Characterization of new high-temperature piezoelectric single crystals in the system RCa4O(BO3)3 (R = Gd, Sm, La and Y)

压电晶体是现代固体声学和声电子学的关键材料。特别感兴趣的是那些在非常高的温度（高达10000 ℃和更高）下具有合理的压电响应的材料。这种晶体的数量正在消失，研究它们在非常高的温度下的物理性质是相当复杂的实验问题。请注意，高温性能的知识不仅对可能的应用很重要，而且对临界条件下材料行为的基本理解也很重要。该项目的目标是研究在非常高的温度（约10000 ℃）下先进压电晶体的材料参数（弹性、压电和介电常数以及电阻率）。研究的对象是一个新的单斜晶系的压电氧硼酸盐，其通式为RCa_4O（BO_3）_3（其中R = Gd，Sm，La和Y）。上述单晶在高温下的材料参数实际上是未知的。此外，文献中报道的某些氧硼酸盐单晶的室温材料参数是矛盾的。

Piezoelectric crystals are key materials for modern solid state acoustics and acoustoelectronics. Of particular interest are materials those possess a reasonable piezoelectric response at very high temperatures (up to 10000 C and higher). The number of such crystals is vanishing and the study of their physical properties at very high temperatures is rather complex experimental problem. Notice that the knowledge of the high temperature properties is important not only for possible applications but also for basic understanding of materials behavior under critical conditions. The objective of the project is the study of material parameters (elastic, piezoelectric and dielectric constants, as well as electrical resistivity) of advanced piezoelectric crystals at very high temperatures (about 10000 C). The object under study is a new family of monoclinic piezoelectric oxoborates with the general formula RCa4O(BO3)3 (where R = Gd , Sm, La and Y). Material parameters of above single crystals at high temperatures are practically unknown. Moreover, room temperature material parameters of some oxoborates single crystals reported in literature are contradictory.