Effect of degree of crystallographic texture on ferro‐ and piezoelectric properties of Ba_0.85Ca_0.15TiO₃ piezoceramics

Abstract

Crystallographic texturing is a promising approach to reduce the performance gap between randomly oriented polycrystalline piezoelectrics and perfectly oriented single crystals. Here, the influence of the degree of crystallographic texture on the electromechanical properties and their temperature stability of the lead‐free perovskite ferroelectric Ba0.85Ca0.15TiO3 is investigated. Samples with a broad range of (100),(001) crystallographic texture (Lotgering factor 26%‐83%) were prepared by the reactive templated grain growth method. Crystallographic and microstructural analysis have been carried out using X‐ray diffraction and scanning electron microscopy, while the temperature‐dependent electromechanical properties were characterized by dielectric, piezoelectric, polarization, and strain measurements. It was revealed that the total bipolar strain and the coercive field are linearly dependent on the Lotgering factor. The total bipolar strain increased by 80%, whereas the coercive field decreased by 18% due to crystallographic texturing. Likewise, the temperature stability of the electromechanical properties of the samples was found to be dependent on the degree of texture. A sample with a high degree of texture exhibited a Curie temperature of 117°C, which is 21% higher compared to a counterpart with a low degree of texture. This was related to chemical inhomogeneity and a modified internal mechanical stress state.

Exceptionally High Piezoelectric Coefficient and Low Strain Hysteresis in Grain-Oriented (Ba, Ca)(Ti, Zr)O3 through Integrating Crystallographic Texture and Domain Engineering

“…(d) Unipolar strain vs electric field ( S – E ) curves. (e) Strain hysteresis H s as a function of maximum field induced strain S max for modified BT-based ceramics. ,− ,− Please note large strain with low strain hysteresis in the textured BCTZ ceramics (this work). (f) Polarization vs electric field ( P – E ) hysteresis loops for both randomly oriented and textured BCTZ ceramics.…”

“…[001] c grain-oriented BCTZ ceramics with texture degree as high as ∼98.6% were developed by templated grain growth. Indeed, a very high d 33 ∼ 755 pC/N and an extremely large d 33 * ∼ 2027 pm/V, along with an ultralow H s ∼ 4.1%, were simultaneously achieved, and these are superior to those of BT-based ceramics developed thus far. ,− ,− ,− The underlying mechanisms for the exceptionally high piezoelectric performance were also addressed. This work not only paves a new path to produce high d 33 / d 33 *–low H s piezoelectrics for precisely controlled device applications, but also can provide guidelines for further development of novel functional materials with superior properties.…”

“…However, the obtained comprehensive piezoelectric properties are still inferior or only comparable to those of the BZT-50BCT ceramics. Moreover, modified BT-based ceramics usually have large hysteresis ( H s ) in strain–electric field curves, ,− ,,− which seriously degrades their actuating performance and restricts their applications in precisely controlled devices and systems. ,, In particular, besides maximizing the d 33 value, a large strain ( d 33 *) together with a low stain hysteresis are very important for high-precision piezoelectric actuator applications. Hence, the following question arises: Can the two critical challenges (i.e., large hysteresis and the bottleneck for piezoelectric performance) be overcome simultaneously in modified BT-based ceramics to expand their application areas?…”

Domain wall-grain boundary interactions in polycrystalline Pb(Zr0.7Ti0.3)O3 piezoceramics

“…Ferroelectric ceramics are widely applicable in electronic devices and are indispensable in actuators, high-dielectric-constant capacitors, piezoelectric sensors, and ultrasonic transducers [1][2][3]. Microstructural and crystallographic parameters, such as crystal structure [4], degree of crystallographic texture [5,6], lattice distortion [7], and porosity [8] are commonly used to tailor their application-relevant electrical and electromechanical properties. Grain-size engineering is one of the most important tools and was previously used to tailor properties, such as permittivity [9], strain [10], fracture toughness [11], polarization reversal [12], electrical fatigue [13], high-power piezoelectric properties [14], and even phase transitions [15].…”

Influence of crystallographic structure on polarization reversal in polycrystalline ferroelectric/ferroelastic materials

“…The polarization reversal process in these materials is relatively complex, since the movement of the domain walls is influenced by local electric and mechanical boundary conditions within individual grains. Other important influencing parameters are also lattice distortion, 2 degree of crystallographic texture, 3,4 or grain size. 5 However, arguably one of the most dominating parameters is the material's crystal structure.…”