An MgB.sub.2-based superconducting wire for a liquid hydrogen fluid level sensor which can maintain an unimmersed portion of the MgB.sub.2-based superconducting wire for a liquid hydrogen fluid level sensor in a non-superconducting state even without heating the unimmersed portion is provided. A wire for a liquid hydrogen fluid level sensor comprises an MgB.sub.2-based superconductor which contains Mg, B, and Al. The critical temperature at which the electrical resistance becomes essentially zero is 20-25 K, and the transition width, which is the difference between the temperature at which the electrical resistance begins to decrease toward zero and the critical temperature, is at most 5 K.

An MgB.sub.2-based superconducting wire for a liquid hydrogen fluid level sensor which can maintain an unimmersed portion of the MgB.sub.2-based superconducting wire for a liquid hydrogen fluid level sensor in a non-superconducting state even without heating the unimmersed portion is provided. A wire for a liquid hydrogen fluid level sensor comprises an MgB.sub.2-based superconductor which contains Mg, B, and Al. The critical temperature at which the electrical resistance becomes essentially zero is 20-25 K, and the transition width, which is the difference between the temperature at which the electrical resistance begins to decrease toward zero and the critical temperature, is at most 5 K.

Provided herein are the metalloborane compounds, MOF-metalloborane compositions, and hydrogen storage system used for high density hydrogen storage. The compounds and compositions may have the structure M.sub.2B.sub.6H.sub.6 or MOF-M.sub.2B.sub.6H.sub.6-dicarboxylic acid. Particularly the transition metal M may be titanium or scandium and the MOF may be MOF5. The hydrogen storage systems hydrogen absorbed to the metalloborane compounds or to the MOF-metalloborane compositions. Methods of storing hydrogen are provided comprising flowing or passing hydrogen gas for absorptive contact with the metalloborane compounds or to the MOF-metalloborane compositions. Also provided is a method for calculating the hydrogen storage capacity of a metalloborane is provided in which random sampling of the thermodynamic states of a two-system model of hydrogen in the presence of a metal organic framework-metalloborane crystal structure is used to calculate probability of hydrogen absorption.

Provided herein are the metalloborane compounds, MOF-metalloborane compositions, and hydrogen storage system used for high density hydrogen storage. The compounds and compositions may have the structure M.sub.2B.sub.6H.sub.6 or MOF-M.sub.2B.sub.6H.sub.6-dicarboxylic acid. Particularly the transition metal M may be titanium or scandium and the MOF may be MOF5. The hydrogen storage systems hydrogen absorbed to the metalloborane compounds or to the MOF-metalloborane compositions. Methods of storing hydrogen are provided comprising flowing or passing hydrogen gas for absorptive contact with the metalloborane compounds or to the MOF-metalloborane compositions. Also provided is a method for calculating the hydrogen storage capacity of a metalloborane is provided in which random sampling of the thermodynamic states of a two-system model of hydrogen in the presence of a metal organic framework-metalloborane crystal structure is used to calculate probability of hydrogen absorption.

A method of preparing a MnB-based magnetic material, the method including the steps of preparing a mixture including manganese oxide and boron, and heat-treating the mixture under an inert atmosphere, a MnB-based magnetic material prepared thereby, and a material absorbing or shielding electromagnetic waves, or a semiconductor, electronic, communication, or display device including the MnB-based magnetic material, are provided.

A method of preparing a MnB-based magnetic material, the method including the steps of preparing a mixture including manganese oxide and boron, and heat-treating the mixture under an inert atmosphere, a MnB-based magnetic material prepared thereby, and a material absorbing or shielding electromagnetic waves, or a semiconductor, electronic, communication, or display device including the MnB-based magnetic material, are provided.

A rapid preparation method of transition metal borides includes steps of: using a tungsten rod as the cathode, and a block mixture of boron powder and metal oxide as the anode, the block mixture and the tungsten rod are placed in an plasma device; the plasma device is evacuated, and then filled with a buffer gas and an electric arc is started to obtain a transition metal boride. The present disclosure adopts the direct current arc plasma method with the advantages of simple operation, low cost, environmental friendliness and controllable reaction atmosphere to prepare the transition metal boride, the preparation process is simple, the preparation process is fast, and the environment will not be affected.

A rapid preparation method of transition metal borides includes steps of: using a tungsten rod as the cathode, and a block mixture of boron powder and metal oxide as the anode, the block mixture and the tungsten rod are placed in an plasma device; the plasma device is evacuated, and then filled with a buffer gas and an electric arc is started to obtain a transition metal boride. The present disclosure adopts the direct current arc plasma method with the advantages of simple operation, low cost, environmental friendliness and controllable reaction atmosphere to prepare the transition metal boride, the preparation process is simple, the preparation process is fast, and the environment will not be affected.

A rapid preparation method of transition metal borides includes steps of: using a tungsten rod as the cathode, and a block mixture of boron powder and metal oxide as the anode, the block mixture and the tungsten rod are placed in an plasma device; the plasma device is evacuated, and then filled with a buffer gas and an electric arc is started to obtain a transition metal boride. The present disclosure adopts the direct current arc plasma method with the advantages of simple operation, low cost, environmental friendliness and controllable reaction atmosphere to prepare the transition metal boride, the preparation process is simple, the preparation process is fast, and the environment will not be affected.

A rapid preparation method of transition metal borides includes steps of: using a tungsten rod as the cathode, and a block mixture of boron powder and metal oxide as the anode, the block mixture and the tungsten rod are placed in an plasma device; the plasma device is evacuated, and then filled with a buffer gas and an electric arc is started to obtain a transition metal boride. The present disclosure adopts the direct current arc plasma method with the advantages of simple operation, low cost, environmental friendliness and controllable reaction atmosphere to prepare the transition metal boride, the preparation process is simple, the preparation process is fast, and the environment will not be affected.