New Niobium Capacitors with Stable Electrical Parameters

Abstract

The replacement of the anode material in tantalum capacitors by a new generation of high CV niobium powders offers the possibility to get an economical alternative to tantalum for a wide range of applications. Due to the high CV potential of niobium powder there is also an alternative to low voltage aluminum electrolytic capacitors. We developed a new niobium capacitor which shows stable electrical values. By optimizing the structure of the dielectric and the cathodic layers as well as the process parameters we gained a capacitor which can be used up to105 °C. Electrical characteristics and lifetest behavior of niobium capacitors out of 100 k–150 k CV/g powder will be discussed.

Anodic Oxidation of Niobium Sheets and Porous Bodies

“…These results yield an oxidation constant of 3 nm/V for Nb, in good agreement with literature data, and about 1.5 higher than the typical values on Ta ͑2 nm/V͒. [2][3][4] Evaluation of the V(t) and j(t) curves.-Figure 1 shows the j(t) and V(t) curves of the Nb sheets for starting current densities of 0.010, 0.025, 0.035, 0.050, and 0.067 mA/cm 2 . As can be seen in the constant current range, the V(t) curves have the steepest slope (dV/dt) in the starting period of the formation.…”

“…Available electronically June 16, 2003. The Nb/Nb 2 O 5 system is a candidate to replace the widely used Ta/Ta 2 O 5 system in solid electrolyte capacitors in some applications. [1][2][3][4][5] Advantages of the Nb/Nb 2 O 5 system are the high dielectric permittivity 6 ( r Ϸ 42) of Nb 2 O 5 , the relatively low price of niobium, and the vastness of niobium reserves. 7 However, some properties of niobium, like its high oxygen absorbing capacity, 2,8 strong chemical affinity to oxygen, carbon, and nitrogen, 2 as well as the existence of its suboxides, NbO 2 , NbO, and Nb͑O͒ beside the desirable Nb 2 O 5 , makes this system hard to handle.…”

EELS of Niobium and Stoichiometric Niobium-Oxide Phases—Part I: Plasmon and Near-Edges Fine Structure

“…It is in particular the (amorphous) Nb 2 O 5 that is studied intensively in context with applications in catalysis (Tanabe, 2003), as a sensing material (Hyodo et al, 2006), with biomimetic implant coating (Eisenbarth et al, 2007), and with coating for antireflection camera lenses (Leitel et al, 2006). A high technological potential has been attributed to Nb-based solid electrolyte capacitors with Nb 2 O 5 dielectric layers formed by anodic oxidation on Nb or NbO (Zillgen et al, 2002; Zednicek et al, 2005). Moreover, niobium may form a complex native oxide layer that affects, e.g., the properties of superconducting Nb cavities for particle accelerators (Delheusy et al, 2008).…”

Anodically formed oxide films on niobium: Microstructural and electrical properties

“…[9][10][11][12][13][14] As a consequence, major capacitor manufacturers launched production of niobiumbased capacitors in 2001 which have the potential to replace tantalum in certain applications. [15][16][17][18][19] One drawback of Nb-based capacitors which is often referred to in the literature is the pronounced temperature sensitivity of the Nb 2 O 5 film. [20][21][22][23] Since the fabrication process of solid electrolyte capacitors with MnO 2 cathode comprises several production steps at elevated temperatures, the comprehensive understanding of the influence of heat treatments on the electrical properties of nanoscale Nb 2 O 5 layers on niobium is essential.…”