Effect of substrate clamping on evolution of properties in homovalent and heterovalent relaxor thin films

Relaxor ferroelectrics, well known for their large dielectric and piezoelectric response, are attracting growing interest in thin-film form driven by a need miniaturized devices. Fundamental understanding control of the performance relaxors as thin films, however, is underdeveloped relative to studies bulk versions. One obvious challenge substrate clamping, which reduces yet systematic comparisons effect clamping on different relaxor materials missing. Here, impact epitaxial constraint behavior properties both homovalent ${\mathrm{BaZr}}_{0.5}{\mathrm{Ti}}_{0.5}{\mathrm{O}}_{3}$ heterovalent $\mathrm{Pb}{\mathrm{Mg}}_{1/3}{\mathrm{Nb}}_{2/3}{\mathrm{O}}_{3}$ studied (001)-, (011)-, (111)-oriented films. While orientations heterostructures show little variation permittivity, strong orientational observed heterostructures, with films exhibiting 67% higher permittivity than (001)-oriented difference that attributed how along crystallographic axes interacts polar-structure nucleation growth. Measurements anisotropy confirm trend---with just half much heterostructures. These results indicate susceptibility compared relaxors, implying random fields could be advantageous such geometries applications.