Single crystal growth, characterization, piezoelectric properties, and spectral analysis for Zn4B6O13 and Ni:Zn4B6O13 crystals

Abstract

Borate crystal Zn₄B₆O₁₃ (ZBO) exhibits excellent optical properties and exceptional thermal stability. In this study, large-sized ZBO and Ni-doped ZBO (Ni:ZBO) single crystals were grown using the Kyropoulos method, and their structural, thermal, electro-elastic, and optical properties were comprehensively investigated. Ni²⁺ doping substituted Zn²⁺ without altering the cubic crystal structure, slightly increasing the thermal expansion coefficient to 5.72 ± 0.08 × 10^{− 6} K⁻¹ in the temperature range of 25–670 °C while maintaining a remarkably low value compared to most laser crystals. Ni:ZBO displayed enhanced piezoelectric performance (d₁₄ = 1.49 pC N⁻¹ at room temperature), ∼21% higher than ZBO, and retained a high degree of temperature stability. Optical analysis showed high transmittance from 241 nm to the mid-infrared range and characteristic absorption peaks. Additionally, strong short-wavelength emission at 440 nm was observed in the Ni:ZBO crystal, indicating its potential as a high-quality gain medium for blue-violet laser generation. These findings underscore the promise of Ni:ZBO as a material suitable for high-temperature piezoelectric and laser crystal applications.