High temperature electrical conduction in nanoscale hafnia films under varying oxygen partial pressure

2010 ◽  
Vol 97 (8) ◽  
pp. 082102 ◽  
Author(s):  
Changhyun Ko ◽  
Michael Shandalov ◽  
Paul C. McIntyre ◽  
Shriram Ramanathan
Keyword(s):  
High Temperature ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Electrical Conduction

Characterization of YBa2Cu4O8 high temperature electrical properties and thermodynamic stability

1991 ◽  
Vol 6 (10) ◽  
pp. 2054-2058 ◽  
Author(s):  
B-S. Hong ◽  
T.O. Mason
Keyword(s):  
High Temperature ◽  
Electrical Property ◽  
Electrical Properties ◽  
Seebeck Coefficient ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Pressure Range ◽  
Stability Range

Via in situ electrical property measurements (conductivity, Seebeck coefficient) over the temperature range 500–800 °C and oxygen partial pressure range 10−4-1 atm, the equilibrium transport properties and stability range of YBa2Cu4O8 were determined. YBa2Cu4O8 behaves like the intrinsically mixed-valent compound, magnetite (Fe3O4), with small variations in electrical properties with changes in oxygen partial pressure. The decomposition boundary to YBa2Cu3O6+y (or YBa2Cu3.5O7.5±z) and CuO occurs at log(po2, atm) = −1.24 × 104/T(K) + 11.01(773 ⋚ T(K) ⋚ 1073).

High temperature potential/pH diagrams for the chlorine–water system

1985 ◽  
Vol 63 (4) ◽  
pp. 935-939 ◽  
Author(s):  
Barbara Kolodziej ◽  
Fathi Habashi
Keyword(s):  
High Temperature ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Water System ◽  
Temperature Potential ◽  
Lower Temperature ◽  
Hcl Concentration ◽  
Chlorine Water

Thermodynamic evidence supports the view that the reaction [Formula: see text] takes place above 127 °C at pH = 0. An increase in HCl concentration and/or oxygen partial pressure allow the reaction to proceed at lower temperature.

High temperature X-ray diffraction studies of the decomposition mechanism of YBa2Cu3O7−δ at an oxygen partial pressure less than 10 Pa

1995 ◽  
Vol 10 (3) ◽  
pp. 165-169 ◽  
Author(s):  
W. Pitschke ◽  
W. Bieger ◽  
G. Krabbes ◽  
U. Wiesner
Keyword(s):  
High Temperature ◽  
Solid State ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Solid State Reaction ◽  
Peritectic Reaction ◽  
Decomposition Reaction ◽  
Primary Decomposition ◽  
X Ray Diffraction ◽  
X Ray

The crystallographic data of YBa2Cu3O7−δ, Y2BaCuO5, BaCu2O2, and YBa4Cu3O9 at high temperatures and p(O2)<10 Pa have been derived on the basis of HT-XRD measurements. Whereas Y2BaCuO5 expands nearly isotropically, YBa2Cu3O7−δ and BaCu2O2 show anisotropic expansions. Furthermore, the first decomposition step of the considered compounds at p(O2)<10 Pa was observed. BaCu2O2 melts congruently at T ≍ 1273 K and Y2BaCuO5 decomposes via a peritectic reaction into Y2O3, Y2BaO4 and melts at T ≍ 1323 K. A solid-state reaction into Y2BaCuO5 and BaCu2O2 was indicated for YBa2Cu3O7−δ at T ≍ 1123 K. Because YBa4Cu3O9 becomes unstable at T ≍ 1123 K, this compound cannot be formed by the primary decomposition reaction of YBa2Cu3O7−δ

“Migration of Sintered Nanosilver Die-attach Material on Alumina Substrate at High Temperatures”

2010 ◽  
Vol 2010 (HITEC) ◽  
pp. 000026-000031 ◽  
Author(s):  
Yunhui Mei ◽  
Dimeji Ibitayo ◽  
Xu Chen ◽  
Susan Luo ◽  
Guo-Quan Lu
Keyword(s):  
High Temperature ◽  
Electric Field ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
External Pressure ◽  
Alumina Substrate ◽  
Electrode Pair ◽  
Electrode Gap ◽  
Die Attach ◽  
Silver Dendrites

A nanoscale silver paste that can be sintered at temperatures below 300°C without external pressure is emerging as a promising die-attach material for implementing the low-temperature joining technology in high-temperature packaging. In this paper, we report our findings on silver migration in sintered nanosilver electrode-pair patterns on alumina substrate. The electrode pairs were biased at electric field ranging from 10 to 100 V/mm and at temperature between 250 °C and 400°C in dry air. Leakage currents across the electrodes were measured as the silver patterns were tested in an oven. Silver dendrites formed across the electrode gap were observed under an optical microscope and analyzed using scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). Silver migration was found in samples tested at 400°C, 350°C, and 300°C, and 250°C. The measurements on leakage current vs. time were characterized by an initial incubation period, called “lifetime”, followed by a sharp rise as silver dendrites were shorting the electrodes. A rapid rise in the “lifetime” with decreasing oxygen partial pressure was also found. A simple phenomenological model was derived to account for the observed dependence of “lifetime” on electric field, temperature, and oxygen partial pressure. The reliability of sintered nanosilver die-attachment over silver migration in high temperature applications can be significantly improved through packaging or encapsulation to reduce oxygen exposure.

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