en گروه پلیمر Polymers Technical Note Technical Note <div style="text-align: justify;"><span style="font-size:11.0pt"><span style="line-height:107%"><span new="" roman="" style="font-family:" times="">Repeated heat treatment on manganese-bismuth (MnBi) in a tube furnace increases the homogeneity of rare-earth-free magnets. Ferromagnetic low temperature phase (LTP) MnBi is formed after heating Mn and Bi in a ratio of 2:1 at 1000 </span></span></span><span style="font-size:11.0pt"><span style="line-height:107%"><span style="font-family:Symbol">&deg;</span></span></span><span style="font-size:11.0pt"><span style="line-height:107%"><span new="" roman="" style="font-family:" times="">C for 1 h and then 400 </span></span></span><span style="font-size:11.0pt"><span style="line-height:107%"><span style="font-family:Symbol">&deg;</span></span></span><span style="font-size:11.0pt"><span style="line-height:107%"><span new="" roman="" style="font-family:" times="">C for 1 h. Areas with comparable compositions of Mn and Bi are detected, but some Mn and Bi remains segregate after using this stepped heating 3 times. The subsequent annealing at 340 </span></span></span><span style="font-size:11.0pt"><span style="line-height:107%"><span style="font-family:Symbol">&deg;</span></span></span><span style="font-size:11.0pt"><span style="line-height:107%"><span new="" roman="" style="font-family:" times="">C gives rise to higher magnetizations and coercivity than those using 410 </span></span></span><span style="font-size:11.0pt"><span style="line-height:107%"><span style="font-family:Symbol">&deg;</span></span></span><span style="font-size:11.0pt"><span style="line-height:107%"><span new="" roman="" style="font-family:" times="">C annealing. Increasing the starting Mn:Bi ratio to 4:1 reduces the coercivity and remanent magnetization due to the increase in Mn oxidation at the expense of ferromagnetic phase.</span></span></span></div> MnBi,Rare-earth-free magnet,Coercivity,Remanent magnetization,Tube furnace 1 6 http://ijmse.iust.ac.ir/browse.php?a_code=A-10-4351-1&slc_lang=en&sid=1 Chitnarong Sirisathitkul schitnar@mail.wu.ac.th 1800319475328460018406 1800319475328460018406 Yes Division of Physics, School of Science, Walailak University Patchara Sukonrat patchara.su@hotmail.com 1800319475328460018407 1800319475328460018407 No Office of Scientific Instrument and Testing, Prince of Songkla University Pongsakorn Jantaratana fscipsj@ku.ac.th 1800319475328460018408 1800319475328460018408 No Department of Physics, Kasetsart University Thanida Charoensuk cthanida@mail.wu.ac.th 1800319475328460018409 1800319475328460018409 No Walailak University