A thermometer for soil temperature measurement application using sol-gel derived nanoceramic NiMn2O4 powder is constructed and tested in the field. The nanoceramic NiMn2O4 powder has been synthesized using solution route and characterized using FESEM/EDS and XRD. FESEM result confirms its uniform morphology and the formation of the nanopowder. EDS confirms that the powder consists of Ni, Mn, and O2. Based on the XRD analysis with the help of the Scherrer equation, the average crystallite size becomes 34nm. The powder is then compressed in electrically insulator but thermally conductor tube to make the thermometer. Two pieces of folded and rolled Aluminum foils as electrical contacts followed by lead wires were connected to the two opposite terminals of the tube. The thermometer is calibrated using homemade LM35 IC temperature sensor integrated with Atmega328 microcontroller and FTO film coated based glass electric heater. The thermometer can measure a soil temperature up to 42°C in two or three digit precision.
