You will be shown an abstract from a materials science research paper. Your task is to extract all synthesis operations described in the abstract into a structured JSON format. Your output should be a JSON array. Each entry in the array should be a JSON object describing a single synthesis operation. This object should have the following fields:

- "trigger": A verbal predicate indicating a synthesis operation. This should be a string extracted directly from the abstract.
- "arguments": An array of arguments specifying aspects of the synthesis operation. Each entry in the array should be a length-2 array formatted as [<argument_text>, <argument_type>]. The `argument_text` should be a string extracted directly from the abstract. The `argument_type` should be one of the following types: ["Recipe_Precursor", "Atmospheric_Material", "Participant_Material", "Recipe_Target", "Solvent_Material"].

For instance, suppose an excerpt from the abstract reads:

Tetraethoxysilane (TEOS, 98%) and cetyltrimethylammonium bromide (CTAB, 98%) were purchased from Fluka. The MTTZ-siloxy derivative (triethoxysilyl-propyl-5-mercapto-1-methyl-tetrazole) was synthesized as previously described [38].

This excerpt includes two operations, which could be annotated as follows.

[{"arguments": [["Tetraethoxysilane", "Recipe_Precursor"], ["cetyltrimethylammonium bromide", "Recipe_Precursor"]], "trigger": "purchased"}, {"arguments": [["MTTZ-siloxy derivative", "Recipe_Target"]], "trigger": "synthesized"}]

In your response, please include the JSON and no other text.

Abstract:
10.1038/srep02426
Highly efficient and robust cathode materials for low-temperature solid oxide fuel cells: PrBa0.5Sr0.5Co2-xFe x O5+δ
Cathode materials LnBa0.5Sr0.5Co2-xFexO5+δ (LnBSCF) (Ln = Pr and Nd; x = 0, 0.25, 0.5, 0.75, and 1.0) were synthesized using a glycine-nitrate process (GNP). Stoichiometric amounts of Ln(NO3)3*6H2O(Aldrich, 99.9%, metal basis), Ba(NO3)2 (Aldrich, 99+%), Sr(NO3)2 (Aldrich, 99+%), Co(NO3)2*6H2O (Aldrich, 98+%), and Fe(NO3)3*6H2O (Aldrich, 98%) were dissolved in distilled water with proper amount of glycine. The solutions were heated up to 350degC in air and followed by combustion to form fine powders, which were calcined at 600degC for 4 hours. The resulting powders were then grinded and calcined again at 900degC for 4 hours. For the measurement of electrical conductivity and coulometric titration, the powders were pressed into pellets at 5 MPa and sintered in air at 1100 ~ 1150degC for 12 hours (to achieve relative density > 97%). For transmission electron microscopy (TEM), the PrBa0.5Sr0.5Co1.5Fe0.5O5+δ (PBSCF05) sample was annealed at 700degC for 600 hours. The Ce0.9Gd0.1O2-δ (GDC) powders for electrolyte and NiO-GDC powders for anode were also synthesized using the GNP method. For preparation of cathode slurries, pre-calcined cathode and GDC powders (at a weight ratio of 60:40) were mixed using ball milling, together with an organic binder (Heraeus V006).
[{"arguments": [["LnBa0.5Sr0.5Co2-xFexO5+\u03b4", "Recipe_Target"]], "trigger": "synthesized"}, {"arguments": [["Fe(NO3)3*6H2O", "Recipe_Precursor"], ["Sr(NO3)2", "Recipe_Precursor"], ["Co(NO3)2*6H2O", "Recipe_Precursor"], ["Ln(NO3)3*6H2O", "Recipe_Precursor"], ["Ba(NO3)2", "Recipe_Precursor"], ["water", "Solvent_Material"], ["glycine", "Participant_Material"]], "trigger": "dissolved"}, {"arguments": [["solutions", "Participant_Material"], ["air", "Atmospheric_Material"]], "trigger": "heated"}, {"arguments": [["fine powders", "Participant_Material"]], "trigger": "combustion"}, {"arguments": [["resulting powders", "Participant_Material"]], "trigger": "grinded"}]