A simple method for the preparation of pure hafnium

The separation of zirconium and hafnium by fractional precipitation as pyrophosphate¹ has been extended for the preparation of pure hafnium. The favourable uptake of hafnium, in spite of the decreasing tendency of partition factor when hafnium concentration is high, is maintained for all concentration of hafnium (relative to zirconium). Particularly significant is the fact that at very high concentrations of hafnium (at≈84%) the uptake of zirconium sharply falls. So pure hafnium can be prepared from natural zirconium by a simple process of eight or nine stages of fractional precipitations as pyrophosphate. This process yields reactor grade zirconium on the one side and pure hafnium on the other side.     

Solvent extraction separation of hafnium with 4-methyl-3-pentene-2-one

A new method for the extractive separation of hafnium from zirconium is presented. Zirconium is extracted with pure mesityl oxide from 4M nitric acid/4M sodium nitrate medium, followed by extraction of hafnium with mesityl oxide from 0.4M hydrochloric acid/2M ammonium thiocyanate medium. It is possible to accomplish clean separations of Hf from Zr in ratios from 1:20 to 1:200. The separation of hafnium from commonly associated elements such as scandium, yttrium, uranium, thorium, alkali and alkaline earth metals in 500:1 weight ratio to hafnium is also possible.     

Spectrophotometric study of a hafnium-hematein chelate

A spectrophotometric study of an analytically useful hafnium chelate of hematein is presented. The stoichiometry, the formation constant, the optimal pH range and the free energy of formation of the chelate are described. Beer's law is obtained in the range 3–25 μg of hafnium(IV).The red-brown chelate, of probable formula HfO[hematein]₂, can be used for the colorimetric determination of hafnium in the presence of zirconium, if the molar concentrations of both metals are the same. The molar absorptivity of the hafnium chelate is 5.8·10⁴ 1 mole^-1 cm^-1 at 520 nm and pH 2.0 at room temperature.     

铪元素及其同位素的发现：技术进步和思想发展的共同结晶

1869年，门捷列夫在第一张元素周期表中的锆元素后留出原子量为180的元素位置，预测铪与锆同族。1913年，原子序数和莫斯莱定律的提出揭示了铪元素在周期表中位置排列的实质，为铪元素的发现提供理论基础。20世纪20年代，玻尔理论的发展证实铪与锆同族，指导科学家从锆矿石中寻找铪元素。1923年，赫维西和科斯特借助X射线光谱技术发现铪元素，彰显了X射线光谱技术的独特价值。20世纪30年代以后，同位素理论和质谱技术促成了铪同位素的发现，使人们对铪元素有了新的认识。总之，铪元素及其同位素的发现是技术进步和思想发展的共同结晶。     

Studies on the extraction and determination of metals-I Extraction of hafnium into methyl isobutyl ketone and tributyl phosphate

The effect of various factors on the distribution of hafnium ( 5.60 × 10⁻⁴M) between different acids and methyl isobutyl ketone (MIBK) or tributyl phosphate (TBP) was studied by using ^{176 + 181} Hf as a tracer, when the extraction is made from 7.5–11M hydrochloric acid with an equal volume of IM TBP in benzene, hafnium is extracted quantitatively (>99%). The hafnium can be stripped with 1–3M hydrochloric acid.     

The influence of dissociation on simultaneous determination of zirconium and hafnium with Xylenol Orange

The molar absorptivities of the zirconium and hafnium Xylenol Orange (1:1) complexes are said to be similar in the acidity range 0.1-2.0M HCl. However, the absorbances obtained for the zirconium-Xylenol Orange complex in the acidity range 0.5-2.0M HCl are much higher than those for the same concentrations of hafnium. The absorbance differences are generally due to the higher stability of the zirconium complex at such acidities. Calculations based on the conditional stability constants of these complexes show the influence of dissociation on the results of simultaneous determination of zirconium and hafnium with Xylenol Orange.     

Simple spectrophotometric method for determination of zirconium or hafnium in selected molybdenum-base alloys

A simple analytical procedure is described for determining zirconium or hafnium in molybdenum-base alloys by formation of the Arsenazo III complex of zirconium or hafnium in 9 M hydrochloric acid medium. The absorbance is measured at 670 nm. Molybdenum (10 mg), titanium (1 mg), and rhenium (10 mg) have no adverse effect. No prior separation is needed. The relative standard deviation is 1.3-2.7%.     

Extraction properties of octaethyltetraamidopyrophosphate (OETAPP)

The extraction of thorium and hafnium was studied in the system of 0.1M OETAPP in CHCl₃/HCl or HNO₃ at acid concentrations of 1–10 M. It has been found by the dilution method that under the experimental conditions mono- and disolvates of thorium nitrate or hafnium chloride, the disolvate of thorium chloride or the monosolvate of hafnium nitrate are formed. The solvation and hydration energies of thorium chloride in the system of 1M ThCl₄ in 1M HCl−1M OETAPP in CHCl₃ as well as their difference were calculated.     

Selective Determination of Hafnium with Solid Surface Room Temperature Phosphorescence Optosensing

Abstract

An optosensing method for selective determination of hafnium has be developed. It is based on the phenomenon that when the complex formed by 8-hydroxy-5-quinolinesulfonic acid with hafnium is absorbed on the strongly basic anion exchange resin, the phosphor can produce room temperature phosphora-scence (RTP) in aqueous medium. The hafnium can be determined selectively in the presence of zirconium. The RTP intensity is linear up to 4×10^-5 M of hafnium, the detection limit is found to be 5×10^-8 M of hafnium.     

On the microscopic distinction of zirconium and hafnium

A method has been worked out for the microscopic distinction of zirconium and hafnium by means of the reagent of MARTINI, quinoline and ammonium thiocyanate. When using this reaction exactly as described by MARTINI, there generally is a difference in the shape of the primarily formed crystals. When using 25% formic acid as a solvent instead of HCl 1:2, hafnium, always gives a good reaction, whereas the zirconium reaction is prevented.     

The effect of hafnium alkoxysiloxane precursor structure of disperse phase on the morphology of nanocomposites based on polyaryleneetherketone

Amorphous polyaryleneetherketone tetrakis(phenyldiethoxysiloxy)hafnium or tetrakis(methyldiethoxysiloxy) hafnium are used as precursors of disperse phase of composites. One of the factors determining the morphology of filled polymer films and the size and shape of particles forming in polymer in situ is the activity of alkoxy groups of metal alkoxysiloxane precursor in hydrolysis and condensation reactions. When using tetrakis(phenyldiethoxysiloxy)hafnium instead of tetrakis(methyldiethoxysiloxy)hafnium, nanocomposites obtained via the sol-gel method are characterized by a uniform distribution of spherical particles of disperse phase.     

Solvent extraction of hafnium(IV) by N-benzoyl-N-phenylhydroxylamine

The extraction of hafnium(IV) tracer by N-benzoyl-n-phenylhydroxylamine (BPHA) from 1M perchloric acid has been investigated and stability constants have been calculated for the complexes Hf(BPHA)(i)((4-i)+) (i = 1cdots, three dots, centered4). It was found that variation of perchlorate concentration in the range 0.5-2.0M at constant acidity has no effect on the distribution of hafnium.     

Determination of hafnium by neutron activation, and variation in the Zr/Hf ratio of some granite masses

A fairly quick method for the separation of hafnium from irradiated rock samples is described and results of the hafnium determinations are reported. The distribution of zirconium and hafnium and the variation of the Zr/Hf ratio in three calc-alkali granite masses are discussed. Reasons are suggested for the observed decrease in the Zr/Hf ratio during the crystallization of igneous rocks.     

Determination of zirconium and hafnium with xylenol orange and methylthymol blue

Both Xylenol Orange and Methylthymol Blue are highly selective and sensitive reagents for zirconium and hafnium forming intensely red complexes in an acidic medium. The factors affecting the color formation have been studied. The properties of the complexes have been determined and compared. In general, zirconium forms a more stable complex with the two dyes than hafnium, and Xylenol Orange forms a stronger complex with either zirconium or hafnium than Methylthymol Blue. Hydrogen peroxide can completely mask the zirconium complexes of either dye but only slightly affects the hafnium complex of Xylenol Orange. Zirconium and hafnium can both be determined without separation using peroxide as a masking agent and sulfate as a demasking agent. A bleaching reaction was observed when small amounts of hafnium were added to the red zirconium complex of Methylthymol Blue in 2.4 N perchloric acid or a small amount of zirconium was added to the red hafnium complex of Methylthymol Blue solution at pH 2 to 3.     

金属有机化合物的分析(Ⅴ)——双(烷基环戊二烯基)二卤化钛、锆、铪的纸色谱与核磁共振谱关系的研究

文献报导,仅Subbotina,A.I.等用纸色谱法研究了Cp₂TiCl₂与CpTiCl₅二化合物的分离。我们试图用薄层色谱法分离双(烷基环戊二烯基)二卤化钛、锆、铪化合物,未获成功。改用纸色谱法,取得良好的效果,并对各类化合物所得R_f值与它们的核磁共振谱的δ值之间的变化关系作了研究。     

Possibilities of using hafnium neutron filters for reactor NAA with fast neutrons

The possibilities of using hafnium irradiation filters for reactor fast neutron activation analysis have been evaluated. The filter characteristics of hafnium for this application are discussed and compared with some traditional filter materials. The main advantage for hafnium is its ability to remove a great portion of the slowing down neutrons, which may enhance the sensitivity of determination via threshold reactions.     

Thermodynamics of oxidation of zirconium and hafnium borides

Gibbs thermodynamic potentials of oxidation of zirconium and hafnium diborides with molecular and atomic oxygen and nitrogen monoxide were calculated for a temperature range of 20–2500°C. Oxidation of zirconium and hafnium borides with atomic oxygen was found to be the most expected reaction. The probability of oxidation is lower for zirconium boride than that for hafnium boride.     

Cation-exchange separation of hafnium and zirconium from accompanying ions

Hafnium and zirconium are not retained on the strongly acidic cation-exchange resin Dowex 50 from a mixture consisting of methanol and 12M nitric acid (19:1) which is 0.1M in trioctylphosphine oxide. On the other hand most other elements investigated are strongly adsorbed on the resin from this medium so that they are readily separated from hafnium and zirconium. These elements include titanium, rare earths, alkali metals, alkaline earth metals, iron, cobalt, manganese and zinc. This separation technique has been found to be suitable for the separation of tracer and milligram amounts of hafnium and zirconium from accompanying metal ions. If in place of methanol other organic solvents such as acetone, tetrahydrofuran and methyl glycol are used the selectivity of the separation of zirconium and hafnium from the other elements is decreased. The same effect is observed when hydrochloric acid is used in the mixtures instead of nitric acid.     

X-ray determination of traces of hafnium in zirconium metal or traces of zirconium in hafnium metal after separation by ion exchange

A method is proposed for the determination of traces of hafnium in zirconium metal or zirconium in hafnium metal. The trace metals are first separated from the matrix metals on an ion-exchange column and then determined by X-ray analysis.     

Thermal neutron activation analysis of hafnium in zircaloy with a Van de Graaff accelerator

Thermal neutron activation analysis of hafnium in zircaloy was investigated with a Van de Graaff accelerator. Thermal neutrons were obtained by moderating Be−D fast neutrons with paraffin blocks.^179mHf isotope with a half-life of 18.6 s, produced by¹⁷⁸Hf(n, γ)^179mHf reaction, was utilized in the present analysis. This method made it possible to analyze hafnium rapidly and non-destructively by using scandium as an internal standard material. Several tens to hundreds of ppm of hafnium in zircaloy samples were determined within 2 minutes with a precision of about ±1%.