A Brief History of Tantalum

In 1801, Charles Hatchett, a British chemist, analyzed a collection of minerals preserved in British museums and discovered a new element, Columbium (later renamed Columbium), in honor of Colombia, where the ore was made. In 1802, Anders Gustav Ekberg, a Swedish chemist, crystallized tantalum from niobium in Scandinavia.

tantalum

Because tantalum and niobium have very similar properties and specific gravity, many scientists at the time mistakenly believed that the two elements were the same substance. In 1844, German chemist Rosser used chemical methods to prove that tantalum and niobium are two elements.

In 1903, pure tantalum was produced for the first time. Tantalum capacitors manufactured with tantalum, with high capacity, small size, and high reliability, are still irreplaceable components in the electronics industry.

With the continuous miniaturization and portability of global electronic products since 1990, tantalum capacitors have been widely used. Today, tantalum capacitors are shipped about 100 billion times a year.

There are three major Tantalum companies operating in the world today: the US Cabot group, the German HCST group, and China Swing Orient Tantalum Industry Co., Ltd. These three companies produce more than 80 percent of the world’s tantalum products.

Tantalum used in electronics accounts for 60% of total production. But tantalum is not just used as a capacitor. Nickel-tantalum alloy is widely used in advanced aero-engine blades.

Before 2007, the world’s major sources of tantalum were Australia and Brazil. In 2000, the world’s major producing countries produced approximately 1,100 tons of tantalum concentrate, of which Australia accounted for 45%, mainly at Greenbush and Wodgina mines, while Brazil accounted for 17%, Rwanda 12%, and Congo 9%. At the time, Congo was in the midst of a second civil war, and large numbers of rebels smuggled Congolese tantalum mines into Rwanda for export under the Rwandan name.

In 2003, the Democratic Republic of Congo (DRC) signed a peace agreement with rebels in the east that ended a second civil war. But the rebels in eastern DRC have not really laid down their arms, and are no longer engaged in open, large-scale fighting with government forces. The rebels continue to splinter and regroup, with new rebels popping up every now and then. Congo and the surrounding great lakes countries are backward industrially, all guns and ammunition are imported, and any imports must be accompanied by foreign currency. Both the rebels and the great lakes countries are eyeing tantalum as a new source of revenue.

Tantalum has supported the fighting in eastern Congo. Subsequently, the world’s major tantalum deposits have undergone a stunning reversal. Cheap Labour in eastern Congo, using baskets and hammer shovels, has been digging holes in droves, defeating Australian tantalum miners armed with big mining machines. Australia’s tantalum mines, unable to compete with a shoveled army of poor Congolese, went bust and quit altogether.

In 2007, Rwanda and the Democratic Republic of Congo had the world’s largest and second-largest share of tantalum mines. On January 9, 2007, Apple’s Steve Jobs launched the first iPhone. In 2014, most of the world’s tantalum mines were exported by Rwanda and DRC, including 600 tons from Rwanda and 200 tons from DRC, accounting for more than 70% of the world’s tantalum output.

In 2010, the U.S. implemented the Dodd-Frank Wall Street reform and consumer protection act, which requires U.S. companies that purchase tantalum products and other materials to investigate their supply chains and determine that the materials are not sourced from conflict zones in the democratic republic of Congo. The United States describes minerals from the eastern DRC region that have been repeatedly contested by rebels and government forces as conflict minerals.

Rwanda, Tanzania, and Bolivia are investing in the construction of tantalum and niobium smelting plants due to the implementation of the Dodd-Frank Act in the US and the Conflict Minerals Regulation in the EU. It is expected that the supply of tantalum raw materials in the world, especially in Africa, will become more and tighter in the future.

Stanford Advanced Materials (SAM) is a trusted supplier of high-quality capacitor grade tantalum powdercapacitor grade tantalum wire, and a wide variety of tantalum products. Please visit https://www.samaterials.com/ for more information.

Tracing Tantalum from Mine to Manufacture

tracing tantalum

Step 1: Mining in Rwanda, Africa

Step 2: Refining in Macedonia, Greece

Step 3: Manufacturing in the USA

Step 4: Shipping from the USA

Step 5: Final Assembly in China, Asia

Step 6: Distribution to Consumers

The African country of Rwanda is the world’s biggest supplier of tantalum: a rare mineral used to make capacitors found in devices like smartphones and laptops. In 2014, most of the world’s tantalum mines were exported by Rwanda and DRC, including 600 tons from Rwanda and 200 tons from DRC, accounting for more than 70% of the world’s tantalum output.

Tantalum ore can be refined into tantalum metal and processed into various tantalum products, which are widely used in modern industry. For example, tantalum crucible is used in manufacturing super-alloys and electron-beam melting; tantalum ribbon can be used as a light source material for halogen lamps, sodium lamps, auto lamps, quartz glass lamps, etc.; tantalum plate is used in manufacturing superalloys and electron-beam melting, and so on.

Stanford Advanced Materials supplies high-quality tungsten products to meet our customers’ R&D and production needs. Please visit https://www.samaterials.com for more information.

What is the Prospect of New Tantalum Niobium Materials?

Rare metal material technology is one of the most important subjects in the field of material science and engineering in the new century, and it is the key material for the development of high and new technology, while tantalum niobium material plays an important role in this process. The development of modern high technology, such as information technology, new energy technology, space technology, biological technology, and superconducting technology, is closely related to rare metal materials, especially tantalum and niobium.

technology and media

Tantalum niobium materials have more and more development space in the field of high technology. Firstly, tantalum and niobium capacitors are expanded to the high-capacity field. Secondly, the cutting tools of cemented carbide are developing towards the direction of the super hard and fine tip, and the application market is expected to keep a steady climb. Thirdly, tantalum-niobium is applied in the aerospace industry, and tantalum-niobium alloys and other special alloys will continue to be developed steadily.

In recent years, the demand for special niobium steel continues to grow. Special superconducting materials will be widely used in magnet materials and high and new computing technologies, and are being further developed. New applications of tantalum and niobium materials will be developed continuously. According to the development process of the world’s high-tech industry, the tantalum and niobium industry will continue to grow by more than 12% in the next 5-10 years.

Main products and functional properties

At present, the main products of the tantalum and niobium industry include tantalum powder (capacitor grade, metallurgical grade), tantalum wire, tantalum carbide, tantalum, and tantalum alloy ingots, tantalum and tantalum alloy processing materials (tantalum plate, strip, tube, bar, wire), tantalum target material, tantalum oxide (industrial, optical glass, high purity), lithium tantalate single crystal; Niobium powder (capacitor grade, metallurgical grade) niobium sheet, niobium and its alloy ingots, niobium and its alloy adding materials (plate, strip, tube, rod, wire), niobium oxide (electrical grade, industrial, light glass, high purity), niobium carbide, lithium niobate single crystal, niobium and its alloy superconducting materials, etc.

About 60% of the world’s tantalum is used to make tantalum capacitors. Tantalum powder and wire are the key materials for manufacturing tantalum capacitors, which are widely used in mobile phones, computers, digital products, automobiles, aerospace electronics, and other fields. Tantalum and niobium targets are used in semiconductor devices and liquid crystal display technology, niobium oxide, niobium powder, and niobium wire are used in manufacturing ceramic capacitors and niobium capacitors.

Superalloys can be produced by adding tantalum or niobium to tungsten, molybdenum, nickel, cobalt, vanadium and iron-based alloys or by adding other metal elements to tantalum and niobium. Superalloys are important structural materials for aerospace engines, land-based airflow turbine engines, modern weapons, and harsh industrial environment facilities. Tools and drill tools made of carbides such as tantalum carbide and niobium carbide can withstand a high temperature of nearly 3000℃, and their hardness can be comparable with diamond.

Since niobium and tantalum have good superconductivity, adding niobium and tantalum into the materials used for making wires and cables can greatly reduce the loss of electric energy and thus save electric energy. Tantalum niobium is a high-quality material resistant to acid and liquid metal corrosion. It can be used in digesters, heaters, coolers, and various devices and utensils in the chemical industry. In addition, the tantalum niobium and its alloy can also be used as nuclear reactor cladding materials and high-energy physics superconducting devices. Moreover, tantalum is ideal bio-adaptive material and is widely used in medical surgery.

Stanford Advanced Materials supplies high-quality tantalum niobium products to meet our customers’ R&D and production needs. Please visit http://www.samaterials.com for more information.

Overview of the Properties of Tantalum Compounds

Tantalum oxide

The most useful tantalum oxide is tantalum pentaoxide (Ta2O5). Ta2O5 is white fine crystal powder, tasteless and odorless, with a specific gravity of 8.71g/cm3 and a melting point of 1870℃. Tantalum is amphoteric but apparently acidic, insoluble in water, most acids, and bases, but slowly dissolved in hot hydrofluoric and peroxy acids.

tantalum oxide

Ta2O5 has both α and βvariants, and its transition temperature is 1320℃, beyond which Ta2O5 turns white to gray. Different oxides have different crystal structures, so their lattice constants, densities, and other properties are obviously different. It is known that amorphous Ta2O5 begins to crystallize at 500℃ to form a low-temperature crystal (T type), converts to a temperature crystal (M type) at 830℃, and forms a high-temperature crystal (H type) at more than 830℃.

Tantalum halide

In tantalum halides, halogens in high-priced pentahalides are more easily replaced by oxygen to form stable halogen oxides. Most of the halogens of tantalum are volatile compounds, among which fluoride is well soluble in water and only partially hydrolyzed.

Tantalum(V) chloride (TaCl5) is a white powder and yellow when it is not pure. It has a melting point of 220℃, a boiling point of 223℃-239℃, and a specific gravity of 3.68g/cm3. It is volatile and has strong moisture absorption. It is unstable at high temperatures and decomposes to form metal tantalum at vacuum temperatures above 800℃. In addition to the high-priced TaCl5, the low-priced chlorides of tantalum include TaCl4, TaCl3, and TaCl2, which are volatile substances.

Tantalum bromide (TaBr5) is an orange crystal, soluble in water and hydrolyzed, soluble in methanol, ethanol, and CCl4, and soluble in aniline and liquid ammonia for reactions. Tantalum iodide (TaI5) is a black crystal that can be heated to sublimate without decomposition and readily hydrolyzes in moist air, releasing hydrogen iodide.

Tantalum carbide

Ta2C and tantalum carbide (TaC) are the main carbides of tantalum, and Ta2C has both alpha -Ta2C and beta -Ta2C isomers. TaC is a dark brown powder with a melting point of 3880℃, a boiling point of 5500℃ and a density of 14.4g/cm3. It has good chemical stability and can only be dissolved in mixed solutions of nitric acid and hydrofluoric acid. The carbide of tantalum is not easy to be oxidized in the air when the temperature is lower than 1000 ~ 1100℃. Nitrogen compounds are readily formed by the action of nitrogen or ammonia.

Tantalum hydride

Tantalum hydrides are very stable at room temperature in the air. Hydrogen is released by decomposition when heated to 1000 ~ 1200℃ under a high vacuum. Below 350℃, tantalum almost has no interaction with hydrogen, and the reaction speed increases with the increase of temperature. At a certain temperature and pressure, the maximum hydrogen content in tantalum hydride corresponds to H/Ta of 0.02 ~ 0.08(TaH0.2 ~ TaH0.8).

Tantalum nitride

There are three kinds of tantalum nitride: TaN, Ta2N, and Ta3N5. Tantalum nitrite is a bluish-gray powder with a melting point of 2980 ~ 3090℃ and a density of 14.4g/cm3. It is insoluble in nitric acid, hydrofluoric acid, and sulfuric acid, but soluble in hot alkaline solution and releases ammonia or nitrogen. Tantalum nitride generates oxides when heated in air, releasing nitrogen.

Tantalum selenite

TaSe2, its resistivity is 2.23 x 10-3 Ω. Cm, with the relative friction coefficient of 0.08 in the air at room temperature, the oxidation temperature of 600 ℃ in air, and the decomposition temperature of 900 ℃ in a vacuum.

Tantalum silicone

The main silicide of tantalum is TaSi2, and there are also some other compounds such as Ta2Si and Ta5Si3. Ta2Si has a melting point of 2200 ℃, a density of 8.83 g/cm3 and a resistance of 8.5 Ω. Cm. It is not eroded by mineral acids, but can be decomposed by hydrofluoric acid, and can be completely decomposed by molten Na2CO3 and NaOH.

Tantalate

Ta2O5 can be fused with oxides, hydroxides, or carbonates of more than 50 elements from all 8 groups in the periodic table of chemical elements to form various complex types of tantalates, which may be expressed in the following general formula: xMeO•yTa2O5 (Me = alkali metal).

Almost all alkali tantalates have a high degree of polymerization in aqueous solution and are insoluble compounds in water solution. Alkali tantalate can be reduced by hydrogen: 2MeTaO3+H2=Me2O+2TaO2+H2O, with a reaction temperature of 600~700℃. Except for alkali tantalates, most tantalates are insoluble in water.

Most tantalate crystals (such as lithium tantalate) are ferroelectric. They belong to the category of thermoelectric devices that have spontaneous polarization. Their polarization value is related to electric field voltage and has Curie temperature. Tantalum ferroelectric materials also have the characteristics of voltage, electro-optic and nonlinear optics. Some tantalates are semiconductor materials with narrow channels and are important materials for manufacturing electronic industrial components.

Stanford Advanced Materials supplies high-quality tantalum products to meet our customers’ R&D and production needs. Please visit http://www.samaterials.com for more information.

Tantalum VS Niobium

Tantalum and niobium belong to one family in the periodic table. Due to their similar physical and chemical properties, as well as growing together in the same ore body, they are known as the twin of metals.

ta vs nb

Tantalum and niobium were discovered in 1801 and 1802 by Charles Hatchett, a British chemist, and Ekberg, a Swedish chemist. Tantalum niobium ore is the main ore of tantalum and niobium, and a small amount of tantalum and niobium exist in tungsten and some rare earth ores.

Properties

Tantalum and niobium are both high-melting metals with melting points of 2996℃ and 2468℃ respectively. Tantalum and niobium have very stable chemical properties, not only insoluble in nitric acid, and hydrochloric acid, but also insoluble in aqua regia. Tantalum is malleable and can be pulled into strands thinner than human hair or rolled into foil thinner than paper. Tantalum and niobium are both excellent superconducting materials with characteristics of compression and wear resistance.

Applications

Tantalum and niobium are widely used in various fields because of their excellent properties mentioned above.

1. Capacitor

Tantalum can form a compact and stable amorphous oxide film with high dielectric strength, so it is easy to control the anodic oxidation process of the capacitor accurately and conveniently. Tantalum powder sintered blocks can obtain a large surface area in a small volume, so tantalum capacitors are the most excellent capacitors with small volume, large capacity, low leakage current, long service life, and excellent comprehensive performance. Under normal conditions, tantalum capacitors are smaller in size, higher in capacity, and more stable in function than ceramic capacitors, aluminum capacitors, and thin-film capacitors.

Tantalum capacitors have excellent characteristics that cannot be compared with many other capacitors. In the field of microelectronics science and surface mount technology, there is almost no other equivalent capacitor to compete with them. Therefore, 60~ 65% of tantalum is used in the manufacture of tantalum capacitors in the form of capacitor grade tantalum powder and tantalum wire.

Compared with tantalum, the main disadvantages of niobium capacitors are large leakage current (generally 5-10 times of tantalum), low breakdown voltage (< 10V), and low operating temperature (< 105℃), which are not suitable for capacitors with high-reliability requirements and high rated voltage. However, in the range of low voltage (< 10V) and large capacity (> 100muf), niobium capacitors may partially replace tantalum capacitors of the same level.

2. Metallurgical industry

In the metallurgical industry, niobium is mainly used to manufacture high-temperature resistant alloy steel and improve the strength of steel. In the smelting of carbon steel, the strength of the steel can be increased by more than one-third by adding only a few parts per million of niobium. Superalloys made of niobium, tantalum, tungsten, aluminum, nickel, cobalt, vanadium, and other metals are good structural materials for supersonic jet aircraft, rockets, and missiles.

3. Mechanical industry

In the mechanical industry, the cutting tool made of carbides such as niobium carbide and tantalum carbide can withstand a high temperature of nearly 3000℃, and its hardness can be comparable with that of the diamond, the hardest substance in the world.

4. Biomedical industry

Tantalum is an ideal bio-adaptive material in medicine. When it comes in direct contact with human bones, muscle tissues, and fluids, it can adapt to biological cells and has an excellent affinity with almost no human stimulation and side effects. Tantalum can not only be used to make bone plates, screws and clamping rods for fracture treatment, but also can be directly used to repair bones with tantalum plates and pieces and replace broken bones due to trauma with tantalum strips. Tantalum wire and foil can be used to suture nerves, muscles and blood vessels above 1.5 mm, while the extremely thin tantalum wire can replace tendons and even nerve fibers.

Stanford Advanced Materials supplies high-quality tantalum and niobium products to meet our customers’ R&D and production needs. Please visit http://www.samaterials.com for more information.

How is the Tantalum Made?

Tantalum is a sensible choice whenever high corrosion resistance is required. This platinum-gray-colored metal has a density of 16.6 g/cm3 which is twice as dense as steel. With its combination of specific physical and chemical properties, tantalum is an important product in many applications. Do you know how tantalum is made?

tantalum

Tantalum smelting process

Tantalum niobium ore is the main raw material for the production of tantalum, but it is often associated with a variety of metals, so the main step is the decomposition of tantalum smelting concentrates, purification, and separation of tantalum and niobium, producing the pure compound of tantalum and niobium, finally, we can produce metal.

To achieve ore–decomposition, we can use the hydrofluoric acid decomposition method, sodium hydroxide melting method, and chlorination. The method can be used in the separation of tantalum and niobium by solvent extraction, fractional crystallization, and ion exchange method.

Preparation of tantalum

The preparation of tantalum is the process of reducing pure tantalum compounds to metal tantalum. The raw materials are five tantalum oxide, tantalum chloride, five tantalum fluoride, and fluoride (such as K2TaF7,). The reducing agent is sodium, magnesium, other active metals, and carbon and hydrogen. The melting point of tantalum is as high as 3669K, so it is a powder or spongy metal after reduction. It is necessary to further smelting or refining, in order to get dense metal.

The tantalum preparation methods are sodium thermal reduction, carbon thermal reduction, and molten salt electrolysis. Sodium thermal reduction of potassium tantalate is the most widely used method of tantalum production in the world.

The tantalum powder has a complex shape and a large specific surface area. Carbon thermal reduction of five oxidation of tantalum has been an industrial method for the production of tantalum, but because the purity of the product is not high enough, is not as widely used as the sodium reduction method. The molten salt electrolysis method is divided into two ways: electrolyte electrolysis and oxygen-free electrolyte electrolysis. Molten salt electrolysis can only produce metallurgical grade tantalum powder. Five hydrogen fluoride reduction is considered to be one of the most promising methods for tantalum production, but it has not been used in industrial production because of the high requirements of equipment material and environmental protection.

The majority of tantalum powder is directly used for tantalum capacitors in the electronic manufacturing industry, so the tantalum milling process, such as the preparation of tantalum metal is also from tantalum and tantalum powder by vacuum heat treatment, capacitor grade tantalum powder hydrogenation method category.

Sodium thermal reduction process

Sodium metal thermal reduction method is an important method for the production of tantalum powder, is the main method of industrial production of tantalum powder (including metallurgical Ta powder), the metal tantalum powder particle shape is complex, large surface area, suitable for anode material for tantalum electrolytic capacitors, by electron beam melting, vacuum arc melting of tantalum or tantalum sintered in vacuum refining, made of high purity tantalum ingot or rod, and then processed into a variety of tantalum.

In order to obtain high purity tantalum powder, in addition to the main raw material, sodium and potassium fluorotantalate diluent (or NaCl+KCI), sodium chloride (argon or helium) must reach the required purity, must also be dehydration treated strictly at different temperatures in advance. It is also necessary to carry out the vacuum heat treatment at the temperature of 598 ~ 648K. After vacuum heat treatment, potassium fluorotantalate can remove the residual organic matter and hydrogen fluoride, and become the potassium fluorotantalate grain refinement, obtaining fine tantalum powder in reduction.

Since the 1970s, it has been widely used to increase the specific capacitance of tantalum powder. The commonly used doping agent is phosphate, which can be mixed before or after the crystallization of potassium fluoride and can be added before the vacuum heat treatment of tantalum powder. The doping can prevent the sintering of tantalum powder during the sintering of the tantalum anode block, thus avoiding the reduction of the specific surface area of the tantalum anode block. We can remove oxides from metal sodium with the metal-ceramic filter or cold trap method.

The process of reduction of potassium and sodium fluoride in an inert atmosphere at 1153 ~ 1173K temperature and the reduction products are metal tantalum powder, potassium fluoride, sodium fluoride, and diluent which are not involved in the reaction.

Before the 1950s, the solid metal sodium and potassium fluorotantalate layer was placed in the reactor of bomb explosion reduction reaction, although the product of tantalum powder is fine particle size, large surface area, oxygen, and carbon content is high, no practical value.

In this way, the reaction period is too long, the product size is coarse, and can only be used as 3000/uF.V/g low volume tantalum powder. After improvement by liquid-solid mixed loading reaction of sodium-based reduction, the production cycle is shortened 3/4 than gas-liquid reaction, tantalum powder volume increased by more than 30%, but still not ideal will be phased out.

With tantalum capacitors being small and micro, the corresponding need to adopt more surface area tantalum powder, mainly used in the liquid reduction, mainly supplemented by mixing sodium, doping technology, the volume rate of tantalum powder increased to 1000uF-V yield every year.

The fluoride was removed by dipping, and then washed with HCl18% and HF1% solution at 1 2H for 363K, then washed with pure water and dried at 353K temperature. For the preparation of capacitor grade tantalum powder, tantalum powder should be the original size distribution, vacuum heat treatment (see tantalum powder vacuum heat treatment), crushing and screening and modulation post-processing, if necessary, will also increase the magnesium reduction deoxygenation, pickling, washing and plastic processing, in order to obtain high quality and low and high specific capacitance of capacitor grade tantalum powder.

It is expected that the continuous improvement and development of tantalum powder produced by sodium reduction is the result of the miniaturization, miniaturization, and cost reduction of electronic products. Since the 1960s, the specific capacitance of tantalum powder has been increasing, and the capacitance ratio of tantalum powder has reached 22000~26000uF•V/g in the United States, Japan, Germany, and other countries.

Please visit http://www.samaterials.com for more information.

How is Tantalum Metal Used in Various Industries Made?

Tantalum is a metal element with the element symbol of Ta, an atomic number of 73, a density of 16.68g/cm, and a melting point of 2980 DEG C. Pure tantalum with blue color and excellent ductility can be rolled into a very thin plate in the cold state without intermediate annealing.

tantalum powder

Tantalum has a series of excellent properties such as high melting point, low vapor pressure, and cold processing performance, high chemical stability, anti-corrosion ability, constant liquid metal oxide film, which has important applications in electronics, metallurgy, chemical industry, aerospace, medical health, and scientific research and other high-tech fields.

Discovery history

In the middle of the Seventeenth Century, a heavy black mineral was found in North America and was sent to the British Museum. After about 150 years, until 1801, the British chemist C.Hatchett accepted the analysis task of the ore in the British Museum, discovered a new element, and named it columbium, which is to commemorate the earliest discovered mineral areas — Columbia.

In 1802, when the Swedish chemist A.G.Ekaberg analyzed a mineral in Scandinavia, making their acid fluoride salt after recrystallization, leading to the discovery of the new element, he named the element tantalum referred to in Greek mythology, Jose Tantalus, the son of God’s name.

Due to the nature of columbium and tantalum being very similar, people once thought that they are the same kind of elements. In 1809, the British chemist William Hyde Wollaston compared tantalum and Columbium oxide, although different density value, he believes that the two are identical materials.

In 1844, the German chemist Heinrich Rose dismissed the conclusion that tantalum and Columbium are the same element, and identified that they are two different elements by chemical methods. He named them “Niobium” and “Pelopium”.

In 1864, Christian Wilhelm Blomstrand, and Louis Joseph Troost clearly demonstrated that tantalum and niobium are two different chemical elements, and determine the chemical formula of some related compounds. The early tantalum metal has more impurities. Werner von Bolton was first made pure tantalum metal in 1903.

Scientists first extract tantalum from niobium with the method of hierarchical crystallization, which is found by de Marinilla in 1866. Today, scientists are using a solvent extraction method for the solution containing fluoride.

Preparation technology

The preparation of tantalum is the process of reducing pure tantalum compounds to metal tantalum. The raw materials are five tantalum oxide, tantalum chloride, five tantalum fluoride, and fluoride (such as K2TaF7,). The reducing agent is sodium, magnesium, other active metals, and carbon and hydrogen. The melting point of tantalum is as high as 3669K, so it is powder or spongy metal after reduction. It is necessary to further smelting or refining, in order to get dense metal.

The tantalum preparation methods are sodium thermal reduction, carbon thermal reduction, and molten salt electrolysis. Sodium thermal reduction of potassium tantalate is the most widely used method of tantalum production in the world.

The tantalum powder has a complex shape and a large specific surface area. Carbon thermal reduction of five oxidation of tantalum has been an industrial method for the production of tantalum, but because the purity of the product is not high enough, is not as widely used as the sodium reduction method. The molten salt electrolysis method is divided into two ways: electrolyte electrolysis and oxygen-free electrolyte electrolysis. Molten salt electrolysis can only produce metallurgical grade tantalum powder. Five hydrogen fluoride reduction is considered to be one of the most promising methods for tantalum production, but it has not been used in industrial production because of the high requirements of equipment material and environmental protection.

The majority of tantalum powder is directly used for tantalum capacitors in the electronic manufacturing industry, so the tantalum milling process, such as the preparation of tantalum metal is also from tantalum and tantalum powder by vacuum heat treatment, capacitor grade tantalum powder hydrogenation method category.

Tantalum-Powder
Tantalum-Powder

Production of tantalum powder

Sodium metal thermal reduction method is an important method for the production of tantalum powder, which is the main method of industrial production of tantalum powder (including metallurgical Ta powder). The particle shape of metal tantalum powder with the large surface area is complex, which is suitable for anode material for tantalum electrolytic capacitors by electron beam melting and vacuum arc melting of tantalum or tantalum sintered in vacuum refining, then the high purity tantalum rod made and then processed into a variety of tantalum.

Since the 1970s, it has been widely used to increase the specific capacitance of tantalum powder. The commonly used doping agent is phosphate, which can be mixed before or after the crystallization of potassium fluoride and can be added before the vacuum heat treatment of tantalum powder. The doping can prevent the sintering of tantalum powder during the sintering of the tantalum anode block, thus avoiding the reduction of the specific surface area of the tantalum anode block. We can remove oxides from metal sodium with the metal-ceramic filter or cold trap method.

The process of reduction of potassium and sodium fluoride in an inert atmosphere at 1153 ~ 1173K temperature and the reduction products are metal tantalum powder, potassium fluoride, sodium fluoride, and diluent which are not involved in the reaction.

Before the 1950s, the solid metal sodium and potassium fluorotantalate layer was placed in the reactor of bomb explosion reduction reaction, although the product of tantalum powder is fine particle size, large surface area, oxygen, and carbon content is high, no practical value.

With tantalum capacitors being small and micro, the corresponding need to adopt more surface area tantalum powder, mainly used in the liquid reduction, mainly supplemented by mixing sodium, doping technology, the volume rate of tantalum powder increased to 1000uF – V yield every year.

tantalum-capacitors
tantalum-capacitors

The fluoride was removed by dipping, and then washed with HCl18% and HF1% solution at 1 2H for 363K, then washed with pure water and dried at 353K temperature. For the preparation of capacitor grade tantalum powder, tantalum powder should be the original size distribution, vacuum heat treatment (see tantalum powder vacuum heat treatment), crushing and screening and modulation post-processing, if necessary, will also increase the magnesium reduction deoxygenation, pickling, washing and plastic processing, in order to obtain high quality and low and high specific capacitance of capacitor grade tantalum powder.

It is expected that the continuous improvement and development of tantalum powder produced by sodium reduction is the result of the miniaturization, miniaturization, and cost reduction of electronic products. Since the 1960s, the specific capacitance of tantalum powder has been increasing, and the capacitance ratio of tantalum powder has reached 22000~26000uF•V/g in the United States, Japan, Germany, and other countries.

Stanford Advanced Materials supplies high-quality tantalum products to meet our customers’ R&D and production needs. Please visit http://www.samaterials.com for more information.

Applications of Tantalum in the Electronic Industry

Tantalum and its alloy have a high melting point, corrosion resistance, excellent high-temperature strength, and are free of radioactive, etc, are widely used in the electronics industry, chemical industry, aerospace, weapon system, the medical field, etc. Applications of tantalum materials in the electronic industry mainly include tantalum capacitors, integrated circuits, electron tubes, storage devices, and passive devices.

tantalum

Tantalum Capacitors

Tantalum capacitors have strong corrosion resistance and can maintain stable electrical and physical and chemical properties under various environmental conditions. In addition, it also has a high resistance rate (7.5 x 1012 Ω cm), a large dielectric constant (27.6), and a small leakage current.

Tantalum Capacitors
Tantalum Capacitors

Tantalum has the characteristics of a valve metal, and the dense oxide film generated on its surface has unidirectional conductivity, which is suitable for capacitors. Tantalum capacitors are large in capacity and small in volume. Their capacitance is three times that of aluminum capacitors, while their volume is much smaller than that of aluminum capacitors. The tantalum capacitor has a working temperature range of 80 ~ 200 ℃, so it can meet the demand of different temperatures. In addition, tantalum capacitors also have strong stability and heat resistance, which makes them highly reliable materials in the electronics industry, as well as widely used in military and high-tech fields that need to ensure high reliability.

Integrated circuit

Tantalum has been introduced into the semiconductor industry as a barrier layer film material to prevent the diffusion of copper atoms to silicon wafers. Copper does not form a compound with tantalum and nitrogen, so tantalum and tantalum base films are used as a barrier layer to prevent the diffusion of copper. In order to prevent copper atoms from diffusing into silicon matrix, tantalum nitride, tantalum silicide, tantalum carbide, tantalum nitride silicide, tantalum nitride carbide, and other tantalum base films are used as barrier layers with good effects.

Tantalum-based films have high conductivity, high thermal stability, and excellent corrosion resistance, which are highly resistant to foreign atoms.

Tantalum
Tantalum in Semiconductor Chips

Memory device

Tantalum oxide based resistance variable memory (RRAM) has the advantages of simple structure, fast reading and writing speed, strong miniaturization and compatibility with the CMOS process. Tantalum oxide material has good thermal stability that can reach 1100 ℃. There are only two stable phases between the tantalum and oxygen, namely Ta2O5 and TaO2, which also have two very high oxygen capacity ratio under the high temperature of 1000 ℃.

Passive device

When tantalum nitride film is exposed to air, an oxide layer will naturally form on the surface to protect the film from erosion in the presence of water vapor and voltage. Tantalum nitride chip resistors do not cause catastrophic failure of the device due to poor package or protective coating integrity.

At present, the application field of capacitor grade tantalum wire is further expanded with the rapid development of the electronic market. However, the development of tantalum capacitors has been greatly restricted due to various reasons, such as the increase in production cost, the further consumption of resources, and the intensified competition among ceramic capacitors.

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How is Tantalum used in Modern Stomatology?

Tantalum metal (Ta) has excellent corrosion resistance, high melting point, high strength, and abrasion resistance, which has been widely used in aircraft, rockets, and other heat-resistant materials as well as industrial fields requiring high-strength parts. In addition, tantalum metal has good physical and mechanical properties and good biological compatibility, which makes it a new kind of biological material after titanium metal.

oral implant implantation

Nowadays, tantalum metal has been widely used in oral implant implantation, femoral head necrosis treatment, coronary artery stent implantation, acetabular prosthesis implantation, surgical suture line production, and other medical fields. The application of medical tantalum and porous tank in stomatology is introduced below.

Oral Implant Implantation
Oral Implant Implantation

Tantalum has been used as an implant material in the repair and treatment of patients with missing teeth. With the development of science and technology, porous tantalum has also been tried to be used in the field of implants. Due to its outstanding mechanical properties, biological properties, elastic modulus equivalent to bone tissue, and high friction coefficient, it can provide good bone bonding and initial stability for the implant, which is called a bone trabecular implant. In addition, its elastic modulus (between the cancellous bone and dense bone) is the same as that of bone tissue, which enables the implant to disperse the dental forces into the surrounding bone during long-term oral functional load, thus avoiding stress concentration.

Experiments have shown that traditional implants can absorb 30% of the load energy, while porous tantalum implants can absorb 50% to 75%. The high friction coefficient makes tantalum have good initial stability in the process of implant implantation, so as to improve the bonding rate of implant teeth, especially for the implant patients with poor bone quality. The three-dimensional structure of porous tantalum has pores, which are conducive to the attachment of bone marrow mesenchymal stem cells and osteoblasts on its surface, and the pore structure is similar to bone tissue, which provides a good scaffold for the growth of bone tissue.

Microstructure of the porous tantalum material
The microstructure of the porous tantalum material

Relevant studies have confirmed that porous tantalum granules have a good ability to induce osteogenesis, and its effect on repairing jaw defects is better than that of bio-oss bone powder commonly used in clinical practice. The porous tantalum granules and bio-oss bone powder were implanted into the defect area of the right and left mandible of beagle dogs respectively. Three months later, gross specimens, X-ray images, and hard tissue sections showed that porous tantalum granule group had a higher bone formation amount and bone tissue maturity than the control group.

Due to their good biocompatibility, tantalum and porous tantalum have important clinical value and application prospects in many fields of medicine, such as stomatology, bone surgery, cardiovascular surgery, and biomedical engineering. The application of surface modification technology will enable tantalum metal and porous tantalum to have more excellent biological properties, thus greatly improving the ability of tantalum and porous tantalum implants to combine with the surrounding bone interface.

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Why is Tantalum Widely Used in Electronic Industry?

Since the 1950s, TZM alloy (Mo-0.5 Ti-0.1 Zr-0.02 C) has been developed to meet the needs of the nuclear power system, aviation, and aerospace industry. It is the most widely used molybdenum alloy in the industry and the earliest refractory alloy used as a high-temperature structural material. However, the low-temperature brittleness of molybdenum alloy greatly limits its application.

tantalum metal

Tantalum metal has a lower plastic brittle transition temperature (196 ℃) and has better performance on the workability, weldability, ductility, and oxidation resistance at room temperature than that of molybdenum and tungsten in refractory metals. In addition, tantalum and its alloys with high melting point (2996 ℃), corrosion resistance, excellent high-temperature strength, and free of radioactive, etc, are widely used in the electronics industry, chemical industry, aerospace, weapon system, and the medical field, etc.

Tantalum metal
Tantalum metal

The applications of tantalum materials in the electronics industry mainly include tantalum capacitors, integrated circuits, electron tubes, memory devices, and passive devices.

Tantalum capacitor

Tantalum has the metal property of a valve, and the compact oxide film formed on its surface has unidirectional conductivity, which is suitable for making capacitors. Tantalum capacitors have a large capacity and small volume, and their capacitance is three times that of aluminum capacitors, but their volume is much smaller than that of aluminum capacitors. The working temperature of the tantalum capacitor ranges from -80 to 200 ℃, which can meet the demand of different temperatures. Besides, tantalum capacitors have strong stability and heat resistance performance and become a kind of material with high reliability in the electronics industry, which is widely used in military and high-tech fields that need to ensure high reliability.

Tantalum capacitor
Tantalum capacitor

Integrated circuit

Tantalum material is introduced into the semiconductor industry as a barrier layer thin-film material used to prevent the diffusion of copper atoms to silicon wafers. There are no compounds are formed between copper and tantalum, and copper and nitride, so tantalum and tantalum base membranes are used as barrier layers to prevent copper diffusion, and the typical thickness of the barrier layer is 0.005 ~ 0.01μm. In order to prevent the diffusion of copper atoms into the silicon matrix, tantalum nitride, tantalum silicide, tantalum carbide, and silicon nitride are used as barrier layers.

Memory device

Tantalum oxide matrix resistive memory (RRAM) has the advantages of simple structure, fast read and write speed, strong instability, and compatibility with the CMOS process. The permittivity of tantalum oxide material is very high, which is about 25. Moreover, there are only two stable phases between ta-O, Ta2O5 and TaO2, which have high oxygen capacity ratio under the high temperature of 1000 ℃.

Passive device

When tantalum nitride film is exposed to air, the surface will naturally form a layer of the oxide layer to protect the film from erosion in the presence of water vapor and voltage. The chip resistance of tantalum nitride will not cause catastrophic failure of the device due to the poor integrity of the package or protective coating.

RRAM
RRAM

When researchers discovered tantalum’s high-temperature resistance, good ductility, and corrosion resistance, the research on tantalum metal began. At present, the application field of capacitor grade tantalum wire is further expanded with the rapid development of the electronic market. However, the development of tantalum capacitors is greatly restricted due to various reasons, such as the increase in production cost, the further consumption of resources, and the intensification of the competition between ceramic and other capacitors.

In recent years, the market consumption of capacitor tantalum wire has been maintained at about 160 tons per year. With the development and use of military capacitors and the miniaturization and chip type of capacitors, the capacitor-grade tantalum wire gradually develops toward the thick and thin poles.

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