Internal Friction in ZrO₂ Containing CaO

Area of Science:

• Materials Science
• Solid State Physics
• Ceramic Engineering

Background:

• Zirconium dioxide (ZrO2) stabilized with calcium oxide (CaO) is a crucial ceramic material.
• Understanding internal friction in calcia stabilized zirconia (CSZ) is vital for its mechanical and electrical applications.
• Previous studies have linked electrical resistivity to oxygen vacancy behavior in CSZ.

Purpose of the Study:

• To investigate the effect of varying CaO content on the internal friction of polycrystalline ZrO2.
• To characterize the nature of internal friction peaks and their relationship to microstructural features and oxygen vacancies.
• To examine the impact of high-temperature annealing on internal friction properties.

Main Methods:

• Internal friction measurements were performed on CSZ samples with CaO concentrations ranging from 4 to 20 mole percent.
• Experiments were conducted at a frequency of 1 kHz, with temperature scans to identify friction peaks.
• Samples were subjected to annealing at 1000 °C for 1000 hours to study microstructural evolution effects.

Main Results:

• A symmetrical internal friction peak was observed between 10-20% CaO, peaking around 300 °C at 1 kHz.
• Below 10% CaO, a non-symmetrical peak appeared at higher temperatures, possibly indicating a two-phase structure.
• Annealing reduced peak height, showing a different composition dependence compared to electrical resistivity annealing results.

Conclusions:

• Oxygen vacancies in CSZ likely exist in multiple binding states, influencing internal friction.
• The symmetrical peak is attributed to oxygen vacancy motion, correlating with electrical resistivity data.
• Complex models are needed to fully describe the behavior of oxygen vacancies in CSZ.