcline and plagioclase) were characterised quantitatively by means of a spectral analysis and abrasion analysis. The results show that the micro-texture of exposed minerals is greatly smoothened on wavelengths from 100 to 500 μm. Fine-grained quartz or feldspar crystals tend to be rougher than medium of large-sized crystals. Quartz exhibits more favourable properties than feldspar between 100 and 500 μm; this is especially true for fine quartz crystals. The correlation that more content of coarse-grained quartz leads to high friction value cannot be proved in this research.     

Study on the growth of potassium titanate nanostructures prepared by sol-gel-calcination process

Potassium titanate (K₂O·nTiO₂, n = 4 or 6) nanostructures were prepared by a sol-gel method. The growth of potassium tetratitanate (K₂Ti₄O₉) and potassium hexatitanate (K₂Ti₆O₁₃) nanorods was obtainable in a range of Ti(OC₂H₅)₄/CH₃OK molar ratio from 1 to 2 and heating temperature from 800 °C to 950 °C with different morphologies and size distributions of the products. The role of pre-crystallized K₂O phase on the growth behavior of K₂O·nTiO₂ (n = 4 or 6) nanostructures was demonstrated by structural and morphological observation.     

常压放电低温等离子体辐射特性测量实验

本文在自行设计的放电电极板上实现常压下的空气辉光放电(APGD),产生出一薄层的低温等离子体,利用光栅单色仪及测试声强和温度的仪器对所产生的等离子体的光辐射、声辐射和热辐射特性进行实验测量.数据处理后的分析结果表明,该APGD等离子体的光辐射强度及声辐射和热辐射强度,以及总辐射能量基本上都与电极板的加载功率呈线性关系,而且各种形式的能量各占比例是一定的.研究结果表明可以通过沿面APGD的辐射特性与加载功率之间的关系来描述APGD等离子体的特性,以及控制等离子体的产生量.     

Ammonium and potassium removal for anaerobically digested wastewater using natural clinoptilolite followed by membrane pretreatment

On the basis of the wastewater characteristic of anaerobically digested wastewater, this work studied the individual and simultaneous adsorption of ammonium and potassium ions by the natural clinoptilolite. Langmuir, Freundlich, Langmuir-Freundlich, and Toth model were employed to fit the experimental isotherm data and the fitting performances of different models were compared. Both the individual and simultaneous adsorption kinetics of ammonium and potassium were studied at various pHs and temperatures. The individual adsorption of ammonium was very fast and potassium uptake was even faster than that of ammonium. The adsorption approached equilibrium within 1h in most cases. Five models, including pseudo-first-order, pseudo-second-order, Vermeulen's model, squared driving force model and Elovich equation were used to fit the individual and simultaneous adsorption kinetics of ammonium and potassium. The validities of the fittings for the ammonium and potassium adsorption kinetics were also evaluated.     

Elastic-plastic-brittle transitions of potassium dihydrogen phosphate crystals: characterization by nanoindentation

Potassium dihydrogen phosphate (KDP) crystals are widely used in laser ignition facilities as optical switching and frequency conversion components. These crystals are soft, brittle, and sensitive to external conditions (e.g., humidity, temperature, and applied stress). Hence, conventional characterization methods, such as transmission electron microscopy, cannot be used to study the mechanisms of material deformation. Nevertheless, understanding the mechanism of plastic-brittle transition in KDP crystals is important to prevent the fracture damage during the machining process. This study explores the plastic deformation and brittle fracture mechanisms of KDP crystals through nanoindentation experiments and theoretical calculations. The results show that dislocation nucleation and propagation are the main mechanisms of plastic deformation in KDP crystals, and dislocation pileup leads to brittle fracture during nanoindentation. Nanoindentation experiments using various indenters indicate that the external stress fields influence the plastic deformation of KDP crystals, and plastic deformation and brittle fracture are related to the material’s anisotropy. However, the effect of loading rate on the KDP crystal deformation is practically negligible. The results of this research provide important information on reducing machining-induced damage and further improving the optical performance of KDP crystal components.The full text can be downloaded at https://link.springer.com/article/10.1007/s40436-020-00320-3     

Ag/Cu共渗不锈钢表面的微观结构及抗菌性能研究

以银铜合金为靶材,利用辉光等离子体在AISI304不锈钢表面同时渗入银和铜,制备性能优良的抗菌不锈钢。对渗层的形貌、化学组成、耐蚀性能和抗菌性能进行了研究,结果表明,所得渗层在不锈钢表面分布均匀,Ag/Cu元素质量比为4.9∶3;不锈钢表面渗层腐蚀电位由-0.103V提高到0.07V,自腐蚀电流密度从1.66×10-7A/cm2降至5.813×10-9A/cm2,耐腐蚀性能有所提高;渗层对大肠杆菌和金黄色葡萄球菌的杀菌率均达100%。     

探讨复混肥钾含量检验结果准确度的影响因素

本文从四苯硼酸钾重量法测定复混肥钾含量的分析步骤入手,探讨影响检验结果准确度的因素。     

双层辉光离子渗镀钽

介绍了一种新型离子渗镀钽的工艺方法。较好解决了渗镀钽时供给活性钽粒子的总是比方法工艺简单，操作方便，效率高。为充分利用和节约使用昂贵的钽探索了一条实用可行的途径。     

火焰原子吸收光谱法测定浸渍液中钾、钙、铜、铁

提出了用空气-乙炔火焰原子吸收光谱法进行镉镍电池浸渍液中钾、钙、铜、铁含量的测定,介绍了钾、钙、铜、铁最佳测定条件及呈良好线性范围的浓度,同时对样品消化处理条件及在测定样品中的干扰因素进行了综合考虑。该方法具有很好的灵敏度和重现性,具有方法步骤简单、操作容易、干扰少等特点。测定样品钾、钙、铜、铁含量的相对标准偏差均小于1.0%。标准加入回收率均在97.0%~100.0%范围内。达到了实验室分析与质量的控制。适用于镉镍电池浸渍液中含有较多共同被测离子钾、钙、铜、铁的生产现场控制分析和样品系统分析。     

Enhanced piezoelectric properties of potassium niobate single crystals with fine engineered domain configurations

Potassium niobate (KNbO₃) single crystals were grown by a top seed solution growth (TSSG) method. At first, the electric field was applied along [0 0 1]_c (cubic notification system) direction of KNbO₃ crystals to induce the engineered domain configurations into KNbO₃ crystals. Prior to domain engineering, the piezoelectric properties of [0 0 1]_c oriented KNbO₃ single-domain crystals were measured. These measured values were completely consistent with the calculated apparent d₃₁ and d₃₂. Finally, the engineered domain configurations were induced into KNbO₃ crystals. As a result, piezoelectric properties increased with decreasing domain sizes of the engineered domain configuration.     

Synthesis and structural characterization of copper incorporated manganese oxide OMS-2 materials synthesized via potassium birnessite

Metal ion incorporated tunnel structured manganese oxide OMS-2 has been recently exploited as potential materials in the field of heterogeneous catalysis Cryptomelane type copper incorporated manganese oxide OMS-2 type tunnel structured material has been synthesized by hydrothermal method using birnessite-containing potassium as a parent precursor instead of using birnessite containing sodium. Crystal structure and thermal stability of as synthesized materials are characterized by using XRD and TGA. Surface area and morphology of newly synthesized copper incorporated OMS-2 type materials have been studied by BET and SEM analyses.     

Effect of surface treatment with potassium persulfate on dispersion stability of multi-walled carbon nanotubes

Muti-walled carbon nanotubes (MWCNTs) were treated with different concentrations of potassium persulfate (KPS; K₂S₂O₈) to improve their dispersion stability, which were characterized by thermal gravimetric analysis, ultraviolet/visible spectroscopy, field emission scanning electron microscopy and field emission transmission electron microscopy. The amount of sulfate groups on the MWCNTs increased with increasing KPS concentration, which enhanced the hydrophilicity, but deteriorated the dispersion stability. The optimal KPS concentration for the best dispersion stability of the KPS-treated MWCNTs was 0.01 M.     

常压辉光放电等离子体制备荧光碳纳米粒子

采用常压辉光放电等离子体制备了超细荧光碳纳米粒子。分别采用聚乙二醇(PEG)2000和聚乙烯吡咯烷酮(PVP)20000作为表面活性剂和表面修饰剂,利用辉光放电等离子体射流产生的大量高能电子等活性粒子分解乙醇溶液制备碳纳米粒子。采用透射电子显微镜和荧光分光光度计对生成物的形貌和荧光特性进行了检测。结果表明,生成物为石墨相的荧光碳纳米颗粒。随着反应时间的延长,生成物的荧光强度增强;采用PEG-2000修饰后产物的荧光强度比采用PVP-20000更强;丝状放电模式下生成物的荧光强度高于辉光放电模式。制备的碳纳米颗粒的荧光量子产率为46.58%。     

K_2O对白榴石生成的影响

以钾长石、碳酸钾为主要原料,设计高、中、低3种不同钾含量的配方固相合成白榴石晶体,探讨K2O的含量对白榴石生成的影响。通过实验发现,适当地提高配方中K2O的含量对白榴石生成是有利的,但当配方中K2O远高于其在白榴石中的理论含量时,其在高温下完全熔融成玻璃熔态物质,没有白榴石晶体的生成;当K2O的含量为25.4%,在1250℃熔融保温60min,其热膨胀系数为20.74×10-6℃-1(30～700℃),平均晶粒尺寸为3μm。     

Effect of waterglass on water stability of potassium magnesium phosphate cement paste

This paper studied the influence of waterglass on the early water stability of potassium magnesium phosphate cement (MKPC). Mass loss and residual strength were used to reflect the water stability of MKPC pastes exposed to different curing conditions. Experimental results indicated that the addition of waterglass could accelerate early hydration of MKPC, reduce the crystallinity of hydration products, and improved the pore structures significantly. The early water stability of MKPC was greatly improved due to the significant decreased dissolution of hydration products and pore volume of hardened MKPC.     

SiH4辉光放电的质谱研究

本文报道了采用四极质谱计在制备ａＳｉ∶Ｈ薄膜的ＰＣＶＤ系统中对ＳｉＨ４射频辉光放电进行在线的质谱研究。获取了在不同电离电压下的ＳｉＨ４质谱和不同辉光放电功率下的ＳｉＨ４质谱。     

Investigation into the room temperature creep-deformation of potassium dihydrogen phosphate crystals using nanoindentation

It has been a tremendous challenge to manufacture damage-free and smooth surfaces of potassium dihydrogen phosphate (KDP) crystals to meet the requirements of high-energy laser systems. The intrinsic issue is whether a KDP crystal can be plastically deformed so that the material can be removed in a ductile mode during the machining of KDP. This study investigates the room temperature creep-deformation of KDP crystals with the aid of nanoindentation. A stress analysis was carried out to identify the creep mechanism. The results showed that KDP crystals could be plastically deformed at the nanoscale. Dislocation motion is responsible for creep-deformation. Both creep rate and creep depth decrease with decrease in peak force and loading rate. Dislocation nucleation and propagation bring about pop-ins in the loaddisplacement curves during nanoindentation.The full text can be downloaded at https://link.springer.com/article/10.1007/s40436-018-0234-9     

The influence of composition on optical properties of ferroelectric potassium lithium niobate single crystals

Homogeneous crack-free Potassium Lithium Niobate (KLN) single crystals with different Li content were grown up by the TSSG technique. Lattice vibration spectra of these samples were investigated using Raman spectroscopy. The results showed that characteristic Raman spectra of the [NbO₆]⁷⁻ octahedral ions were strikingly influenced by the Li ions. Thus, the symmetric bend vibration mode ν₅ of the KLN sample with higher Li content was split into three Raman peaks, while the sample with lower Li content displayed a single peak, supporting that the bend vibration modes of the [NbO₆]⁷⁻ octahedrons were obviously perturbed by Li ions occupying C-sites. Enhanced Raman peak intensities of the KLN sample post-annealed at 900 °C for 24 h evidenced that content of defects in KLN crystal might be reduced. The transmittance spectra showed that the crystal with higher Li content had better transmittance intensity.