A high-temperature and high-field nuclear magnetic resonance instrument.

In the course of constructing an apparatus suitable for studies of nuclear magnetic resonance at high temperatures and high fields we developed a furnace with a new heating element which has been applied for the first time to NMR studies. The furnace can work in a 8-T field of a superconducting magnet system at temperatures up to 2200 K. Because of its geometrical form the heating element does not cause any measurable disturbing magnetic fields resulting from the heating current, and has many advantages compared to conventional heating elements. The temperature at which, up to this moment, we could observe NMR in external fields of 8 T amounts to 1200 K. The specifically adapted NMR probe works at radio frequencies up to 50 MHz. With this apparatus we carried out measurements of the magnitude, sign, and temperature dependence of the Knight shift of Mo in molybdenum metal.