Growth features of RENi2B2C (RE=Y, Ho, Tb) single crystals

Effect of B and C concentration on crystallization and properties of HoNi2B2C

“…In previous works [12,15,16] it was confirmed that the HoNi 2 B 2 C phase forms via the peritectic reaction with HoB 2 C 2 phase as a primary phase. The following phases besides of HoNi 2 B 2 C were detected in as-cast samples: HoB 2 C 2 , HoNiBC, HoNi 4 B, Ho 2 Ni 3 B 6 HoNi 3 B 2 , Ni 2 B, and Ni 3 B.…”

“…Such composition variation can be caused unintended mass losses during synthesis of polycrystalline materials, which can amount 0.2-2 wt.% depending on the method of preparation applied. During the FZ crystal growth process additional losses of B and C can arise in the melt from reactions with the oxygen traces, but also segregation effects may occur causing chemical inhomogeneity along the crystal or even the more dramatic effect of constitutional supercooling and secondary phase precipitation [15,16]. According to our experience the principle effects observed, are caused by composition fluctuations of the light elements boron and carbon.…”

“…Phase diagram studies, which comprise both crystallization features of the RE-Ni-B-C alloy systems and the constitution of the RENi 2 B 2 C compounds, are necessary requirements for the successful bulk single crystal growth of a great number of RENi 2 B 2 C compounds (RE = Y, Tb, Dy, Ho, Er, and Tm) as well as related solid solution compounds by a floating zone (FZ) technique with optical heating [15][16][17][18]. The high chemical and physical perfection of crystals of 6 mm in diameter and 20-50 mm length as was confirmed by metallographic, SEM and neutron diffraction studies.…”

“…But the properties can also fluctuate along and across the growth axis of one particular crystal. For the first time single crystalline HoNi 2 B 2 C specimens with re-entrant superconductivity were prepared by the FZ method [15,16]. For preparation of HoNi 2 B 2 C single crystals with desired properties, small composition variations of ∼0.2 at.% of the polycrystalline feed rod can play a crucial role.…”

Rare-earth metal transition metal borocarbide and nitridoborate superconductors

“…Single crystals of RNi 2 [B 2 C] with R ¼ Pr, Tb, Dy, and Ho few mm in size were grown by a cold crucible method using RF-heating [51]. Larger crystals of high quality (low widths of superconducting transition temperature and magnetic ordering temperatures, if applicable) with R ¼ Y, Pr, Tb, Ho and M ¼ Ni were grown by RF-zone melting from polycrystalline materials [38][39][40][52][53][54][55]. This technique was also suitable for crystals of solid solution phases with two different rare-earth metals [56].…”