Dielectric and physical properties of BaZrO3 single crystals

Lead zirconate titanate (PZT) is the most widely used piezoelectric material because of its excellent properties, but it is currently facing global restrictions due to Pb toxicity. In the efforts to develop lead-free... [ view full abstract ]

Lead zirconate titanate (PZT) is the most widely used piezoelectric material because of its excellent properties, but it is currently facing global restrictions due to Pb toxicity. In the efforts to develop lead-free piezoelectric materials, solid solutions based on the BaZrO₃-BaTiO₃-CaTiO₃ system (BCTZ) have been identified as promising candidates ^[1]. Its phase diagram is key to understand its piezoelectric properties ^[2].

The work presented here will focus on the least known end-member of the BCTZ system: cubic BaZrO₃. Pure BaZrO₃ has attracted a lot of attention for its dielectric properties at low temperatures, with a behavior reminiscent of quantum paraelectrics ^[3]. However, because of its very high melting point, experimental investigations have been mostly limited to polycrystalline samples. Here, we report on the growth and characterization of BaZrO₃ single crystals obtained by different techniques. The dielectric properties were measured down to 4.2 K and exhibit up to two anomalies, one being common to all samples and probably intrinsic in origin, while the other does not appear in all samples and has to be extrinsic. The chemical composition was analyzed by combining both energy-dispersive X-ray spectroscopy and secondary ion mass spectrometry, revealing Sr and Hf as main impurities. Temperature dependent Raman spectroscopy was performed from ambient conditions down to 4 K and confirms that the cubic phase remains stable down the lowest temperatures. Possible origins for the intense 2^nd-order  Raman spectrum will be discussed, in combination with first-principle lattice dynamics calculations.

[1] Liu and Ren, Phys. Rev. Lett. 103, 257602 (2009)

[2] Keeble et al., Appl. Phys. Lett. 102, 092903 (2013)

[3] Akbarzadeh et al., Phys. Rev. B 72, 205104(2005)