Fast Bolometric Response of Bulk La0.7Sr0.3MnO3Electroceramic Structures

We report on the performance of a microwave electroceramic bolometer of hybrid Laο.7Srο.3ΜnΟ3/Αl2O3(0.2 χ 2 χ 4 mm3) structnre.The estimated thermal resistance of the bulk ceramic manganite film-single crystal sapphire interface is about 500 K/W at room temperature.This resistance is the main thermal barrier in the heat sink system and has been found to be slightly dependent on temperature.When compared with the high -Τ superconducting bolometers, the Laο7Srο3ΜnΟ3 microwave electroceramic bolometer works in a more wide temperature range, from 77 Κ to 330 K, excluding the narrow temperature interval at the metal-insulator phase transition (T = 230 K).The microwave electroceramic bolometer sensitivity and the time constant at room temperature have been found to be 0.1 V/W and 100 ms, respectively.To improve the bolometer performance the point contact has been fabricated by a break junction technique.The optimization of a microwave electroceramic bolometer design brought to a considerable improvement of basic bolometer characteristics.The microWave sensitivity was about 0.3 V/W and the time constant was less than 100 ns.