Fast bolometric response of bulk La0.7Sr0.3MnO3 electroceramic structures

We report on the performance of a microwave electroceramic bolometer of hyb rid La0.7Sr0.3MnO3/Al2O3 (0.2 x 2 x 4 mm(3)) structure. The estimated therm al resistance of the bulk ceramic manganite film-single crystal sapphire in terface is about 500 K/W at room temperature. This resistance is the main t hermal barrier in the heat sink system and has been found to be slightly de pendent on temperature, When compared with the high-ire superconducting bol ometers, the La0.7Sr0.3MnO3 microwave electroceramic bolometer works in a m ore wide temperature range, from 77 K to 330 K, excluding the narrow temper ature interval at the metal-insulator phase transition (T = 230 K). The mic rowave electroceramic bolometer sensitivity and the time constant at room t emperature have been found to be 0.1 V/W and 100 ms, respectively. To impro ve the bolometer performance the point contact has been fabricated by a bre ak junction technique. The optimization of a microwave electroceramic bolom eter design brought to a considerable improvement of basic bolometer charac teristics. The microwave sensitivity was about 0.3 V/W and the time constan t was less than 100 ns.