On the efficiency of 𝑀𝑔/𝑁𝑏 diboride solid solution in enhancing the thermal stability of 𝑀𝑔𝐵2 superconductor

A comparative analysis of the thermal stability of 𝑀𝑔/𝑁 𝑏 diboride solid solution and pure 𝑀𝑔𝐵 2 was carried out. The specific heat capacity of these materials below the critical temperature of 𝑀𝑔𝐵 2 , which is an essential characteristic for assessing their thermal stability, was evaluated. Based on the 𝑎𝑏 𝑖𝑛𝑖𝑡𝑖𝑜 calculations of the phonon density of states for both compounds, it was demonstrated that 𝑀𝑔𝑁 𝑏𝐵 4 is characterized by a higher phonon density of states in the frequency range of 5–7.5 THz compared with 𝑀𝑔𝐵 2 . 𝑀𝑔𝑁 𝑏𝐵 4 was also found to exhibit a higher heat absorbing capacity at low temperatures. The specific heat capacity of 𝑀𝑔𝑁 𝑏𝐵 4 at low temperatures exceeds that of 𝑀𝑔𝐵 2 by 50 %, thus indicating its better thermal stability. The potential of 𝑀𝑔𝑁 𝑏𝐵 4 solid solution for practical application in superconducting wires made of 𝑀𝑔𝐵 2 was outlined.