High-temperature piezoelectric single crystal ReCa(4)O(BO(3))(3) for sensor applications

Area of Science:

• Solid State Physics
• Materials Science
• Crystal Growth

Background:

• Rare-earth calcium oxyborate (ReCOB) materials are investigated for their unique physical properties.
• The Czochralski pulling method is a standard technique for growing large, high-quality single crystals.
• Understanding the electrical properties of these materials is crucial for their application in electronic devices.

Purpose of the Study:

• To grow large-size and high-quality ReCa(4)O(BO(3))(3) (ReCOB) single crystals.
• To investigate the electrical properties of Yttrium calcium oxyborate (YCOB) at various temperatures.
• To evaluate the potential of ReCOB crystals for sensing applications, particularly at elevated temperatures.

Main Methods:

• Single crystals of ReCa(4)O(BO(3))(3) were grown using the Czochralski pulling method.
• Electrical properties, including dielectric permittivity, piezoelectric strain coefficient, and electromechanical coupling, were measured.
• Electrical resistivity, Q values, and frequency/temperature coefficients were determined for YCOB across a broad temperature range.

Main Results:

• YCOB crystals exhibited a dielectric permittivity of approximately 11, a piezoelectric strain coefficient of 6.5 pC/N, and electromechanical coupling of 12.5%.
• A high piezoelectric voltage coefficient of ~0.067 Vm/N was observed.
• YCOB demonstrated high electrical resistivity (2 x 10^8 Ohm.m at 800°C), Q values of 4,500 at 950°C, and a frequency/temperature coefficient of -75 to -85 ppm/K between 30°C and 950°C.

Conclusions:

• YCOB crystals possess significant piezoelectric properties and good electrical insulation at high temperatures.
• The material shows stable performance over a wide temperature range, with some temperature-independent characteristics.
• ReCOB crystals, due to their robust electrical properties at elevated temperatures, are promising candidates for advanced sensing applications.