Figure 4

mass specrtometer (mass 18) in N2 50ml/min
TGA and differential scanning calorimeter DSC analyses in N2 (50 ml min-1) were conducted using a Netzsch STA 449 coupled to a mass spectrometer QMS 403 Netzsch. 

Dilatometer
The linear thermal expansion of pelletized materials was performed using dilatometer Netzsch DIL402C according to ASTM E228-17 with alumina as the reference material in dry air 50 ml min-1 in range 25-1,000oC, 5oC min-1. 

TGA in air
Temperature-dependent mass change profiles (TGA) in dry air (50 ml min -1) were performed using Netzsch 209F1 carried out between room temperature and 1,000oC, 5oC min-1. 
Samples (10-20 mg) of sintered perovskites were examined by the temperature-programmed oxidation (TPO) method.


Samples of BaFe0.6Co0.3Nb0.1O3-x (BFCN) and BaCo0.7Yb0.2Bi0.1O3-x (BCYB) were prepared via the conventional solid-state reaction method. 
Analytical-grade powders BaCO3, Fe2O3, Co3O4, Nb2O5, Yb2O3 and Bi2O3, (commercially available) were initially mixed with a mortar and pestle; 
according to the molar ratios of Ba:Fe:Co:Nb = 1:0.6:0.3:0.1 and Ba:Co:Yb:Bi = 1:0.7:0.2:0.1. 
The obtained mixtures were heated first at 950 then at 1,050oC (BFCN) and 1,100oC (BCYB) for 12 h.

grounded with a mortar and pestle before TGA

for dilatometer
To prepare cylindrical pellets (8 mm diameter), samples of the synthesized powders (0.5 g) were cold-isostatically pressed at 10k psi. All pellets were sintered in air at 1,100oC, for 4 h at a heating rate of 5oC min-1. 
The density of the sintered pellets was about 96% as determined by pycnometer.