We report temperature-dependent dielectric permittivity, thermal conductivity and mechanical resonances of as-grown hybrid perovskite single crystal CH 3 NH 3 PbBr 3 . Structural phase transitions are analysed using new experimental techniques, where thermal conductivity by steady-state process and elastic modulai by ultra-resonance spectroscopy is carried out through [100] and [110] directions, respectively. Performing thermal conductivity measurement on small-sized samples usually pose a significant challenge due to its dimensional limit. Following the steady-state technique, we measured the thermal conductivity of around 1 W m −1 K −1 in the temperature range 100–300 K on 2 × 2 mm 2 size crystal. This is found to be comparable with I +3 anion-based hybrid perovskites as reported by Pisoni et al 2014 J. Phys. Chem. Lett. 5 2488. Room temperature electrical resistivity and dielectric permittivity of order 10 9 and 10 2 , respectively, shows sharp transitions while approaching 150 K, which strongly supports first-order structural transition. Thermally activated resistivity behaviour above 280 K follows 1/ T dependence, yielding activation energy of 0.2 eV. Softening of elastic moduli on approaching the phase transition is analysed from resonant ultrasound spectroscopy measurement. Square of the resonance frequency is found to diverge below 236 K, which inhibits any further experimental determination of elastic moduli at low temperature.

中文翻译：

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甲基铵溴化铅单晶的电学、热学和弹性性能

我们报告了生长的杂化钙钛矿单晶 CH 3 NH 3 PbBr 3 的温度相关介电常数、热导率和机械共振。使用新的实验技术分析结构相变，其中分别通过 [100] 和 [110] 方向进行稳态过程的热导率和超共振光谱的弹性模量。由于其尺寸限制，对小尺寸样品进行热导率测量通常构成重大挑战。遵循稳态技术，我们在 2 × 2 mm 2 尺寸的晶体上在 100–300 K 的温度范围内测量了大约 1 W m -1 K -1 的热导率。发现这与 Pisoni 等人 2014 J. Phys 报道的基于 I +3 阴离子的杂化钙钛矿相当。化学 莱特。5 2488。室温电阻率和介电常数分别为 10 9 和 10 2 级，在接近 150 K 时显示急剧转变，这强烈支持一级结构转变。280 K 以上的热激活电阻率行为遵循 1/ T 依赖性，产生 0.2 eV 的激活能。从共振超声光谱测量分析接近相变时弹性模量的软化。发现共振频率的平方在低于 236 K 时发散，这会抑制在低温下对弹性模量进行任何进一步的实验确定。280 K 以上的热激活电阻率行为遵循 1/ T 依赖性，产生 0.2 eV 的激活能。从共振超声光谱测量分析接近相变时弹性模量的软化。发现共振频率的平方在低于 236 K 时发散，这会抑制在低温下对弹性模量进行任何进一步的实验确定。280 K 以上的热激活电阻率行为遵循 1/ T 依赖性，产生 0.2 eV 的激活能。从共振超声光谱测量分析接近相变时弹性模量的软化。发现共振频率的平方在低于 236 K 时发散，这会抑制在低温下对弹性模量进行任何进一步的实验确定。