The crystals are grown using a Crystal System Corp. optical furnace (FZ-T-4000-H) equipped with four parabolic mirrors and 300 W lamps. CLBLCO powder is first prepared using solid state reaction from stoichiometric proportions of La2O3 (99.99 %), CaCO3 (99.9 %), BaCO3 (99.9 %), and CuO(99 %). The starting materials are mixed, calcined, and ground repeatedly at 900, 925, 950, 950 °C for 24 hours, then tested for impurities using XRD. The CLBLCO powder is then packed into rubber tubes and hydrostatically pressed at 400 MPa, producing 15–20 cm×∅ 7 mm cylindrical rods. The density of the rods reaches more than 90 % after sintering them at 1040 °C for 24 hours ensuring stable uninterrupted growth. The growth is carried out at a rate of 0.35 mm/h in argon atmosphere with 0.05–0.1 % oxygen, with both feed and seed rotating in opposite directions at 15 rpm. The growth lasts up to 10 days resulting in 50–100 mm long crystals. The grown crystals are annealed in argon at 850 °C for 120 hours to relieve thermal stress, and, when needed, to remove excess oxygen for magnetic measurement (μSR and elastic neutron scattering). It is important to mention that we do not find any traces of copper on the furnace quartz tube as usually happens with LSCO growth. Therefore, we do not add any excess copper to the initial powder.
We also perform Inductively-coupled plasma atomic-emission spectroscopy (ICP-AES)  measurements on the crystals and the starting powders. For ICP, we prepare 10 test tubes with the 100 mg of crystal dissolved in “Trace Select” grade Nitric Acid, as well as 5 test tubes of the starting powder. ICP allows us to measure the molar ratio of Ca, Ba, and La to Cu in the mixture. Knowing that we have 3 Cu atoms per unit cell, we found Ca=0.102±0.005, Ba=1.565±0.05, and La=1.319±0.02 atoms per unit cell in the powder case. The nominal values should be Ca=0.1, Ba=1.65, and La=1.25. This sets the sensitivity of the ICP technique. For the crystal, we find that Ca=0.102±0.005, Ba=1.57±0.02, and La=1.295±0.006 atoms per unit cell. Therefore, there is no difference in the Ca, Ba, or La content, between the crystals and powders within the accuracy of the measurement.